Chapt. 13 Hormones & Sex

Define the difference between biological sex, gender identity, sexual behaviour and sexual orientation

1. Biological sex: anatomical, physiological & genetic characteristics of being male/female/intersexed.
2. Gender identity: A person's private, subjective sense of their gender
3. Sexual behaviour: A person's sexual acts
4. Sexual orientation: a person's

In what 2 fundamental ways do hormones influence sex?

1. DEVELOPMENTAL/ORGANIZATIONAL : By influencing the development from conception to sexual maturity of the anatomical, physiological and behavioural characteristics that distinguish one as female or male
- considered more permanent e.g. exposing developin

Give an example of why the differentiation between developmental and activational changes in sex hormones is not as clear as once assumed?

The brain continues to develop into late teens, adolescent hormone surges can have both developmental and activational effects

What are endocrine glands?

Organs whose primary function appears to be the release of hormones

Name some other organs (not referred to as endocrine glands) that are part of endocrine system

Stomach, liver, intestine & body fat -release hormones into general circulation

Name the 10 endocrine glands

Pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovaries, testies Mnemonic: "People Had Purpose To Promote Tomatoes And Pickles On Top" (of their hamburgers)

What are the 2 types of glands and how are they different?

Exocrine glands (e.g. sweat glands) release chemicals into ducts which carry them to their targets
Endocrine glands (ductless glands) release hormones directly into the circulatory system. Once released hormone travels via circulatory system until it reac

What are gonads? What is their function?

Male : testes - produce sperm cells
female: ovaries - produce ova
Sperm & Ova = gamete cells

What is a zygote?

a single cell created by the gamete cells (sperm and ova)
Contain all info necessary for normal growth of adult organism in it's natural environment

How many chromosomes are in body cells (except gamete cells)?
How many chromosomes are in gamete cells?

23 pairs in body cells
Ova and sperm cells contain 23 single chromosomes (1 of each pair)

What are sex chromosomes? Describe both male and female sex chromosomes

Chromosomes that contain genetic programs that direct sexual development.
Females = 2 X chromosomes (large)
Males = 1 X (large) and 1 Y (small) chromosome
Ovum = 2 X chromosome
Sperm cells = 50% have X chromosome, 50% have Y chromosome

Why are sex chromosomes called X and Y chromosomes?

They are all X shaped but Y chromosome is much smaller and originally was mistakenly thought to be Y shaped.

How many proteins do Y-chromosomes and X chromosome genes encode?

Y-chromosome = 27
X chromosome =approx. 1500

What are the 3 Classes of Hormones?

1. steroids - long chains of amino acids synthesized from cholesterol => small and fat-soluble
2. peptides (short chains) and proteins (long chains) of amino acids (e.g. growth hormone)
3. amino acid derivatives - simply synthesized from an amino acid mol

What do steroid hormones do?

All hormones that influence sexual development and activation of sexual behaviour are steroid hormones. Because they are small and fat-soluble they readily penetrate cell membranes and often affect cells in a 2nd way.
Most other hormones produce effects b

How do steroid hormones affect cells in a 2nd way? How does this differ from amino acid derivative hormones and peptide hormones?

Once inside cell, they can bind to receptors in the cytoplasm or nucleus and directly influence gene expression.
amino acid derivative hormones and peptide hormones affect gene expression less commonly and by less direct mechanisms

What are the 2 main classes of sex/gonadal (steroid) hormones and which hormones are the most common in each?

Gonads of both sexes release the same 3 hormones:
1. Androgens (e.g. testosterone) - released mostly by testes.
2. Estrogens (e.g. estriadiol) - released mostly by ovaries
- But estrogens are not female hormones and androgens male hormones e.g. testostero

What is the 3rd class of steroid hormones? What is the most common hormone in this class? What is its purpose?

Progestins (e.g. progesterone) - helps women prepare uterus and breasts for pregnancy - unknown function in men

How is the adrenal cortex involved in sex hormones?

Also releases small amounts of all 3 sex hormones
-therefore gonads are not the only endocrine glads that produce sex hormones - if you castrate an adult male, they still have all 3 hormones.
Adrenal cortex (outside layer of adrenal glands) regulates gluc

What is the Master gland and why is it called that?

Pituitary gland - because most of its hormones are tropic hormones

What are tropic hormones? Give an example

Tropic hormones primary function is to influence the release of hormones from other glands (tropic = able to stimulate or change something). They are all peptides.
Gonadotropin = pituitary tropic hormone that travels thru circulatory system to gonads wher

Describe the pituitary gland

2 glands = posterior pituitary and anterior pituitary - which fuse during embryological development.

