Lenschow C, Sigl-Glöckner J, Brecht M. Development of rat female genital cortex and control of female puberty by sexual touch.
PLoS Biol 2017;
15:e2001283. [PMID:
28934203 PMCID:
PMC5608169 DOI:
10.1371/journal.pbio.2001283]
[Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 08/17/2017] [Indexed: 12/05/2022] Open
Abstract
Rat somatosensory cortex contains a large sexually monomorphic genital representation. Genital cortex undergoes an unusual 2-fold expansion during puberty. Here, we investigate genital cortex development and female rat sexual maturation. Ovariectomies and estradiol injections suggested sex hormones cause the pubertal genital cortex expansion but not its maintenance at adult size. Genital cortex expanded by thalamic afferents invading surrounding dysgranular cortex. Genital touch was a dominant factor driving female sexual maturation. Raising female rats in contact with adult males promoted genital cortex expansion, whereas contact to adult females or nontactile (audio-visual-olfactory) male cues did not. Genital touch imposed by human experimenters powerfully advanced female genital cortex development and sexual maturation. Long-term blocking of genital cortex by tetrodotoxin in pubescent females housed with males prevented genital cortex expansion and decelerated vaginal opening. Sex hormones, sexual experience, and neural activity shape genital cortex, which contributes to the puberty promoting effects of sexual touch.
We recently identified the somatosensory representation of rat genitals; remarkably, this cortical region—genital cortex—is sexually monomorphic, despite the marked sexual dimorphism of external genitals in rats. Most intriguing was the observation that genital cortex doubles in size during puberty. In order to shed light on this unusual expansion, we studied genital cortex development and sexual maturation in the female rat. We first showed that sex hormones are likely to cause the pubertal expansion of genital cortex. Next, we examined whether sexual experience affects the development of female genital cortex. Raising females together with adult males advanced genital cortex expansion, but cohousing with adult females or exposure to nontactile male cues was not sufficient to drive genital cortex growth. Surprisingly, artificial genital touch led to an early onset of female puberty and growth of genital cortex. In line with this finding, we find that if genital cortex activity is blocked, the advancing effects of adult males on puberty and genital cortex growth are inhibited. Together, our results point to an important role of genital cortex in the puberty-promoting effects of sexual touch.
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