Temporal relationship of the induction of tolerance and physical dependence after continuous intoxication with maximum tolerable doses of ethanol in rats.
Rats were treated by intragastric intubation of a 20% ethanol solution in doses of 9-15 g/kg in 3-5 fractions for 1-7 days. Both tolerance and physical dependence were demonstrated after this treatment with the maximum tolerable doses to only a few days. Tolerance was assessed by signs of severity of intoxication: coma, loss of righting reflex, ataxia-3, ataxia-2, ataxia-1, sedation, and neutrality. During withdrawal, as blood ethanol concentrations approached 100 mg/dl the ethanol dependence phase was characterized by the onset of signs and responses of progressive severity: hyperactivity, tremors, spastic rigidity, and spontaneous convulsive seizures. A significant degree of tolerance was demonstrated for all signs of intoxication after 4 days of treatment, but did not reach maximum level even after 7 days. The severity of the withdrawal reactions intensified progressively to a maximum intensity after 4 days of treatment when as many as 72% of animals exhibited severe withdrawal signs and reactions including convulsive seizures. These different time courses suggest that tolerance and physical dependence are mediated through different mechanisms.
D000437:Alcoholism; D000818:Animals; D004195:Disease Models, Animal; D004361:Drug Tolerance; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051381:Rats; D013375:Substance Withdrawal Syndrome; D013997:Time Factors
D000431:Ethanol