Naloxone-induced hypoalgesia: effects of noradrenergic antagonists and agonist

Abstract

The present experiments confirmed that rats injected with naloxone and exposed to a heated floor acquired a hypoalgesic response, as indexed by the latencies to lick their paws. The expression of these latencies were unaffected by yohimbine, clonidine, propranolol, or by relatively moderate doses of prazosin, suggesting that the conditioned hypoalgesic response induced by pairings of naloxone and a heated floor is not mediated by the release and turnover of noradrenaline.