Gender and the Nervous System

Question 1

Organizational effect

Answer 1

The ability of circulating steroids to permanently alter the state of the body or brain during early, critical developmental stages

Early testosterone exposure is the cue for differentiation of the brain along the male trajectory via the organizational effect

Question 2

Aromatase

Answer 2

Expressed in many animals; converts testosterone to estradiol, which signals male-type differentiation mediated through estrogen receptors

Role unknown in humans

Question 3

Androgen insensitivity disorder (AID)

Answer 3

Caused by a loss of function mutation in the androgen receptor; leads to development of female phenotype in XY individuals

Question 4

Congenital adrenal hyperplasia

Answer 4

Caused by 21-hydroxylase deficiency leading to early exposure to high levels of androgens; causes phenotypic masculinization of an XX individual including ambigulous genitalia

Question 5

What is the role of testosterone in regulating FHSH release?

Answer 5

Neurons in the preoptic hypothalamus release LHRH in a pulsatile fashion in both males and females; in females, however, these neurons are linked by gap junctions, causing a much larger cyclic release of FSH and LH

Exposure to testosterone prevents gap junction coupling of FSHS-releasing cells in the pre-optic hypothalamus in males

Question 6

What is the role of estrogen and progesterone in modulating CNS excitability?

Answer 6

Estrogen and progesterone metabolites interact directly with GABA-A receptors to increase channel open time, leading to diminished CNS hyperexcitability

Periods of low estrogen/progesterone may correlate with increased CNS excitability / irritability

Question 7

What is the role of vasopressin receptor in sexual behavior?

Answer 7

Vasopressin Receptor expression in prarie voles correlates with monogamous sexual behavior

Meadow voles express vasopressin receptor to a lesser degree and exhibit greater promiscuity