NEUROPARSINS STIMULATE INOSITOL PHOSPHATE FORMATION IN LOCUST RECTAL CELLS

1. Neuroparsins induced InsP cascade in the migratory locust rectal cells. Due to InsP3 and InsP2 accumulation, an InsP4 production and low InsP1 levels with LiCl, results were consistent with existence of inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate, two molecules known to provoke Ca2+ release from internal stores. 2. Because the InsP cascade was mimicked with 1-stearoyl-2-arachidonoyl-sn-glycerol and phorbol-12-myristate-13-acetate and conversely was inhibited with polymyxin B, phosphorylation of enzymes acting on InsP metabolism was dependent on protein kinase C. 3. Adenylate cyclase or guanylate cyclase systems did not modify InsP production. 4. Phospholipase C and protein kinase C activities required primarily action of Ca2+, with possible feedback control.