The Effect of Hypertension on the Expression of the TRPM2 and TRPM8 Ion Channel Genes in the Hypothalamus and Kidneys: the Relationship with Blood Pressure

While studying arterial hypertension, increasing attention is being paid to TRP (Transient Receptor Potential) ion channels, which are believed to be involved in the pathogenesis of this disease. However, the exact mechanisms of this involvement remain to be determined. The TRPM2 and TRPM8 ion channels of the hypothalamus and kidneys may be involved in the regulation of blood pressure in hypertensions. In this work, quantitative RT-PCR was used to compare the expression of the TRPM2 and TRPM8 ion channel genes in normotensive Wistar Albino Glaxo (WAG) rats and rats with inherited stress-induced arterial hypertension (ISIAH) in the hypothalamus, as the center of regulation of visceral functions, and in the kidney, as an organ that is directly involved in the mechanisms of blood pressure regulation. It was shown that hypertensive rats differ from normotensives in the mRNA levels of Trpm2 and Trpm8 in both the hypothalamus and kidney. In the hypothalamus, the expression of the genes of these ion channels is reduced—Trpm2 by 20%, Trpm8 by 100%, whereas in the kidney the expression is significantly (1.5–2 times) increased for both genes. A direct correlation was identified between the mRNA level of Trpm2 and Trpm8 in the anterior hypothalamus and the level of systolic blood pressure in hypertensive rats (r = 0.633, p = 0.027 and r = 0.658, p = 0.039—for Trpm2 and Trpm8 respectively). It was found that the antihypertensive drug losartan increases the expression of the Trpm2 gene in the hypothalamus without affecting expression of this gene in the kidney. The results obtained in this study expand the understanding of the functional significance of the hypothalamic ion channels TRPM2 and TRPM8, and also suggest their involvement in the central mechanisms of blood pressure regulation in rats with inherited arterial hypertension.