Shift of threshold temperature for shivering and heat polypnea as a mode of thermal adaptation

Changes in monoamines in rat hypothalamus during cold acclimation

“…NE in the VMH, on the other hand, started to increase with some delay, being significantly elevated first on day 7, with a tendency for further increase in the course of cold acclimation. Thus, with respect to the well-known transition from shivering to non-shivering thermogenesis in cold acclimation (Bru¨ck et al, 1970), the data of the present study suggest the involvement of NE in the PO in the adjustment of shivering (adjustment of neuronal activity of the PH), and of NE in the VMH in the adjustment of non-shivering thermogenesis. Ingenito (1968), Ingenito and Bonnycastle (1967) demonstrated no changes in hypothalamic NE concentration after 4 h cold exposure (5 1C), and it was slightly increased following 15 and 30 days cold exposure (1 1C).…”

“…However, it is certain that chronic cold exposure alters the activities of NE-neurons in the PH. Continuous cold exposure decreases thermoregulatory shivering (Bru¨ck et al, 1970), and cold induced Fos was high at 3 and 24 h after the exposure, but it was almost the same as in controls after 14D (Miyata et al, 1995). Thus, we hypothesize that the neuronal signal from the PH that activates shivering thermogenesis may be reduced after 28D of cold exposure, and the low level of NE in the PH is probably due to the replacement by non-shivering thermogenesis (NST) of shivering thermogenesis.…”

“…The aforementioned results suggest that neuronal activity in these hypothalamic regions in response to cold stimuli changes during cold acclimation. It is reported that long-term cold exposure over several weeks induces adaptive changes of the thermoregulatory response in rodents, namely, a decrease in shivering thermogenesis (Bru¨ck et al, 1970), and an increase in the capacity of non-shivering thermogenesis in BAT (Himms-Hagen, 1984). Considering these data, we hypothesized that the neuronally active site in the hypothalamus involved in the maintenance of body temperature in cold environment may shift to the VMH (non-shivering thermogenesis) from the PH (shivering thermogenesis) under the control of the PO (thermoregulatory center) during cold acclimation.…”

Lasting Effect of Infantile Cold Experience on Cold Tolerance in Adult Rats

“…2 shows, colonic temperatures at the onset of shivering were lower in N-CA and A-CA rats than in N-WA ones, indicating the suppression of shivering in cold-acclimated rats. This mechanism enables the cold acclimated animals to use the full amount of nonshivering thermogenesis before the less eco-nomical shivering is actuated, as suggested by BRUCK et al (1970). In fact, it is reflected in the finding that N-CA and A-CA animals maintained higher colonic peratures than did N-WA ones in the cold (Table 3).…”

Neurophysiological aspects of the long-term adaptation to cold in mammals: The role of central and peripheral thermoreceptors

“…The changes are manifest both as an attenuation of cold sensation (Kozyreva and Yakimenko, 1978;Kozyreva, 2005) the cold defense responses towards the range of lower temperatures (Bruck et al, 1970;Zeisberger, 1978, 1986;Kozyreva and Verkhogliad, 1997). This may be taken to mean that changes in the regulatory characteristics of the thermal homeostasis system have occurred.…”