Abstract
Estradiol participates in the control of energy homeostasis, as demonstrated by an increase in food intake and in body weight gain after ovariectomy in rats. In the present study, female Wistar rats (200-230 g, N = 5-15 per group), with free access to chow, were individually housed in metabolic cages. We investigated food intake, body weight, plasma leptin levels, measured by specific radioimmunoassay, and the hypothalamic mRNA expression of orexigenic and anorexigenic neuropeptides, determined by real-time PCR, in ovariectomized rats with (OVX+E) and without (OVX) estradiol cypionate treatment (10 microg/kg body weight, sc, for 8 days). Hormonal and mRNA expression were determined at pre-feeding and 4 h after food intake. OVX+E rats showed lower food intake, less body weight gain and lower plasma leptin levels. In the OVX+E group, we also observed a reduction of neuropeptide Y (NPY), agouti-related protein (AgRP) and cocaine- and amphetamine-regulated transcript (CART) mRNA expression in the arcuate nucleus and a decrease in orexin A in the lateral hypothalamic area (LHA). There was an increase in leptin receptor (LepRb), melanocortin-4 receptor (MC4-R), CART, and mainly corticotropin-releasing hormone (CRH) mRNA in the paraventricular nucleus and LepRb and CART mRNA in the LHA. These data show that hypophagia induced by estradiol treatment is associated with reduced hypothalamic expression of orexigenic peptides such as NPY, AgRP and orexin A, and increased expression of the anorexigenic mediators MC4-R, LepRb and CRH. In conclusion, estradiol decreases food intake, and this effect seems to be mediated by peripheral factors such as leptin and the differential mRNA expression of neuropeptides in the hypothalamus.
Highlights
Gonadal hormones influence food intake and body weight in many mammalian species, including mice, rats, and women [1,2]
The present study demonstrated that estradiol treatment of OVX rats induced lower food intake, less body weight gain and lower plasma leptin levels both before and after feeding
Www.bjournal.com.br neuropetides in specific hypothalamic nuclei showed that estradiol can modify the mRNA expression of neuropeptides and receptors localized in the ARC, PVN and lateral hypothalamic area (LHA)
Summary
Gonadal hormones influence food intake and body weight in many mammalian species, including mice, rats, and women [1,2]. To evaluate whether estradiol modulates responses to orexigenic or anorexigenic signals in the hypothalamus, the present study determined food intake, body weight changes and the hypothalamic expression of mediators involved in the control of energy homeostasis before and after food intake in ovariectomized rats with and without estradiol treatment. Effect of estradiol on food intake, body weight gain, plasma leptin levels, and hypothalamic mRNA expression
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