Effects of repeated electroconvulsive shock on serotonin1A receptor binding and receptor-mediated hypothermia in the rat.

Chronic treatment with electroconvulsive shock or antidepressant drugs has been reported to attenuate the hypothermia induced by 8-hydroxy-2-(di-n-propyl)aminotetralin (8-OH-DPAT), a serotonin1A receptor agonist. In the present study, the binding of [3H]8-OH-DPAT to serotonin1A receptors was assessed after treatment of rats with electroconvulsive shock. The effect of electroconvulsive shock on 8-OH-DPAT-induced hypothermia also was evaluated. Male rats were handled or received electroconvulsive shock for either 1 or 10 days and were killed 2 days later. Ten days of electroconvulsive shock decreased beta-adrenergic receptor binding in the cerebral cortex, as previously reported. However, the binding of [3H]8-OH-DPAT to serotonin1A receptors in the cortex or hippocampus was not affected by repeated electroconvulsive shock. In the hypothalamus, 10 days (but not 1 day) of electroconvulsive shock significantly decreased the binding of [3H]8-OH-DPAT. In addition, 10 days of electroconvulsive shock resulted in an attenuation of the hypothermic response to 8-OH-DPAT, when compared to the response in handled controls. The electroconvulsive shock-induced suppression of the hypothermic response to 8-OH-DPAT was no longer evident 2 weeks after the last of 10 daily treatments. A single shock did not affect the hypothermic response to 8-OH-DPAT. The electroconvulsive shock-induced decrease in the binding of [3H]8-OH-DPAT in the hypothalamus may be related tot the electroconvulsive shock-induced attenuation of the hypothermic response to 8-OH-DPAT.