Expression and localization of aquaporins in the renal system of the goat (Capra hircus) under tropical climatic conditions

Abstract

Abstract A lack of adequate quality and quantity of water impacts goat physiology. Goats may adapt in harsh climatic conditions lacking water by changing their expression of aquaporin (AQP) genes for effective water absorption. The present study aimed to study the seasonal mRNA expression of aquaporins (AQP1, AQP2 and AQP3) in the renal system of goat (Capra hircus) concerning their thermoregulation. Tissue samples of the renal cortex, renal medulla, ureter and urinary bladder of 10 male goats aged two years were collected from the slaughterhouse at Karnal, Haryana each during the summer (hot), spring (thermoneutral) and winter (cold) seasons and analyzed for gene expression by real time-polymerized chain reactions and their immunolocalization. The physiological responses of the animals were recorded before slaughtering of experimental animals. The study confirmed the mRNA expression and immunohistolocalization of AQP1, AQP2 and AQP3 in the renal system of goats. AQP1 was found to be higher in the cortex of the renal system during summer in comparison to winter. The relative expressions of AQP2 and AQP3 were higher in the renal medulla than in the renal cortex during the summer. The seasonal variations in AQP1 mRNA expression was found non-significant in ureter of goats, but significantly (p < 0.05) higher during summer comparison to winter in urinary bladder of goat. The relative expression of AQP2 and AQP3 were found to be upregulated in both ureter and urinary bladder tissue sample during summer. The relative mRNA expression of AQP3 was found to be significantly (p < 0.05) higher in ureter and urinary bladder as compared to AQP1 and AQP2 during summer season. The fluctuations in aquaporins gene expression during water stress and hyperosmotic conditions of renal cells suggest the aquaporins genes’ beneficial participation in preserving the body's water balance.Variations in the serumhormone assay components were observed in the goats during the summer seasons. The significant (p < 0.05) increase in the aldosterone (ALD) andvasopressin/anti-diuretic hormone (ADH) concentrations was high during summer, showing a direct relationship with efficient water balancing mechanisms in the body of goat during different seasons in tropical climatic conditions.