CHRONIC TREATMENTS WITH 5-HT1A AGONISTS ATTENUATE POSTHYPOXIC MYOCLONUS IN RATS

Following 10 min cardiac arrest and resuscitation, male Sprague-Dawley rats developed posthypoxic myoclonus. This phenomenon peaked at 14 da ys and disappeared by 60 days after cardiac arrest. From previous resu lts, the 5-hydroxytryptamine (5-HT) system was implicated in the patho genesis of the disease. In the present study, we investigated the invo lvement of 5-HT1A receptors in posthypoxic myoclonus in rats. Single i njections of 5-HT1A agonists, buspirone (5 and 10 mg/kg body wt.) or 8 -OH-DPAT (1, 2, and 4 mg/kg), had no effect on either the intensity or time course of the disease. In contrast, multiple injections (twice a day for 7 or more days) of buspirone (10 mg/kg) or 8-OH-DPAT (4 mg/kg ) significantly attenuated the myoclonus scores of animals (p < 0.05). The results indicate that chronic stimulation of 5-HT1A receptors in the brain may accelerate endogenous compensatory mechanisms and shorte n the time course of the disease.