Determination of Apelin as immunohistochemically in gastric tissue of young rats applied monosodiumglutamate and increased, restricted food intake

Apelin, a recently discovered peptide hormone, has a widespread pattern of expression in thorough the body and it is produced in several tissues, including stomach, brain, lung, lactating breast and adipose tissues and body. Apelin has important physological roles in regulation of cardiovascular, gastrointestinal, endocrin and immune systems besides food and water intake. It has also effects on the pathogenesis of Diabetes Mellitus, hypertension and heart failure. Monosodium glutamate (MSG) is an agent that can cause obesity or metabolic sendrom in a long period. The aim of this study was to investigate the structural alterations and apelin immunoreactivity in rat stomach induced by food-restriction, increased food intake and MSG application.Twenty four neonate Wistar male rats were used in the study. The rats were divided to four equal groups. Group I: Control, Group II: Increased food intake, Group III: Restricted food intake, Group IV: MSG applied groups. All the rats used the study were decapitated under ketamine anestesia at the end of 40th day of the study and stomach tissues were removed. Following routine light microscopy procedure, tissues were embeded in paraffin blocks. The slides obtained from paraffin blocks were histologically stained and avidin- biotin-peroxidase method were applied to determine apelin immunoreactivity.Compared to the control group, examining of stomach tissue slides revealed that there was dilatation of lumens in the gastric glands, desquamation of the surface epithelium on the apical mucosa, loss of superficial epithelial cells in the restricted food intake group and especially the MSG applied group. However, increased food intake group was close to the controls. A foamy appearence was observed more intensively in gastric glands of stomach mucosa of the restricted food intake group and less intensively between gastric gland cells of the increased food intake group. There was no foamy appearence in lamina propria of gastric mucoza in the MSG applied group. However, the most distinct alterations in gastric mucosa were determined in the MSG applied group among all the groups. In addition, mononuclear cell infiltrations in lamina propria and apopitotic cells in basale of gastric glands of the restricted food intake group.In immunohistochemical staining for apelin appied to the slides of gastric tissues in all the groups, immunopositive reaction was determined in only mucosa layer. Immunopositive cells for apelin were more profound and apparent in base of the glands. The degree of immunohistochemical staining for apelin was determined as (+1) in restricted food intake group, (+2) in control group, (+3) in increased food intake group and (+4) in MSG applied groups.In conclusion, increased food intake, restricted food intake and MSG application cause progresively increased histological alterations in gastric mucosa and apelin immunoreactivity in gastric tissue is decreased in restriction of food intake while increased in MSG application and increment of food intake.Key words: Apelin, immunohistochemical, stomach, rat