Zheng_2002_Acta.Pharmacol.Sin_23_477

AIM: To investigate effects of morphine on acquisition process of rats a nd interactions of opioid and cholinergic systems by Morris water maze performance.
METHODS: Morris water maze was used to measure the latency of rats with drug s treatment to find the covert platform.
RESULTS: Chronic morphine administration (10 mg/kg) impaired the acquisition process of rats in Morris water maze task. Appreciable difference was identified with morphine 10 mg/k g group compared with morphine 3 mg/kg group. Co-administration of morphine (10 mg/kg) and scopolamine (3 mg/kg) aggravated acquisition impairment induced by morphine 1 0 mg/kg or scopolamine alone, though scopolamine itself induced no salient changes in acquisition capabilities of rats. In addition, physostigmine (0.1 mg/kg) could appreciably attenuate morphine-induced acquisition impairment. CONCLUSION: Morphine 10 mg/kg evidently impaired acquisition process of rats. There was a close relationship between the acquisition capabilities of morphine-treated rats and the functions of cholinergic system.