The Effect Of Melatonin On The Chickens' Immune Function With Different Illumination

In order to study the effect of different levels of melatonin on the immune function of chicken, three groups of 4-weeks chickens under different lighting conditions were divided into 6h short lighting, 18h long lighting and 12h control groups, After three weeks of control lighting,three tests were conducted contents of CD3+,CD4+,CD8+T cells and Bu-1a+B cells were examined in peripheral blood by using flow cytometry in different lighting conditions;change of monocyty macrophage phagocytic reaction were examined by spectrophotometer and carban particles clearance test ,and dyed with HE in the routine method, observed and photographed under the microscope, and finally stage micrometer scale was used to measure thymic corpuscle diameter, bursa of fabricius nodule area and splenic corpuscle diameter. The result indicated: Contents of CD3+,CD4+,CD8+T cells and Bu-1a+ B cells were magnified significantly with the lighting time increasing and due to the level of the melatonin inhibited in the long time lighting. Result were significantly differen(tp<0.05)or quite significantly differen(tp<0.01)in comparison with that in the control group of same batch. These results showed that the levels of melatonin have significantly affected on the quantities of T,B lymphocytes and their subtypes. It was indicated that the melatonin could improve the immune function by increasing the percentage content of T, B lymphocytes and their subtypes in the peripheral blood , Monocytes macrophage function phagocytic index were magnified significantly. Result were significantly different(p<0.05)or quite significantly different(p<0.01)in comparison with that in the control group of same batch. These results showed that the levels of melatonin have significantly affected on the monocytes macrophage function phagocytic index. It was indicated that the melatonin could enhance the immune function by increasing the monocyte phagocytic capacity in the peripheral blood, furthermore, With the lighting time increasing, thymic corpuscle diameter, bursa of fabricius nodule area and splenic corpuscle diameter index were decreased in same batch. Result were significantly different (p<0.05 or P<0.01) compared with the control group. The observation under the microscope showed that the diameter and number of thymic corpuscle in 6h lighting group increased and the lymphocytes become denser ;the bursa of fabricius nodule area enlarge and lymphocytes were in denser arrangement; the diameter of the splenic corpuscle increased, the germinal center of splenic corpuscle become obvious, and the periarterial lymphatic sheaths thickened. The results showed that different levels of melatonin have significant effect on the tissue structure of chickens'lymphoid organs under different lighting conditions, It was indicated that melatonin could affect the development of the main lymphoid organs, then affect the secretion of lymphocytes, thereby influence the entire immune function.