[Frontiers in Bioscience 16, 74-104, January 1, 2011]

Central neural pathways for thermoregulation

Shaun F. Morrison1, Kazuhiro Nakamura2

1Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006 USA, 2Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Temperature sensation
3.1. Cutaneous thermal receptor afferent pathway
3.1.1. Cutaneous thermoreception
3.1.2. Dorsal horn
3.1.3. Lateral parabrachial nucleus
3.2. Visceral and spinal thermal receptor afferents
3.3. Temperature sensation within the preoptic area (POA)
3.4. Sensorimotor integration of thermoregulation in the POA
3.4.1. Role of POA neurons in the cold-defense responses to cutaneous thermal afferents
3.4.2. Febrile response to the pyrogenic mediator, prostaglandin (PG) E2
4. Pathways to thermoregulatory effectors
4.1. Thermoregulatory behavior
4.2. Cutaneous vasoconstriction (CVC)
4.3. Thermogenesis in brown adipose tissue (BAT)
4.3.1. Rostral ventromedial medulla contains BAT sympathetic premotor neurons
4.3.2. Dorsomedial hypothalamus (DMH) neurons drive BAT thermogenesis
4.3.3. Spinal sympathetic mechanisms controlling BAT thermogenesis and CVC
4.4. Cardiac thermogenesis
4.5. Shivering thermogenesis
4.6. Evaporative cooling
5. Summary and perspective
6. Acknowledgement
7. References

1. ABSTRACT

Central neural circuits orchestrate a homeostatic repertoire to maintain body temperature during environmental temperature challenges and to alter body temperature during the inflammatory response. This review summarizes the functional organization of the neural pathways through which cutaneous thermal receptors alter thermoregulatory effectors: the cutaneous circulation for heat loss, the brown adipose tissue, skeletal muscle and heart for thermogenesis and species-dependent mechanisms (sweating, panting and saliva spreading) for evaporative heat loss. These effectors are regulated by parallel but distinct, effector-specific neural pathways that share a common peripheral thermal sensory input. The thermal afferent circuits include cutaneous thermal receptors, spinal dorsal horn neurons and lateral parabrachial nucleus neurons projecting to the preoptic area to influence warm-sensitive, inhibitory output neurons which control thermogenesis-promoting neurons in the dorsomedial hypothalamus that project to premotor neurons in the rostral ventromedial medulla, including the raphe pallidus, that descend to provide the excitation necessary to drive thermogenic thermal effectors. A distinct population of warm-sensitive preoptic neurons controls heat loss through an inhibitory input to raphe pallidus neurons controlling cutaneous vasoconstriction.