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Advances in Physiology Education Sep 2015Thermoregulation is the maintenance of a relatively constant core body temperature. Humans normally maintain a body temperature at 37°C, and maintenance of this... (Review)
Review
Thermoregulation is the maintenance of a relatively constant core body temperature. Humans normally maintain a body temperature at 37°C, and maintenance of this relatively high temperature is critical to human survival. This concept is so important that control of thermoregulation is often the principal example cited when teaching physiological homeostasis. A basic understanding of the processes underpinning temperature regulation is necessary for all undergraduate students studying biology and biology-related disciplines, and a thorough understanding is necessary for those students in clinical training. Our aim in this review is to broadly present the thermoregulatory process taking into account current advances in this area. First, we summarize the basic concepts of thermoregulation and subsequently assess the physiological responses to heat and cold stress, including vasodilation and vasoconstriction, sweating, nonshivering thermogenesis, piloerection, shivering, and altered behavior. Current research is presented concerning the body's detection of thermal challenge, peripheral and central thermoregulatory control mechanisms, including brown adipose tissue in adult humans and temperature transduction by the relatively recently discovered transient receptor potential channels. Finally, we present an updated understanding of the neuroanatomic circuitry supporting thermoregulation.
Topics: Adaptation, Physiological; Adult; Body Temperature; Body Temperature Regulation; Female; Fever; Humans; Hypothermia; Male; Sensitivity and Specificity; Shivering; Skin Temperature; Sweating; Thermoreceptors; Thermosensing
PubMed: 26330029
DOI: 10.1152/advan.00126.2014 -
Physiological Reviews Apr 2020The transient receptor potential ankyrin (TRPA) channels are Ca-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only... (Review)
Review
The transient receptor potential ankyrin (TRPA) channels are Ca-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.
Topics: Animals; Calcium Signaling; Channelopathies; Chemoreceptor Cells; Humans; Inflammation; Mechanoreceptors; Mechanotransduction, Cellular; Nociception; Nociceptors; Pain; Sensory Receptor Cells; TRPA1 Cation Channel; Thermoreceptors; Thermosensing
PubMed: 31670612
DOI: 10.1152/physrev.00005.2019 -
American Journal of Physiology.... Nov 2011Body temperature regulation is a fundamental homeostatic function that is governed by the central nervous system in homeothermic animals, including humans. The central... (Review)
Review
Body temperature regulation is a fundamental homeostatic function that is governed by the central nervous system in homeothermic animals, including humans. The central thermoregulatory system also functions for host defense from invading pathogens by elevating body core temperature, a response known as fever. Thermoregulation and fever involve a variety of involuntary effector responses, and this review summarizes the current understandings of the central circuitry mechanisms that underlie nonshivering thermogenesis in brown adipose tissue, shivering thermogenesis in skeletal muscles, thermoregulatory cardiac regulation, heat-loss regulation through cutaneous vasomotion, and ACTH release. To defend thermal homeostasis from environmental thermal challenges, feedforward thermosensory information on environmental temperature sensed by skin thermoreceptors ascends through the spinal cord and lateral parabrachial nucleus to the preoptic area (POA). The POA also receives feedback signals from local thermosensitive neurons, as well as pyrogenic signals of prostaglandin E(2) produced in response to infection. These afferent signals are integrated and affect the activity of GABAergic inhibitory projection neurons descending from the POA to the dorsomedial hypothalamus (DMH) or to the rostral medullary raphe region (rMR). Attenuation of the descending inhibition by cooling or pyrogenic signals leads to disinhibition of thermogenic neurons in the DMH and sympathetic and somatic premotor neurons in the rMR, which then drive spinal motor output mechanisms to elicit thermogenesis, tachycardia, and cutaneous vasoconstriction. Warming signals enhance the descending inhibition from the POA to inhibit the motor outputs, resulting in cutaneous vasodilation and inhibited thermogenesis. This central thermoregulatory mechanism also functions for metabolic regulation and stress-induced hyperthermia.
Topics: Animals; Awards and Prizes; Body Temperature Regulation; Central Nervous System; Feedback, Physiological; Fever; Humans; Neural Pathways; Preoptic Area; Signal Transduction; Skin; Skin Temperature; Thermoreceptors; Thermosensing
PubMed: 21900642
DOI: 10.1152/ajpregu.00109.2011 -
Cell Mar 2002A distinct subset of sensory neurons are thought to directly sense changes in thermal energy through their termini in the skin. Very little is known about the molecules...
