Effect of Long-Term Hypodynamy on Alkaline Phosphatase Activity of Small Intestine in Japanese Quail Chicks

Abstract

The functional development of the small intestine was investigated in Japanese quail chicks subjected to simulated microgravity (hypodynamy) on the second day after hatching and reared under these conditions to 63 days of age. On days 5, 7, 14, 21, 28, 35, 42, 56 and 63 the activity of brush-border-bound alkaline phosphatase (AP) in the duodenum and jejunum were determined in experimental animals as well as in control quail chicks housed in a floor box during these periods. As compared with control quails the experimental animals displayed a significantly increased enzyme activity until day 42 in the duodenum and day 35 in the jejunum (P < 0.001) whereas in older quails no significant enzymatic differences between these groups was found. However, a decrease in food consumption due to a partial physical constraint cannot be excluded. Moreover, the results suggested that the activity of AP in the control birds did not change substantially during all the periods examined. In contrast, in older hypodynamy quail the AP activity significantly decreased in the duodenum on days 56 and 63 and in the jejunum on days 42, 56 and 63, respectively. These results indicate that a) the enhanced intestinal function in early periods of life may reflect the higher sensitivity of small intestine to simulated weightlessness, b) the decrease of the AP activity in older animals to the level of controls might be considered as a part of intestinal mechanisms involved in adaptation of quail chicks to long-term hypodynamy, c) different activity of AP in the small intestine of Japanese quail may not have resulted only from hypodynamy but also due to decreased food intake.