Abstract: Objective To study the topography and plasma level of somatostatin of rats in order to explore the effects of somatostatin in inhibiting acid secretion in the course of ageing. Methods Different Wistar rats of different age were selected. The rats were divided into two groups: 20 young rats(age 3 months) weight 200-250 g, and 15 old rats(age 24-30 months) weight 400-450 g. The somatostatin plasma level in rats was assayed by radioimmunoassay every month, At the meantime, the frozen section of the rats sinus ventriculi were obtained to study the topography of somatostatin by immunohistochemical staining. Results The rats in different groups had different concentration of somatostatin with a high somatostatin level in old rats group. There was a significant difference between the two groups(P<0.01). The topography of somatostatin determined by immunohistochemical staining showed that the rat gastric sinus D cell shape was irregular and full of somatostatin compound. The D cell had deeper colour. The quantity and concentration of D cell in old rats gastric sinus were more than that in young rats(age 3 months). The difference between the two groups was significant(P<0.05). Conclusion The quantity of D cell and the level of somatostatin in old rats gastric sinus were higher than that in young rats. These phenomena might be associated with regulation disturbance of acid secretion in older rats.

Key words: older rat, gastric mucosa, somatostatin, immunohistochemistry