EFFECTS OF CHRONIC MIANSERIN ADMINISTRATION ON SEROTONIN METABOLISM AND RECEPTORS IN THE 5-HYDROXYTRYPTOPHAN DEPRESSION MODEL

Akiyoshi, Jotaro, Kounosuke Tsuchiyama, Yuuko Mizobe, Makoto Nakamura, Hiromitsu Kuranaga and Haruo Nagayama: Effects of Chronic Administration on Serotonin Metabolism and Receptors in the 5-Hydroxytryptophan Depression Model. Prog. Neuro-Psychopharmacol. & Biol. Psychiat. 1994, 18(1): 165-179. 1. To further investigate a previous postulate that increased serotonergic activity may cause depression, the effects of chronic mianserin administration on 5-HT, its metabolites, and the subtypes of 5-HT receptors were studied. 2. The levels of 5-HT, 5-hydroxyindoleacetic acid, 5-HTP, 5-HT turnover and their response to 5-HTP administration all exhibited no change following mianserin treatment. 3. The B-max value of the high affinity site of the 5-HT-1A receptor increased and the B-max value of 5-HT-2 receptor decreased with no change in the low affinity site of the 5-HT-1A receptor nor in the 5-HT-1B receptor. 4. The response to 5-HTP administration showed no change in any of these receptors. 5. These results suggest that the chronic mianserin administration might block both the 5-HT-2 and 5-HT-1A receptors in the 5-hydroxytryptophan depression model.