Opiate-induced inhibition of calcium flux in immune cells

Abstract

Administration of morphine as a subcutaneous implant inhibits the initial influx of calcium (Ca2+) induced by mitogens in mouse splenocytes. This effect was not reproduced by incubation of splenocytes with morphine (10(-8)-10(-4)M). Within T cell subpopulations, CD4+, but not CD8+ cells were affected. Adrenalectomy abolished this effect of morphine in CD4+ but not B cells. Moreover, simultaneous administration of the opiate antagonist naltrexone blocked the effect of morphine in B cells, but not in CD4+ cells. These data indicate that inhibition of Ca2+ influx by morphine may be mediated through distinct glucocorticoid-dependent and independent mechanisms. The morphine-induced inhibition of Ca2+ influx in immune cells reported here may be an early event mediating opiate-induced immunosuppression.