EVIDENCE FOR AN ADIPOKINETIC FUNCTION OF THE RPCH ACTIVITY PRESENT IN THE DESERT LOCUST NEUROENDOCRINE SYSTEM

Abstract

1. Red pigment concentrating hormone-like activity (RPCA) has been demonstrated and quantified in the head or cephalic neuroendocrine system of several insects. Schistocerca gregaria adults contained the highest levels of RPCA. 2. RPCA was found in all post-embryonic life cycle stages of S. gregaria, and seems to be present in equal quantities in both males and females. Adult locusts contain significantly more RPCA than do immature animals. 3. RPCA is concentrated in the locust CC glandular lobe hut is also present in the CC storage lobe, brain and hemolymph of both mature and immature animals. Significant variations in CC RPCA content have been demonstrated in both mature and immature stages. 4. Synthetic red pigment concentrating hormone (RPCH) is adipokinetic in both intact and neck-ligatured S. gregaria adults and in intact immature animals. Doses of about 6 ng and 50 ng, respectively, result in minimal and maximal adipokinetic responses. RPCH selectively elevates hemolymph 1.2-diglycerides. 5. RPCH in large doses was without effect on crustacean hemolymph lipid levels. 6. Evidence favoring the biological and structural similarity of RPCH and locust adipokinetic hormone is discussed.