Immobilization stress in rats: Effect on rectal temperature and possible role of brain monoamines in hypothermia

Abstract

Immobilization of albino rats for 2 h showed ambient temperature-dependent changes in rectal temperature, hypothermia at temperatures below 30 degrees C, and hyperthermia at 35 degrees C and above. Adrenalectomized (Adre) rats showed more hypothermia compared to sham operated controls at 25 +/- 2 degrees C. The increased hypothermia in adrenalectomized rats was reversed by 10 mg/kg IP or 100 microgram/rat ICV of hydrocortisone. Groups of rats pretreated with desmethylimipramine (DMI, 25 mg/kg IP) and 6-hydroxydopamine (6-HD, 100 microgram/rat ICV) or methyl ester of parachlorophenylalanine (ME-PCPA, 100 microgram/rat ICV for 3 days) or 5,6-dihydroxytryptamine (DHT, 75 microgram/rat ICV) showed significantly less hypothermia at the end of 2 h of immobilization. Applying analysis of variance test, the hypothermia in Adre, ME-PCPA and DHT groups, was found to be not significantly different from their respective control groups between 0 and 45 min of immobilization but was significantly different between 45 to 120 min of immobilization. DMI-6-HD group however, showed significant difference between 0--45 min only and not between 45--120 min of immobilization. The results suggest that the early phase of immobilization induced hypothermia between 0--45 min is dopamine and the late phase of hypothermia between 45--120 min is 5-hydroxytryptamine mediated.

Changes in the colonic temperature and metabolism during immobilization stress in repetitively immobilized or cold-acclimated rats.

“…The present study indicates that an immobilization stress imposed here did not cause hypothermia, in contrast to the previous report (AMAR and SANYAL, 1981), stating that immobilization of rats showed ambient temperature-dependent changes in body temperature : hypothermia at temperatures below 30°C, and hyperthermia at 35°C and above. The present experiment was performed at 25°C.…”

Posterior subthalamic nucleus (PSTh) mediates innate fear-associated hypothermia

“…Both learned fear and mild innate fear stimuli, such as ferret or fox odorants, induce hyperthermia in rodents 25,26,27 . On the other hand, potent stress or fear stimuli that threaten the survival of animals, such as long-lasting immobile stress and hypoxia, induces hypothermia 9,[28][29][30] . Moreover, potent innate fear odor 2MT can trigger acute hypothermia accompanying robust defensive behaviors, such as freezing 33,34,35 .…”

“…It has also been reported that innate fear stimuli, such 4 as ferret or fox odor, induces hyperthermia in rats 26,27 . On the other hand, long-term restraint/immobilization, hypoxia or inescapable stress have been shown to evoke hypothermia in mammals [28][29][30] . In humans, fear or anxiety has a similar effect on body temperature changes and vasoconstriction/vasodilation, creating rapid chills or hot sensation 31,32 .…”

Comparative and combined studies on anti-ulcer effect of two plant extracts in experimental models of gastric ulcer in SD rats

“…The stomach was incised along with the greater curvature and examined for ulcers as described earlier. [11] Cold-restraint Stress Induced Ulcers Rats of either sex weighing 120-150 g were immobilized for 2 h at 4°C following the method of immobilization as described earlier by Amar and Sanyal (1981) (12). Briefly, the animals were starved for 24 h with free access to water and 60 min after receiving the corresponding treatment, they were fully stretched and strapped to a wooden plank with adhesive tape after securing each limb to the plank individually.…”

“…[14] The dissolved mucosubstances in the gastric juice or gastric mucosal homogenate were estimated in the alcoholic precipitate obtained by adding 90 % alcohol in 9:1 ratio as described earlier. [10,11] Total hexoses were estimated using the method developed by Winzler. [15] Hexosamine was estimated using method developed by Dische and Borenfreund.…”