Effect of raphe lesions on the development of acute tolerance to ethanol and pentobarbital

Abstract

The effect of electrolytic lesions in the median and dorsal raphe nuclei was tested on acute tolerance development to ethanol and pentobarbital in the rat, as measured by motor impairment on the moving belt test. Acute tolerance to ethanol (1.7 g/kg, IP) or pentobarbital (17.5 mg/kg, IP) was monitored at 12.5, 25, or 50 min in separate subgroups tested only once each. One week of recovery was allowed between ethanol and pentobarbital tests. Median raphe lesions delayed the development of acute tolerance, whereas dorsal raphe lesions produced a negligible effect. These results were seen with both ethanol and pentobarbital. The mesolimbic 5-HT pathway from the median raphe nucleus is important in the development of acute tolerance to ethanol and pentobarbital, as was shown to be the case previously for chronic tolerance.

Rapid and Chronic: Two Distinct Forms of Ethanol Tolerance in Drosophila

“…Conversely, acute tolerance in rats has been found to be similar to rapid and chronic tolerance in its susceptibility to various types of interventions. For example, AFT, like rapid and chronic tolerance, could be inhibited by NMDA receptor antagonists or by serotonin depletion, consistent with the operation of common pathways (Khanna et al, 2002); furthermore, brain lesion studies also yielded similar results for acute and chronic forms of tolerance (Campanelli et al, 1988;Khanna et al, 1987). Although suggestive, these correlative studies obviously do not prove that different forms of tolerance share the same underlying cellular mechanisms.…”

Immunocytochemical study of the forebrain serotonergic innervation in Sardinian alcohol-preferring rats

“…In fact, the injection of 5,6-dihydroxytryptamine into the brain has been shown to decrease alcohol tolerance in rats (Melchior et al 1976;Khanna et al 1979;Holman et al 1985) and C57Bl mice (Melchior et al 1986), and to increase alcohol intake in rats (Myers et al 1975). Other authors have also shown that electrolytic lesions to the raphe delayed the development of acute tolerance to ethanol (Le et al 1981;Zhukov et al 1985;Campanelli et al 1988). Fig.…”

Age Differences in the Expression of Acute and Chronic Tolerance to Ethanol in Male and Female Rats

“…Some researchers argue that both acute and chronic tolerance represent the same underlying process as evidenced, for example, by a reduction or complete blockade in the development of both acute and chronic tolerance after lesions of the median raphe nucleus (Campanelli et al, 1988; Khanna et al, 1987). Kalant and colleagues postulated two potential explanations underlying the association between acute and chronic tolerance (Kalant et al, 1971).…”