Functional role of the preoptic area and anterior hypothalamus in thermoregulation in freely moving rats

Ishiwata, Takayuki; Hasegawa, Hiroshi; Yazawa, Tetsuo; Otokawa, Minoru; Aihara, Yasutsugu

doi:10.1016/s0304-3940(02)00266-5

Cited by 35 publications

(25 citation statements)

References 15 publications

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“…Consistent with this notion, Chen et al (5) demonstrated an inhibitory influence of preoptic neurons on nonshivering thermogenesis: microinjection of the excitatory amino acid DL-homocysteic acid into the POA attenuated nonshivering thermogenesis elicited by electrical stimulation of the ventromedial hypothalamus. Similarly, perfusion of the POA with tetrodotoxin induced hyperthermia and tachycardia in conscious rats, suggesting an inhibitory function of the POA with respect to heat production (13). On the other hand, administration of GABA in the present study had no significant effect on T tail , which was within the baseline level of 29 -32°C.…”

Section: Discussioncontrasting

confidence: 44%

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Osaka

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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Osaka, Toshimasa. Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats. Am J Physiol Regul Integr Comp Physiol 287: R306 -R313, 2004. First published March 18, 2004 10.1152/ajpregu.00003.2004.-Bilateral microinjections of GABA (300 mM, 100 nl) or the GABA A receptor agonist muscimol (100 M, 100 nl) into the preoptic area (POA) of the hypothalamus increased the rate of whole body O 2 consumption (V O2) and the body core (colonic) temperature of urethane-chloralose-anesthetized, artificially ventilated rats. The most sensitive site was the dorsomedial POA at the level of the anterior commissure. The GABA-induced thermogenesis was accompanied by a tachycardic response and electromyographic (EMG) activity recorded from the femoral or neck muscles. Pretreatment with muscle relaxants (1 mg/kg pancuronium bromide ϩ 4 mg/kg vecuronium bromide iv) prevented GABAinduced EMG activity but had no significant effect on GABA-induced thermogenesis. However, pretreatment with the ␤-adrenoceptor propranolol (5 mg/kg iv) greatly attenuated the GABA-induced increase in V O2 and tachycardic responses. Accordingly, the GABA-induced increase in V O2 reflected mainly nonshivering thermogenesis. On the other hand, cooling of the shaved back of the rat by contact with a plastic bag containing 28°C water also elicited thermogenic, tachycardic, and EMG responses. Bilateral microinjections of the GABA A receptor antagonist bicuculline (500 M, 100 nl), but not the vehicle saline, into the POA blocked these skin cooling-induced responses. These results suggest that GABA and GABA A receptors in the POA mediate cold information arising from the skin for eliciting coldinduced thermogenesis. thermoafferent; neurotransmitter; nonshivering thermogenesis THE PREOPTIC AREA (POA) of the hypothalamus is considered to be the primary locus for body temperature regulation, because it integrates thermoafferent signals from the skin and other parts of the body and exerts control over the thermoefferent mechanisms (3,8,15,25). However, the neurotransmitter that mediates thermoafferent signals to the POA is largely unknown, even though there is a great deal of electrophysiological and pharmacological evidence implicating a role for a variety of neurotransmitters, peptides, and cytokines (2, 6, 10, 32).The POA contains GABAergic neurons (27), spontaneously releases GABA to the extracellular space (9, 29), and expresses GABA A receptors (7). Perfusion of the POA with the GABA A agonist muscimol induces hyperthermia, which is not affected by antipyretics and is thus independent of fever, in freely behaving rats (19). Warm-sensitive and thermally insensitive neurons are inhibited by the GABAergic mechanism in the POA (28). Furthermore, it was recently reported that the extracellular GABA level in the POA was increased by acute cold exposure and decreased by heat exposure (14). Therefore, it is possible that GABA is involved in the mechanism of thermoregulation in the POA.Body temperature is regulated by the balance between heat ...

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Section: Discussioncontrasting

confidence: 44%

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Osaka

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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“…When core temperature is being maintained at a set point, cardiovascular responses to cold ambient temperatures are closely related to the mechanism for heat production in rats (Chambers et al 2000), which increases in a parallel fashion with HR. Microdialysis studies in the preoptic anterior hypothalamus have also indicated a correlation between HR and body temperature (Ishiwata et al 2002). This relationship has also been shown in nonhuman primates where disruption of the preoptic anterior hypothalamus by direct cooling leads to high HR and T C , while warming leads to low HR and T C (Morishima and Gale 1972).…”

Section: Discussionmentioning

confidence: 68%

Pharmacological and behavioral determinants of cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, and para-methoxyamphetamine-induced hyperthermia