How does posterior pituitary develop

Develops from small outgrowth of hypothalamic tissue that eventually dangles from the hypothalamus on the end of the pituitary stalk

How does the anterior pituitary develop?

Begins as part of the same embryonic tissue that eventually develops into the roof of the mouth - during course of development it pinches off and migrates upward to assume its position next to the posterior pituitary.
It is the anterior pituitary that is

What is the major difference in endocrine function of women and men?

In women - levels of gonadal and gonadotropic hormones go thru cycle that repeats every 28 days approx.
In men - levels of gonadal and gonadotropic hormones change little from day to day.

What experimental evidence showed that cycling levels of hormones did not come from the anterior pituitary gland itself?

Transplant studies (Harris, 1950) female rat (cycling) pituitary transplanted to male rat -> became a steady-state pituitary, and a male steady state pituitary gland transplanted into a female rat became cycling. Therefore patterns of hormone release come

How did visual input & seasonal variations of light-dark cycle play into the puzzle of what controlled the pituitary?

Seasonal variations in light-dark cycle triggered many breeding-related changes in hormone release in birds & animals that breed only during specific times of the year. If lighting conditions were reversed (e.g. transporting animals across the equator), t

From where does the anterior pituitary receive neural input ?

It doesn't. It receives no neural input whatsoever from hypothalamus or any other neural structure

What mechanism is used by the hypothalamus to control the posterior pituitary?

Posterior pituitary: Paraventricular nuclei & supraoptic nuclei synthesize the 2 major hormones of the post. pituitary: Vasopression and oxytocin
- are transported along axons of these neurons to terminals in posterior pituitary and stored there until arr

What does oxytocin and vasopressin do?

Oxytocin stimulates contractions of uterus during labour and ejection of milk during suckling
Vasopressin (antdiuretic hormone) facilities reabsorption of water by kidneys

What are neurons that release hormones into general circulation called?

neurosecretory cells

What mechanism is used by the hypothalamus to control the anterior pituitary?

More difficult to explain due to it being neuron free.
Harris theory: release of hormones was itself regulated by hormones released from hypothalamus.
2 findings support this:
1. Hypothalamopituitary portal system = vascular network (portal veins) - carri

What is the Hypothalamopituitary portal system?

Network of hypothalamic capillaries feeds a bundle of portal veins (veins that connect one capillary network w/ another) that carries blood down the pituitary stalk into another network of capillaries in the anterior pituitary

What are a) hypothalamic releasing and b) hypothalamic release-inhibiting hormones?

a) Hypothalamic hormones that stimulate the release of an anterior pituitary hormone.
b) Hypothalamic hormones that inhibit the release of an anterior pituitary hormone
Both control the release of hormones from anterior pituitary
and are all peptides.

What is thyrotropin-releasing hormone?

Thyrotropin-releasing hormone triggers release of thyrotropin from anterior pituitary which stimulates the release of hormones from the thyroid gland

What is Gonadotropin-releasing hormone

Hormone that stimulates the release of both the anterior pituitary's gonadotropins: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Where do the 3 different signals that regulate hormone release come from?

1. Signals from nervous system (neural signals): all endocrine glands except anterior pituitary
2. Signals from hormones
3. Signals from nonhormonal chemicals in the blood.

Describe the Modal of Gonadal Endocrine Release (hypothalamic-pituitary-gonadal-axis)

Brain
Hypothalamus (releases gonadotropin-releasing hormones)
Hypothalamic portal system
Anterior Pituitary (releases gonadotropin)
General circulation
Gonads (releases estrogens, androgens, progestins)
Body Tissues
- Behaviour is influenced by gonadal ho

What are the 3 kinds of signals that regulate hormone release?

1. Signals from nonhormonal chemicals (e.g. glucose -> insulin)
2. Signals from other hormones (pulsate release & feedback)
3. Signals from the nervous system (experience)

How do nonhormonal chemicals affect hormone release?

Glucose, calcium, & sodium levels in blood influence release of particular hormones (e.g. blood glucose <=> insulin)

What is Pulsatile hormone release?

Hormones tend to be discharged several times per day in large surges, typically lasting a few minutes - which affects hormone levels in the blood. Result in minute-to-minute fluctuations in circulating hormone levels.

