Abstract

Physiological

1. Puncture with an instrument sterilized only by boiling causes marked hyperpyrexia when a proper region of the brain is reached.

2. The mid-ventral portion of the caudate nucleus is such a point. Vertical punctures made here are likely to emerge in the region of the tuber cinereum.

3. But the tuber cinereum and infundibulum are not essential to heat puncture hyperthermia, as shown by punctures from orbit to caudate nucleus not involving this vicinity.

4. In puncturing the caudate nucleus one is almost certain to perforate the ventricle, but puncture into the lateral ventricle does not in itself necessarily cause hyperthermia.

Pharmacological

1. Injected into the general circulation:

The minimal dose of chloral hydrate which causes a distinct temperature decrease is about 20 mgm. per kilo animal. The chief factor appears to be muscular rest.

The minimal dose of antipyrin to cause a distinct fall in body temperature is about 60 mgm. per kilo. 300 mgm. is necessary to cause marked respiratory increase.

2. Given into the region of the caudate nucleus (and lateral ventricle):

Chloral hydrate in doses as small as 6 mgm. per kilo or over gives a distinct temperature decrease. Hyperpnea and vasodilation seem to be important factors.

Antipyrin in doses of 20 mgm. per kilo and more gives a definite fall in body temperature with hyperpnea which appears to be the chief factor. Peripheral vasodilation, if present after this method, is very transitory.

3. Strong alcohol, 25 per cent or 95 per cent, in the lateral ventricle raises the body temperature as corrosives do. Five per cent alcohol appears to have the opposite effect.

4. Quinin hydrochlorid injected into the general circulation in doses of about 2 mgm. per kilo gave a slow temperature fall of not more than 0.25°. Doses ranging from 0.6 to 5.5 mgm. injected directly into the brain gave falls of from 0.6 to 1.1° with either vasodilation or hyperpnea or both.

5. Epinephrin introduced into the brain of rabbits on winter diet always gave a fall in temperature in doses of 0.01 and 0.1 mgm. per kilo. No external cause was apparent.

6. Caffein in doses of 0.6 to 1.2 mgm. per kilo intracerebrally raises the body temperature usually 0.5° or more. Vasoconstriction and dilation of the pupils are noted, and sometimes signs of marked excitement. Similar doses in the general circulation have little or no effect on the body temperature.

7. Beta-tetrahydronaphtylamin in the general circulation caused entirely without symptoms a rise of 0.5° within three hours after a dose of 0.02 gram. The same dose in the brain of a somewhat larger rabbit caused in an hour a rise of 1.1° with all the characteristic symptoms of this drug followed by convulsions and death.