Effects of dietary n-6/n-3 polyunsaturated fatty acid ratios on the mass, and histological and ultrastructures of liver, spleen and thymus of 70-day-old Yangzhou goslings

Liver Function of Male Rats Exposed to Manganese at Different Time Points

As an essential trace element in the human body, manganese (Mn) is involved in many important biochemical reactions. However, excessive exposure to manganese can cause multiple systematic damages to the body. This study aims to investigate the effects of manganese exposure on serum hepatic enzymes in male rats at different time points. After adaptive feeding for 7 days, male Sprague-Dawley (SD) rats were injected intraperitoneally with 30 mg/kg MnCl₂·4H₂O once a day for 21 days at zeitgeber time point 2 (ZT2), ZT8, ZT14, and ZT20, respectively. We found that short-term repeated exposure to manganese caused slower body weight gain and increased relative liver and spleen weight index in male rats at different time points. Moreover, serum total bile acid (TBA) increased while aspartate aminotransferase (AST) decreased at ZT2, ZT8, and ZT20. Cholinesterase (ChE) decreased at ZT2 and ZT20, lactic dehydrogenase (LDH) decreased at ZT2, ZT14, and ZT20, and acid phosphatase (ACP) decreased at ZT2 and ZT14. Alkaline phosphatase (ALP) decreased at ZT2, ZT14, and ZT20, but increased at ZT8. Alanine amino transferase (ALT) decreased at ZT2 and ZT20, but increased at ZT8. There was a negative correlation between relative liver weight index with AST, ACP, ALP, and LDH, while a positive correlation with TBA. However, relative spleen weight index had a positive correlation with relative liver weight index and TBA, while a negative correlation with ALT, AST, ACP, ALP, LDH, and ChE. Our study shows that the injury of liver function is caused by short-term repeated manganese exposure at different time points. The time effect should be considered in manganese toxicity evaluation.

Morphological characterization of postembryonic development of blood-spleen barrier in duck

The spleen is the largest peripheral lymphoid organ and an important site of immune response, in which the blood–spleen barrier (BSB) plays a significant role to resist various pathogens. The BSB structure of duck spleen is different from that of chicken and mammals. However, no information about the development of BSB after the postembryonic age has been reported in ducks. The current study observed the spleen of 1, 7, 14, 21, 35, and 60-day-old ducks by light and electron microscopy to analyze the cellular structural development. The results showed that the spleen index was continuously increased from 1 to 14-day-old ducks. During their early age, the spleen of ducks showed no definite zone of white and red pulp, but the area of the white pulp was large compared to that of the red pulp. The diameter of the ellipsoid was constantly increased in up to 35-day-old duck spleen, while the periellipsoidal lymphatic sheath (PELS) and periarterial lymphatic sheath continuously developed after 1 D. The reticular fibers developed with age; their branching reached the ellipsoidal wall to show a developed framework in the BSB of 14-day-old ducks. After 7 D, the endothelial cells of the sheathed capillary showed a typical cuboidal shape; between these cells, the gaps increased as age advanced, while the thickness of the basement membrane and collagen fibers increased in 35-day-old ducks. The mechanical filtration function of BSB by intravenous injection showed a 1-layer ring of carbon particles restricted in the white pulp in 1-day-old duck spleen; however, in 14 to 60 D, these particles were restricted in the ellipsoid and PELS, forming 2-layer rings of carbon particles. Collectively, the cellular features of the duck BSB developed up to 35 D of postembryonic age to perform their immune function.