Effect of lithium salt(Li)administnation to caudate-putamen nucleus (CPN) on pain response in the rat was studied by chronic cannula implantation and direct injection of drugs into the brain structurementioned above. The results were as follows:( 1 ) The injection of Li into anterior part of the head of CPN of rats produced significantly the analgesic effect that could be antagonized by naloxone

atropine

phento-lamine.propranolol

lysergic acid diethylamide and bicuculline

but not by haloperidol.(2) The injection of Li into central part of the head of CPN of rats did not produce analgesic effect.The results above showed that microinjection of Li into different parts of the head of CPN could give rise to different effects on pain response and the analgesic effect of Li could be related to metabolic changes of endogenous opioid peptides

acetylcholine

noradrenaline

gama aminobutyric acid and 5-hydroXytryptamin aad mediated by their receptors respectively