User:Carissa92/sandbox/DraftClass(Neuroscience-of-sex-differences)

Final article: https://en.m.wikipedia.org/wiki/User:Carissa92/sandbox/Final(Neuroscience-of-sex-differences)

Original Article (as of 3/25)

Hormones[edit]

Steroid hormones have several effects on brain development as well as maintenance of homeostasis throughout adulthood. One effect they exhibit is on the hypothalamus, where they increase synapse formation. Estrogen receptors have been found in the hypothalamus, pituitary gland, hippocampus, and frontal cortex, indicating the estrogen plays a role in brain development.  Gonadal hormone receptors have also been found in the basal fore-brain nuclei.[18]

Estrogen and the female brain[edit]

Estradiol influences cognitive function, specifically by enhancing learning and memory in a dose-sensitive manner. Too much estrogen can have negative effects by weakening performance of learned tasks as well as hindering performance of memory tasks; this can result in females exhibiting poorer performance of such tasks when compared to males.[18]

It has been suggested that during development, estrogen can exhibit both feminizing and defeminizing effects on the human brain; high levels of estrogen induce male neural traits to develop while moderate levels induce female traits. In females, defeminizing effects are resisted because of the presence of α-fetoprotein (AFP), a carrier protein proposed to transport estrogen into brain cells, allowing the female brain to properly develop. The role of AFP is significant at crucial stages of development, however. Prenatally, AFP blocks estrogen. Postnatally, AFP decreases to ineffective levels; therefore, it is probable that estrogen exhibits its effects on female brain development postnatally.[19]

Ovariectomies, surgeries inducing menopause, or natural menopause cause fluctuating and decreased estrogen levels in women. This in turn can "attenuate the effects" of endogenous opioid peptides. Opioid peptides are known to play a role in emotion and motivation. β-endorphin (β-EP), an endogenous opioid peptide, content has been found to decrease (in varying amounts/brain region), post ovariectomy, in female rats within the hypothalamus, hippocampus, and pituitary gland. Such a change in β-EP levels could be the cause of mood swings, behavioral disturbances, and hot flashes in post menopausal women.[17]

Testosterone and the male brain[edit]

Testosterone heavily influences male development; a study found that perinatal females introduced to elevated testosterone levels exhibited male behavior patterns. In the absence of testosterone, female behavior is retained.[16] Testosterone's influence on the brain is caused by organizational developmental effects. It has been shown to influence proaptotic proteins so that they increase neuronal cell death in certain brain regions. Another way testosterone affects brain development is by aiding in the construction of the "limbic hypothalamic neural networks".[16]

Oxytocin and Vasopressin[edit]

Oxytocin is positively correlated with maternal behaviours, social recognition, social contact, sexual behaviour and pair bonding. Oxytocin appears at higher levels in women than in men.[20] Vasopressin on the other hand is more present in men and mediates sexual behavior, aggression and other social functions.[20][21]

Sources Cited by Original Article:

[16] Simerly RB (February 2005). "Wired on hormones: endocrine regulation of hypothalamic development". Current Opinion in Neurobiology. 15 (1): 81–5. doi:10.1016/j.conb.2005.01.013. PMID 15721748.

[17] Genazzani AR, Pluchino N, Luisi S, Luisi M (2007). "Estrogen, cognition and female ageing". Human Reproduction Update. 13 (2): 175–87. doi:10.1093/humupd/dml042. PMID 17135285.

[18] Korol DL (November 2004). "Role of estrogen in balancing contributions from multiple memory systems". Neurobiology of Learning and Memory. 82 (3): 309–23. doi:10.1016/j.nlm.2004.07.006. PMID 15464412.

[19] Bakker J, Baum MJ (January 2008). "Role for estradiol in female-typical brain and behavioral sexual differentiation". Frontiers in Neuroendocrinology. 29 (1): 1–16. doi:10.1016/j.yfrne.2007.06.001. PMC 2373265. PMID 17720235.

[20] Carter CS (January 2007). "Sex differences in oxytocin and vasopressin: implications for autism spectrum disorders?" (PDF). Behavioural Brain Research. 176 (1): 170–86. doi:10.1016/j.bbr.2006.08.025. PMID 17000015.