How does hormonal feedback work?

Circulating hormones often provide feedback to the structures that are involved in their release (pituitary hypothalamus and other brain sites).
Their function is to maintain stable blood levels of hormones.

Explain the effects of experience on neronal hormone release

Effects of experience on hormone release are usually mediated by signals from the nervous system. Hormone release can be regulated by experience. (E.g. species that breed only in spring release sex hormone triggered by increased sunlight)
Thus hormonal an

Describe the gonadal structures of the fetus at 6 weeks

Regardless of genetic sex, primordial gonads are seen.
Each has an outer covering (cortex) which has potential to develop into an ovary
Each has a centre (medulla) that has potentila to develop into a testis

How does the Y chromosome trigger changes to the primordial gonads at 6-weeks?

Sry gene on Y chromosome triggers synthesis of Sry protein. When S gene is expressed, it causes the medulla (core) of primordial gonads to grow and develop into testes. (In the absence of Sry protein the cortical cells of primordial gonads automatically d

What happens if Sry protein is injected into genetic female 6 wks post conception?

Result is a genetic female with testes

What happens if Sry protein is blocked in male fetus?

Result is genetic male with ovaries

Name and describe the 2 internal reproductive ducts (systems)

1. Wolffian system: Precurser to male reproductive ducts. (seminal vesicles and vas deferens) - occurs when testosterone is present
2. Mullerian system: Capacity to develop into female reproductive ducts (uterus, fallopian tubes) - occurs in absence of te

What happens in the 3rd month of male fetal development?

Testes secrete testosterone (stimulates development of Wolffian system) and Mullerian-inhibiting substance (causes Mullerian system to degenerate) and testes to descend into the scrotum.

What happens to genetic females who are injected with testosterone during appropriate female development?

When exposed to testosterone during that sensitive period (3 months), genetic females develop male and female reproductive ducts

What happens to female fetal development at this point?

Ovaries are almost completely inactive during fetal development. Development of Mullerian system occurs in a fetus that is not exposed to testicular hormones during critical fetal period.

Define ovariectomy, orchidectomy, and gonadectomy

Ovariectomy (oophorectomy): Removal of ovaries
Orchidectomy (orchiectomy): Removal of testes
Gonadectomy (castration): Surgical removal of gonads (ovaries or testes)

What happens in ovariectomized female fetuses, orchidectomized male fetuses?

All develop female reproductive ducts.

What are the 4 universal parts to the bipotential precursor of external reproductive organs?
When do they develop into male/female organs?
What do they grow into in males & females?

1. Glans (head of penis, clitoris)
2. Urethral folds (fuses in male, enlarges in female -> labia minoria)
3. Lateral bodies (form shaft of penis, or hood of clitoris)
4. Labioscrotal swellings (form scrotum, or labia majora in female)
- Develop 6 weeks po

What are secondary sex characteristics? When do they appear?

Features other than the reproductive organs that distinguish sexually mature men and women
Develop during puberty - transitional period
Fertility achieved, growth spurts and secondary sex characteristics appear

What happens in the anterior pituitary during puberty

Increased release of hormones:
Growth hormone = does not have a gland as primary target - acts directly on bone and muscle tissue - produces growth spurt.
Gonadotropic & adrenocorticotropic (adrenals) hormones = initiate maturation of genitals and develop

Guiding hormonal principal for normal pubertal sexual maturation

Males: androgen levels are higher than estrogen levels = masculinization (defeminization)
Females: estrogen levels are higher than androgen levels = feminization (demasculinization)

What happens to castrated individuals prior to puberty?

They do not become sexually mature without replacement hormone injections of androgens or estrogens

What does androstenedione do?

Hormone released by adrenal cortex. Responsible for pubic hair and axillary (underarm) hair growth in females. (even though it's seen as a "male hormone")
Sexual attraction shows up just before puberty - possibly the awakening of Adrenal gland. Believed a

Describe rat study (Pfeiffer, 1936) gonadotropin release (earliest)

Neonatal rats (males & females) - some gonadectomized some intact, some received gonad transplants (ovaries or testes) some did not.
Findings:
a) Gonadectomizing rats of either genetic sex caused them to develop into adults w/ female cyclic patterns of go

What is now evident from Pfeiffer's experiments

Evidence of the role of perinatal (at time of birth) androgens overriding preprogrammed cyclic female pattern of gonadotropin release from the hypothalamus thus initiating the development of the steady male pattern.
(Pfeiffer incorrectly concluded the pre

What is the aromatization?

i) Gonadal and adrenal sex hormones are steroid hormones - derived from cholesterol thus are readily converted from one to the other.
ii) Slight changes occur under influence of enzymes (proteins that influence biochemical reactions w/o participating) e.g

Why does perinatal testosterone not directly masculinize the brain according to the aromatization hypothesis?

