IMMOBILIZATION STRESS INDUCES ALTERATIONS OF 2ND-MESSENGER SYSTEMS INTHE GERBIL BRAIN

The effects of immobilization stress on the cerebral second messenger (adenylate cyclase and phosphoinositide) were investigated autoradiogr aphically in mongolian gerbils. After 10 min (10-min stress group, n = 7), or after 6 h (6-h stress group, n = 7) of fixation on a flat boar d while supine, in vitro autoradiography was performed using H-3!fors kolin (H-3-FK) and H-3!phorbol-12,13-dibutyrate (H-3-PDBu) as specifi c ligands to identify the distribution of adenylate cyclase and protei n kinase C, respectively. In another group of 7 gerbils (control group ), the same autoradiographic procedure was performed immediately after the animals were removed from the cage. In the 10-min stress group, F K binding was significantly decreased in the hypothalamus and amygdala , but significantly increased in the basal ganglia including the cauda te-putamen and globus pallidus. FK binding in the 6-h stress group ten ded to increase throughout the brain, rising significantly in the basa l ganglia. PDBu binding in either stress group did not change signific antly compared to the control group in any region except the hippocamp al CA3 region of the 6-h stress group. Under immobilization stress, th e adenylate cyclase system may undergo time-dependent and regionally s pecific changes, while the phosphoinositide system remains relatively stable.