Dopamine Intervention in Induction of Polycystic Ovary by Morphine in the VMH of Female Rat

Background: Morphine significantly reduces the chance ofpregnancy in rat and causes infertility. The occurrence of irregularmenstrual cycles in humans has been reported by morphine.Also level of estradiol decreases in ovary after injectionof morphine in rat. In the mechanism of morphine action, it isbelieved that the drug stimulates three types of opioid receptorsmu, delta and kappa. Stimulation of these receptors decreasesinput of calcium into the cell, increase output of potassium fromthe cell and decrease cAMP in the cell. The release of norepinephrineis an important factor in the hypothalamus -pituitarygonad axis. The effects of opioids on the release of dopamine inthe ventromedial hypothalamus (VMH) has not been yet investigatedwhich is our goal.Materials and Methods: Female rats (۲۲۰-۳۰۰ g) kept understandard conditions. Using a stereotactic device, they were surgicallycoordinated: Anterior-posterior: -۱/۹۲, ventral: ۹, lateral:۰.۵. After a week recovery they were microinjected morphine(۰.۱, ۰.۲, ۰.۴ μg/rat, once intra-VMH). To investigate the dopamineintervention with the morphine sulpiride (۰.۱, ۰.۲, ۰.۴, μg/rat once intra-VMH) was injected intra-VMH prior to morphineto inhibit the dopamine D۲ receptor. The control group receivedphysiological saline (۱ μL/rat, intra-VMH). Three days after theexperiment, the uterus, the ovary and the brain samples werecollected in %۱۰ formalin and studied histopathologically usinghematoxylin and eosin.Results: The ovaries in group in which morphine was injectedintra-VMH showed polycystic features as compared to thecontrol group. With the presence of sulpiride prior to morphineintra-VMH the polycystic ovary was decreased.Conclusion: These results indicate that morphine disrupts fertility.This effect is most probably is resolved by dopamine D۲receptor signaling blocking.

کلیدواژه ها:

Dopamine ، Morphine ، Polycystic Ovary ، Ventromedial Hypothalamus ، Female Rat