The brain is masculinized by estradiol ("feminizing hormone") that has been aromatized from perinatal testosterone.

What is the evidence for the masculinizing of the brain by estradiol as theorized in the aromatization hypothesis?

1. Findings demonstrate masculinizing effects on brain from early estradiol injections in mice & rats.
2. Masculinization of brain (in response to testosterone) does not occur when aromatization is blocked or when androgens cannot be aromatized.

How does the aromatization hypothesis explain the lack of masculinization in genetic females by mother's estriodol in fetal blood supply?

Alpha fetoprotein in blood during perinatal period deactivates circulating estradiol in fetal blood supply by binding to it.

What are the 2 reasons alpha fetoprotein does not deactivate circulating estradiol and block masculinization of genetic male?

a) Because testosterone is immune to alpha fetoprotein, and travels from testes to brain cells where it is converted to estradiol.
b) And alpha fetoprotein does not readily penetrate the blood brain barrier

List 5 findings influencing the modern perspective on the sexual differentiation of the mammalian brain

1. Sex differences in brain structure and function develop by different mechanisms (e.g. aromoatase found in only a few areas in rat brain e.g. hypothalamus, and thus only in these ares that aromatization is critical for masculinization in presence of tes

Describe the early experiments of perinatal hormones and behaviour development - Phoenix et al.: masculinization and defeminization effects of testosterone on genetic females.

Perinatal injections of testosterone masculinizes and defeminizes genetic female's adult copulatory behaviour
- Injected pregnant guinea pigs w/ testosterone
When litters were born female offspring were ovariectomized.
When ovariectomized females reached

Lordosis

Intromission-facilitating arched-back posture that signals female rodent receptivity

Describe the study on lack of early exposure of testosterone in male rats (Grady, Phoenix & Young)

1. Male rats castrated shortly after birth failed to display normal male copulatory pattern of mounting, intromission, ejaculation when treated with testosterone and given access to sexually receptive female.
2. When injected w/ estrogen and progesterone

What is the critical time period to obtain effects of perinatal testosterone on behavioural development?

Restricted to the first 11 days after birth

Role of hormones on proceptive behaviours

Not much known. Perinatal testosterone has been reported to:
1. Disrupt the proceptive hopping, darting and ear wiggling of receptive female rats,
2. Increase aggressiveness of female mice
3. Disrupt maternal behaviour of female rats
4. Increase rough soc

Defeminization and Masculinization are not the same thing - explain.

Male behaviour and female behaviours can co-exist in the same individual - they do not necessarily change in opposite directions in the individual receives physiological treatment (hormones or brain lesions)
Examples:
1. Male behaviours (e.g. mounting rec

What are the general findings in correlational human research of hormone effects on behavioural development

There is no convincing evidence that differences in prenatal androgen exposure contribute to behavioural differences observed among women or among men (although prenatal androgen exposure contributes to differences in interests, spatial ability, & aggress

Describe the case of Anne S. ("The Woman who Wasn't")

Diagnosis: Complete Androgenic Insensitivity Syndrome
External genitalia = normal
Internal genitalia = vagina - 4 cm long & underdeveloped uterus.
= genetic male but insensitive to androgens but had Sry protein so developed testes.
= Her testes released M

Androgenic Insensitivity Syndrome

Androgen receptors are totally non responsive - stems from a mutation to androgen receptor gene (see Anne S. case study) Rare 5 in 100,000 births
Partial androgenic insensitivity is more common. and individuals face many sexual ambiguities

The little Girl who grew into a Boy "Elaine" Case Study

Born with ambiguous external genitals raised by parents as a girl. At puberty she suddenly began to develop male secondary sex characteristics (& was distressed).
Surgical treatments (increase size of vagina and decrease size of clitoris) & hormonal treat

Adrenogenital syndrome

Caused by congenital adrenal hyperplasia - congenital deficiency in release of cortisol hormone from adrenal cortex, Results in compensatory adrenal hyperactivity and excessive release of adrenal androgens.
- Has little effect on development of genetic ma

Dr. John Money and the boy without a penis (David Reimer case study): Social Learning Model of Psycho Social Development

Ablatio penis - Twin boys - penis of one accidentally burned off during circumcision at 7 months old. John Money - Sex researcher & behaviourist - "Social Learning Model of Psycho Social Development"
Money claimed baby's sex was neutral for first 2 years.

