Skin TRPA1 ion channel participates in thermoregulatory response to cold. Comparison with the effect of TRPM8.

There was no clear evidence of the TRPA1 ion channel involvement in the formation of thermoregulatory responses. The present results convincingly show that the skin TRPA1 ion channel activation has significant influence on the formation of thermoregulatory responses of the body to cooling; it is especially strongly manifested for the metabolic component. At the TRPA1 activation by its agonist AITC (0.

Effect of Activation of Peripheral Ion Channel TRPM8 on Gene Expression of Thermosensitive TRP Ion Channels in the Hypothalamus. Comparison with the Effect of Cooling.

Experiments on rats showed that activation of the peripheral ion channel TRPM8 with menthol and rapid cooling (decrease in core temperature by 3°C) led to 1.5-fold activation of the expression of TRPV3 ion channel gene in the posterior hypothalamus, but had no effect on the expression of this gene in the anterior hypothalamus. Neither stimulation of peripheral TRPМ8, nor acute cooling affected the expression of genes for other thermosensitive ion channels (TRPV1, TRPV2, TRPV4, TRPA1, and TRPМ8) in the hypothalamus.

Participation of Purinergic PX Receptors in the Thermoregulatory Response to Cooling.

We studied the role of purinergic PX receptors in the body response to cooling. In experiments on rats, PX receptor antagonist PPADS was administered in different modes, which resulted in changes of different characteristics of the thermoregulatory response to cold. Iontophoresis of PX antagonist into the skin decreased the thermal thresholds of all thermoregulatory responses to cooling, which can attest to a modulating effect of PX receptors on peripheral thermosensitive afferents.

[Effect of TRPM8 ion channel activation on thermoregulatory response to cooling].

In rats, the effect of activation of the cold- and menthol-sensitive TRPM8 ion channel on different thermoregulatory parameters: total oxygen consumption, carbon dioxide release, respiration coefficient, constriction response of skin blood vessels, muscle activity, was studied. Activation of TRPM8 with menthol even in thermoneutral conditions produces an increase in oxygen consumption and a decrease in respiratory coefficient, which may suggest enhanced non-shivering thermogenesis and lipolysis. Rapid cooling against the background of TRPM8 activation is characterized by a decrease in the temperature thresholds of all thermoregulatory responses without associated changes in sequences of their initiation as well as in enhancement of metabolic component of emergency thermogenesis which leads to improved maintenance of core temperature in conditions when external cold acts on the organism.

The role of alpha1- and beta-adrenoceptors in initiation and development of thermoregulatory reactions during fast and slow cooling.

Ionophoretic application of alpha1- and beta-adrenoceptor blockers into the skin produces no effect on the parameters of thermal homeostasis under thermoneutral conditions. alpha1-Adrenoblocker verapamil inhibits cold shivering during fast and slow cold exposure; it elevates the temperature threshold and moderates the vasoconstrictor response during rapid cooling. These changes are accompanied by a compensatory decrease in the threshold and stimulation of non-shivering thermogenesis.

Effect of substance P on thermoregulation parameters during different cooling modes.

The modulatory effect of ionophoretic application of substance P to the skin on the formation of the cold-triggered thermal protection reactions depends on the rate of cooling. During rapid cooling substance P enhances heat production, while during slow cooling it promotes constriction of skin blood vessels aimed at reduction of heat emission.

[Characteristics of responses of the sympatho-adrenal system to various types of cooling].

Fast cooling involving the dynamic activity of the skin cold receptors seems to establish a condition for changes in catecholamine concentration at a lesser decrease of body temperature as compared with slow cooling.

Effects of slow and rapid cooling on catecholamine concentration in arterial plasma and the skin.

Norepinephrine (NE) and epinephrine (Epi) concentrations in arterial plasma and in skin tissue were measured chromatographically before and after external cooling. Urethan-anesthetized rats were cooled either slowly (0.004-0.