A distinct subset of sensory neurons are thought to directly sense changes in thermal energy through their termini in the skin. Very little is known about the molecules that mediate thermoreception by these neurons. Vanilloid Receptor 1 (VR1), a member of the TRP family of channels, is activated by noxious heat. Here we describe the cloning and characterization of TRPM8, a distant relative of VR1. TRPM8 is specifically expressed in a subset of pain- and temperature-sensing neurons. Cells overexpressing the TRPM8 channel can be activated by cold temperatures and by a cooling agent, menthol. Our identification of a cold-sensing TRP channel in a distinct subpopulation of sensory neurons implicates an expanded role for this family of ion channels in somatic sensory detection.
Topics: Amino Acid Sequence; Animals; Antipruritics; CHO Cells; Calcium; Calcium Channels; Cloning, Molecular; Cold Temperature; Cricetinae; Humans; In Situ Hybridization; Menthol; Mice; Molecular Sequence Data; Neurons, Afferent; Patch-Clamp Techniques; Phylogeny; Sequence Alignment; TRPC Cation Channels; Thermoreceptors; Tissue Distribution
PubMed: 11893340
DOI: 10.1016/s0092-8674(02)00652-9 -
Pharmacology & Therapeutics Dec 2022Chronic pain is a major burden for the society and remains more prevalent and severe in females. The presence of chronic pain is linked to persistent alterations in the... (Review)
Review
Chronic pain is a major burden for the society and remains more prevalent and severe in females. The presence of chronic pain is linked to persistent alterations in the peripheral and the central nervous system. One of the main types of peripheral pain transducers are the transient receptor potential channels (TRP), also known as thermoTRP channels, which intervene in the perception of hot and cold external stimuli. These channels, and especially TRPV1, TRPA1 and TRPM8, have been subjected to profound investigation because of their role as thermosensors and also because of their implication in acute and chronic pain. Surprisingly, their sensitivity to endogenous signaling has been far less studied. Cumulative evidence suggests that the function of these channels may be differently modulated in males and females, in part through sexual hormones, and this could constitute a significant contributor to the sex differences in chronic pain. Here, we review the exciting advances in thermoTRP pharmacology for males and females in two paradigmatic types of chronic pain with a strong peripheral component: chronic migraine and chemotherapy-induced peripheral neuropathy (CIPN). The possibilities of peripheral druggability offered by these channels and the differential exploitation for men and women represent a development opportunity that will lead to a significant increment of the armamentarium of analgesic medicines for personalized chronic pain treatment.
Topics: Female; Humans; Male; Analgesics; Chronic Pain; Migraine Disorders; Sex Characteristics; Transient Receptor Potential Channels; Peripheral Nervous System Diseases; Antineoplastic Agents; Thermoreceptors
PubMed: 36202261
DOI: 10.1016/j.pharmthera.2022.108297 -
Temperature (Austin, Tex.) 2017This brief review aims to provide an updated account of the cardiovascular events of awakening, proposing a testable conceptual framework that links these events with... (Review)
Review
This brief review aims to provide an updated account of the cardiovascular events of awakening, proposing a testable conceptual framework that links these events with the neural control of sleep and the autonomic nervous system, with focus on the hypothalamic orexin (hypocretin) neurons. Awakening from non-rapid-eye-movement sleep entails coordinated changes in brain and cardiovascular activity: the neural "flip-flop" switch that governs state transitions becomes biased toward the ascending arousal systems, arterial blood pressure and heart rate rise toward waking values, and distal skin temperature falls. Arterial blood pressure and skin temperature are sensed by baroreceptors and thermoreceptors and may positively feedback on the brain wake-sleep switch, thus contributing to sharpen, coordinate, and stabilize awakening. These effects may be enhanced by the hypothalamic orexin neurons, which may modulate the changes in blood pressure, heart rate, and skin temperature upon awakening, while biasing the wake-sleep switch toward wakefulness through direct neural projections. A deeper understanding of the cardiovascular events of awakening and of their links with skin temperature and the wake-sleep neural switch may lead to better treatments options for patients with narcolepsy type 1, who lack the orexin neurons.
PubMed: 28680929
DOI: 10.1080/23328940.2017.1295128