Effects of intraventricularly injected 6-hydroxydopamine on carotid sinus baroreceptor reflex in rabbits.

Effects of 6-hydroxydopamine (6-OH-DA) injected into the lateral brain ventricle on the carotid sinus baroreceptor reflex were studied in rabbits anesthetized with alpha-chloralose and urethane. As short term effects, injection of 500 mug/kg of 6-OH-DA caused a fall in blood pressure and heart rate, enhanced the depressor and bradycardia responses to electrical stimulation of the carotid sinus nerve (CSN), and inhibited the pressor response to carotid occlusion. These effects reached the maximum with 2 hrs and disappeared by the 4th hr.

Correlation between brain monoamine levels and postictal coma following electroshock.

Duration of postictal coma following maximal electroshock seizure and monoamine levels in the whole brain were measured in mice. Pretreatment with intraperitoneal alpha-methyl-p-tyrosine (alpha-MT), 5-hydroxytryptophane (5-HTP), or intraventricular 6-hydroxydopamine (6-OHDA) prolonged the coma duration, whereas p-chlorophenylalanine (PCPA) did not affect the coma, and L-DOPA tended to shorten the coma and counteracted the effect of alpha-MT. When the shock was repeated five times with one hour intervals, the duration of coma was progressively increased being accompanied by elevated serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) levels in the brain.