Ethanol-stimulated serotonin release in the ventral hippocampus: An absence of rapid tolerance for the alcohol-preferring P rat and insensitivity in the alcohol-nonpreferring NP rat

R. J. Thielen, D. J. Bare, W. J. McBride, L. Lumeng, T. K. Li

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Abstract

This study examined the acute effects of intraperitoneal administration of ethanol on the extracellular levels of serotonin (5-HT) in the ventral hippocampus (vHIP) of adult, male alcohol-preferring P and -nonpreferring NP rats. Using in vivo microdialysis coupled with HPLC and electrochemical detection, the effects of acute administration of saline or 1.0, 1.75, or 2.5 g/kg ethanol on the extracellular levels of 5-HT in the vHIP were examined. Saline and 1.0 g/kg ethanol did not alter the extracellular levels of 5-HT. However, the 1.75-g/kg dose resulted in a transient increase in 5-HT levels in the vHIP of P rats only. Administration of 2.5 g/kg ethanol increased 5-HT levels to 180% of baseline in P rats (P < .05), but was without effect on NP rats. The 2.5-g/kg dose also significantly increased the extracellular levels of 5-HT in the vHIP of P rats, which had been pretreated with the same dose of ethanol 18-24 h earlier (P < .05). Comparison of the response of ethanol pretreated P rats with animals that had been pretreated with saline 24 h earlier did not reveal any significant differences in ethanol-stimulated increases in 5-HT levels between the groups. These data suggest that ethanol may activate terminals of the median raphe 5-HT system in P rats because the vHIP receives its 5-HT inputs primarily from the median raphe nucleus (MRN). Rapid tolerance does not develop to this activation of the system in the vHIP of P rats. In addition, the data suggest that the 5-HT system in the vHIP of NP rats may be relatively insensitive to the stimulating effect of acute ethanol of 5-HT release.

Original languageEnglish (US)
Pages (from-to)111-117
Number of pages7
JournalPharmacology Biochemistry and Behavior
Volume71
Issue number1-2
DOIs
StatePublished - Jan 2 2002

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Keywords

  • Acute ethanol
  • Alcohol-nonpreferring NP rats
  • Alcohol-preferring P rats
  • Median raphe nucleus
  • Microdialysis
  • Serotonin
  • Ventral hippocampus

ASJC Scopus subject areas

  • Biochemistry
  • Behavioral Neuroscience
  • Pharmacology

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