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 electroconvulsive shock (ESC) on the hypothermic response (HTR) induced by 8-hydroxy-2-(di-n-propyramino) tetralin (8-OH-DPAT) as an index of the function of 5-HT1A receptors was investigated in the rat. 2. 8-OH-DPAT dose-dependently decreased the rectal temperature. 3. Pretreatment with parachlorophenylalanine increased HTR. 4. Chronic administration of the antidepressants, trazodone, imipramine, amitriptyline, and fluoxetine had no effect on HTR, whereas administration of clorgyline attenuated HTR significantly. 5. Repeated ECS had no effect on HTR. 6. These results suggest that the action site of 8-OH-DPAT is post-synaptic 5-HT1A receptors and that the chronic administration of some antidepressants and ECS has no direct action on these receptors. 7. Therefore, the antidepressant effects of these drugs are not produced by direct action on postsynaptic 5-HT1A receptors.