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Life Sci. 1992;50(20):1535-41.

Antinociceptive interactions of opioid delta receptor agonists with morphine in mice: supra- and sub-additivity.

Author information

1
Department of Pharmacology, University of Arizona Health Sciences Center, Tucson 85724.

Abstract

In this study, the antinociceptive interactions of fixed ratio combinations of intracerebroventricularly (i.c.v.) given morphine and subantinociceptive doses of the delta agonists, [D-Pen2, D-Pen5]enkephalin (DPDPE), [D-Ala2, Glu4]deltorphin (DELT) or [Met5]enkephalin (MET) were examined using the mouse warm water tail flick test. When morphine was coadministered with DPDPE or DELT in a 4:1 and 9:1 mixture, respectively, a synergistic antinociceptive effect was observed. In contrast, when morphine was coadministered with MET in a 1:2 fixed ratio mixture, a subadditive interaction occurred. These results demonstrate both positive and negative modulatory interactions of delta agonists with morphine in an antinociceptive endpoint and that these interactions can be either supra- or subadditive. The data support the concept of a functional interaction between opioid mu and delta receptors and a potential regulatory role for the endogenous ligands of the opioid delta receptor.

PMID:
1315897
DOI:
10.1016/0024-3205(92)90144-e
[Indexed for MEDLINE]

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