Editing Hypothalamus (section)

===Sexual dimorphism===
Several hypothalamic nuclei are [[sexually dimorphic]]; i.e., there are clear differences in both structure and function between males and females.<ref name="ReferenceA">{{cite journal | vauthors = Hofman MA, Swaab DF | title = The sexually dimorphic nucleus of the preoptic area in the human brain: a comparative morphometric study | journal = Journal of Anatomy | volume = 164 | pages = 55–72 | date = June 1989 | pmid = 2606795 | pmc = 1256598 }}</ref> Some differences are apparent even in gross neuroanatomy: most notable is the [[sexually dimorphic nucleus]] within the [[preoptic area]],<ref name="ReferenceA"/> in which the differences are subtle changes in the connectivity and chemical sensitivity of particular sets of neurons. The importance of these changes can be recognized by functional differences between males and females. For instance, males of most species prefer the odor and appearance of females over males, which is instrumental in stimulating male sexual behavior. If the sexually dimorphic nucleus is lesioned, this preference for females by males diminishes. Also, the pattern of secretion of [[growth hormone]] is sexually dimorphic;<ref>{{cite journal | vauthors = Quinnies KM, Bonthuis PJ, Harris EP, Shetty SR, Rissman EF | title = Neural growth hormone: Regional regulation by estradiol and / or sex chromosome complement in male and female mice | journal = Biology of Sex Differences | volume = 6 | pages = 8 | year = 2015 | pmid = 25987976 | pmc = 4434521 | doi = 10.1186/s13293-015-0026-x | doi-access = free }}</ref> this is why in many species, adult males are visibly distinct sizes from females.

====Responsiveness to ovarian steroids====
Other striking functional dimorphisms are in the behavioral responses to [[ovarian steroids]] of the adult. Males and females respond to ovarian steroids in different ways, partly because the expression of [[estrogen]]-sensitive neurons in the hypothalamus is sexually dimorphic; i.e., estrogen receptors are expressed in different sets of neurons.{{cn|date=May 2022}}

[[Estrogen]] and [[progesterone]] can influence gene expression in particular neurons or induce changes in [[cell membrane]] potential and [[kinase]] activation, leading to diverse non-genomic cellular functions. Estrogen and [[progesterone]] bind to their cognate [[nuclear hormone receptor]]s, which translocate to the cell nucleus and interact with regions of DNA known as [[hormone response element]]s (HREs) or get tethered to another [[transcription factor]]'s binding site. [[Estrogen receptor]] (ER) has been shown to transactivate other transcription factors in this manner, despite the absence of an [[estrogen response element]] (ERE) in the proximal promoter region of the gene. In general, ERs and [[progesterone receptor]]s (PRs) are gene activators, with increased mRNA and subsequent protein synthesis following hormone exposure.{{citation needed|date=February 2013}}

Male and female brains differ in the distribution of estrogen receptors, and this difference is an irreversible consequence of neonatal steroid exposure.{{citation needed|date=December 2021}} Estrogen receptors (and progesterone receptors) are found mainly in neurons in the anterior and mediobasal hypothalamus, notably:
* the [[preoptic area]] (where [[LHRH]] neurons are located, regulating dopamine responses and maternal behavior;<ref>{{cite journal | vauthors = Castañeyra-Ruiz L, González-Marrero I, Castañeyra-Ruiz A, González-Toledo JM, Castañeyra-Ruiz M, de Paz-Carmona H, Castañeyra-Perdomo A, Carmona-Calero EM | title = Luteinizing hormone-releasing hormone distribution in the anterior hypothalamus of the female rats | journal = ISRN Anatomy | volume = 2013 | pages = 1–6 | year = 2013 | pmid = 25938107 | pmc = 4392965 | doi = 10.5402/2013/870721 | doi-access = free }}</ref>
* the [[periventricular nucleus]] where [[somatostatin]] neurons are located, regulating stress levels;<ref>{{cite journal | vauthors = Isgor C, Cecchi M, Kabbaj M, Akil H, Watson SJ | title = Estrogen receptor beta in the paraventricular nucleus of hypothalamus regulates the neuroendocrine response to stress and is regulated by corticosterone |journal=Neuroscience|volume=121|issue=4|pages= 837–45 | year = 2003|pmid=14580933|doi=10.1016/S0306-4522(03)00561-X | s2cid = 31026141 }}</ref>
* the [[ventromedial hypothalamus]] which regulates hunger and sexual arousal.