Features of the morphofunctional state of parotid salivary glands in six-month-old rats with experimentally induced fetal macrosomia

Abstract

The paper aims at studying the features of the morphofunctional state of parotid gland tissue in six-month-old rats born with induced macrosomia in its different variations. It has been known that the amount and quality of saliva are important indicators of teeth and gums health condition. The aim of the study is to examine experimentally the features of postnatal morphogenesis of parotid salivary glands in six-month-old rats with fetal macrosomia and compare the morphofunctional condition of parotid glands between two groups of 6-month-old and 3-month-old rats with induced macrosomia. Materials and methods. Four macrosomia models have been used by applying a high-calorie diet and hypokinesia to pregnant Wistar rats. After birth, the descendant rats have been weighed and divided into groups taking into account their calculated weight-length parameters. Four main groups and a comparison group have been created. The main (macrosomic) groups consist of species with the following parameters: (1) long body length and relatively decreased body weight; (2) balanced intrauterine development; (3) standard body length and intrauterine obesity; (4) standard body weight and intrauterine obesity induced by hypokinesia of a pregnant female rat. At the age of 6 months, the rats have been sacrificed. The absolute and relative weights of parotid glands have been evaluated. A histopathologic analysis revealing DNA and RNA (Gallocyanin-chrome alum technique) has been carried out after coating the parotid glands with paraffin; the PAS-reaction has been used to reveal glycoproteins. The serocytes nuclei cross section, the content of DNA in the cell nucleus, and the content of RNA in cytoplasm have been measured using computer images. Using the images obtained with confocal laser scanning microscopy, the gland acini cross section and the acini cross section perimeter of the parotid gland have been measured. The same technique has been used to measure the serocyte cross section. Caspase-3 immunehistochemical staining has been performed. Results . The macrosomic animals born with balanced intrauterine development and intrauterine obesity have shown signs of serocyte apoptosis, stroma widening and sclerosis, and the macrophage-lymphocyte infiltration of parotid gland stoma at the age of six month. Such manifestations attain their maximum in the animals whose macrosomia is induced by the hyper-calorie diet and the hypokinetic conditions in the pregnant rat females. Also, the enlargement and euchromatization of serocytes nuclei is observed in the animals in these groups, which indicate an increase in the morphofunctional activity of an individual serocyte. In the macrosomic rats born with signs of body mass deficiency, the islets of inactive serocytes are observed, the morphofunctional load of serocytes is relatively low, and in addition, there are no signs of serocytes failure or active compensatory processes. Comparison of the morphofunctional condition of the parotid gland at the age of 3 and 6 months has revealed that the age-specific enlargement of the parotid gland is less in the rats born with macrosomia and with both body mass deficiency and obesity, than that in the comparison group. The rats born with signs of body mass deficiency show an economic type of gland functioning, whereas the animals born with intrauterine obesity show signs of parotid gland atrophy with compensatory morphofunctional activation of functioning serocytes. Conclusion. The somatometric features of fetal macrosomia affect the morphofunctional features of the parotid gland of descendant animals at the age of 6 months (mature age).