L52 Sexual Differentiation of the Brain + look at highlighted Essentials

Question 1

_____distribution of many diseases based on gender is very common

Answer 1

unequal

*anorexia common in females
tourettes common in males

*strongly indicates different levels of vulnerability for various disorders based on gender

Question 2

define dimorphic.

Answer 2

occurring in two distinct forms

Question 3

what 3 ways are male and females way proven to be dimorphic?

Answer 3

1. sexual behavior between m/f is different
2. the way intellectual problems are solved between m/f are different
3. there are different hormonal environments in m/f

Question 4

___ are better at verbal fluency, while ___ are better at 3D problem solving

Answer 4

females

males

Question 5

gonadotrophin release (LH, FSH) is under control of what via the what?

Answer 5

hypothalamus

via the anterior pituitary

Question 6

females have a _____ hormonal pattern while males have a ____ hormonal pattern

Answer 6

cyclic

acyclic

Question 7

what are the areas of the hypothalamus that are considered dimorphic?

Answer 7

• sexually dimorphic nucleus (SDN aka INAH-1)
• interstitial nuclei of the anterior hypothalamus (INAH-2,3,4)
• suprachiasmatic nucleus (SCN)
• supraoptic nucleus (SON)
• paraventricular nucleus (PVN0
• ventromedial nucleus (VMN)

Question 8

what are 2 other areas of the brain that express dimorphism?

Answer 8

corpus callosum

anterior commisure

Question 9

what 2 things explain the nature of sexual dimorphism?

Answer 9

1. size and # of neurons in a nuclei
   - males have a larger SDN and it has more neurons than females
2. NT content, uptake, release and synthesis may vary between m/f

Question 10

____ is 2x as large in heterosexual males when compared to homosexual males

Answer 10

INAH-3

Question 11

a smaller INAH-3 nucleus correlates with an attraction towards ____

Answer 11

males

Question 12

a larger ____ + the total cell number counted within the nucleus is seen in homosexual males versus heterosexual males

Answer 12

SCN

Question 13

what does the SRY (sex determining region of the y-chromsome) code for?

Answer 13

TDF (testes determining factor)

Question 14

in experiments where XX-genotypes have a SRY gene, what will happen?

Answer 14

testes will develop

Question 15

what cells produce testosterone?

Answer 15

Leydig cells of the testes

Question 16

describe androgen insensitivity syndrome

Answer 16

mutated androgen receptor – Leydig cells may be able to produce testosterone, but the testosterone receptor is absent

these pt’s undergo “testicular feminization” and have normal female genetalia + breasts

puberty is characterized by amenorrhea + absent pubic/axillary hair

(balls are inside?)

Question 17

when is the critical period of sexual differentiation

Answer 17

12-20 weeks of gestation

Question 18

____ released during the critical period leads to permanent structural differentiation of the body and the brain

Answer 18

testosterone

Question 19

testosterone is converted to _____ via ____ which binds to its receptor in the nucleus and alters transcription and translation

Answer 19

estradiol
aromatase

*TESTOSTERONE DOES NOT ACT DIRECTLY ON THE CELLS OF THE DEVELOPING NERVOUS SYSTEM

Question 20

it is vital to have ____ and ___ in the critical period to lead to final masculinization

Answer 20

testosterone

estradiol

Question 21

where are the greatest concentration of estradiol receptors found?

Answer 21

hypothalamus

*not surprising, it contains most of the sexually dimorphic nuclei of the brain

Question 22

Describe fetal exposure to dietylsilbsetrol (DES)

Answer 22

prenatal exposure during the critical period causes an enlarged SDN in females

result was an increased occurrence of bisexual + homosexual girls = “DES daughters”