Describe the case of Ms. C.

48 yr old married woman - felt she had the brain of a man
- Born with intersexed genitalia (neither male or female)
- At 6 months Doctors removed odd tissue, shaped labia e - she wasn't told
- At 12 - daily estrogen pills induced puberty, developed breast

Describe the Anon Paper in Nature Magazine: Beard Growth & testosterone.

Associated beard growth and testosterone levels.
- Wanted to know if beard growth could be associated with sexual activity
Remote island away from partner for long periods of time & his beard growth diminished. When he returned beard growth accelerated.
-

Describe the measurement of scrotums on Renaissance statues in Europe (Nature Magazine)

Normally there is an asmmetry in the scrotal sac of men. Right-handed men's right testis hangs higher (heavier), left handed men have left testis that hang higher (heavier).
- Wondered if artists knew this & whether they were basing judgments on physics (

What is a 45X, 46XY chromosome? How does it affect sexual development?

Possible that during development some of the cells in your body can diverge as they undergo mitosis, in some cases the chromosome does not get passed over to both daughter cells.
In this type of case you get a 45 X, 46 XY chromosome.
- A portion of the ce

Sexual Maturity & Effects of Gonadal Hormones
Study of the Orchidectomized Norwegians -Bremer

215 Norwegians, (102 of which were sex offenders, 16 sexual deviants, 24 psychopaths, 109 mentally disabled, 53 schizophrenics, 10 epileptics, 3 others). and had agreed to chemical castration to reduce length of prison terms.
Generalizations;
1. Orchidect

What is the history of castration for sexual deviancy?

Castration was started by psychiatry in late 1800s to treat hypersexuality.
- In Europe castration was brought in by various countries to treat sex offenders (mandatory in Nazi Germany)
- Eventually physical castration gave way to chemical castration
- In

List the 3 main problems with the Norwegian study

1. Is decrease in sexual interest an effect of hormones (decrease in testosterone) or experiential differneces (thinking one cannot have sex anymore w/o testicles)? (e.g.loss of confidence, perceiving themselves as less sexual?).
2. No control group at al

What were the 2 assumptions underlying chemical castration of sex offenders?

1. They have an excess of gonadal hormones (causing their offensive behaviour), but in many cases they have hypofunction of gonads (decrease in testosterone).
2. Major assumption that testosterone is causing the sexual behaviour. However, rape is not sexu

What were some of the somatic effects of the Castrated Men in the Norwegian study?
How did castration affect schizophrenic or epileptic symptoms?

18% of castrates had:
- excessive weight gain (10-50 kg)
- Appearance of accelerated aging
- Complaints of weakness
- Other deleterious effects on health
Castration had no effect on schizophrenic or epileptic symptoms

Following orchidectomy for prostate cancer, what were some of the side-effects experienced?

No sexual interest increased from 27.6% to 63.6% after surgery
Men who achieved no erections increased from 35% to 78.6%
Following physical or chemical castration you get a % of individuals who show a decrease in sexual interest and ability to maintain an

1st case of testosterone replacement therapy

19 yr old WWI veteran - castrated by a shell fragment. Body was soft, hips grew wider, shoulder narrower, had little drive. Testosterone injections into muscle tissue - by 5th injection erections were rapid & prolonged, gained 18 lbs in 12 wks.

2 erroneous assumptions arose from testosterone replacement therapy

1. level of man's sexuality is a function of amount of blood-borne testosterone - wrong; there is a minimum threshond of testosterone necessary to subserve erection ability and sexual interest/behaviour - above threshold levels change nothing.
2. Man's se

Describe the Grunt & Young guinea pig experiment that tested higher-than-necessary base-line levels of testosterone in healthy males following castration.

1st rated sexual behaviour of each male guinea pig
Then on basis of ratings, divided them into 3 experimental groups, low, medium & high
Following castration, sexual behaviour of all guinea pigs fell to negligible levels within a few weeks,
After initiati

What is the function of estrogen in maintaining male sexual function?

