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Fig. 13.4 In male mice, testosterone regulation of Kiss1 in the anteroventral periventricular
nucleus (AVPV) is mediated via estrogen signaling while in the arcuate nucleus (ARC), testoster-
one acts through both androgen and estrogen signaling. ( a ) Data show the effects of castration
(Cast) and dyhydrotestosterone (DHT) or estradiol (E2) treatment on Kiss1 mRNA in the AVPV
and ARC. Values (mean ± SEM) without common notation (a, b, c) differ signifi cantly ( P < 0.05).
Data taken from Smith JT, Dungan HM, Stoll EA, Gottsch ML, Braun RE, Eacker SM, Clifton
DK, Steiner RA 2005 Differential regulation of KiSS-1 mRNA expression by sex steroids in the
brain of the male mouse. Endocrinology 146:2976-2984 with permission from The Endocrine
Society. ( b ) Schematic diagram demonstrating the likely pathways leading to Kiss1 regulation by
testosterone (T) in the male. AR androgen receptor; ER α estrogen receptor α
Recent data show sex steroids also regulate kisspeptin expression outside the
hypothalamus. Kiss1 mRNA expression in the medial nucleus of the amygdala, a
region implicated in various aspects of reproduction, including social and emotional
behaviors, appears greater in males than in females [ 58 ]. Moreover, the expression
appears to be upregulated by testosterone and/or estradiol. Testosterone's inductive
effect on Kiss1 expression in the male amygdala most likely occurs through estro-
gen receptor-dependent pathways, not through the androgen receptor, because DHT
treatment had no affect on amygdala Kiss1 levels. The precise role for kisspeptin in
the amygdala is not yet known. Sexual behavior is an obvious candidate, but it
should be noted that male Kiss1r knockout mice display normal sexual behaviors
when adequate sex steroid levels are provided [ 18 ].
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