Reduction in the number of serotonin receptors in the brainstem of morphine dependent rats

Relation to blockade of naloxone precipitated jumping by serotonin agonists

R. Samanin, L. Cervo, C. Rochat, E. Poggesi, T. Mennini

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

The effect of various drugs was studied on the naloxone-precipitated withdrawal syndrome of morphine-dependent rats. Quipazine and metachlorophenylpiperazine, two agents mimicking serotonin at central receptors, markedly lowered the frequency of jumping in abstinent rats; m-chlorophenylpiperazine significantly blocked diarrhea as well. Ptosis and diarrhea but not jumping were significantly reduced by clonidine. None of the withdrawal signs considered was significantly affected by propranolol or haloperidol. A significant reduction in the number of 3H-serotonin binding sites was found in the brainstem of morphine-dependent rats, but no change was observed in the number of serotonin receptors in the cortex. The hypothesis is proposed that in morphine dependent rats a central serotoninergic hypofunction, probably related to a decrease in the number of serotonin receptors in the brainstem, occurs as a consequence of persistent activation of central serotonin function by long-term treatment with morphine. This mechanism appears to play a major role in the compulsive jumping shown by morphine-dependent rats after naloxone injection. Alpha2 adrenergic sites may play a role in the manifestation of other withdrawal signs examined in this study.

Original languageEnglish
Pages (from-to)1141-1146
Number of pages6
JournalLife Sciences
Volume27
Issue number13
DOIs
Publication statusPublished - 1980

Fingerprint

Serotonin Receptor Agonists
Serotonin Receptors
Naloxone
Morphine
Brain Stem
Rats
Serotonin
Diarrhea
Quipazine
Serotonin Agents
Clonidine
Haloperidol
Propranolol
Adrenergic Agents
Chemical activation
Binding Sites
Injections
Pharmaceutical Preparations

ASJC Scopus subject areas

  • Pharmacology

Cite this

Reduction in the number of serotonin receptors in the brainstem of morphine dependent rats : Relation to blockade of naloxone precipitated jumping by serotonin agonists. / Samanin, R.; Cervo, L.; Rochat, C.; Poggesi, E.; Mennini, T.

In: Life Sciences, Vol. 27, No. 13, 1980, p. 1141-1146.

Research output: Contribution to journalArticle

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