Effect of insulin on serotonin, 5-hydroxyindole-acetic acid, norepinephrine, epinephrine and corticosterone contents in chick.

Pineal serotonin (5-HT), 5-hydroxyindole-acetic acid (5-HIAA), norepinephrine (NE), epinephrine (E) and adrenal corticosterone, NE and E contents were measured spectrofluorometrically 5, 15, 30 and 60 min after insulin treatment to induce hypoglycemic stress. In the pineal gland, hypoglycemic stress caused dramatic decrease of 5-HT, resulted in initial decrease followed by an increase of 5-HIAA and brought about changes of NE and E. Corticosterone content in the adrenal gland increased significantly following treatment with insulin. Adrenal NE and E contents plummetted to control value followed by quick resynthesis. The findings indicate that insulin-induced hypoglycemia greatly modulates the activities of pineal and adrenal glands.