201. The effect of intracerebroventricular administration of catecholamines and their antagonists on rectal temperature of Mastomys natalensis
- Author
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Rikhab C. Srimal, Dhawan Bn, and Rajesh Shukla
- Subjects
Hyperthermia ,Male ,medicine.medical_specialty ,Dopamine ,Adrenergic beta-Antagonists ,Propranolol ,Body Temperature ,Norepinephrine ,Catecholamines ,Isoprenaline ,Internal medicine ,medicine ,Animals ,Tolazoline ,Adrenergic alpha-Antagonists ,Injections, Intraventricular ,Pharmacology ,biology ,Chemistry ,Temperature ,General Medicine ,Thermoregulation ,Hypothermia ,medicine.disease ,biology.organism_classification ,Apomorphine ,Muridae ,Endocrinology ,Mastomys ,Female ,medicine.symptom ,medicine.drug - Abstract
Noradrenaline (NA), adrenaline (ADR), isoprenaline (ISO) and dopamine (DA) were given through a chronically implanted cannula in the lateral cerebral ventricle of Mastomys natalensis. Low doses of NA (0.05-0.25 microgram) reduced rectal temperature while larger doses (0.35 microgram upwards) produced dose-dependent hyperthermia. The hypothermic effect was antagonised by alpha-adrenoceptor and the hyperthermia by beta-adrenoceptor antagonists. alpha-Methyl noradrenaline produced less hyperthermia but it antagonised the hyperthermic effect of NA. Adrenaline (0.1-10 microgram) was ineffective per se but when given after tolazoline it produced hyperthermia and after propranolol it produced hypothermia. The dose-dependent hyperthermia with isoprenaline (0.1-10 microgram) was blocked by propranolol and MJ-1999. Dopamine (0.5-20 microgram) and its agonists apomorphine, amantadine and BS 9641 produced hyperthermia which was antagonised by haloperidol and pimozide but not by alpha- or beta adrenoceptor antagonists. Noradrenaline (1.0 microgram) produced hypothermia at ambient temperature of 10 degrees C and 16 degrees C. It had no effect at 20 degrees C which seems to be the thermoneutral zone for mastomys. The hyperthermic effect at 33 degrees C was less than at 24 degrees C. Dopamine (10 micrograms) response was attenuated at 33 degrees C and unaffected at other ambient temperatures. It is concluded that alpha- and beta-adrenoceptors and DA-receptors exist in the central thermoregulatory mechanism in mastomys. The alpha-receptors are concerned with lowering the body temperature whereas the beta-receptors and DA-receptors are involved in raising it.
- Published
- 1981