In ovo embryotoxicity of α-endosulfan adversely influences liver and brain metabolism and the immune system in chickens

There is a lack of laboratory-based embryonic chicken toxicity studies with the ecologically relevant low dose/s of endosulfan that utilizes a more practical approach such as the chorioallontoic membrane (CAM) injection. In this investigation, 2μg AR grade α-endosulfan/egg (40% of LD50 for embryos) was injected through the CAM in 12-day-old chicken embryos and the activities of glucose-6-phosphatase (G6Pase, EC 3.1.3.9), fructose 1,6-diphosphatase (FDPase, EC 3.1.3.11), adenosine triphosphatase (ATPase, EC 3.6.1.3) and succinic dehydrogenase (SDH, EC 1.3.99.1) and DNA and RNA content in liver and brain tissues and acetyl cholinesterase (AChE, EC 3.1.1.7) in the latter were determined at 24, 48, and 72 h post-exposure. The wet weight of the embryos did not differ between groups. Following endosulfan exposure, except increase in the hepatic ATPase activity (P < 0.01), there was a significant decrease in the following parameters: G6Pase activity in both the liver and brain (P < 0.01), SDH activity in the brain (P < 0.01), brain overall DNA and RNA concentration (P < 0.05), brain AChE activity (P < 0.01). Exposure of 18-day-old embryos to 2-μg endosulfan for 24 h caused decrease (P < 0.01) in the lymphocyte count and IgG content. Histopathology of thymus and bursa of Fabricius revealed a reduction in the population of thymic follicles, smaller thymocytes with the clear vacuoles in cytoplasm and fewer bursocytes accompanied by infiltration of erythrocytes in lymphoid follicles of the endosulfan-treated embryos. It was inferred that in ovo injection of 0.041 μg/g egg weight of α-endosulfan suppress gluconeogenesis (main energy source in embryonic life), nerve transmission, and immunity.