Role of Melatonin on Follicle Development and Apoptotic Changes in Pinealectomized Rat Ovary

Önder ÇELİK, Hakan PARLAKPINAR, Şeyma HASÇALIK, Bülent MIZRAK, Murat ÖZŞAHİN

Malatya, Turkey

OBJECTIVE: The aim of this study is to determine the effect of pinealectomy and exogenous melatonin
STUDY DESIGN: Twenty-one Wistar rats were divided into 3 groups: (I) Sham-operated (Non-Px), (II) pinealectomized (Px), (III) pinealectomized and melatonin. Sham and Px groups had received vehicle whereas group III had received 4 mg/kg melatonin. Terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end-labeling activity (TUNEL) assessment was used to identify follicles that contain fragmented nuclei, an indication of apoptosis. TUNEL staining was evaluated semi-quantitatively and ovarian cysts were counted.
RESULTS: In Px group, TUNEL activity was significantly higher than sham group. Melatonin administration did not reduce the intensity of TUNEL positive follicles. The difference between pinealectomy and melatonin groups regarding TUNEL activity was insignificant. Significantly increased ovarian cysts were detected after pinealectomy and melatonin did not prevent this increase. Px and melatonin groups were not significantly different than each other regarding the TUNEL activities and ovarian cysts.
CONCLUSIONS: Pinealectomy increases ovarian cysts and apoptosis in the follicles that can not be prevented by melatonin which was probably a result of the dose and duration of melatonin.
(Gynecol Obstet Reprod Med;14:1 19 - 24)
Key Words: Rat ovary, Apoptosis, Ovarian cyst, TUNEL, Pinealectomy, Melatonin