Hypothalamic TRPM8 and TRPA1 ion channel genes in the regulation of temperature homeostasis at water balance changes.

ABSTRACT

The role of the hypothalamic cold-sensitive ion channels - transient receptor potential melastatin 8 (TRPM8) and transient receptor potential ankyrin 1 (TRPA1) in homeostatic systems of thermoregulation and water-salt balance - is not clear. The interaction of homeostatic systems of thermoregulation and water-salt balance without additional temperature load did not receive due attention, too. On the models of water-balance disturbance, we tried to elucidate some aspect of these problems. Body temperature (Tbody), O2 consumption, CO2 excretion, electrical muscle activity (EMA), temperature of tail skin (Ttail), plasma osmolality, as well as gene expression of hypothalamic TRPM8 and TRPA1 have been registered in rats of 3 groups control; water-deprived (3 days under dry-eating); and hyperhydrated (6 days without dry food, drinking liquid 4 % sucrose). No relationship was observed between plasma osmolality and gene expression of Trpm8 and Trpa1. In water-deprived rats, the constriction of skin vessels, increased fat metabolism by 10 % and increased EMA by 48 % allowed the animals to maintain Tbody unchanged. The hyperhydrated rats did not develop sufficient mechanisms, and their Tbody decreased by 0.8 °C. The development of reactions was correlated with the expression of genes of thermosensitive ion channels in the anterior hypothalamus. Ttail had a direct correlation with the expression of the Trpm8 gene, whereas EMA directly correlated with the expression of the Trpa1 gene in water-deprived group. The obtained data attract attention from the point of view of management and correction of physiological functions by modulating the ion channel gene expression.