Sexual Differentiation of Neuronal Circuitry in the Hypothalamus

Matsumoto, Akira; Sekine, Y.; Murakami, Shigeyuki; Arai, Yasumasa

doi:10.1201/9781439832288.ch12

Cited by 19 publications

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“…This includes the sexually dimorphic nucleus of the preoptic area, which is 3 to 5 times larger in the male, [21] or the medial nucleus of the amygdala, also larger in males than in females [7,22]. Other dimorphisms include differences in dendritic spine density [23][24][25][26][27][28] neurite branching [29] or astrocyte complexity [30][31][32]. Many of these sex differences are localized to regions that are necessary for adult sex behavior, including the arcuate nucleus, the ventromedial nucleus of the hypothalamus, and the preoptic area.…”

Section: Sex Differences In the Rodent Brainmentioning

confidence: 99%

Cellular mechanisms of estradiol-mediated masculinization of the brain

Schwarz

McCarthy

2008

The Journal of Steroid Biochemistry and Molecular Biology

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The sexual differentiation of reproductive physiology and behavior in the rodent brain is largely determined by estradiol aromatized from testicular androgens. The cellular mechanisms by which estradiol masculinizes the brain are beginning to emerge and revealing novel features of brain development that are highly region specific. In the preoptic area, the major site controlling male sexual behavior, estradiol increases the level of the COX-2 enzyme and its product, prostaglandin E2 which promotes dendritic spine synaptogenesis. In the ventromedial nucleus of the hypothalamus, the major site controlling female reproductive behavior, estradiol promotes glutamate release from synaptic terminals, activating NMDA receptors and the MAP Kinase pathway. In the arcuate nucleus, a major regulator of anterior pituitary function, estradiol increases GABA synthesis, altering the morphology of neighboring astrocytes and reducing formation of dendritic spines synapses. Glutamate, GABA and the importance of neuronal-astrocytic cross talk are emerging as common aspects of masculinization. Advances are also being made in the mechanistic basis of female brain development, although the challenges are far greater.

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Section: Sex Differences In the Rodent Brainmentioning

confidence: 99%

Cellular mechanisms of estradiol-mediated masculinization of the brain

Schwarz

McCarthy

2008

The Journal of Steroid Biochemistry and Molecular Biology

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“…These organizational actions of sex steroids seem to induce permanent sexual dimorphism in synaptic connections. Although it is not known how sex steroids act on developing brain tissue, resulting in sexual difference in neuronal circuitry, it is possible to speculate that axons of sex steroid-sensitive neurons exposed to sex steroids during developmental period would grow and branch more rapidly than sex steroidinsensitive neurons [55].…”

Section: Discussionmentioning

confidence: 99%

Prenatal testosterone improves the spatial learning and memory by protein synthesis in different lobes of the brain in the male and female rat

et al. 2008

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Abstract:The high density of the steroid hormone receptors in the structures of temporal lobe involved in learning and memory, such as the hippocampus, perirhinal cortex, entorhinal cortex and amigdaloid complex, shows that there must be a direct relationship between gonadal hormones and organizational effects of steroid hormones in those structures during development of the nervous system. The present study was undertaken in order to investigate the effect of testosterone administration during the third week of gestation on the spatial memory formation of the offspring rats and the level of soluble proteins in the temporal lobe and frontal lobe of brain, as evidence of important organizational effects of androgens during prenatal development in brain sexual dimorphism. Animals have received testosterone undecanoate on days 14, 15, 16 and 19, 20, 21 of gestation. Learning and memory tests were started 100 days after the testosterone treatment. At the end of the experiments, the temporal and frontal lobes of brain were removed for assessing the level of soluble proteins. Testosterone treatment significantly improved spontaneous alternations percentage of male offspring in Y-maze task comparative with female offspring and reference memory in radial 8 arm-maze task (decreasing in number of reference memory errors in both male and female offspring groups), suggesting effects of both short and long-term memory. Also, testosterone significantly increased the brain soluble protein level of treated female rats in 14-16 prenatal days compared with the control group as well as the brain soluble protein level of treated male rats. These results suggest that steroid hormones play an important role in the spatial learning and memory formation by means of protein synthesis in different lobes of the brain.

