Signaling Pathway: An In Vitro and In Vivo Study1

During spermatogenesis, extensive restructuring of cell junc-tions takes place in the seminiferous epithelium to facilitate germ cell movement. However, the mechanism that regulates this event remains largely unknown. Recent studies have shown that nitric oxide (NO) likely regulates tight junction (TJ) dynam-ics in the testis via the cGMP/protein kinase G (cGMP-depen-dent protein kinase, PRKG) signaling pathway. Due to the prox-imity of TJ and adherens junctions (AJ) in the testis, in particular at the blood-testis barrier, it is of interest to investigate if NO can affect AJ dynamics. Studies using Sertoli-germ cell cocul-tures in vitro have shown that the levels of NOS (nitric oxide synthase), cGMP, and PRKG were induced when anchoring junc-tions were being established. Using an in vivo model in which adult rats were treated with adjudin [a molecule that induce