The endogenous feeding suppressant, 2-buten-4-olide, impairs the pulsatile secretion of luteinizing hormone through endogenous opioid peptides

Fasting reduces the kiss1 mRNA levels in the caudal hypothalamus of gonadally intact adult female rats

Kisspeptin, which is the product of the kiss1 gene and its receptor kiss1r, have emerged as the essential gatekeepers of reproduction. The present study used gonadally intact female rats to evaluate fasting-induced suppression of the KiSS-1 system of anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) under normal physiological conditions. Starting on the day of estrous, one group of rats was subjected to 72 h of food deprivation, while the other group of rats was able to continue feeding ad libitum. The length of the estrous cycle was significantly longer in the food-deprived rats as compared to the feeding rats. At the end of the 72-h food deprivation period, all of the food-deprived rats were at the diestrous phase, with their serum concentrations of LH and leptin significantly lower than that observed in the feeding rats. In addition, as compared to the feeding rats, the expression levels of kiss1 mRNA were significantly lower in the food-deprived rats in the posterior hypothalamic block, which contained the ARC, but not in the anterior hypothalamic block, which contain the AVPV. However, both the kiss1r mRNA expression levels in the anterior and posterior hypothalamic blocks and the neurokinin B and neurokinin 3 receptor mRNA expression levels in the posterior hypothalamic block were not significantly different between the feeding and food-deprived rats. Thus, lower kiss1 mRNA levels in the ARC appear to be responsible for the fasting-induced inhibition of gonadotrophin secretion and subsequent prolongation of the estrous cycle.

Impact of the UV-B filter 4-(Methylbenzylidene)-camphor (4-MBC) during prenatal development in the neuroendocrine regulation of gonadal axis in male and female adult rats

4-(Methylbenzylidene)-camphor (4-MBC), a UV-B ray filter, is an endocrine disruptors (ED). Our goal was to study the effect of 4-MBC on the neuroendocrine parameters that regulate reproduction in adult female and male rats that received this disrupter during prenatal development. The 4-MBC was administered (sc) to female rats (FO) since pregnancy onset, in doses of 100mg/kg every other day. The litters (F1) were sacrificed at 70 days to determine gonadotrophin serum levels and also GnRH and the amino acids glutamate, aspartate and GABA release from the hypothalamus. The male litter rats (F1) present at adult age a decrease in serum LH and FSH concentration and so also GnRH, excitatory amino acids and GABA hypothalamic secretion. The female litters (F1) rats present at adult age an increase in serum LH and FSH concentration, whereas hypothalamic GnRH release was not modified. In these animals a significant increase of hypothalamic aspartate release as well as GABA secretion decrease were observed. Glutamate secretion was not modified. All these changes were accompanied by an advance (3 days) on the vaginal opening in 4-MBC rats group. In conclusion, prenatal administration of 4-MBC disrupts the gonadal axis in a sexual dimorphic mode that could be connected with the physiological sexual differences in the development of gonadotrophin secretion hypothalamic control mechanisms.

2-buten-4-olide, an endogenous feeding suppressant, improves spatial performance through brain acidic fibroblast growth factor in mice

Endogenous sugar acid 2-buten-4-olide, a satiety substance, has been shown to increase the blood glucose, norepinephrine, and glucocorticoid concentrations that are known to modulate learning and memory processes. The glucose-induced release of acidic fibroblast growth factor facilitated the hippocampus-dependent memory function. In the present study, we investigated the effect of 2-buten-4-olide on the spatial performance of male DDY mice undergoing the water maze task. The intraperitoneal injection of 2-buten-4-olide (5 mg/kg) facilitated the spatial performance, which was indicated by a reduction in the escape latency in which the mouse finds and climbs the goal platform in comparison to the vehicle-injected control mice. In the probe test after removing the platform, the 2-buten-4-olide-treated mice stayed a longer time in the quadrant where the platform was originally located and crossed more frequently at the platform location than did the control mice. The pretreatment of acidic fibroblast growth factor antibody injected into the lateral ventricle eliminated the effect of 2-buten-4-olide both during the training sessions and during the probe test. Therefore, 2-buten-4-olide was found to improve the spatial performance, and this effect is mediated, at least in part, by acidic fibroblast growth factor.

Hormonal control of mRNA expression of immunoglobulin binding factor in uterine cervix

Uterine cervical mucus contains an immunoglobulin binding factor (IgBF). It may play a role in preventing antibody production against sperm in the female reproductive tract. To elucidate the mechanism involved in the production of activated IgBF, we determined the effects of hormones on the expression of mRNAs of IgBF and of protein disulfide isomerase (PDI), activating enzyme, in uterine cervix by quantitative RT-PCR. The uterine cervices of female rats were excised at preovulatory, ovulatory, and postovulatory phases. The human uterine cervical adenocarcinoma cells (TCO-2) were cultured for 24 h in serum-free medium containing 17beta-estradiol or progesterone. Expression of IgBF and PDI mRNAs was significantly highest during the ovulatory phase. 17beta-estradiol stimulated the expression of both mRNAs in TCO-2; whereas progesterone was ineffective. In conclusion, estrogen regulates the production of IgBF by the endocervix and PDI in vivo, thereby increasing the level of activated IgBF in the female reproductive tract during the ovulatory phase, allowing sperm to enter the uterine cavity.

Orexins, orexigenic hypothalamic neuropeptides, suppress the pulsatile secretion of luteinizing hormone in ovariectomized female rats

It is well known that feeding disorders are deeply related to reproductive dysfunction, and some feeding regulatory factors may modulate the reproductive function. We examined the effect of orexins, the newly discovered orexigenic hypothalamic neuropeptides, on the pulsatile secretion of LH to clarify their influence on the reproductive function. We administered orexins or saline into the third ventricle of bilaterally ovariectomized (OVX) rats, and measured the serum LH concentration by RIA in blood samples drawn every 6 min for 2 hours to analyze the pulsatile secretion. In the orexin-treated groups, the mean LH concentration and the pulse frequency were significantly reduced (p < 0.01), but the pulse amplitude did not differ significantly. These data indicate that orexins suppress the pulsatile secretion of LH by influencing GnRH neurons at the hypothalamic level.