RESUMEN
We investigated the effects of menstrual cycle phase on thermal sensation, thermal pleasantness, and autonomic thermoregulatory responses during mild cold exposure. Eight healthy young women participated. Experiments were conducted in the follicular and luteal phases: 120 min exposure at 23.5 °C after 40-min at a baseline temperature of 29 °C. Body core temperature was higher (P = 0.01) in the luteal phase than in the follicular phase. Thermal sensation of the whole body (P = 0.59), hands (P = 0.46), and toes (P = 0.94), and thermal pleasantness of the whole body (P = 0.79) were no different between phases. In both phases, mean skin temperature decreased (P = 0.00) in the same manner without any change in metabolic rate (P = 0.90). These results suggest the change of body core temperature in the menstrual cycle phases has no effect on thermal perception of cold or on autonomic cold-defense response.
Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Ciclo Menstrual/fisiología , Sistema Nervioso Autónomo/fisiología , Frío , Femenino , Fase Folicular/fisiología , Hemodinámica , Hormonas/sangre , Humanos , Fase Luteínica/fisiología , Percepción/fisiología , Temperatura Cutánea/fisiología , Adulto JovenRESUMEN
Hypohydration caused by exercise in the heat attenuates autonomic thermoregulation such as sweating and skin blood flow in humans. In contrast, it remains unknown if behavioral thermoregulation is modulated during hypohydration. We assume that thermal unpleasantness could drive the behavioral response, and would also be modulated during hypohydration. Nine healthy young men participated in the present study. Body and skin temperatures were monitored. Ratings of thermal sensation and pleasantness were conducted. After approximately 45 min rest at 27 degrees C, they performed 50-min cycling exercise, which was at the level of 40% of heart rate range at 35 degrees C (hypohydration trial) or at the level of 10% of heart rate range at 23 degrees C (control trial), respectively. Subjects returned to the rest at 27 degrees C, and the ambient temperature was then changed from 22 to 38 degrees C. Body weight decreased by 0.9+/-0.1% immediately after exercise in the hypohydration trial and 0.3+/-0.1% in the control trial. In the cold, no significant difference in thermal sensation or pleasantness was observed between trials. There was no significant difference in thermal pleasantness between trials in the heat, although thermal sensation in the heat (32.5-36 degrees C) was significantly lower in the hypohydration trial than in the control trial. In addition, laser Doppler flow of the skin and sweat rate were attenuated in the heat in the hypohydration trial. These results may indicate that mild hypohydration after exercise in the heat has no influence on behavioral responses to the heat.
Asunto(s)
Sistema Nervioso Autónomo/fisiopatología , Regulación de la Temperatura Corporal , Deshidratación/etiología , Deshidratación/fisiopatología , Ejercicio Físico , Calor , Adulto , Temperatura Corporal , Peso Corporal , Deshidratación/psicología , Humanos , Masculino , Concentración Osmolar , Flujo Sanguíneo Regional , Piel/irrigación sanguínea , Temperatura Cutánea , Sudoración , Sensación Térmica , Adulto JovenRESUMEN
The aim of this study was to determine whether estrogen modulates central and peripheral responses to cold in female rats. In ovariectomized female rats with and without administered estrogen [E(2) (+) and E(2) (-), respectively], the counts of cFos-immunoreactive cells in the medial preoptic nucleus (MPO) and dorsomedial hypothalamic nucleus (DMH) in the hypothalamus were greater in the E(2) (+) rats than in the E(2) (-) rats at 5 degrees C. Examination of the response of normal female rats to exposure to 5 degrees C at different phases of the estrus cycle revealed that counts of cFos-immunoreactive cells in the MPO, DMH, and posterior hypothalamus and the level of uncoupling protein 1 mRNA in the brown adipose tissues were greater in the proestrus phase than on day 1 of the diestrus phase. This result was linked to the level of plasma estrogen. The body temperature during cold exposure was higher in the E(2) (+) rats than in the E(2) (-) rats and was also higher in the proestrus phase than on day 1 of the diestrus phase. We conclude that estrogen may affect central and peripheral responses involved in thermoregulation in the cold.
Asunto(s)
Aclimatación/fisiología , Tejido Adiposo/fisiología , Regulación de la Temperatura Corporal/fisiología , Estrógenos/farmacología , Respuesta al Choque Térmico/fisiología , Hipotálamo/fisiología , Ovariectomía , Aclimatación/efectos de los fármacos , Tejido Adiposo/efectos de los fármacos , Animales , Regulación de la Temperatura Corporal/efectos de los fármacos , Frío , Femenino , Respuesta al Choque Térmico/efectos de los fármacos , Hipotálamo/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into two categories, "temperature sensation" and "thermal comfort." Although several studies have investigated regional differences in temperature sensation, less is known about the sensitivity differences in thermal comfort for the various body regions. In the present study, we examined regional differences in temperature-related sensations with special attention to thermal comfort. Healthy male subjects sitting in an environment of mild heat or cold were locally cooled or warmed with water-perfused stimulators. Areas stimulated were the face, chest, abdomen, and thigh. Temperature sensation and thermal comfort of the stimulated areas were reported by the subjects, as was whole body thermal comfort. During mild heat exposure, facial cooling was most comfortable and facial warming was most uncomfortable. On the other hand, during mild cold exposure, neither warming nor cooling of the face had a major effect. The chest and abdomen had characteristics opposite to those of the face. Local warming of the chest and abdomen did produce a strong comfort sensation during whole body cold exposure. The thermal comfort seen in this study suggests that if given the chance, humans would preferentially cool the head in the heat, and they would maintain the warmth of the trunk areas in the cold. The qualitative differences seen in thermal comfort for the various areas cannot be explained solely by the density or properties of the peripheral thermal receptors and thus must reflect processing mechanisms in the central nervous system.
Asunto(s)
Temperatura , Sensación Térmica/fisiología , Abdomen/inervación , Abdomen/fisiología , Sistema Nervioso Autónomo/fisiología , Regulación de la Temperatura Corporal/fisiología , Frío , Cara/inervación , Cara/fisiología , Calor , Humanos , Masculino , Estimulación Física , Temperatura Cutánea/fisiología , Adulto JovenRESUMEN
We report a new system for monitoring sensations of many body parts as well as comprehensively showing the distribution of overall skin temperature (T(sk)) and temperature-related sensations. The system consists of a console with 52 levers to report temperature-related sensations and software that facilitates the visualization of the distribution of T(sk) and temperature-related sensations by displaying them on a model of the human body. The system's utility was demonstrated with a physiological experiment involving three males and three females. They were exposed to step changes of ambient temperature from 23 degrees C to 33 degrees C. We measured T(sk) at 50 points, and the subjects concurrently provided estimates of local temperature sensation and thermal comfort/discomfort at 25 loci. This system greatly facilitates the perception and analysis of spatial relationships and differences in temperature and sensation in various areas of the body.