ABSTRACT
BACKGROUND AND OBJECTIVE: The most important alkaloid of opium family, morphine, may show unfavorable effect on the reproductive organs. This research investigated the effect of microinjection of morphine into the rat's ventromedial hypothalamus (VMH) on cystic genesis in the ovary and the health of neurons of VMH. MATERIALS AND METHODS: Female rats (Wistar, weighing 200-250 g) kept under standard conditions were cannulated under anesthesia by Stoelting stereotaxic instrument at the coordinates anterior-posterior: -1.92, ventral: 9, lateral: 0.5. After being recovered, they were microinjected single morphine (0.1-0.4 µg/rat, once intra-VMH) and/or naloxone hydrochloride (0.1-0.4 µg/rat, once intra-VMH) using a 5-µL Hamilton syringe with the polyethylene tubing. The control group solely given physiological saline (1 µL/rat, intra-VMH). Three days after the experiment, both ovary and brain samples were collected from the control and the experimental groups, and they were studied histopathologically. The brain samples were checked out with the aid of the cresyl violet, and the ovaries were stained by the hematoxylin and eosin. The samples were also biometrically examined to compare the ovaries' cystic formations. Also, the number of healthy or injured neurons in the nuclei was compared. RESULTS: The ovaries of morphine-treated rats showed polycystic characteristics in comparison with the control samples. In addition, the brain slices of the morphine-treated rats illustrated a significant decrease in intact neurons. Both mal effects were resolved in the presence of naloxone. CONCLUSION: These results may show that the morphine induces anovulatory infertility probably by hypothalamus-pituitary-ovary axis dysfunction.