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Lecture series G-post midterm neuro > G01-Sexual Differentiation > Flashcards

G01-Sexual Differentiation Flashcards

1
Q

Describe the the distribution of diseases among sexes and give some examples

A

Unequal distribution
anorexia –> female
tourette’s syndrome –> male

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2
Q

What is one behavior that varies between males and females that tells us there must be a difference between male and female brains

A

Sexual behavior

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3
Q

Variations in problem solving also exists b/w genders, give an example

A

females are better at verbal fluency tests were males are better at 3D problem solving

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4
Q

The third indicator for sexual dimorphism is?

A

hormones

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5
Q

Gonadotrophin release (LH/FSH) is under control of what?

A

hypothalamus via the AP

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6
Q

males vs females give the cycles

A

male –> acyclic pattern

women —> cyclic due to menstruation

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7
Q

To no surprise, as it controls the endocrine system, ANS, behavior and motivation, gender variation is where?

A

hypothalamus

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8
Q

What are the structures with identified differences between male and female brains (sexually dimorphic areas)

A
  1. Sexual dimorphic nucleus (SDN aka INAH-1)
  2. Interstitial nuclei of the Anteriro Hypothalamus (INAH-2,3,4)
  3. Suprachiasmic Nucleus (SCN)(remember location of circadian clock)
  4. Supraoptic nucleus ( SON)
  5. Paraventricular Nucleus (PVN)
  6. Ventromedial Nucleus (VMN)
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9
Q

What are some other areas, besides, the hypothalamus that express dimorphism?

A

corpus callosum

anterior commissure

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10
Q

Most sexual differences of morphological in nature such as?

A

size and number of neurons in a nuclei

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11
Q

This is seen in the SDN where in the males it is larger or smaller and has greater or less neurons than females?

A

males it is larger

has more neurons than females

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12
Q

What are other morphological dimorphisms in males and females?

A

neurotransmitter content, uptake, release and synthesis

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13
Q

In terms of the hypothalamuc nuclei and sexual orientation. Who has a larger INAH-3 straight men or gay men?

A

heterosexual males have twice as large INAH-3 when compared to the INAH-3 of homosexual men

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14
Q

What is the size difference in heterosexual vs homosexual women?

A

identical size variation between hetero and homo females

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15
Q

What other structure is actually larger in homosexual males versus heterosexual males?

A

SCN is larger in homosexual males versus heterosexual males

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16
Q

Based on the information studied is sexual orientation based on brain development?

A

yes sexual orientation is linked to structural dimorphisms

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17
Q

what is the basic scheme for sexual differentiation?

A

Chromosomes –> gonads –> hormones –> body or brain

18
Q

Any y chromosome will create what?

A

a male

19
Q

What gene on the y chromosome codes for TDF (testes determining factor) hence creating a male

A

SRY (sex determining region of the y chromosome )

20
Q

If there is an absence of SRY then what happens?

A

TDF is also absent and baby will develop ovaries by default

21
Q

In experiments where XX genotypes have SRY gene added, what happens?

A

babies develop testes, thus SRY=male

22
Q

Leydig cells of the testes produce what hormones?

A

produce testosterone and androgen and therefore makes a male

23
Q

Ovaries produce what hormones?

A

estradiol and estrogen hence making a female

24
Q

Androgen Insensitivity syndrome is a genetic (x linked recessive) disease process. In genetic males (XY), the SRY gene is normally expressed and testes develop, but what happens?

A

the testes remain in the body cavity.

25
Q

Why in androgen insensitivity syndrome do the testes remain in the body cavity?

A

due to a mutated androgen receptor, testosterone produced by testicular Leydig cells has no effect on sexual differentiation

26
Q

What is the phenotype of these patients?

A

patients under go testicular feminization and have normal external female genitalia (breasts as well)

27
Q

When is it apparent that a child has androgen insensitivity syndrome?

A

when the patient lacks a menstruation cycle called amenorrhea and there is spare/absent pubic/axillary hair

28
Q

When is the critical period of sexual differentiation?

A

is at 12-20 weeks of gestation as a result of testosterone secretion to create a male
there is no such phenomenon for female development

29
Q

Testosterone released during the critical period leads to what?

A

permanent structural differentiation of the body and brain

30
Q

Describe the molecular mechanism of Testosterone Action

A

Although testosterone is responsible for male differentiation, it DOES NOT act directly on the cells of the developing nervous system

31
Q

Testosterone is converted to what ?

A

to Estradiol (via aromatase) which binds to its receptor on the nucleus and alters gene transcription and translation

32
Q

Thus what two things are necessary in the critical period that leads to final masculinization?

A

both testosterone and estradiol

33
Q

Estradiol receptors are in the greatest concentration in which part of the brain?

A

hypothalamus, which should not be surprising as it contains most of the sexually dimorphic nuclei of the brain

34
Q

What happened to female babies with fetal exposure to Diethylsilbsetrol (DES)?

A

Prenatal exposure during the critical period caused an enlarged SDN in females

35
Q

What happens to babies with an enlarged SDN?

A

increased occurrence of bisexual and homosexual girls –> DES daughters

36
Q

Define Bulimia

A

an eating disorder characterized by recurrent binge eating, followed by compensatory measures, such as self induced vomiting

37
Q

Ventromedial nucleus decreases feeding behavior and is bigger in which sex?

A

bigger in males

38
Q

Lateral Hypothalamus increases feeding behavior and is bigger in which sex?

A

bigger in females

39
Q

what are some chemicals that may interfere with sexual differentiation of the brain?

A 
Organochlorine pesticides 
PCBs
Dioxins 
Alkylphenol polyethoxylates 
Phytoestrogens 
Alkylphenols 
Phthalate esters 
Bisphenol-A
40
Q

Summarize the nuclei and which is bigger in which sex

A

(i) SDN (INAH-1) , INAH-3, Ventromedial Nucleus—> All bigger in males SCN
(ii) Lateral Hypothalamus –> All bigger in females
(iii) SCN —> larger in homosexual men

Lecture series G-post midterm neuro (9 decks)

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