Central Thermoregulation

Central neural circuits orchestrate a homeostatic repertoire to maintain body temperature during environmental temperature challenges. Heat loss mechanisms for heat defense include cutaneous vasodilation and evaporative cooling. The activation of these effectors is regulated by parallel but distinct, effector-specific, core efferent pathways within the central nervous system that share a common peripheral thermal sensory input. The central thermoregulatory system receives signals related to changes in environmental temperature through thermoreceptors in primary sensory nerve endings distributed in the skin. The spinoparabrachiopreoptic thermal afferent pathway that triggers involuntary thermoregulatory responses is distinct from the spinothalamocortical pathway, in which lamina I neurons synapse on neurons in the thalamus that project to the primary somatosensory cortex, which leads to perception and discrimination of cutaneous temperature. Glutamatergic stimulation of MnPO neurons, rather than those in medial (MPO) or lateral preoptic areas, evokes thermogenic, metabolic and tachycardic responses similar to those evoked during cold-defense. The rRPa is a prominent site of neurons that multisynaptically innervate BAT, the heart, skeletal muscle fibers and cutaneous blood vessels.