In the absence of testosterone estrogens may maintain some sexual function.
Estradiol may be sufficient for sexually stimulated erections, but my not maintain sexual interest and nocturnal erections
- It could be thats the aromatization of testosterone in

Dihydrotestosterone

nonaromatizable androgen restores copulatory behaviour of castrated male primates
Fails to restore copulatory behaviour of castrated male rodents.

Describe how we know that there are different mechanisms of copulatory behaviour by testosterone in primates & rodents

Restoration of copulatory behaviour by testosterone occurs by different mechanisms in rodents and primates
- Direct effect of testosterone in primates (non aromatized)
- Produced by estradiol aromatized from testosterone in rodents

How frequent are the cycles of gonadal release in sexually mature female rats & guinea pigs

4-day cycles

Describe the pattern of release of estrogens & progesterone in the developing follicle (ovarian structure) prior to ovulation

Gradual increase in secretion of estrogens in the 2 days before release
Sudden surge in progesterone as egg is released -> estrus

Estrus

Period of 12-18 hours during which female is fertile, receptive, proceptive and sexually attractive (smelling of chemicals that attract males)

Receptive females

likely to assume lordosis posture when mounted

Proceptive females

Likely to engage in behaviours that serve to attract the male

Estrus cycle

Cycle of sexual receptivity
There is evidence of a close relationship between a female's cycle of sexual receptivity and sexual behaviour in many species. It is under hormonal control.
- increase in sex in ovulatory phase
- decrease in sexual activity (bu

Proof of relationship between cycle of receptivity & sexual behaviour in females

Ovariectomies on female rats and guinea pigs produce a rapid decline of proceptive and receptive sexual behaviours
Estrus can be induced by injection of estradiol followed (1.5 days later) by an injection of progesterone

In what way do female primates (incl. humans) differ from rats, guinea pigs and other mammals in terms of hormonal control on behaviour ?

Female primates are the only female mammals motivated to copulate during periods of nonfertility
Also, ovariectomy has little effect on sexual motivation or behaviour

What are the consequences of ovariectomies in women

Decreased vaginal lubrication and sterility

Have any patterns emerged that characterize fluctuations in human female sexual motivation?

no

What is the paradoxical aspect of female sex drive?

There is evidence that sex drive of women is under control of androgens not estrogens - enough androgens (testosterone) are released from adrenal glands to maintain sexual motivation even after ovaries have been removed
Testosterone has the clearest relat

What are the 3 kinds of research findings that support the theory that androgens control human female sexuality - describe each.

1. Animal studies: Nonhuman female primates: replacement injections of testosterone, but not estradiol increased the proceptivity of ovariectomized and adrenalectomized rhesus monkeys
2. Correlational studies of healthy women: measures of sex increase in

Does testosterone skin patch work for women w/ libido problems?

No. Most women w/ low sex drive do not have low blood testosterone levels.

What are anabolic steroids?

Steroids (e.g. testosterone) that have anabolic (growth-promoting) effects.

Is testosterone effective as an anabolic drug?

No, it breaks down soon after injection and it has undesirable side effects
Synthesized anabolic steroids all have side effects - illegal

Do anabolic steroids have an effect on athletic performance?

Despite inconsistent experimental evidence, results achieved are convincing.

What are the physiological effects of anabolic steroids on men?

1. Testicular atrophy (wasting away of the testes) - Negative feedback from high levels of anabol. steroids reduces gonadotropin release & leads to reduction in testicular activity
2. Gynecomastia (breast growth in men - can occur probably as the results

what are the physiological effects of anabolic steroids on women?

1. Amenorrhea (cessation of menstruation)
2. Sterility
3. Hirsutism (excessive growth of body hair)
4. Clitoris growth
5. Baldness
6. Shrinking of the breasts
7. Deepening and coarsening of voice
- Appear to be irreversible

what are the additional physiological effects of anabolic steroids on both sexes?

Muscle spasms, muscle pains, blood in urine, acne, general swelling from retention of water, bleeding of tongue, nausea, vomiting , variety of psychotic behaviours (incl. fits of depression and anger)
- Oral anabolic steroids produce cancerous liver tumou

Animal studies on anabolic steroids

Male mice exposed to 4 anabolic steroids for 6 months (similar to level used by athletes).
By 20 months (6 moths after steroid exposure termination) 52% of steroid-exposed mice had died compared to 12% of control mice.

What are the behavioural effects of anabolic steroids?

