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Pharmacol Biochem Behav. 1994 Dec;49(4):1093-100.

Modulation of free intracellular calcium and cAMP by morphine and cannabinoids, alone and in combination in mouse brain and spinal cord synaptosomes.

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Department of Pharmacology and Toxicology, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298-0613.


Changes in [Ca++]i and cAMP were evaluated as possible mechanisms by which the cannabinoids enhance the antinociception of morphine. The addition of subactive concentrations of delta 9-(THC) and morphine in combination to brain synaptosomes did not result in an enhanced decrease in [Ca++]i; however, this drug combination enhanced decreases in [Ca++]i in spinal cord synaptosomes. The combination of CP55,940 and morphine produced enhanced decreases in [Ca++]i in both brain and spinal cord synaptosomes. In brain synaptosomes, the combination of delta 9-THC and morphine produced an additive decrease in cAMP accumulation, whereas no significant change was observed with this combination in the spinal cord. Thus, the difference in the modulation of [Ca++]i but not cAMP in the brain in vitro may be a predictor of the greater-than-additive antinociceptive effects observe in vivo.

[Indexed for MEDLINE]

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