Thermal regulation neurotransmitters – mediators, hormones
The exact mechanism of chemical neuromediation in the preoptic region of the anterior part of the hypothalamus (ACP) has not been elucidated, although it is known that several different substances are involved. Noradrenaline and 5-hydroxytryptamine are synaptic neurotransmitters in the thermostat, and acetylcholine is in the “set point”.
The latter is also very sensitive to local changes in the ratio of sodium and calcium concentrations. The introduction of sodium in the preoptic region of the hypothalamus causes a rapid increase in body temperature, and the introduction of calcium – the same rapid its fall. The role of prostaglandins as mediators in the “set point” is limited to participation in the increase of its temperature in febrile states. It is believed that prostaglandins do not matter in maintaining the normal temperature of the “set point”.
Instructions emanating from the hypothalamic preoptic region are performed through the neuroendocrine system. Under the control of the sympathetic nervous system are sweating, piloerection, skin blood flow, as well as the release of adrenaline and noradrenaline from the adrenal medulla and adrenergic nerve endings. In general, heat retention is noradrenergic, and heat loss is a cholinergic function.
Muscle tone and tremor are mediated through the spinal cord and the motor neurons located in its lower part. Metabolism is regulated by TSH and, probably, ACTH, the release of which from the pituitary is under the control of the ri-leasing factors of the posterior part of the hypothalamus. Feedbacks of this system are very subtle and complex.
Higher brain centers are also involved in thermoregulation. As emphasized above, volitional behavior aimed at maintaining a person’s temperature includes the choice of clothing, shelter, nature of physical activity and nutrition. It is possible that cortical perceptions, both conscious and unconscious, of the weather and seasons are a source of information for the preoptic region of the hypothalamus.