No (or rare) increase in aggression, no increase in sexual motivation. potential disruptive effects on male copulatory behaviour in humans and rodents

How do injections of Estradiol have neuroprotective results?

Estradiol can reduce brain damage associated with stroke and various neurodegenerative disorders.
Estradiol administered to rats just before, during or just after induction of cerebral hypoxia reduced subsequent brain damage.

List 7 Neurotrophic effects of estradiol that could account for the reduction of damage in the brain after stroke.

1. Reduces inflammation
2. Encourages axonal regeneration
3. Promotes synaptogenesis
4. Increases adult neurogenesis
5. Injection of estradiol initially increased no. of new neurons in
dentate gyri of adult female rat hippocampi
7. Increases survival rate

Postive and negative effects of estradiol's neuroprotective properties

Accounts for
1. women's greater longevity
2. lower incidence neuropsychological disorders (e.g. Parkinson's)
3. Also may explain the decline in memory and other cognitive deficts experienced by postmenopausal women

Improving the effectiveness of estradiol therapy

a) Therapy is effective only if estradiol treatment is commenced at menopause or shortly thereafter.
b) Chronically high doses administered to postmenopausal women are unnatural and potentially toxic recomend estradiol levels should mimic natural cycle of

What brain areas are indicated in sexual practices and preferences but have not been scientifically studied?

The association cortex and other frontal areas that serve our highest processing levels

Why has research on neural mechanisms of sexual behaviour focused solely on hypothalamic circuits?

1. Because of difficulties studying mechanisms of complex human behaviours, researchers focus on simple controllable copulatory behaviours (e.g. ejaculation, mounting, lordosis)
2. Because hypothalamus controls gonadotropin release it's an obvious place t

What are the structural differences between male and female hypothalamus (ie. sexually dimorphic nucleus)?

Medial preoptic, preoptic, suprachiasmatic, and anterior regions in the hypothalamus all differ between sexes

How do nuclei in the medial preoptic area differ in males and female rats?

Nuclei in medial preoptic area (anterior hypothalamus) of rat hypothalamus is several times larger in males.(1970s, Roger Gorski). Found in monkeys
At birth sexually dimorphic nuclei of male and female rats are the same. In first few days after birth, mal

Describe how the Medial preoptic area affects male sexual behaviour:

Area of hypothalamus that plays a key role in male sexual behaviour
- includes sexually dimorphic nucleus
- evidence is mixed but favours hyopotheses that this area is involved in motivational aspects rather than that functional ability to copulate

Describe lesion studies of the medial preoptic area and its effects on male sexual behaviour and how it differs from effects on female sexual behaviour

Bilateral medial preoptic lesions appear to abolish male copulatory behaviour in both sexes.
a) Destruction of entire area abolishes sexual behaviour in males of all mammalian species studied
b) Does not eliminate female sexual behaviour of females, but d

Describe electrical stimulation and testosterone implant studies of medial preoptic area & male sexual behaviour

Electrical stimulation elicits copulatory behaviour in male rats
Copulatory behaviour can be reinstated in castrated male rats by medial implants of testosterone in preoptic area.

What is the connection between the preoptic area and dopamine?

Medial preoptic circuits that control male sexual behaviour seem to be dopaminergic.
Dopamine agonists microinjected facilitate male sexual behaviour and dopamine agonists block it.

Explain the medial preoptic area's connection w/ the lateral tegmental field & how it affects male sexual behaviour

Medial preoptic area appears to control sexual behaviour via at tract that projects to an area of the midbrain: lateral tegmental field.
Destruction of this tract disrupts sexual behaviour in male rats
Activity of individual neurons in lateral tegmental f

Explain the connection between the ventromedial nucleus (VMN) and Female sexual behaviour

Contains circuit that appear critical for female sexual behaviour
- Female rats w/ bilateral lesions of VMN do not display lordosis and are likely attack suitors who become too ardent

Describe the VMN's priming effect on estradiol

Progesterone by itself does not induce estrus.
- Estradiol primes the nervous system so that progesterone has an effect
- Mediated by large increases in the no. of progesterone receptors that occur in the VMN & surrounding area following an estradiol inje

Periaqueductal gray (PAG) and the VMN

Influence of VMN appears to be mediated by a tract that descends to the PAG of the tegmentum.
Destruction of this tract (or PAG lesions) eliminates female sexual behaviour

Male rate sexual behaviour is influenced by which tract?

medial preoptic area -> lateral tegmental field

Female rate sexual behaviour is influenced by which tract?

