Effect of long-term nicotine treatment on [3H]nicotine binding sites in the rats brain.
Male rats were receiving nicotine (base), 50 mg/kg in their drinking fluid for 9 and 41 weeks, respectively. A markedly reduced intake of fluid was observed during both regimes of nicotine treatment. At withdrawal of nicotine after 9 weeks of treatment the intake of water was immediately increased up to control level while in rats with 41 weeks of exposure the intake of drinking fluid increased to 65% over the control level still 14 days after withdrawal of nicotine. Tolerance to nicotine was measured after 7 days of abstinence in rats treated for 9 weeks. No significant change in cholineacetyltransferase (ChAT) activity or number of muscarinic binding sites in brain was observed after 9 or 41 weeks of nicotine treatment. Twenty-four hours after withdrawal from the 41 weeks nicotine treatment there was a significant increase of 46% in the number of [3H] nicotine binding sites in the hippocampus while the number of binding sites was decreased by 44% in the cortex and unchanged in the midbrain. On day 14th of abstinence these changes had disappeared. Following 9 weeks of nicotine treatment no change in [3H] nicotine binding was observed after 24 h or 7 days of abstinence.
D000818:Animals; D001665:Binding Sites; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004327:Drinking Behavior / Q000187:drug effects; D004361:Drug Tolerance; D009538:Nicotine / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000378:metabolism*; D013997:Time Factors
D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D009538:Nicotine; D002795:Choline O-Acetyltransferase