Nonshivering thermogenesis in adult and aged C57BL/6J mice housed at 22°C and at 29°C

Talan, Mark I.; Kirov, S. A.; Kosheleva, Nadejda A.

doi:10.1016/s0531-5565(96)00095-2

Cited by 13 publications

(7 citation statements)

References 32 publications

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“…A decrease in either peripheral temperature or core temperature will produce an increase in metabolic heat production. Although skin cooling‐induced thermogenesis was accompanied by a slight (0.2–0.4°C) decrease in T c , a larger (1–7°C) decrease in T c is generally employed to elicit body cooling‐induced thermogenesis (Nour et al 1984; Asami et al 1988; Zhang et al 1995; Talan et al 1996; Tanaka et al 2001). Moreover, in the present study, the increase in was well correlated with T s but not with T c .…”

Section: Discussionmentioning

confidence: 99%

“…For this purpose, anaesthetized rats were used because their baseline metabolic rate is stable and various surgical or pharmacological manipulations are possible. Although anaesthetized animals retain only limited ability to maintain body temperature, in particular, by metabolic heat production, acute body cooling increases activity of the sympathetic nerves innervating the interscapular brown adipose tissue (Talan et al 1996; Morrison, 1999) and elicits non‐shivering thermogenesis (Nour et al 1984; Talan et al 1996). Moreover, anaesthetized animals can exhibit shivering in response to lowering body temperature (Asami et al 1988; Zhang et al 1995; Tanaka et al 2001).…”

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Thermogenesis elicited by skin cooling in anaesthetized rats: lack of contribution of the cerebral cortex

Osaka

2004

The Journal of Physiology

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Non-noxious cooling stimuli were delivered to the shaved back of urethane-chloraloseanaesthetized, artificially ventilated rats using a plastic bag containing water at 24-40• C. Cooling of the skin by 2-6• C increased the rate of whole body oxygen consumption (V O 2 ) and triggered electromyographic (EMG) activity recorded from the neck or femoral muscles. The cooling-inducedV O 2 responses did not depend on core (colonic) temperature and followed skin temperature in a graded manner. Pretreatment with the β-blocker propranolol (10 mg kg −1 , I.V.) greatly attenuated theV O 2 response but did not affect the EMG response. On the other hand, pretreatment with the muscle relaxant pancuronium bromide (2 mg kg −1 , I.V.) affected theV O 2 response very slightly but completely abolished the EMG activity. Accordingly, the cooling stimulus activated mainly non-shivering thermogenesis. Next, the contribution of the cerebral cortex to the cooling-induced thermogenesis was examined. Power spectral analysis of the electroencephalogram (EEG) showed that the cooling stimulus largely inhibited delta (0.5-3 Hz) waves, enhanced theta (3-8 Hz) waves, and slightly increased frequencies higher than 8 Hz. Pinching the hindpaw elicited changes in EEG similar to those elicited by skin cooling but did not increase theV O 2 . Therefore, there was no relationship between changes in the EEG and the magnitude of thermogenesis. Finally, skin cooling increased theV O 2 of decorticated rats but did not increase that of decerebrated rats. The results suggest that the subcortical forebrain structure, but not cortical activation, is indispensable for non-shivering thermogenesis elicited by cooling stimulation of the skin.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Thermogenesis elicited by skin cooling in anaesthetized rats: lack of contribution of the cerebral cortex

Osaka

2004

The Journal of Physiology

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“…At this temperature, HR is generally in the range of 350 -400 beats/min, in contrast to the range of 550 -600 beats/min when studied at the typical T a used for in vivo mouse physiology (21-23°C). Our prevailing hypothesis has been that the tachycardia associated with a cool T a reflects the recruitment of sympathetically mediated nonshivering thermogenesis (13,23,33,51). We have shown that when female Swiss mice are acclimated to various ambient temperatures for 48 h, a strong positive and linear relationship between HR and T a prevails (48).…”

