Chronic intragastric administration of gamma-butyrolactone produces physical dependence in baboons

Amy K. Goodwin, Roland R. Griffiths, P. Rand Brown, Wolfgang Froestl, Cornelis Jakobs, K. Michael Gibson, Elise M. Weerts

Research output: Contribution to journalArticle

Abstract

Rationale: Abuse of gamma-hydroxybutyrate (GHB) and its precursors is a public health concern. Gamma-butyrolactone (GBL) is found in commercially available products and, when ingested, is metabolized to GHB. Objective: The goal was to evaluate the physical dependence potential and behavioral effects of GBL. Methods: Vehicle and then GBL were administered continuously (24 h per da y) in baboons (Papio anubis, n=5) via intragastric catheters. GBL dosing was initiated at 100 mg/kg/day and then progressively increased stepwise by increments of 100 mg/kg to a final dose of 600 mg/kg. The number of food pellets earned, fine-motor task performance, and observed behaviors were used as dependent measures. Precipitated withdrawal was evaluated after administration of GABA-B and benzodiazepine receptor antagonists during chronic GBL dosing (400-600 mg/kg). Spontaneous withdrawal was evaluated after discontinuation of chronic GBL 600 mg/kg. Blood GHB levels were determined during chronic dosing of each GBL dose by isotope dilution assay. Results: Chronic GBL dose-dependently decreased food-maintained behavior, disrupted performance on the fine-motor task, and produced signs of sedation and muscle relaxation. The GABA-B antagonist SGS742 [56 mg/kg, intramuscular (IM)] precipitated a withdrawal syndrome, whereas the benzodiazepine antagonist flumazenil (5 mg/kg, IM) produced little or no effect. Signs of physical dependence were also demonstrated when chronic GBL dosing was discontinued. Analysis of plasma indicated GBL was metabolized to GHB; levels were 825 to 1,690 μmol l -1 GHB and 2,430 to 3,785 μmol l-1 GHB after week 1 of 400 and 600 mg/kg/day, respectively. Conclusions: These data indicate that, like GHB, chronic GBL dosing produced physical dependence that likely involved the GABA-B receptor.

Original languageEnglish (US)
Pages (from-to)71-82
Number of pages12
JournalPsychopharmacology
Volume189
Issue number1
DOIs
StatePublished - Nov 1 2006

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Keywords

  • GABA-B receptor antagonists
  • GHB
  • Operant behavior
  • Withdrawal

ASJC Scopus subject areas

  • Pharmacology

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