PERIPHERAL AND CENTRAL SEROTONERGIC SYSTEMS IN RATS SUBJECTED TO FOOTSHOCK OR WATER-IMMERSION RESTRAINT STRESS

The effects of footshock and water-immersion restraint stress on serot onergic measures in blood and various parts of rat brain have been stu died. 5-HIAA level was found to be increased in blood following both t ypes of stress compared to controls, although there were no difference s between two groups of stressed rats. Footshock induced a significant rise in tryptophan content in all brain areas studied and also in blo od relative to either restrained or control rats. 5-HT level remained essentially constant in blood and all parts of brain except in medulla oblongata following footshock whereas in rats subjected to water-imme rsion restraint stress an elevation in 5-HT level in some brain areas was found. Despite these changes relative to controls there were no si gnificant differences in 5-HT content between two groups of stressed a nimals. 5-HIAA level increased following footshock relative to restrai ned rats, in which even a fall in 5-HIAA level was noticed in hypothal amus and medulla oblongata relative to controls. 5-HIAA/5-HT ratio, an index of serotonin turnover, was found to be significantly higher in all parts of brain except in hippocampus following footshock relative to restrained rats. This may indicate an enhanced 5-HT metabolism in r ats subjected to footshock and rather depressed 5-HT turnover in restr ained rats when compared to controls.