Activation of brain areas in rat following warm and cold ambient exposure.
ABSTRACT Environmental thermal stimuli result in specific and coordinated thermoregulatory response in homeothermic animals. Warm exposure activates numerous brain areas within the cortex, hypothalamus, pons and medulla oblongata. We identified these thermosensitive cell groups in the medulla and pons that were suggested but not outlined by previous physiological studies. Using Fos immunohistochemistry, we localized all the nuclei and cell groups in the rat brain that were activated by warm and cold ambient exposure. These neurons located in the hypothalamus and the brainstem, are part of a network responsible for the thermospecific response elicited by thermal stress. Comparison of the distribution of Fos-immunoreactive cells throughout the rat brain revealed topographical differences between the patterns of activated cells following warm and cold environmental exposure. Among several brain regions, warm exposure elicited c-fos expression specifically in the ventrolateral part of the medial preoptic area, the central subdivision of the lateral parabrachial nucleus and the caudal part of the peritrigeminal nucleus, whereas cold stress resulted in c-fos expression in the ventromedial part of the medial preoptic area, the external subdivision of the lateral parabrachial nucleus and the rostral part of the peritrigeminal nucleus. These neurons are part of a network coordinating specific response to warm or cold exposure. The topographical differences suggest that well-defined cell groups and subdivisions of nuclei are responsible for the specific physiological (endocrine, autonomic and behavioral) changes observed in different thermal environment.
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ABSTRACT: From mouse to man, brown adipose tissue (BAT) is a significant source of thermogenesis contributing to the maintenance of the body temperature homeostasis during the challenge of low environmental temperature. In rodents, BAT thermogenesis also contributes to the febrile increase in core temperature during the immune response. BAT sympathetic nerve activity controlling BAT thermogenesis is regulated by CNS neural networks which respond reflexively to thermal afferent signals from cutaneous and body core thermoreceptors, as well as to alterations in the discharge of central neurons with intrinsic thermosensitivity. Superimposed on the core thermoregulatory circuit for the activation of BAT thermogenesis, is the permissive, modulatory influence of central neural networks controlling metabolic aspects of energy homeostasis. The recent confirmation of the presence of BAT in human and its function as an energy consuming organ have stimulated interest in the potential for the pharmacological activation of BAT to reduce adiposity in the obese. In contrast, the inhibition of BAT thermogenesis could facilitate the induction of therapeutic hypothermia for fever reduction or to improve outcomes in stroke or cardiac ischemia by reducing infarct size through a lowering of metabolic oxygen demand. This review summarizes the central circuits for the autonomic control of BAT thermogenesis and highlights the potential clinical relevance of the pharmacological inhibition or activation of BAT thermogenesis.Frontiers in Neuroscience 01/2014; 8:14.
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ABSTRACT: Introduction: Cryotherapy is useful in the management of muscle-skeletal injuries, due to the effects of tissue cooling; however, few studies have evaluated the effectiveness of diferents forms of cryotherapy to maintain cooling after application and the effects of post-cooling activity on the recovery on the skin temperature. Objectives: To compare the effects of three modalities of cryotherapy on the skin temperature (ST) and its variation during the rewarming, under two different activities. Methods: An experimental study with 36 subjects randomly allocated to either three groups: crushed ice pack (CI), massage with ice (MI) or ice-water immersion (WI), these modalities were applied for 15min in the calf. Subsequently each group was subdivided randomly in: rest or gait followed by rest. For the analysis a paired Student's t test and ANOVA for repeated measurements were applied with α=0.05. Results: The three modalities decreased skin temperature, with a greater effect caused by MI (-27.6°C). During rewarming the three groups increased temperature, regardless the activity post-cooling (P <0.0001). The ST recovery was minor in the WI group. Only the group that received CI and the rewarming was walking followed by rest, reached the initial ST. Conclusions: The three modalities decreased skin temperature but the MI showed the greatest cooling on ST, however the WI maintained by major time this decreasing during the rewarming without influence of activity. Salud UIS 2011; 43 (2): 119-129Salud UIS 08/2011; 43(2):119-129.
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ABSTRACT: Thermogenesis, the production of heat energy, is the specific, neurally regulated, metabolic function of brown adipose tissue (BAT) and contributes to the maintenance of body temperature during cold exposure and to the elevated core temperature during several behavioral states, including wakefulness, the acute phase response (fever), and stress. BAT energy expenditure requires metabolic fuel availability and contributes to energy balance. This review summarizes the functional organization and neurochemical influences within the CNS networks governing the level of BAT sympathetic nerve activity to produce the thermoregulatory and metabolically driven alterations in BAT thermogenesis and energy expenditure that contribute to overall energy homeostasis.Cell metabolism 03/2014; · 17.35 Impact Factor