Expression and Immunolocalization of Aquaporins in the Buffalo Liver and Adipose Tissue

Abstract

Increasing incidences of fatty liver in humans and animals worldwide is the leading cause of liver related morbidities. Currently, in the face of the growing global increase in fatty liver, and the necessity to explore new factors significantly affecting it, aquaporins (AQPs) have become the focus of interest for many researchers. AQPs are membrane integral proteins involved in the transport of water, glycerol and other small solutes. These are expressed in all tissues and play multiple roles under normal and pathophysiological conditions. Despite ongoing advancements in understanding the involvement of aquaporins in metabolic processes, there remains a notable lack of knowledge concerning cellular and subcellular localization of the AQPs in bovine tissues and organs. Understanding this could provide a new therapeutic target for metabolic syndromes such as fatty liver disease in bovine. In this study, AQPs in bovine liver, adipose tissue and gall bladder are examined using immunohistochemistry. AQP9 immunoreactivity is predominantly detected at the sinusoidal surfaces of hepatocytes. AQP8 is mostly intracellular and localized to the central vein and sinusoid, whereas AQP7 is found around the portal vein. Notably, AQP3 is observed in the bovine gall bladder and adipose tissue but not in the liver. In adipose tissue, AQP7 is also detected in the cytoplasmic membranes of adipocytes. AQPs in liver and adipose tissue were also studied using the western blotting technique. Higher AQP9 and AQP3 expression is observed in the liver and adipose tissue, respectively, indicating they are the dominant aquaporins in these tissues. This suggests they could be potential therapeutic targets for treating fatty liver disease and other metabolic disorders in bovine.