THE EFFECT OF CHRONIC ADMINISTRATION OF ANTIDEPRESSANTS AND ELECTROCONVULSIVE SHOCK ON THE 5-HT1A RECEPTOR-MEDIATED HYPOTHERMIC RESPONSE INDUCED BY 8-OH-DPAT IN THE RAT

1. The effect of chronic administration of antidepressants and electro convulsive shock (ESC) on the hypothermic response (HTR) induced by 8- hydroxy-2-(di-n-propyramino) tetralin (8-OH-DPAT) as an index of the f unction of 5-HT1A receptors was investigated in the rat. 2. 8-OH-DPAT dose-dependently decreased the rectal temperature. 3. Pretreatment wit h parachlorophenylalanine increased HTR. 4. Chronic administration of the antidepressants, trazodone, imipramine, amitriptyline, and fluoxet ine had no effect on HTR, whereas administration of clorgyline attenua ted HTR significantly. 5. Repeated ECS had no effect on HTR. 6. These results suggest that the action site of 8-OH-DPAT is postsynaptic 5-HT 1A receptors and that the chronic administration of some antidepressan ts and ECS has no direct action on these receptors. 7. Therefore, the antidepressant effects of these drugs are not produced by direct actio n on postsynaptic 5-HT1A receptors.