Manifestation of multidrug resistance protein 3 (MRP3) in liver and kidney cells in cholestasis: effects of hyperprolactinemia

Role of Prolactin in the Regulation of Bicarbonates Biodynamics in Female Rat Model of Cholestasis of Pregnancy

We studied possible involvement of prolactin in the regulation of bicarbonate biodynamics using female rat model of cholestasis of pregnancy induced by transplantation of the donor pituitary under the renal capsule of a recipient (hyperprolactinemia) and bile duct ligation (cholestasis). The concentration of bicarbonates in the bile and blood, their excretion, clearance, and reabsorption, as well as glomerular filtration rate and excretion of sodium ions were assessed. It was found that the main effect of prolactin was directed to the kidney-regulated pool of bicarbonates and consisted in stimulation of their clearance and inhibition of reabsorption, which led to a decrease in bicarbonate blood concentration. Parallel influence of prolactin on the clearance of bicarbonates and sodium ions was observed.

Expression of Multidrug Resistance Protein 2 (mrp2) in the Liver and Kidney Cells of Female Rats with Modeled Cholestasis of Pregnancy

Using immunohistochemical method with semiquantitative analysis of images, we showed that mrp2 expression in response to cholestasis decreased in hepatocytes and cholangiocytes, and remained unchanged in the kidney structures. A decrease of mrp2 expression in renal tubules leading to a decrease of metabolic intoxication of the kidney was demonstrated in cholestasis of pregnancy model. In bile ducts cells, negative correlations of mrp2 with previously measured levels of prolactin receptors, CFTR, and mrp3 were revealed. In renal structures and in hepatocytes, no correlations were found between the expression of these proteins. We hypothesize that prolactin produces a direct effect on mrp2 expression in bile ducts cells mediated by prolactin receptors in cholangiocytes. The absence of correlations between mrp2 and the above-mentioned proteins in hepatocytes and renal structures is most likely related to prolactin effects on other systemic regulators.