Neonatal agonism of ERalpha masculinizes serotonergic (5-HT) projections to the female rat ventromedial nucleus of the hypothalamus (VMN) but does not impair lordosis - PubMed (original) (raw)

Neonatal agonism of ERalpha masculinizes serotonergic (5-HT) projections to the female rat ventromedial nucleus of the hypothalamus (VMN) but does not impair lordosis

Heather B Patisaul et al. Behav Brain Res. 2009.

Abstract

Serotonin (5-HT) is known to play a role in the suppression of the lordosis response in males. We have previously shown that there is a sex difference in the density of 5-HT immunoreactive (5-HT-ir) fibers in the ventrolateral division of the adult ventromedial nucleus of the hypothalamus (VMNvl) and that neonatal administration of estradiol (E2) increases 5-HT-ir in the female VMNvl to male-typical levels. Here we demonstrate that postnatal administration of the ERalpha agonist 1,3,5-tris(4-Hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), but not the ERbeta agonist diarylpropionitrile (DPN), also masculinizes 5-HT-ir in the female VMNvl, suggesting a mechanistic role for ERalpha in this process. Sexual receptivity, as ascertained by the lordosis quotient, was unaffected by either PPT or DPN treatment but nearly abolished by estradiol benzoate (EB), a synthetic estrogen with high affinity for both ERalpha and ERbeta. Collectively, these observations show that postnatal estrogens increase the density of 5-HT projections to the VMNvl via an ERalpha dependent mechanism, but that this increased inhibitory input is not sufficient to suppress the lordosis response.

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Figures

Figure 1

Lordosis quotient, an indicator of female sexual receptivity, in the first (A) and second (B) round of behavioral testing. Lordosis behavior was significantly lower in the females neonatally treated with EB but unaffected by either of the ER selective ligands.

Figure 2

Confocal images (4 merged optical planes) depicting 5-HT fiber content in the VMNvl. 5-HT labeling was readily observed within extended lengths of fibers. 5-HT immunoreactivity was significantly higher in the males than the control females and significantly increased in the females neonatally treated with EB or the ERα agonist PPT but not the ERβ agonist DPN. (*P ≤ 0.03; Scale bar (white) = 20 μm)

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Neonatal agonism of ERalpha masculinizes serotonergic (5-HT) projections to the female rat ventromedial nucleus of the hypothalamus (VMN) but does not impair lordosis - PubMed (original) (raw)