ABSTRACT

The pineal secretory product, melatonin, is known to exhibit free radical scavenging ability. The integrity of the pineal gland and the presence of endogenous melatonin seem to be necessary to maintain ovarian function. Using Papanicolau method, the present study investigated the effect of pinealectomy on the vaginal epithelial maturation.

Twenty-one pinealectomized rats were randomly assigned into 3 groups with seven rats in each group. The groups consisted of sham-operated (control), pinealectomized only, pinealectomized animals treated with melatonin. Melatonin administration started at the 60th day following pinealectomy and continued for 21 days. At the end of the entire course, smears were obtained from each rats. Smears were stained with usual Papanicolau method, and observed with a light microscope by an experienced cytopathologist. Cytological grading was made according to the extend of parabasal, intermediate, superficial and anuclear squamous cells (Grade 1, 0-25% of cells; Grade 2, 25-50% of cells; Grade 3, 50-75% of cells; Grade 4, more than 75% of cells).

Pinealectomized rats had similar scores for superficial and anuclear cells when compared to sham operated animals. Melatonin group had lower scores for superficial and anuclear cells than those of sham and pinealectomized group. All of three groups had same scores for intermediate and parabasal cells.

The results of this study demonstrated that melatonin attenuate the improvement in vaginal stratification generally observed after pinealectomy. Pinealectomy may maintain the levels of superficial cells that is similar to conventional hormone replacement agents. Potential trophic action of pinealectomy on the vagina may improve the menopausal urogenital symptoms.

Keywords: Vaginal Smear, Papanicolau, Pinealectomy, Melatonin