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

Abstract

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.

Kisspeptin mRNA expression is increased in the posterior hypothalamus in the rat model of polycystic ovary syndrome

“…The PCR conditions were as follows: initial denaturation and enzyme activation at 95 °C for 20 s, followed by 45 cycles of denaturation at 95 °C for 3 s and annealing at 65 °C for 30 s (Kiss1) or 64 °C for 30 s (GAPDH), and then extension at 72 °C for 1 min. The copy numbers of the transcripts were normalized against those of GAPDH transcripts for each sample [18,19].…”

“…These sampling were done on diestrus day in control rats during 12 weeks of age. Anterior and posterior hypothalamic tissue blocks were cut as reported previously and based on rat brain atlas [17,18]. In this cutting method, the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC) are included in the anterior and posterior hypothalamic blocks, respectively.…”

Kisspeptin signalling and its roles in humans

“…Energydeprived rats and sheep had reduced Kiss1 mRNA in their hypothalami, reduced LH levels and pubertal arrest. (47,(124)(125)(126)(127)(128)(129)(130)(131) With kisspeptin administration, puberty resumed, while gonadotrophin and androgen levels normalised. (57,124,125) Interactions between kisspeptins and leptin may account for these observations.…”

Neurokinin B receptor agonist and Dynorphin receptor antagonist stimulated luteinizing hormone secretion in fasted male rodents

“…They also have less body fat and low serum leptin concentration. In rodent, fasting reduces the kiss1 mRNA expression level in ARC and serum LH concentration and prolonged estrous cycle [17]. In this study, we tried to determine whether stimulation of NKB/neurokinin 3 receptor (NK3R) signaling and inhibition of Dyn/kappa-opioid receptor (KOR) signaling recover LH secretion suppressed by negative energy in male rats in order to evaluate the efficacy of such drugs in the treatment for the ovulatory disorder.…”