Effect of hypodynamy on structure and enzymatic activity of duodenal enterocytes of Japanese quail

The effect of hypodynamy on the structure, ultrastructure, and enzymatic activity of the duodenal enterocytes of Japanese quail (Coturnix coturnix japonica) was studied. On the second day after hatching, 42 chicks were placed in individual slings suspended by a flexible metal device in such a manner that their legs could not touch the floor. Feed and water was provided ad libitum. The experimental animals were euthanized at 5, 7, 14, 21, 28, 35, and 42 d of age. The birds of control group were kept under standard conditions on the floor. Samples of the duodenum were routinely processed for a light microscope (LM) and also a transmission electron microscope (TEM), along with the determination for alkaline phosphatase (AP) activity. Morphological changes in enterocytes of chicks reared under hypodynamy from day 2 after hatching were observed on days 5 and 7 of age. LM showed that the apical ends of intestinal villi contained clumps of necrotizing enterocytes, which were more numerous compared to that of the control. TEM revealed a loss of microvilli and changes in both the nucleus and cytoplasm in these cells. Besides considerable damage to mitochondria, they exhibited also typical vesiculation of cytoplasm and damaged intercellular junctions. From day 14 to 42 of age morphological changes were less pronounced. On day 7 of age, the activity of AP in the microvilli of duodenal enterocytes of experimental chicks was increased in comparison with the control (P<0.001). On day 14 of the experiment, AP in the investigated structures showed only a slight increase (P<0.05), and on day 21 was also slightly increased (P<0.01). On days 28, 35, and 42 of age, no significant differences in the activity of AP were observed. Hypodynamy acted as a stress factor on Japanese quail, which was stronger at the beginning of the experiment. The animals gradually adapted to their respective conditions. Our results show that Japanese quail chicks are capable of feed consumption and feed conversion under conditions of hypodynamy.