Effect of Morphine on the Number of Adenohypophysis Acidophil Cells in Male Rat

Introduction: The influence of morphine on pituitary secretion through µmu receptors has been nearly known. It is also reported that morphine has an effect on cell proliferation. In the present study we investigated the effect of morphine on the proliferation of acidophil cells of adenohypophysis in male rat. Method: This study has been carried out on 14 adult male Wistar rats divided into two groups of morphine dependent and control. The animals in morphine-dependent group were addicted through consumption of morphine for 21 days. After controlling withdrawal syndrome signs, serum prolactin level was determined by Elisa method. In the next step after anesthetizing animals and performing cardiac perfusion, the hypophysis was removed and fixed at 10% formalin. After processing, staining was done by routine immuno-histochemistry method and the number of mammotropes and somatotropes in morphine-dependent and control groups were compared. Results: Mean prolactin production in dependent group as compared with control group showed significant increase. There was a significant increase in the ratio of mammotropes to acidophil cells and a significant decrease in the ratio of somototrops to acidophil cells in morphine-dependent group compared to the control group (P<0.05). Conclusion: Morphine dependency may lead to increase in the percentage of prolactin secreting cells and serum prolactin level and decrease of growth hormone secreting cells.