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Contains fulltext : 58048.pdf (publisher's version ) (Closed access), In mammals, stress exposure is frequently associated with an elevated body temperature ['emotional fever', stress-induced hyperthermia (SIH)]. Rectal measurement of body core temperature of the mouse induces a rise of 1-1.5 degrees C over a 10- to 15-min time interval. This phenomenon has been exploited to design a specific test for measuring stress-induced hyperthermia: the singly-housed SIH paradigm in mice. In the present experiments, changes in body temperature and corticosterone levels were studied 10, 30, 60, 90 and 120 min after the first insertion of the rectal probe. In addition, changes in patterns of neural activation, as observed after immunostaining for Fos-immunoreactivity (Fos-IR), were studied in the brains of animals perfused at times 0, 60 or 120 min. Our results show that SIH and corticosterone levels have their peak values between 10 and 30 min and are no longer different from control values after 60 min. Patterns of Fos-IR have been studied in 11 brain areas, of which 2 brain areas (anterodorsal preoptic and periolivary nuclei) showed a continuing rise in Fos-IR after 60 and 120 min, while six nuclei, mostly hypothalamic and septal, showed a peak induction of Fos-IR after 60 min. In three brain areas, no consistent changes in Fos-IR could be observed. The authors conclude that the changes observed in the patterns of Fos-IR, after application of the singly-housed SIH-test in mice, reflect the effects of both the stressor application and the ensuing thermoregulatory responses. The role of each activated brain area in either one of these effects is discussed in view of data available from the literature.

Item does not contain fulltext, When mammals, including man, are confronted with a stressful event, their core body temperature rises, stress-induced hyperthermia. In mice, the stress-induced hyperthermia procedure has been developed to measure antistress or anxiolytic-like effects of psychoactive drugs. Group-housed and singly housed versions of the stress-induced hyperthermia generate comparable results. Because the number of animals needed to perform an experiment is much lower in the singly housed versus the group-housed procedure, the former is the test of choice for pharmacological testing. A typical stress-induced hyperthermia test starts with an injection 60 min before the first rectal temperature measurement (T(1)), followed by a second temperature measurement (T(2)) 10-15 min later. The difference DeltaT (=T(2)-T(1)) is the stress-induced hyperthermia. The procedure also measures the intrinsic activity of drugs on the basal body temperature and DeltaT is relatively independent from the intrinsic temperature effects of drugs. Anxiolytic drugs (benzodiazepines, 5-HT(1A) receptor agonists, alcohol) reduce DeltaT suggestive of anxiolytic-like effects. Because the parameter measured for anxiety in the stress-induced hyperthermia procedure is not dependent on locomotor activity, like in almost all other anxiety tests, the stress-induced hyperthermia procedure is an attractive addition to tests in the anxiety field. Because the stress-induced hyperthermia is also present with a comparable pharmacological profile in females, this procedure has a wide species and gender validity. The procedure was applied in various genetically modified mice [5-HT(1A) and 5-HT(1B) receptor knockout (KO) mice and corticotropin-releasing hormone overexpressing (CRH-OE) mice] to study phenotypic influences of the various mutations on aspects of anxiety. The stress-induced hyperthermia test in singly housed male and female mice appears a useful and extremely simple test to measure effects of drugs on certain aspects

Item does not contain fulltext, Stress-induced hyperthermia (SIH) in singly housed mice, in which the rectal temperature of a mouse is measured twice with a 10-min interval, enables to study the effects of a drug on the basal (T(1)) and on the stress-enhanced temperature (T(2)), 10 min later, using the rectal procedure as stressor. SIH (T(2)-T(1)) reflects a stress-induced phenomenon sensitive to stress- or anxiety-modifying effects of drugs. Several benzodiazepine agonists (diazepam, chlordiazepoxide, oxazepam and alprazolam) dose-dependently antagonized SIH either in NMRI mice from two different breeders or in BALB/c mice. No major differences in the sensitivity for any of the drugs tested were found between strains or between substrains from different breeders. The selective BZ(1) receptor agonists alpidem and zolpidem only at relatively high doses antagonized SIH, whereas flumazenil, FG7142, pentylenetetrazol and phenobarbital did not affect SIH. Alcohol antagonized SIH, and the effects of diazepam could be antagonized by flumazenil. The findings that full BZ receptor agonists have anxiolytic-like effects in the singly housed SIH paradigm are comparable to those previously found in the group-housed version. The singly housed SIH is proposed as a simple and reliable screen for detecting anxiety-like properties of drugs that is valid in every mouse strain tested so far.