The effect of environmental temperature on the sleep were evaluated in young and aged male rats of F344 strain by 24 hr-recordings of electroencephalogram (EEG) and electromyogram (EMG) . The recordings were performed at three different temperatures, 5, 24 and 30°C. All these temperature did not significantly affect the sleep profiles of young rats. At 24°C, referred as a neutral temperature, slow wave sleep (SWS) episodes were more frequent and the duration of each SWS episode was shorter in aged rats than in young rats. At 5°C, total sleep time and total SWS time were both reduced in aged rats. The ratio of paradoxical sleep time in total sleep time was significantly increased in aged rats at 30°C. These results have shown that characteristics of sleep more potently in aged rats than in young rats. There were no significant differences in the brain temperatures and their circadian rhythms between young and aged rats at all environmental temperatures tested. Therefore, an impairment of body temperature regulation in aged rats cannot be the cause of the vulnerability of sleep profiles to temperature stress in aged rats.

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To evaluate the role of prolactin (PRL) in nonshivering thermogenesis (NST), the effects of hyper- and hypo-prolactinemia on in vitro brown adipose tissue (BAT) thermogenesis were investigated. In male rats cold-exposure for 1 hr or 1 day decreased plasma PRL levels, but after cold-acclimation the levels returned to the warm-acclimated control values. Saline injection elevated the plasma PRL level and this elevation was blocked by noradrenaline (NA) . In female animals haloperidol-treatment suppressed, while bromocriptine-treatment enhanced the in vitro responsiveness of BAT to glucagon (G), but not to NA. Dopamine mimicked the responses of BAT to bromocriptine. PRL may inhibit nonshivering thermogenesis, especially by modifying the thermogenic action of G in BAT.

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Body composition of 19 elderly women (mean age: 73.6) and 33 young women (mean age: 20.3), both living in rural area in Kyoto, was compared between summer and winter. Lean body mass, body fat and body water were determined using a bioelectrical impedance analyzer. In elderly women, significant increases in body weight and body fat, and significant decreases in lean body mass and body water were observed in winter, while no significant seasonal change was found in the young women. The survey of every day activity suggests that the increase in body weight and body fat in elderly women is attributable to the decrease in every day activity in winter.

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The purpose of this paper is to evaluate the influence of asymmetric thermal radiation fields upon the human body. These experiments were made to investigate the effects of thermal radiation direction upon the human physiological and psychological responses. There were three combinations of thermal radiation and air temperature. The three conditions were aimed to constant operative temperature and radiative heat exchange. The operative temperature was set 28°C. The directions of thermal radiation upon the human body were irradiated from front, right and back side. There were five Japanese young adults. The results may be summarized as follows: The irradiated direction which skin temperatures were most changed was back side. The skin temperatures that changed extremely were shoulder blade and lower back. Subjective thermal and comfort sensations fluctuated over the wide range when the subject was exposed to asymmetric thermal radiation. The subjective thermal sensation votes irradiated back side was more hot than irradiated front and right side.

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β-Endorphin level was found to be higher in the rat interscapular brown adipose tissue (BAT) than in plasma. Acute cold exposure (5°C, 1 hr) increased plasma β-endorphin level as previously reported, but did not change its BAT level. Cold acclimation (5°C, 4 wks) affected β-endorphine level neither in plasma nor BAT. β-endorphin did not stimulate in vitro BAT oxygen consumption, and did not modify noradrenaline (NA) -induced increase in BAT oxygen consumption. The findings suggest that β-endorphin is not involved directly in regulation of BAT thermogenesis.

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