Vasoactive intestinal peptide exerts an excitatory effect on hypothalamic kisspeptin neurons during estrogen negative feedback.

Hypothalamic kisspeptin neurons are the primary modulators of gonadotropin-releasing hormone (GnRH) neurons. It has been shown that circadian rhythms driven by the suprachiasmatic nucleus (SCN) contribute to GnRH secretion. Kisspeptin neurons are potential targets of SCN neurons due to reciprocal connections with the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN) and the arcuate nucleus of the hypothalamus (ARH). Vasoactive intestinal peptide (VIP), a notable SCN neurotransmitter, modulates GnRH secretion depending on serum estradiol levels, aging or time of the day. Considering that kisspeptin neurons may act as interneurons and mediate VIP's effects on the reproductive axis, we investigated the effects of VIP on hypothalamic kisspeptin neurons in female mice during estrogen negative feedback. Our findings indicate that VIP induces a TTX-independent depolarization of approximately 30% of AVPV/PeN kisspeptin neurons in gonad-intact (diestrus) and ovariectomized (OVX) mice. In the ARH, the percentage of kisspeptin neurons that were depolarized by VIP was even higher (approximately 90%). An intracerebroventricular infusion of VIP leds to an increased percentage of kisspeptin neurons expressing the phosphoSer133 cAMP-response-element-binding protein (pCREB) in the AVPV/PeN. On the other hand, pCREB expression in ARH kisspeptin neurons was similar between saline- and VIP-injected mice. Thus, VIP can recruit different signaling pathways to modulate AVPV/PeN or ARH kisspeptin neurons, resulting in distinct cellular responses. The expression of VIP receptors (VPACR) was upregulated in the AVPV/PeN, but not in the ARH, of OVX mice compared to mice on diestrus and estradiol-primed OVX mice. Our findings indicate that VIP directly influences distinct cellular aspects of the AVPV/PeN and ARH kisspeptin neurons during estrogen negative feedback, possibly to influence pulsatile LH secretion.

Pomegranate Juice and Peel Extracts are Able to Inhibit Proliferation, Migration and Colony Formation of Prostate Cancer Cell Lines and Modulate the Akt/mTOR/S6K Signaling Pathway.

Pomegranate (Punica granatum) is known to contain polyphenols with many potential health benefits, including anti-tumoral, anti-inflammatory, and anti-microbial properties. It has been used in popular medicine for cancer treatment, which still represents the major cause of cancer-related deaths in men worldwide. Importantly, pomegranate peels are valuable by-products of the food industry that are rich in polyphenols. Here we report a comparison between juice and peel aqueous extracts in prostate cancer DU-145 and PC-3 cell lines. Both extracts were able to inhibit the proliferation, migration and colony formation of those cells, although peel extracts presented more robust effects compared to juice. Besides, the growth-related mTOR/S6K signaling pathway presented strong inhibition after pomegranate extracts treatment. This study presents evidence that both juice and isolated peel extracts from promegate fruit have important anti-cancer effects against prostate cancer cells, modulating the mTOR/S6K signaling pathway.