Prolactine receptor expression in kidney tissue of female rats with cholestasis: the effect of hyperprolactinemia

The Role of Hormones and Trophic Factors as Components of Preservation Solutions in Protection of Renal Function before Transplantation: A Review of the Literature

Transplantation is currently a routine method for treating end-stage organ failure. In recent years, there has been some progress in the development of an optimal composition of organ preservation solutions, improving the vital functions of the organ and allowing to extend its storage period until implantation into the recipient. Optimizations are mostly based on commercial solutions, routinely used to store grafts intended for transplantation. The paper reviews hormones with a potential nephroprotective effect, which were used to modify the composition of renal perfusion and preservation solutions. Their effectiveness as ingredients of preservation solutions was analysed based on a literature review. Hormones and trophic factors are innovative preservation solution supplements. They have a pleiotropic effect and affect normal renal function. The expression of receptors for melatonin, prolactin, thyrotropin, corticotropin, prostaglandin E1 and trophic factors was confirmed in the kidneys, which suggests that they are a promising therapeutic target for renal IR (ischemia-reperfusion) injury. They can have anti-inflammatory, antioxidant and anti-apoptotic effects, limiting IR injury.

Prolactin Receptor Isoforms as the Basis of Tissue-Specific Action of Prolactin in the Norm and Pathology

The review describes functional and structural features of different isoforms of prolactin receptor, mechanisms of signaling pathway activation, and molecular messengers involved in the transmission and termination of signal from the prolactin receptor isoforms. Changes in the ratio between prolactin receptor isoforms, key mediators of prolactin signal transduction and termination in various organs and tissues, are analyzed. Special attention is given to the role of molecular mediators and the ratio between the isoforms in normal physiological functions and pathologies. Approaches for therapeutic correction of prolactin signaling impairments are discussed.

Role of Na+/K+-ATPase in Natriuretic Effect of Prolactin in a Model of Cholestasis of Pregnancy

Participation of Na+/K+-ATPase in the natriuretic effect of prolactin in a cholestasis of pregnancy model was investigated. The Na+/K+-ATPase activity in rat kidney medulla, where active sodium reabsorption occurs, decreased in the model of cholestasis of pregnancy and other hyperprolactinemia types compared with intact animals. This effect was not connected with the protein level of α1- and β-subunits of Na+/K+-ATPase measured by Western blotting in the kidney medulla. Decrease in Na+/K+-ATPase activity in the kidney cortex was not significant, as well as decrease in the quantity of mRNA and proteins of the α1- and β-subunits of Na+/K+-ATPase. There were no correlations between the Na+/K+-ATPase activity and sodium clearance, although sodium clearance increased significantly in the model of cholestasis of pregnancy and other hyperprolactinemia groups under conditions of stable glomerular filtration rate measured by creatinine clearance. We conclude that the Na+/K+-ATPase is not the only mediator of the natriuretic effect of prolactin in the model of cholestasis of pregnancy.

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.

Effect of hyperprolactinemia on PRL-receptor expression and activation of Stat and Mapk cell signaling in the prostate of long-term sexually-active rats

The abnormal elevation of serum PRL, referred to as hyperprolactinemia (HyperPRL), produces alterations in several reproductive parameters of male rats such as penile erection or decreased tendency to reach ejaculation. Additionally, this situation produces a significant modification of prostate histology, as observed in the epithelial structure and alveolar area, which could reach a level of hyperplasia in the long-term. In this tissue, HyperPRL produces an increase in expression of PRL receptors and activation of the Stat3 signaling pathway that is correlated with the evolution of prostate pathologies. However, the impact of HyperPRL in long-term sexually active male rats is unknown. In this work, using constantly copulating Wistar male rats with induced HyperPRL, we analyzed the level of serum PRL, the effect on prostate PRL receptors, and activation of pStat3, pStat5 and Mapk signaling pathways. Two procedures to induce HyperPRL were employed, comprising daily IP administration or adenohypophysis transplant, and although neither affected the execution of sexual behavior, the serum PRL profile following successive ejaculations was affected. Messenger RNA expression of the short and long isoforms of the PRL receptor at the ventral prostate was affected in different ways depending on the procedure to induce HyperPRL. The ventral prostate did not show any modification in terms of activation of the pStat5 signaling pathway in subjects with daily administration of PRL, although this was significantly increased in ADH transplanted subjects in the second and fourth consecutive ejaculation. A similar profile was found for the pStat3 pathway which additionally showed a significant increase in the third and fourth ejaculation of daily-injected subjects. The Mapk signaling pathway did not show any modifications in subjects with daily administration of PRL, but showed a significant increase in the second and third ejaculations of subjects with ADH transplants. Thus, although sexual behavior was not modified, HyperPRL modified the expression of PRL receptors and the activation of signal pathways in the prostate tissue. Hence, it is probable that prostatic alterations precede the sexual behavioral deficits observed in subjects with HyperPRL.

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.