Changes in oxygen consumption and radio-iodine (I131) uptake following hypothalamic lesions in the albino rat.

Abstract

1. Bilateral lesions in the caudal hypothalamus of albino rats, designed to sever the efferent pathways from the hypothalamic nuclei, bring about a transient rise in oxygen consumption of about 7 per cent 24 hours after infliction of the lesions followed by a fall of around 10 per cent of the control value 72 hours after the operation. This low oxygen consumption remains constant for as long as 13 days.2. Radio‐iodine (I131) uptake by the thyroid gland over a period of 4 hours was not significantly different from that of a control group, irrespective of the time after the lesions were inflicted.3. The histological structure of the thyroid gland 7 and 14 days after the lesions were made indicated that thyrotrophic hormone production was not reduced but rather might have been somewhat increased after the lesion.4. The fall in oxygen consumption was not related to either body weight or body temperature changes.5. It is suggested that the fall in oxygen consumption is not due to diminished thyroid activity but may be caused by the withdrawal of hypothalamic control of the rate of secretion of adrenalin.