Effect of inhibition of mu opioid receptor in the ventromedial hypothalamus on ovarian cystogenesis induced by morphine in the rat

Morphine has adverse effects on the female reproductive system. The aim of this study was to investigate the interference effects of MgSO4 (intra ventromedial hypothalamus (VMH) and naloxone in the rat with polycystic ovaries induced by morphine.

80 female rats (200-250 g) kept under standard conditions were surgically coordinated (Anterior- Posterior: -1/92, Ventral: 9, Lateral: 0.5) using a stereotactic device. After recovery they were microinjected morphine (0.1-0.4 µg/rat, intra-VMH) and pre-injected naloxone hydrochloride (0.1-0.4 µg/rat, intra-VMH) and also MgSO4 (1-5 µg/rat) prior to the naloxone. The control group received physiological saline (1 µL/rat, intra-VMH). 3 days after the experiment, uterus, ovary and brain samples were collected and studied histopathologically using hematoxylin & eosin.

The ovaries in group in which morphine was injected showed polycystic features as compared to the control group. This effect was reversed by the naloxone pre-injection, but, prior treatment with MgSO4 returned the aspect. However, this substance alone did not have a significant effect on the ovaries. In addition, the inflammatory effect of morphine on the ovary and the uterus was reversed with pre-injection of naloxone, but it was also returned by the MgSO4. These materials did not have significant effect on neurons of VMH.

These results indicate that the effect of morphine is mediated by mu opioid receptor which is dependent to the calcium ion signalling mechanism.