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Effects of dynorphin a and CCK-8 on synaptosomal ~(45)Ca uptake of the rat spinal cord

Wang Xiaojing, Wang Juenfeng, Han Jisheng

Department of Physiology, Beijing Medical University. Beijing, China

Abstract

Cholecystokinin octapeptide (CCK-8) and angiotensin Ⅱ (A Ⅱ) have been shown
in behavioral studies being endogenous antiopioid substrates (AOS). To assess their antiopioid mechanism at postreceptor level, we observed the effects of the three opioids and the two AOS on ~(45)Ca uptake of the rat spinal synaptosomal preparations. Morphine, Dyn A and DPDPE at concentrations of 10 nmol/L to 1#mu#mol/L,produced a mild suppression of 45Ca uptake of synaptosomal preparations from ventral spinal cord. CCK-8 showed a mild suppression only at a concentration of 1#mu#mol/L. In synaptosomes prepared from dorsal spinal cord, Dyn A but not morphine or DPDPE, produced a strong inhibition of ~(45)Ca uptake which was blocked by nor-BNI,a #kappa# receptor antagonist, at 1#mu#mol/L. While CCK-8 (10 nmol/L to 1#mu#mol/L) also suppressed ~(45)Ca uptake, it could antagonize the suppressive effect induced by Dyn A. In contrast to CCK-8, AⅡ(10 nmol/L to 1#mu#mol/L) influenced neither on synaptosomal ~(45)Ca uptake, nor on Dyn A suppression of ~(45)Ca uptake.

Key words: ~(45)Ca uptake;Dorsal spinal cord;Dynorphia A;CCK-8;Angiotensin Ⅱ

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Citing This Article：

Wang Xiaojing, Wang Juenfeng, Han Jisheng. Effects of dynorphin a and CCK-8 on synaptosomal ~(45)Ca uptake of the rat spinal cord. Acta Physiol Sin 1990; 42 (3): (in Chinese with English abstract).