MORPHINE ALTERS THE LEVELS OF GROWTH-HORMONE RECEPTOR-MESSENGER-RNA AND [I-125] GROWTH-HORMONE BINDING IN HUMAN IM-9 LYMPHOBLASTS VIA A NALOXONE-REVERSIBLE MECHANISM

The immune system and the neuroendocrine system are functionally inter active. Lymphocytes possess opioid receptors as well as growth hormone receptors (GHR) by which opioids and growth hormone (GH) may modulate immune functions. In this study, we have investigated the effects of morphine on [I-125]hGH binding and GHR gene expression in human lympho blastoid IM-9 cells. Northern blot analysis revealed significantly alt ered GHR mRNA levels after treatment of the cells with different conce ntrations of morphine for 12 h. Morphine at 10 mu M increased the mRNA levels in a lime-dependent biphasic manner, with maximum levels at 6 and 48 h. The receptor protein, measured by [I-125]GH binding, showed a time-delayed increase compared with the GHR mRNA changes. Pretreatme nt with naloxone inhibited the action of morphine, suggesting involvem ent of classical opioid receptors. The present study demonstrates, for the first time, effects of morphine on GHR mRNA levels and [I-125]GH binding in human cultured lymphocytes. (C) 1997 Elsevier Science Irela nd Ltd.