[21] Skuse DH (2006-11-01). "Sexual dimorphism in cognition and behaviour: the role of X-linked genes". European Journal of Endocrinology. 155 (suppl 1): S99–S106. doi:10.1530/eje.1.02263. ISSN 0804-4643.

Proposed Edited Article

Hormones

Gonadal hormones, or sex hormones, include androgens (such as testosterone) and estrogens (such as estradiol) which are synthesized primarily in the testes and ovaries, respectively. Sex hormone production is regulated by the gonadotropic hormones luteinizing hormone (LH) and follicle-stimulating hormone (FSH), whose release from the anterior pituitary is stimulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. These steroid hormones have several effects on brain development as well as on maintenance of homeostasis throughout adulthood. One effect they exhibit is on the hypothalamus, where they increase synapse formation.

Estrogen receptors have been found in the hypothalamus, pituitary gland, hippocampus, and frontal cortex, indicating the estrogen plays a role in brain development.  Gonadal hormone receptors have also been found in the basal fore-brain nuclei.

Estrogen

Estrogens are a class of hormones that are synthesized from androgens, such as testosterone, in both males in females. About half of the testosterone made in the ovaries is converted to estradiol, the primary estrogen in humans.

During development, estrogen may promote both feminizing and defeminizing effects on the human brain; high levels of estrogen induce male neural traits to develop while moderate levels induce female traits. In females, defeminizing effects are resisted because of the presence of α-fetoprotein (AFP), a carrier protein proposed to transport estrogen into brain cells, allowing the female brain to properly develop. The role of AFP is significant at crucial stages of development, however. Prenatally, AFP blocks estrogen. Postnatally, AFP decreases to ineffective levels; therefore, it is probable that estrogen exhibits its effects on female brain development postnatally.

Estrogen may influence cognitive function, specifically by modulating learning and memory in a dose-sensitive manner. Ovariectomized female rats administered doses of estrogen and progesterone to mimic peak levels during the estrous cycle initially showed impaired learning on a swim task as compared to the untreated group, perhaps as a result of the interaction between estrogen and high levels of stress. During subsequent trials, however, estrogen-treated rats performed better, indicating the effects of estrogen may actually enhance working memory despite promoting a less effective learning approach initially.

Ovariectomies, surgeries inducing menopause, or natural menopause cause fluctuating and decreased estrogen levels in women. This in turn can "attenuate the effects" of endogenous opioid peptides. Opioid peptides are known to play a role in emotion and motivation. β-endorphin (β-EP), an endogenous opioid peptide, content has been found to decrease (in varying amounts/brain region), post ovariectomy, in female rats within the hypothalamus, hippocampus, and pituitary gland. Such a change in β-EP levels could be the cause of mood swings, behavioral disturbances, and hot flashes in post-menopausal women.

Testosterone

The gonadal hormone testosterone is synthesized in both the male testes and female ovaries, at a rate of about 14000 μg/day and 600 μg/day, respectively.

Testosterone heavily influences male development; a study found that perinatal females introduced to elevated testosterone levels exhibited male behavior patterns. In the absence of testosterone, female behavior is retained. Testosterone's influence on the brain is caused by organizational developmental effects. It has been shown to influence proaptotic proteins so that they increase neuronal cell death in certain brain regions. Another way testosterone affects brain development is by aiding in the construction of the "limbic hypothalamic neural networks."

Oxytocin and Vasopressin

Oxytocin is positively correlated with maternal behaviours, social recognition, social contact, sexual behaviour and pair bonding. Oxytocin appears at higher levels in women than in men. Vasopressin on the other hand is more present in men and mediates sexual behavior, aggression, and other social functions.

"To Do"

• Add a subsection on prolactin
• Improve oxytocin and vasopressin subsection
• Define "male behavior patterns" and "female behavior" in testosterone section
• Clean up paragraph about AFP in estrogen section
• Info on neuroprotective effects of estrogen
• Fix "check date values" warnings in References section