2007

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“…Therefore, we hypothesized that infusion of Los into the cerebral ventricle would perfuse to the SFO and other thermoregulatory centers situated in the hypothalamus, inhibiting the heat loss response and accelerating the BHR and HSR during prolonged exercise. The POA/AH is thought to be the primary locus for body temperature regulation (1,5,34,35) due to the fact that it contains both warm-sensitive and cold-sensitive neurons that respond to small changes in temperature (19,48). Moreover, lesions or pharmacological blockade of the POA/AH has been shown to produce a severe impairment in thermoregulation (5,6,34,35).…”

Section: Discussionmentioning

confidence: 99%

“…It has been established that the POA/AH is an integrative region for the maintenance of metabolic, vasomotor, and thermal homeostasis (5,6,34,35). It is important to point out that POA/AH cell groups project to the sympathetic outflow of the tail artery involved in heat loss in the rat (38), producing tail vasodilation when the POA is warmed (19,21,48). In addition, it has recently been shown that inhibition of the POA/AH by local infusion of tetrodotoxin impairs heat loss in running rats (16).…”

Section: Discussionmentioning

confidence: 99%

Central angiotensin AT₁-receptor blockade affects thermoregulation and running performance in rats

Leite

Lacerda²,

Marubayashi³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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The effect of central angiotensin AT 1-receptor blockade on thermoregulation in rats during exercise on a treadmill (18 m/min, 5% inclination) was investigated. Core (T b) and skin tail temperatures were measured in rats while they were exercising until fatigue after injection of 2 l of losartan (Los; 20 nmol, n ϭ 4; 30 nmol, n ϭ 4; 60 nmol, n ϭ 7), an angiotensin II AT 1-receptor antagonist, or 2 l of 0.15 mol/l NaCl (Sal; n ϭ 15) into the right lateral cerebral ventricle. Body heat rate (BHR), heat storage rate, threshold Tb for tail vasodilation (TTbV), time to fatigue, and workload were calculated. During exercise, the BHR and heat storage rate of Los-treated animals were, respectively, 40 and 53% higher (P Ͻ 0.01) than in Sal-treated animals. Additionally, rats injected with Los showed an increased TTbV (38.59 Ϯ 0.19°C for Los vs. 38.12 Ϯ 0.1°C for Sal, P Ͻ 0.02), a higher Tb at fatigue point (39.07 Ϯ 0.14°C Los vs. 38.66 Ϯ 0.07°C Sal, P Ͻ 0.01), and a reduced running performance (27.29 Ϯ 4.48 min Los vs. 52.47 Ϯ 6.67 min Sal, P Ͻ 0.01), which was closely related to the increased BHR. Our data suggest that AT1-receptor blockade attenuates heat dissipation during exercise due to the higher TTbV, leading to a faster exercise-induced increase in Tb, thus decreasing running performance. tail vasodilation; fatigue; heat balance ACTING CENTRALLY, ANGIOTENSIN II (ANG II), exerts thermoregulatory effects characterized by a decreased metabolic rate, a fall in core temperature (T b ), and an increase in tail skin temperature (T tail ) (43,44,46), through angiotensin type 1 (AT 1 ) receptors. These receptors are widely spread through the central nervous system (CNS), including the preoptic area/ anterior hypothalamus (POA/AH), regions of the hypothalamus considered to be the integrative centers of body temperature (5,29,34,35). In addition, the subfornical organ (SFO) is critical for the central actions of ANG II (8, 14). The AT 1 -receptor antagonist losartan (Los) has been used to investigate the role of ANG II in T b . Some studies have observed that intracerebroventricular (icv) injection of Los inhibited the hypothermic effect of ANG II, producing an increase in T b of resting animals exposed to a hot environment (7,27). In addition, Horowitz and colleagues (17,36) showed that central administration of Los elevates the temperature threshold for peripheral vasodilation and causes a downward shift in the threshold for evaporative cooling during heat stress, indicating the involvement of hypothalamic angiotensinergic signaling in thermoregulation. Because hypothermia and increased heat dissipation may be neuroprotective, activation of central angiotensinergic transmission may exert important effects on thermoregulation during exercise, influencing running performance.Elevated internal body temperature and increased heat storage (9, 12, 30) have been considered to be limiting factors that reduce the CNS drive for exercise performance (31,32,40) and precipitate feelings of fatigue, thus protecting the brain from ther...

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Functional role of the preoptic area and anterior hypothalamus in thermoregulation in freely moving rats

Cited by 35 publications

References 15 publications

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Pharmacological and behavioral determinants of cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, and para-methoxyamphetamine-induced hyperthermia

Central angiotensin AT₁-receptor blockade affects thermoregulation and running performance in rats

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Functional role of the preoptic area and anterior hypothalamus in thermoregulation in freely moving rats

Cited by 35 publications

References 15 publications

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats

Pharmacological and behavioral determinants of cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, and para-methoxyamphetamine-induced hyperthermia

Central angiotensin AT1-receptor blockade affects thermoregulation and running performance in rats

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Central angiotensin AT₁-receptor blockade affects thermoregulation and running performance in rats