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The role of the pituitary-adrenal axis in the mediation of morphine-induced hyperthermia of conscious, unrestrained rats was investigated. Rectal (TR) and tail (Tt) temperatures and oxygen uptake rates (VO2) were measured following peripheral or central injection of morphine sulphate (MS) in groups
The role of skeletal muscle thermogenesis (increases in skeletal muscle tone) in the hyperthermic responses of conscious, unrestrained rats given acute or repeated i.p. or i.c.v. injections of morphine sulfate (MS) or beta-endorphin was investigated. Initial blood gas experiments showed that rats
Wistar rats from one supplier have been shown to exhibit the atypical body temperature responses to morphine. In contrast to commonly used rats, in which morphine induced dose-dependent changes in body temperature, the initial administration of morphine (5, 10, 20, and 40 mg/kg, s.c.) to rats of
Morphine action at opiate receptors in the ventral tegmental area (VTA) of the rat brain has been implicated in the production of increased locomotor activity and in morphine's rewarding properties. In the present experiments, bilateral administration of morphine (18 micrograms tapped into the tips
A major inhibitory neurotransmitter of the nervous system, GABA (gamma-aminobutyric acid), is involved in mammalian thermoregulation. The present study investigated the influence of GABAergic neurotransmission-enhancing drugs, in a model of morphine-induced hyperthermia in conscious rats. We used
The mechanism underlying the hyperthermia induced by intrahypothalamic administration of either morphine or beta-endorphin has been investigated in conscious rats. Direct administration of morphine (1--8 micrograms in 1 microliter) or beta-endorphin (1--3 micrograms in 1 microliter) into the
The effect of nicotinamide, administered immediately before the morphine or on the background of already developed morphine hyperthermic reaction, was studied on morphine hyperthermia. It was established that nicotinamide, administered before morphine, inhibited development of morphine hyperthermia,
An accumulating body of evidence indicates that activation of NMDA receptor complexes modulates a number of morphine-induced responses. Because a single injection of morphine increases extracellular glutamate levels and downregulates NMDA receptors, acute morphine appears to increase glutamatergic
Classical conditioning of morphine hyperthermia was examined using an explicit conditioned stimulus (CS) paired with intravenous (IV) morphine administration. Rats were implanted with a jugular vein cannula and a biotelemetry device for monitoring body temperature. The animals were housed 24 h/day
Central neurochemical mechanism underlying the hyperthermic effect of morphine has been investigated in rats. 200 micrograms morphine hydrochloride, when administered through cerebroventricular route at different seasonal air temperature, caused a rise in rectal temperature of rats. This
1. In rats, a subcutaneous injection of morphine (2.5 mg/kg) produced hyperthermia which was greatly attenuated by an intraperitoneal injection of physostigmine (0.1 mg/kg), but not of neostigmine (0.08 mg/kg) and promptly reversed by a subcutaneous injection of nalorphine.2. It is concluded that
Bole of adrenals in morphine-induced hyperthermia was studied in normal, neurotransmitter antagonist-pretreated, chemical-sympathectomized, adrenalectomized or adrenal-demedullated rats. In restrained female rats, 5 mg/kg morphine produced hyperthermia whereas 20 mg/kg and 40 mg/kg produced
The effectiveness of temporal and environmental cues in eliciting conditioned hypothermia and hyperthermia was studied in male Wistar rats using as an unconditioned stimulus an IP injection of 20 mg/kg of morphine sulfate. The relevance of temporal stimuli was minimized in Experiment 1 by
OBJECTIVE
Beta-lactam antibiotics are the first practical pharmaceuticals capable of increasing the expression and activity of the glutamate transporter, GLT-1, in the CNS. However, the functional impact of beta-lactam antibiotics on specific drugs which produce their pharmacological effects by
Controversy exists regarding (a) whether rats become tolerant, or sensitized, to morphine-induced hyperthermia and (b) the directionality of the conditioned pyretic effects of morphine. In these studies, stress produced by temperature-assessment procedures affected rats' pyretic response to