Chlordiazepoxide and morphine reduce pressor response to brain stimulation in awake rats

The effects of intravenous as well as dorsal midbrain injections of morphine and chlordiazepoxide on the blood pressure rise induced by electrical stimulation of the dorsal periaqueductal gray matter (DPAG) were studied in unanesthetized rats. Chlordiazepoxide applied systemically or locally into the DPAG, as well as locally applied but not systemically injected morphine were found to attenuate the centrally-induced hypertension. These data together with others suggest that benzodiazepines as well as local injections of morphine into the DPAG decrease the aversive effect induced by DPAG stimulation.