Hypothalamus, temperature regulation, and feeding in the rat

Hamilton, CL; Ciaccia, PJ

doi:10.1152/ajplegacy.1971.221.3.800

Cited by 25 publications

(9 citation statements)

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“…Similar effects have been reported in pigs (35) and baboons (76). Although similar studies in dogs and rats reported inhibition rather than stimulation of drinking in response to heating of the hypothalamus (30,77), this may have reflected compensatory responses to changes in whole body temperature rather than direct effects of temperature changes in the preoptic area.…”

Section: Integration Of Temperature and Fluid Homeostasissupporting

confidence: 70%

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

Sladek

Johnson

2013

American Journal of Physiology-Regulatory, Integrative and Comp

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Sladek CD, Johnson AK. Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels. Am J Physiol Regul Integr Comp Physiol 305: R669 -R678, 2013. First published July 24, 2013 doi:10.1152/ajpregu.00270.2013.-Maintenance of body water homeostasis is critical for preventing hyperthermia, because evaporative cooling is the most efficient means of dissipating excess body heat. Water homeostasis is achieved by regulation of water intake and water loss by the kidneys. The former is achieved by sensations of thirst that motivate water acquisition, whereas the latter is regulated by the antidiuretic action of vasopressin. Vasopressin secretion and thirst are stimulated by increases in the osmolality of the extracellular fluid as well as decreases in blood pressure and/or blood volume, signals that are precipitated by water depletion associated with the excess evaporative water loss required to prevent hyperthermia. In addition, they are stimulated by increases in body temperature. The sites and molecular mechanisms involved in integrating thermal and osmotic regulation of thirst and vasopressin secretion are reviewed here with a focus on the role of the thermal and mechanosensitive transient receptor potential-vanilloid (TRPV) family of ion channels. thirst; TRPV; vasopressin; hypothalamus MAINTENANCE of a constant body temperature by homeotherms is critically dependent on body water homeostasis, because evaporative cooling is the most efficient means that homeotherms have for dissipating excess body heat. Even at rest, heat is generated as a by-product of basal cellular metabolism and the ongoing muscle activity of the heart beating, respiration, and gastrointestinal motility. For a typical 70-kg man the resting (basal) rate of metabolic heat production is about 80 kcal/h, but intense exercise can increase heat production to 400 -600 kcal/h. Thus the body must have efficient mechanisms for dissipating heat to prevent hyperthermia. In humans, body heat is dissipated by passive transfer of heat from the skin to the air. The heat generated by muscles and internal organs is transferred to the skin by the blood flowing through epidermal capillaries. Thus heat loss can be increased by increasing skin blood flow and by increasing the movement of air next to the skin by removing clothing and standing near a fan or in a breeze. However, evaporative cooling significantly augments heat loss from the skin, because evaporation of 1 gram of water from the skin dissipates 0.6 kcal. Thus a sweat rate of 1 l/h could theoretically remove 600 kcal/h from the body. Furcovered mammals also rely heavily on evaporative cooling for maintaining body temperature with increased body temperature promoting panting, increased salivation, and saliva spreading in dogs, cats, and rats. However, water loss of the magnitude required in many instances to adequately dissipate excess body heat must be compensated to prevent electrolyte imbalance and preserve blood volume for adequate cardiovascular function. Thus mechanis...

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Section: Integration Of Temperature and Fluid Homeostasissupporting

confidence: 70%

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

Sladek

Johnson

2013

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Based on these Wndings it has been proposed that neurons in the dorsomedial hypothalamus play a vital role in a variety of thermoregulatory responses, including behaviour (Nagashima 2006;Dimicco and Zaretsky 2007). Indeed, it has been known for some time that the dorsomedial hypothalamus is involved in chemical signals related to food consumption and ingestive behaviour both of which represent hypothalamic functions linked with thermoregulation (Hamilton and Ciaccia 1971). For instance, leptin, a peptide involved in feeding behaviour, raises body temperature in mice and rats (Stehling et al 1997) and is implicated in the human behavioural, autonomic, and endocrine control of nycthemeral body temperature rhythm (Simon et al 1998).…”

Section: Thermosensors Involved In Behavioural Thermoregulatory Respomentioning

confidence: 99%

Functional architecture of behavioural thermoregulation

Flouris

2010

Eur J Appl Physiol

103

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The human thermoregulatory system relies primarily on behavioural adaptation and secondarily on autonomic and endocrine responses for thermal homeostasis. This is because autonomic and endocrine responses have a limited capacity in preventing hyper/hypothermia in extreme environments. Until recently, the neuroanatomy of behavioural thermoregulation as well as the neuroanatomic substrate of the various thermoregulatory behaviours remained largely unknown. However, this situation has changed in recent years as behavioural thermoregulation has become a topic of considerable attention. The present review evaluates the current knowledge on behavioural thermoregulation in order to summarize the present state-of-the-art and to point towards future research directions. Findings on the fundamental distinction between thermal (dis)comfort and sensation are reviewed showing that the former drives behaviour while the latter initiates autonomic thermoregulation. Moreover, the thermosensitive neurons and thermoeffector functions of behavioural thermoregulation are presented and analysed in a detailed discussion.

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“…Historically, the DMH had been implicated in feeding and metabolic regulation associated with ingestive behavior (for a review, see Ref. 12), phenomena closely linked to thermoregulation for decades (70,105,169). Consequently, the finding that IBAT weight was significantly reduced in rats with lesions of the DMH (13) was interpreted only in this context.…”

Section: Search For a Hypothalamic "Thermogenic Center"mentioning

confidence: 99%

The dorsomedial hypothalamus: a new player in thermoregulation

DiMicco

Zaretsky

2007

American Journal of Physiology-Regulatory, Integrative and Comp

259

218

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Neurons in the dorsomedial hypothalamus (DMH) play key roles in physiological responses to exteroceptive ("emotional") stress in rats, including tachycardia. Tachycardia evoked from the DMH or seen in experimental stress in rats is blocked by microinjection of the GABA(A) receptor agonist muscimol into the rostral raphe pallidus (rRP), an important thermoregulatory site in the brain stem, where disinhibition elicits sympathetically mediated activation of brown adipose tissue (BAT) and cutaneous vasoconstriction in the tail. Disinhibition of neurons in the DMH also elevates core temperature in conscious rats and sympathetic activity to least significant difference interscapular BAT (IBAT) and IBAT temperature in anesthetized preparations. The latter effects are blocked by microinjection of muscimol into the rRP, while microinjection of muscimol into either the rRP or DMH suppresses increases in sympathetic nerve activity to IBAT, IBAT temperature, and core body temperature elicited either by microinjection of PGE(2) into the preoptic area (an experimental model for fever), or central administration of fentanyl. Neurons concentrated in the dorsal region of the DMH project directly to the rRP, a location corresponding to that of neurons trans-synaptically labeled from IBAT. Thus these neurons control nonshivering thermogenesis in rats, and their activation signals its recruitment in diverse experimental paradigms. Evidence also points to a role for neurons in the DMH in thermoregulatory cutaneous vasoconstriction, shivering, and endocrine adjustments. These directions provide intriguing avenues for future exploration that may expand our understanding of the DMH as an important hypothalamic site for the integration of autonomic, endocrine, and behavioral responses to diverse challenges.

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Hypothalamus, temperature regulation, and feeding in the rat

Cited by 25 publications

References 0 publications

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels

Functional architecture of behavioural thermoregulation

The dorsomedial hypothalamus: a new player in thermoregulation

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