Effects of noradrenaline and carbachol on temperature regulation of cold-stressed and cold-acclimated rats

Antagonism of physostigmine induced hypothermia and neuroendocrine changes following exposure to different environmental temperatures

1. The magnitude of physostigmine-induced hypothermia increased with decreasing environmental temperature. 2. The hypothermic response was accompanied by significant changes in plasma levels of corticosterone, glucose and fatty acids. 3. Central cholinergic mediation appears to be a significant component of physostigmine-induced hypothermia and neuroendocrine changes at moderate temperature. 4. At lower ambient temperatures cholinergic blockers produced less antagonism of physostigmine-induced effects. 5. The decreased effectiveness of cholinergic blockers at low environmental temperatures and the increased plasma fatty acid levels under almost all conditions studied may be of importance in considering long term therapy with cholinergic agonists.

Tonic activity of medial preoptic norepinephrine mechanism for body temperature maintenance in sleeping and awake rats

The study was aimed at investigating the possible involvement of tonic activity of the adrenergic receptors in the medial preoptic area (mPOA) for maintenance of body temperature in rats. Differences in drug-induced changes in body temperatures during sleep and wakefulness--during the day and at night--were also investigated. Norepinephrine injected in the mPOA, produced a fall in body temperature, whereas phenoxybenzamine produced an increase. Saline and propranolol produced no alteration. Norepinephrine and phenoxybenzamine produced alterations in sleep-wakefulness also. These changes in sleep-wakefulness did not completely explain the thermal changes. The findings highlight the need for taking into account the basal activity and the time of application of drug in studies on thermo-regulation, using free moving animals.

Involvement of bicuculline-insensitive receptors in the hypothermic effect of GABA and its agonists

GABA, delta-aminovaleric acid (DAVA) and sodium valproate (VPA) decrease core temperature in conscious rats. Bicuculline increases GABA-induced hypothermia, does not modify DAVA (250 mg/kg) and VPA (100 and 400 mg/kg) hypothermia and antagonizes initial hypothermia by DAVA (1000 mg/kg) and VPA (200 mg/kg) and late hypothermia by DAVA (500 mg/kg) and VPA (200 mg/kg). Picrotoxin increases late hypothermia by GABA (250 mg/kg) and VPA (400 mg/kg), but decreases initial hypothermia by VPA (200 mg/kg). Pentylenetetrazol increases variably GABA-induced hypothermia, inhibits early early hypothermia by DAVA and increases hypothermia induced by VPA (400 mg/kg). We conclude that GABA and GABA-agonists (DAVA and VPA) may induce hypothermia partly mediated by activation of bicuculline-insensitive GABA-receptors.

Changes in body temperature after administration of adrenergic and serotonergic agents and related drugs including antidepressants

This survey, the third in a series, presents extensive tabulations of literature, primarily since 1965, on thermoregulatory effects of adrenergic and serotonergic agonists and their antagonists including ergot alkaloids, amphetamines, tryptamines, monoamine oxidase inhibitors, tricyclic and other antidepressants, a variety of other agents which alter presynaptic aminergic mechanisms including reserpine, 6-hydroxydopamine, p-chlorophenylalanine, alpha-methyltyrosines, cocaine, guanethidine and bretylium. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions, such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary drug.

Changes in body temperature after administration of acetylcholine, histamine, morphine, prostaglandins and related agents

This survey, the second in a series, presents extensive tabulations of literature, primarily since 1965, on thermoregulatory effects of cholinergic agonists and antagonists, histamine and H1- and H2-receptor antagonists, narcotic analgesics and antagonists in both non-tolerant and tolerant subjects and of prostaglandins and related agents. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions, such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary drug.