Comparison of changes in serotonergic measures in whole blood or plasma and brain in rats given nicotine and/or stresses.

Effects of two kinds of stresses (electric foot shock and water immersion restraint) on serotonergic measures in whole blood or plasma, and whole brain in rats administered with or without nicotine were studied. Plasma tryptophan levels increased after foot shock, but decreased after restraint. Stresses given to nicotine administered rats resulted in decrease in plasma tryptophan levels. Foot shock increased plasma levels of serotonin (5-HT) and restraint decreased its levels in plasma. Plasma and blood 5-hydroxyin-doleacetic acid (5-HIAA) levels increased in rats given stress and nicotine. 5-HIAA/5-HT ratio (turnover rate of 5-HT) in plasma and blood increased only in rats given stresses and nicotine. Increase in 5-HIAA and 5-HIAA/5-HT ratio in all the rats treated were the major changes in brain. There was no parallelism in changes in serotonergic measures between brain and blood or plasma, thus peripheral changes being possibly independent from changes in brain.