Effects of scopolamine on morphine-induced conditioned place preference in mice.
It is well known that the cholinergic system plays a crucial role in learning and memory. Psychopharmacological studies in humans and animals have shown that a systemic cholinergic blockade may induce deficits in learning and memory. Accumulated studies have indicated that learning and memory play an important role in drug addition. In the present study, in order to get a further understanding about the functions of the cholinergic system in drug-related learning and memory, we examined the effects of scopolamine (0.5, 1.0 and 2.0 mg/kg) on morphine-induced conditioned place preference (CPP). Two kinds of morphine exposure durations (4 days and 12 days) were used. The main finding was that all doses of scopolamine enhanced the extinction of morphine-induced CPP in mice treated with morphine for 12 days. However, in mice treated with morphine for 4 days, all doses of scopolamine did not inhibit morphine-induced CPP. The highest dose (2.0 mg/kg) of scopolamine even significantly delayed the extinction of morphine-induced CPP. Our results suggest that the effects of a systemic cholinergic blockade on morphine-induced CPP depend on the morphine exposure time.
Kunming Institute of Zoology, Chinese Academy of Sciences, China.
Hua
H
Tan
Ning
N
Liu
Fraser A W
FA
Wilson
Yuanye
Y
Ma
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000503:physiopathology; D003214:Conditioning, Classical / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine; D009293:Opioid-Related Disorders / Q000503:physiopathology / Q000523:psychology*; D011950:Receptors, Cholinergic / Q000187:drug effects* / Q000502:physiology; D012601:Scopolamine / Q000494:pharmacology*; D012931:Social Environment; D013997:Time Factors
D011950:Receptors, Cholinergic; D009020:Morphine; D012601:Scopolamine