Effects of xylazine on cerebrospinal fluid catecholamines in the rhesus monkey

The i.v. administration of xylazine, a potent, selective alpha 2-adrenergic receptor agonist, resulted in a 76% decrease in cerebrospinal fluid (CSF) norepinephrine in chair-adapted rhesus monkeys. A significant decrease was observed within 1.5 h of administration and continued through the 3 h course of sampling. Dopamine was maximally decreased by 24% at 1.5 h. Epinephrine was not significantly decreased following xylazine administration. These data suggest that norepinephrine release into monkey CSF, as an index of central or peripheral norepinephrine turnover, is more sensitive to alpha 2-adrenergic agonists than in CSF dopamine or epinephrine.