Kisspeptin increases GnRH mRNA expression and secretion in GnRH secreting neuronal cell lines

Abstract

Kisspeptins, and their G-protein coupled receptor 54 (GPR54), are key components in the regulation of gonadotropin-releasing hormone (GnRH) secretion in humans and other mammals. Several studies demonstrate that the central or systemic administration of kisspeptin increases GnRH and gonadotropin secretion in both prepubertal and adult animals; however, the cellular targets and intracellular mechanisms of action in the central reproductive axis are unclear. In this study, we documented the presence of GPR54 in two GnRH secreting neuronal cell lines (GT1-7 and GN11). Kisspeptin treatment increases GnRH secretion and GnRH mRNA levels in a dose and time dependent manner. 10−9M Kisspeptin maximally stimulated GnRH secretion by 2-fold and GnRH mRNA levels up to 4-fold after 4 hours of treatment in both cell lines. Negative regulation by 17β-estradiol of GnRH secretion and GnRH mRNA was antagonized by kisspeptin. Co-treatment with kisspeptin and 17β-estradiol increased GnRH secretion by 2-fold and GnRH mRNA by 4-fold over estradiol alone in both cell lines. Intracellular signaling pathway studies showed that an ERK1/2 MAPK inhibitor (PD98059) and a PI3K inhibitor, LY29402, attenuated the effects of kisspeptin on GnRH mRNA modulation. Furthermore, Western blot analysis showed that phosphorylation of both MAPK and Akt substrates increased with kisspeptin treatment. This work demonstrates that the kisspeptin-GPR54 system plays a significant role stimulating GnRH secretion and positive regulation of GnRH mRNA levels in GnRH neurons in culture, and also, demonstrates the activation of MAPK and Akt signaling pathways by kisspeptin in GT1-7 and GN11 cell lines.

Kisspeptin antagonist prevents RF9-induced reproductive changes in female rats

“…Kisspeptin was demonstrated to increase the intracellular calcium concentration [Ca 2C ] i in isolated GnRH neurons (Kroll et al 2011) as well as in hypothalamic GT1-7 immortalized cell lines (Ozcan et al 2011). Furthermore, GnRH secretion was increased in kisspeptin-activated GT1-7 cells (Jacobi et al 2007, Novaira et al 2009, Tonsfeldt et al 2011. Taken together, these findings implicate an important role for kisspeptin/GPR54 for the regulation of sexual maturation and the development of the reproductive system.…”

Kisspeptin-GPR54 Signaling in Mouse NO-Synthesizing Neurons Participates in the Hypothalamic Control of Ovulation

“…To gain further insight into the downstream pathways used by kisspeptin-GPR54 signaling to promote nNOS phosphorylation in preoptic neurons, we investigated whether kisspeptin activation of its cognate receptor is coupled with the activation of the phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathway, which is thought to mediate the phosphorylation of Ser1412 in nNOS (Rameau et al, 2007) and has been shown to be stimulated by GPR54 signaling (Stathatos et al, 2005;Novaira et al, 2009). We also explored the putative activation of the ERK1/2 signaling pathway, which has been shown to be stimulated by the activation of GPR54 (Castellano et al, 2006).…”

Rola sygnalizacji kisspeptyny w osi podwzgórze–przysadka–nadnercza — aktualna perspektywa

“…The evidence related to the stimulatory effects of kisspeptins on GnRH neurons has been provided mainly from animal studies [7]. They have shown increased expression of GnRH mRNA by GnRH neurons after kisspeptin exposure [40,41]. Likewise, it has been shown that kisspeptins can evoke an increased firing rate of GnRH neurons as measured by voltage recordings in hypothalamic slices from mice [42][43][44][45], stimulate the release of GnRH in hypothalamus explants [46,47], and cause a dramatic increase in GnRH in the CSF of sheep [48].…”