Interactive effects of morphine and scopolamine, MK-801, propanolol on spatial working memory in rhesus monkeys

Opiate, cholinergic, glutamatergic and beta-adrenergic neurotransmitters play key roles in learning and memory in humans and animals. Dysfunction of the interactions between these neurotransmitters may induce human diseases. In the present study, the interactions of morphine and acetylcholine (ACh), NMDA, and beta-adrenergic receptor antagonist (scopolamine, MK-801, and propanolol) were evaluated in a single-blind design by co-administrations of morphine and these drugs in a delayed response in rhesus monkeys. The results indicated that: (1) Co-administration of morphine and scopolamine deteriorated spatial working memory. (2) Co-treatment of morphine and MK-801 restored impairment caused by morphine and MK-801 in a dose-depending pattern. (3) Morphine plus propranolol impaired spatial working memory. High dose of morphine (0.01 mg/kg) reversed impaired spatial working memory induced by single propranolol and morphine treatment. These data suggested that the interactions of morphine and AChergic, NMDAergic and beta-adrenergic compounds were involved in spatial working memory in rhesus monkeys.