Ventromedial nucleus -> periaqueductal gray

Do heterosexuals & homosexuals differ in levels of circulating hormones?

No

Name 2 common misconceptions of sexual orientation

1. At trait needs to be genetic to be not freely chosen
2. Homosexual male = feminized; Homosexual female = masculinized
- at one point in time there was a mandate that you needed to provide genetic evidence to support any trait that was not deemed "norma

Animal studies: Effects of early hormone exposure on sex preference

Perinatal castration of males has increased their preference as adults for male sex partners
Prenatal testosterone exposure in females has increased their preference as adults for female sex partners

What was the classic underlying misconception with sexual orientation in early studies of animals?

Research on early hormones sexual orientation was seen as a function of animal behaviour. Based on stereotyped characteristics of the opposite sex (feminization/masculinization)
e.g. male mounts male, female mounts female, male mounts male

In relating findings to human populations, what is missing in these animal studies on effects of early hormone exposure on sex preference?

The cognitive and emotional components of human sexuality

What are the studies that are often held up as genetic evidence of homosexuality?

In a group of male homosexuals who had twin brothers, 52% of the monozygotic twin brothers and 22% of the dizygotic twin brothers were gay.
In a group of female homosexuals who had twin sisters, 48% of the monozygotic twin sisters and 16% of the dizygotic

What is the problem with the solely genetic evidence for homosexuality?

When you see all the data - 11% of adopted brothers and 9% of non twin brothers were also gay - thus it points to a non-genetic explanation - if it was all in the genes, then non-twin brothers should be identical to dizygotic twin brothers (genetically co

What is the common misconception regarding hormone levels in homosexuals?

The assumption that homosexuals have lower levels of sex hormones - they don't
- Orchidectomies reduced the sexual behaviour of both homosexuals and heterosexuals to similar extent and did not change sexual orientation. Replacement injections replaced for

What evidence do we have on the effect of perinatal hormone exposure in influencing sexual orientation in humans?

Sparse evidence.
Quasi-experimental study (Ehrhardt et al)
Interviewed adult women whose mothers had been exposed to diethylstilbestrol (DES - synthetic estrogen) prenatally.
Women's were more sexually attracted to women than control group. But only 1 out

What is the fraternal birth order effect?

Probability of a man being homosexual increases as a function of the no. of older brothers he has
- and from the same mother
- increases by 33% for every older brother
-Estimated 15% of gay men can attribute their homosexuality to the fraternal birth orde

What is the Maternal immune hypothesis?

Theory proposed to explain the fraternal birth order effect
Some mothers become progressively more immune to masculinizing hormones in male fetuses and her immune system might deactivate masculinizing hormones in her younger sons.
- As mother is exposed t

What age do girls and boys living in Western countries experience first feelings of sexual attraction?

10 yrs old approx. whether heterosexual or homosexual

Puberty in boys and girls tends to occur at what ages?

Girls: 10.5 yrs
Boys: 11.5 yrs
Although it's been claimed that there has been an acceleration of puberty in NA and Europe there is not evidence in males, and little evidence in females (change in female menstruation is caused often by obesity)
However, we

Why does the emergence of sexual attraction occur before puberty in both sexes?

Hypothesized that it is stimulated by adrenal cortex steroids, and unlike gonadal maturation, adrenal maturation occurs around 10 yrs.

Describe the differences between homosexuals and heterosexuals in the Simon LeVay study

Structure of one anterior hypothalamic nucleus (INAH3) was 2x larger in heterosexual men than heterosexual women and homosexual men.
homosexual men's INAH-3 was intermediate sized
Studied postmortem - virtually every gay man had died of AIDS - big problem

Does sexual identity always coincide with person's anatomical sex?

No way baby!!!

What is Transexualism

Condition of sexual identity
Individual believes he/she is trapped in the body of the other sex
Treatments: Surgical sexual reassignment, Self-castration, Hormone therapy

Male-to-female surgical sexual reassignment

(female-to-male is more complex and less satisfactory)
1st step: psychiatric assessment
2. in-depth counselling
3. Estrogen administration - feminizes body, continues for life
4. Penis & testes surgically removed
5. female external genitalia and vagina ar

Major problem in identifying the causes and mechanisms of transexualism

There are no comparable syndromes in nonhumans

Does sexual reassignment change previous sexual orientation?

No
Some transexuals with male body types are sexually attracted to females, others are sexually attracted to males and some to neither sex