Effects of ovariectomy and hormone replacement on the rat lingual mucosa and parotid glands: histological, immunohistochemical and ultrastructural study

ABSTRACT

Although a close relationship between oral discomfort and menopause is suggested, it is not clear if alterations of sex steroids would cause any histological changes in the oral tissues. The aim of this study was to investigate the possible effects of ovariectomy on rat lingual mucosa and the parotid glands as well as the effects of hormone replacement. Thirty adult female albino rats were included in this study. Ten animals underwent sham operation and considered as control group. The remaining twenty animals underwent ovariectomy. One month later, ten of the ovariectomized animals were given daily oral estrogen and progesteron [hormone replacement therapy group] and other ten animals were left without treatment [ovariectomized group]. Two months later, all animals were sacrificed. Tongues were sagitally cut and paraffin sections were prepared. Sections were stained with H and E and immunohistochemical staining using PCNA antibodies. The thickness of the lingual mucosa was measured using the image analyzer at the apex, dorsum and the ventral region. The parotid glands were processed for light and electron microscopy. Ovariectomized animals presented reduced thickness of the lingual mucosa especially at the tip of the tongue. The lingual papillae were partially disappeared or irregular in appearance. The results of immunohistochemistry showed prolonged turn-over period. The parotid glands demonstrated irregular pattern of the acini. The acini were smaller with hyperchromatic nuclei. There was increased connective tissue and mast cell infiltration. Ultrastructurally, the cells of the acini showed few irregular secretory granules and increased rough endoplasmic reticulum with vacuolization. Hormone replacement partially compensated for these changes. The overall results suggested that sex steroids had a specific role in the maintenance of normal lingual mucosa and parotid glands, and that their deficiency might lead to the onset of oral discomfort in menopausal women which could be reversed by HRT