Different treatment regimens and the development of tolerance to nicotine's anxiogenic effects.
The effects of different treatment regimens were investigated on the development of tolerance to the anxiogenic effect of nicotine (0.45 mg/kg) in the social interaction test of anxiety. Rats received nicotine (0.45 mg/kg/day) by intravenous injections (5 days/week), subcutaneous injections (5 or 7 days/week) or continuous infusion by osmotic minipump. In all groups, 4 days of nicotine treatment resulted in significant decreases in social interaction compared with the vehicle control groups, without changes in locomotor activity, indicating a specific anxiogenic effect. These significant anxiogenic effects persisted even after 4 weeks of treatment although they were less marked, indicating development of partial tolerance. No significant changes in the time spent in social interaction were found when rats were tested undrugged 24 and 72 h after the termination of nicotine treatment. There was no evidence that the treatment regimen affected the rate of development of tolerance, despite very different peak plasma nicotine concentrations.
Irvine
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Centre for Neuroscience, GKT School of Biomedical Sciences, King's College London, UK.
Cheeta
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Marshall
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D000818:Animals; D001007:Anxiety / Q000139:chemically induced* / Q000523:psychology; D004361:Drug Tolerance / Q000502:physiology*; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009538:Nicotine / Q000008:administration & dosage* / Q000097:blood; D018722:Nicotinic Agonists / Q000008:administration & dosage* / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000523:psychology
D018722:Nicotinic Agonists; D009538:Nicotine