Pentobarbital selectively blocks supraspinal morphine analgesia. Evidence for GABAA receptor involvement.

Article date: 1990/12/1

PubMed ID: 1963487

Journal name: Pain (ISSN: 0304-3959)


The possibility that the GABAA receptor is involved in supraspinal morphine analgesia was investigated in rats using pentobarbital and other GABAA receptor-chloride channel ligands. Inhibition of tail-flick was used as an index of analgesia. Pentobarbital almost completely reversed intracerebroventricular (i.c.v.) morphine analgesia, but did not affect intrathecal (i.t.) morphine analgesia. Phenobarbital had a similar effect but was much weaker. Picrotoxin blocked the reversal effect of pentobarbital. Diazepam, when given together with pentobarbital, enhanced the effect of pentobarbital. Furthermore, muscimol reversed i.c.v. morphine analgesia without affecting i.t. morphine analgesia. Our results strongly suggest that the GABAA receptor is involved in supraspinal morphine analgesia.

This document is available from: http://directlinks.cc/files/muscimol/1963487.pdf

Author List: Ding X H, Ji X Q, Tsou K

Publication Types: Comparative Study; Journal Article

Substances mentioned in the article: Receptors, GABA-A; Picrotoxin; Muscimol; Morphine; Pentobarbital; Diazepam; Phenobarbital;

Mesh terms: Analgesia; Animals; Diazepam/pharmacology; Drug Synergism; Injections, Intraventricular; Injections, Spinal; Male; Morphine/antagonists & inhibitors; Muscimol/pharmacology; Pentobarbital/pharmacology; Phenobarbital/antagonists & inhibitors; Picrotoxin/pharmacology; Rats; Rats, Inbred Strains; Receptors, GABA-A/physiology; Spinal Cord/physiology;

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