Hormonal control of neuron number in sexually dimorphic spinal nuclei of the rat: II. Development of the spinal nucleus of the bulbocavernosus in androgen-insensitive (Tfm) rats

Abstract Gonadal hormones contribute to the sexual differentiation of brain and behavior throughout the lifespan, from initial neural patterning to “activation” of adult circuits. Sexual behavior is an ideal system in which to investigate the mechanisms underlying hormonal activation of neural circuits. Sexual behavior is a hormonally regulated, innate social behavior found across species. Although both sexes seek out and engage in sexual behavior, the specific actions involved in mating are sexually dimorphic. Thus, the neural circuits mediating sexual motivation and behavior in males and females are overlapping yet distinct. Furthermore, sexual behavior is strongly dependent on circulating gonadal hormones in both sexes. There has been significant recent progress on elucidating how gonadal hormones modulate physiological properties within sexual behavior circuits with consequences for behavior. Therefore, in this mini-review we review the neural circuits of male and female sexual motivation and behavior, from initial sensory detection of pheromones to the extended amygdala and on to medial hypothalamic nuclei and reward systems. We also discuss how gonadal hormones impact the physiology and functioning of each node within these circuits. By better understanding the myriad of ways in which gonadal hormones impact sexual behavior circuits, we can gain a richer and more complete appreciation for the neural substrates of complex behavior.

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Hormonal control of the development and regulation of tyrosine hydroxylase expression within a sexually dimorphic population of dopaminergic cells in the hypothalamus

Molecular Brain Research ◽

10.1016/0169-328x(89)90075-2 ◽

1989 ◽

Vol 6 (4) ◽

pp. 297-310 ◽

Cited By ~ 132

Author(s):

Richard B. simerly

Keyword(s):

Tyrosine Hydroxylase ◽

Hormonal Control ◽

Sexually Dimorphic ◽

Dopaminergic Cells

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Evidence of Altered Brain Sexual Differentiation in Mice Exposed Perinatally to Low, Environmentally Relevant Levels of Bisphenol A

Endocrinology ◽

10.1210/en.2006-0189 ◽

2006 ◽

Vol 147 (8) ◽

pp. 3681-3691 ◽

Cited By ~ 210

Author(s):

Beverly S. Rubin ◽

Jenny R. Lenkowski ◽

Cheryl M. Schaeberle ◽

Laura N. Vandenberg ◽

Paul M. Ronsheim ◽

...

Keyword(s):

Sex Differences ◽

Bisphenol A ◽

Brain Development ◽

Sexual Differentiation ◽

Female Offspring ◽

Sexually Dimorphic ◽

Critical Periods ◽

Neuron Number ◽

Brain Sexual Differentiation ◽

Estrogenic Chemical

Humans are routinely exposed to bisphenol A (BPA), an estrogenic chemical present in food and beverage containers, dental composites, and many products in the home and workplace. BPA binds both classical nuclear estrogen receptors and facilitates membrane-initiated estrogenic effects. Here we explore the ability of environmentally relevant exposure to BPA to affect anatomical and functional measures of brain development and sexual differentiation. Anatomical evidence of alterations in brain sexual differentiation were examined in male and female offspring born to mouse dams exposed to 0, 25, or 250 ng BPA/kg body weight per day from the evening of d 8 of gestation through d 16 of lactation. These studies examined the sexually dimorphic population of tyrosine hydroxylase (TH) neurons in the rostral periventricular preoptic area, an important brain region for estrous cyclicity and estrogen-positive feedback. The significant sex differences in TH neuron number observed in control offspring were diminished or obliterated in offspring exposed to BPA primarily because of a decline in TH neuron number in BPA-exposed females. As a functional endpoint of BPA action on brain sexual differentiation, we examined the effects of perinatal BPA exposure on sexually dimorphic behaviors in the open field. Data from these studies revealed significant sex differences in the vehicle-exposed offspring that were not observed in the BPA-exposed offspring. These data indicate that BPA may be capable of altering important events during critical periods of brain development.

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