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confidence: 99%

Vagal tone dominates autonomic control of mouse heart rate at thermoneutrality

Swoap¹,

Li²,

Wess³

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

107

109

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Swoap SJ, Li C, Wess J, Parsons AD, Williams TD, Overton JM. Vagal tone dominates autonomic control of mouse heart rate at thermoneutrality. Am J Physiol Heart Circ Physiol 294: H1581-H1588, 2008. First published February 1, 2008 doi:10.1152/ajpheart.01000.2007.-It is generally accepted that cardiac sympathetic tone dominates the control of heart rate (HR) in mice. However, we have recently challenged this notion given that HR in the mouse is responsive to ambient temperature (Ta) and that the housing T a is typically 21-23°C, well below the thermoneutral zone (ϳ30°C) of this species. To specifically test the hypothesis that cardiac sympathetic tone is the primary mediator of HR control in the mouse, we first examined the metabolic and cardiovascular responses to rapid changes in Ta to demonstrate the sensitivity of the mouse cardiovascular system to Ta. We then determined HR in 1) mice deficient in cardiac sympathetic tone ("␤-less" mice), 2) mice deficient in cardiac vagal tone [muscarinic M2 receptor (M2R Ϫ/Ϫ ) mice], and 3) littermate controls. At a Ta of 30°C, the HR of ␤-less mice was identical to that of wild-type mice (351 Ϯ 11 and 363 Ϯ 10 beats/min, respectively). However, the HR of M2R Ϫ/Ϫ mice was significantly greater (416 Ϯ 7 beats/min), demonstrating that vagal tone predominates over HR control at this Ta. When these mice were calorically restricted to 70% of normal intake, HR fell equally in wild-type, ␤-less, and M2R Ϫ/Ϫ mice (⌬HR ϭ 73 Ϯ 9, 76 Ϯ 3, and 73 Ϯ 7 beats/min, respectively), suggesting that the fall in intrinsic HR governs bradycardia of calorically restricted mice. Only when the Ta was relatively cool, at 23°C, did ␤-less mice exhibit a HR (442 Ϯ 14 beats/min) that was different from that of littermate controls (604 Ϯ 10 beats/min) and M2R Ϫ/Ϫ mice (602 Ϯ 5 beats/min). These experiments conclusively demonstrate that in the absence of cold stress, regulation of vagal tone and modulation of intrinsic rate are important determinants of HR control in the mouse. telemetry; intrinsic heart rate; cold stress; caloric restriction; sympathetic nervous system THE FREQUENCY OF CARDIAC CONTRACTION in mammals is achieved through modulation of heart rate (HR) around its intrinsic rate (IHR). HR is slowed by parasympathetic nervous system activity via the muscarinic M 2 receptor (M 2 R) (17) and elevated by sympathetic nervous system activity via the ␤ 1 -adrenergic receptor (39). Blockade of these autonomic inputs indicates that murine IHR is typically about 500 beats/min, well below the generally reported resting HR of about 600 beats/min [reviewed in Ref. 27, supporting the concept that cardiac sympathetic tone predominates at rest in the mouse (19,27)]. However, some recent studies indicate that resting mouse HR is lower than 500 beats/min at rest, calling into question the sympathovagal balance controlling HR in mice (6,11,35).Our laboratories (48, 54 -56) and others (8, 52) have demonstrated that mouse HR is markedly reduced when experiments are conducted in thermoneutral conditions [ambient ...

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“…It is now generally accepted that the metabolic and cardiovascular consequences of the cold stress that exist under standard laboratory conditions accounts for the tachycardia and sympathetic dominance of heart rate at rest (Bissonnette et al 2007; Swoap et al 2004; Talan et al 1996; Wernstedt et al 2006; Williams et al 2002) and, when mice are studied at thermoneutrality, resting heart rate is below 450 beats/min and cardiac autonomic regulation of heart rate is more similar to that of humans than originally reported. Specifically, the Sympatho-Vagal balance index indicates a slight parasympathetic dominance in the control of resting pulse interval in conscious mice (Figure 4).…”

Section: Discussionmentioning

confidence: 96%

Complex and interacting influences of the autonomic nervous system on cardiac electrophysiology in conscious mice

Lujan

Rivers

DiCarlo

2016

Autonomic Neuroscience

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Mice may now be the preferred animal model for biomedical research due to its anatomical, physiological, and genetic similarity to humans. However, little is known about accentuated antagonism of chronotropic and dromotropic properties in conscious mice. Accordingly, we describe the complex and interacting influence of the autonomic nervous system on cardiac electrophysiology in conscious mice. Specifically, we report the effects of single and combined cardiac autonomic blockade on measurements of pulse interval (heart rate), atrio-ventricular interval, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, and Wenckebach cycle length in conscious mice free of the confounding influences of anesthetics and surgical trauma. Autonomic influences were quantified as the change in parameter induced by its selective blocker (Sympathetic or Parasympathetic Effect) or as the difference between the intrinsic value and the value after a selective blocker (Sympathetic or Parasympathetic Tonus). Sympatho-Vagal Balance (SVB) was assessed as the ratio of control interval to intrinsic interval. SVB suggests slight parasympathetic dominance in the control of cardiac electrophysiology intervals. Furthermore, results documents a complex interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system in the control of cardiac electrophysiology parameters. Specifically, the parasympathetic effect was greater than the parasympathetic tonus in the control of cardiac electrophysiology parameters. In contrast, the sympathetic effect was smaller than the sympathetic tonus in the control of cardiac electrophysiology parameters. Results have important implications because actions of pharmacological agents that alter the autonomic control of cardiac electrophysiology are transformed by these interacting mechanisms.

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Nonshivering thermogenesis in adult and aged C57BL/6J mice housed at 22°C and at 29°C

Cited by 13 publications

References 32 publications

Thermogenesis elicited by skin cooling in anaesthetized rats: lack of contribution of the cerebral cortex

Thermogenesis elicited by skin cooling in anaesthetized rats: lack of contribution of the cerebral cortex

Vagal tone dominates autonomic control of mouse heart rate at thermoneutrality

Complex and interacting influences of the autonomic nervous system on cardiac electrophysiology in conscious mice

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