Dependence and withdrawal following intracerebroventicular and systemic morphine administration : functional anatomy and behavior

FRANÇAIS :
La consommation cérébrale de glucose et les effets comportementaux (signes autonomes, sauts, diarrhée, perte de poids) sont étudiés lors d'un sevrage précipité à la morphine chez des rats rendus dépendants par administration intracérébroventriculaire ou sous-cutanée de morphine. Les variations de consommation du glucose observées dans les deux groupes résultent uniquement des effets chroniques de la morphine sur le système nerveux central. Une perte de poids accrue, des animaux traités par sous-cutanée, suggère des effets périphériques indépendants, peut-être transmis par les récepteurs opiacés viscéraux.
ENGLISH :
Regional cerebral glucose utilization (RCGU) and behavior during precipitated morphine withdrawal were studied in rats dependent by either intracerebroventricular (i.c.v.) or subcutaneous (s.c.) administration of morphine. Correlation of RCGU for 24 brain structures comparing i.c.v. vs s.c. morphine-treated rats was highly significant for groups in withdrawal and for controls. Withdrawal behaviors including autonomic signs of withdrawal, withdrawal jumping, and incidence of diarrhea were not different between the two groups in withdrawal (i.c.v. and s.c.). Weight loss during withdrawal increased (P<0,05) in rats made dependent by s.c. morphine administration compared to rats that received morphine by the i.c.v. route. Taken together, these results indicate that RCGU changes during morphine withdrawal result solely from effects of chronic morphine in the central nervous system, not in peripheral sites. The increased weight loss of s.c.-treated, morphine-dependent rats in withdrawal suggests an independent peripheral effect perhaps mediated by visceral opiate receptors. (Extract from author's abstract)