Immunocytochemical evidence for the occurrence of insulin in the frontal ganglion of a lepidopteran insect, the tobacco hornworm moth, Manduca sexta L

Abstract

The frontal ganglion of the adult forms of the tobacco hornworm, Manduca sexta, was investigated immunocytochemically for the occurrence of the gastro-entero-pancreatic (GEP) neurohormonal peptides, namely insulin, nerve growth factor, epidermal growth factor, insulin C-peptide, somatostatin, glucagon, glicentin, pancreatic polypeptide (PP), polypeptide YY (PYY), secretin, vasoactive intestinal peptide (VIP), gastric inhibitory peptide (GIP), gastrin, cholecystokinin (CCK), enkephalin, α- and β-endorphins, substance P, neurotensin, bombesin, motilin, ACTH, serotonin, and calcitonin. Among all the antisera tested, positive immunostaining was obtained with anti-insulin B-chain serum only. The insulin B-chain immunoreactivity was localized in 4-6 large (30-40 μm) neurons, in the neuropile, and in the recurrent nerve. It is speculated that the insulin-like immunoreactive material may be transported to the neurohaemal organ (corpora cardiaca) through the nervi cardiaco-somatogastrici. © 1984.