Vasopressin regulates hypothalamic GnRH synthesis: Histomorphological evidence in hypothalamus and biological effects in GT1-7 cells

Publication date: Available online 23 April 2019Source: Life SciencesAuthor(s): Zhu Zhu, Xiaozhen Zhao, Feng Huang, Feng Wang, Wei WangAbstractAimsTo investigate the direct histomorphological clues and observe the biological effects of VP acting on gonadotropin-releasing hormone (GnRH) secretion.Main methodsImmunofluorescence was conducted to investigate the expressions of GnRH and VP in experimental left varicocele (ELV) rats and ELV repair rats. The colocalization of GnRH and VP was observed by electron microscopy immunohistochemistry. The protein-protein interaction between GnRH and VP was tested by co-immunoprecipitation (co-IP) and the proximity ligation assay (PLA). The effects of intracellular and extracellular VP on GnRH and relative transcription factors (Oct-1, Otx2, Pbx1b and DREAM) were respectively evaluated in VP overexpressed and VP treated GT1-7 cells.Key findingsBoth hypothalamic GnRH and VP decreased in ELV rats and recovered by ELV repair. The overlapped immunolocalizations of GnRH and VP mainly distributed in the lateral part of the arcuate nucleus (ArcL) and median eminence (ME) with a Manders' overlap coefficient of 0.743 ± 0.117. Immunoreactive substances of GnRH and VP existed in the same and adjacent terminals. VP overexpression did not cause any significant effects on the expressions of GnRH and Oct-1, as well as GnRH promoter activity. While 50–200 pg/ml VP treatments increased GnRH mRNA levels in a dose- and time-dependent manner in GT1-7 ...
Source: Life Sciences - Category: Biology Source Type: research