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“…For example, the cyclical pattern of gonadotrophin release in the female (as opposed to tonic release in the male) is associated with a larger AVPV in the female, containing more DA neurones and fewer enkephalin neurones than in the male. Moreover, the cyclical release of gonadotrophins is associated with a greater degree of dopaminergic dendritic aborization and synaptic density in the ARC of the female compared with the male (Matsumoto & Arai 1997, Simerly 2002. Similarly, the size of the mPOA and dendritic spine density within it have been positively correlated with the expression of male sexual behaviour (Rhees et al 1999, Amateau & McCarthy 2004.…”

Section: Steroid Control Of Sexual Differentiation Of Brain Structurementioning

confidence: 99%

“…spine and somatic synapses), size, number and phenotype of neurones in a particular region and astrocyte morphology (Matsumoto & Arai 1997, Simerly 2002. In rodents, all of these differences are due to the effect of neonatal testosterone/oestradiol on programmed cell death, neurite growth, axon guidance and synaptogenesis (Fernandez-Galaz et al 1997, Simerly 2002, see Boxes 6 and 7).…”

Section: Steroid Control Of Sexual Differentiation Of Brain Structurementioning

confidence: 99%

“…Steroid control of sexual differentiation of brain structure) in that the neonatal steroid surge has been demonstrated to reduce the number of DA neurones in the AVPV, and dendritic arborization and synapses of DA neurones in the ARC (Matsumoto & Arai 1997, Simerly 2002. Other neurotransmitter systems that show sexual differentiation are GABA, 5-hydroxytryptamine (5-HT), noradrenaline (NA) and endogenous opiates (see Box 8 for further examples of neurotransmitters and neuromodulators).…”

Section: The Role Of Neurotransmitters In Sexual Differentiation Of Tmentioning

confidence: 99%

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The control of sexual differentiation of the reproductive system and brain

Wilson¹,

Davies²

2007

Reproduction

160

116

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This review summarizes current knowledge of the genetic and hormonal control of sexual differentiation of the reproductive system, brain and brain function. While the chromosomal regulation of sexual differentiation has been understood for over 60 years, the genes involved and their actions on the reproductive system and brain are still under investigation. In 1990, the predicted testicular determining factor was shown to be the SRY gene. However, this discovery has not been followed up by elucidation of the actions of SRY, which may either stimulate a cascade of downstream genes, or inhibit a suppressor gene. The number of other genes known to be involved in sexual differentiation is increasing and the way in which they may interact is discussed. The hormonal control of sexual differentiation is well-established in rodents, in which prenatal androgens masculinize the reproductive tract and perinatal oestradiol (derived from testosterone) masculinizes the brain. In humans, genetic mutations have revealed that it is probably prenatal testosterone that masculinizes both the reproductive system and the brain. Sexual differentiation of brain structures and the way in which steroids induce this differentiation, is an active research area. The multiplicity of steroid actions, which may be specific to individual cell types, demonstrates how a single hormonal regulator, e.g. oestradiol, can exert different and even opposite actions at different sites. This complexity is enhanced by the involvement of neurotransmitters as mediators of steroid hormone actions. In view of current environmental concerns, a brief summary of the effects of endocrine disruptors on sexual differentiation is presented.

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Sexual Differentiation of Neuronal Circuitry in the Hypothalamus

Cited by 19 publications

References 0 publications

Cellular mechanisms of estradiol-mediated masculinization of the brain

Cellular mechanisms of estradiol-mediated masculinization of the brain

Prenatal testosterone improves the spatial learning and memory by protein synthesis in different lobes of the brain in the male and female rat

The control of sexual differentiation of the reproductive system and brain

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