Protein Kinase C and Calcium are Involved in the Action of Juvenile Hormone on Follicle Cells of Rhodnius Prolixus

Abstract

In Rhodnius prolixus juvenile hormone (JH) is known to act at two sites. It acts on the fat body to initiate and sustain the synthesis and release of vitellogenin into the hemolymph. It also acts on the ovary, causing the appearance of large spaces (patency) between the follicular epithelial cells surrounding the developing oocytes; as a result, vitellogenin from the hemolymph gains access to the oocyte surface (Pratt and Davey, 1972). When JH is applied to follicles in vitro, patency is increased in a rapid, dose-dependent and reversible fashion. The development of patency by JH is unaffected by inhibitors of macromolecular synthesis, but is inhibited by ouabain, a specific inhibitor of Na⁺,K⁺-ATPase (Abu-Hakima and Davey, 1977; 1979). JH also exhibits saturable and specific binding to microsomal preparations of follicle cell membranes, and activates a JH-sensitive Na⁺,K⁺-ATPase in these preparations (Ilenchuk and Davey, 1982; 1985). These results suggest that JH binds to a receptor on the follicle cell membrane, but it is not yet clear what further processes in the membrane are interposed between the putative receptor and the activation of the ATPase. The present study explores the possible involvement of protein kinase C and calcium in the development of patency.