LOCOMOTOR ACTIVATION AND DOPAMINE RELEASE PRODUCED BY NICOTINE AND ISOARECOLONE IN RATS

被引:59
作者
WHITEAKER, P
GARCHA, HS
WONNACOTT, S
STOLERMAN, IP
机构
[1] UNIV BATH,SCH BIOL & BIOCHEM,BATH BA2 7AY,AVON,ENGLAND
[2] INST PSYCHIAT,BEHAV PHARMACOL SECT,LONDON SE5 8AF,ENGLAND
基金
英国惠康基金;
关键词
NICOTINE; ISOARECOLONE; LOCOMOTOR ACTIVITY; STRIATUM; FRONTAL CORTEX; DOPAMINE;
D O I
10.1111/j.1476-5381.1995.tb16417.x
中图分类号
R9 [药学];
学科分类号
1007 ;
摘要
1 Isoarecolone was approximately 250 times less potent than nicotine as an inhibitor of [H-3]-nicotine binding to rat brain membranes. Isoarecolone failed to inhibit the binding of the nicotinic ligand [I-125]-alpha-bungarotoxin or of the muscarinic ligand [H-3]-QNB. 2 Nicotine (0.01-30 mu M) evoked the release of [H-3]-dopamine from striatal and frontal cortex synaptosomes, with EC(50) values of approximately 0.5 mu M in each case. This release was largely mecamylamine-sensitive. 3 Isoarecolone (1-200 mu M) evoked predominantly mecamylamine-sensitive dopamine release from both striatal and cortical synaptosomes, with a potency at least 20 times less than that of nicotine. The maximum effect of isoarecolone was less than that of nicotine, particularly in the frontal cortex preparation. 4 In control rats treated chronically with saline, neither nicotine nor isoarecolone had clear effects on locomotor activity at the doses tested. Chronic treatment with nicotine clearly sensitized rats to the locomotor activating effect of nicotine; there was only weak cross-sensitization to isoarecolone. The maximum effect of isoarecolone was seen at a dose about 40 times larger than that of nicotine. 5 The low potency and efficacy of isoarecolone in facilitating sensitized locomotor activity resembled its lower potency and efficacy, compared with nicotine, in evoking dopamine release in vitro. The agonist profile of the nicotinic receptor population mediating dopamine release may determine the pharmacological characteristics of consequent locomotor behaviour.
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页码:2097 / 2105
页数:9
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