Implication of Bioamines in the X-Ray-Induced Temperature Response of Cats and Rabbits

The increase in rectal temperature observed after exposure of the head of a cat to 600 R of x-rays was prevented by pretreatment of the animal with the specific serotonin depleting agent p-chloro-methyl amphetamine. Similarly, the rise in rectal temperature induced in the rabbit by 200 R delivered on the hypothalamic region was shown to be blocked by previous application of either ergotamine or propranolol. Ergotamine itself caused a slight pyrogenic effect, whereas propranolol exerted no influence on the rectal temperature in the concentration employed. On the basis of these findings it seems very likely that in the cat serotonin released by x-irradiation plays an intermediate role in the observed temperature response. It is suggested that x-ray-released catecholamines function as mediator substances in the temperature reaction of the rabbit.