Abstract
Lee, Teel and Gagnon 1 have previously reported that in giant rats produced by the daily administration of alkaline extracts of beef anterior lobe pituitary, the basal gaseous metabolism was found to be somewhat reduced. We have made a further study of the effects of similar extracts in rats before there has been a great increase in weight and before the marked splanchnomegaly has had time to develop.
The immediate effects of growth stimulating extracts∗ were determined in 11 experiments on 3 male and 4 female rats. Doses of 1 or 2 cc. were given intraperitoneally either after preliminary metabolic rate determinations on the same day or to rats in which the basal level had been well established. The metabolic rates were then followed for 3 to 6 hours. In 9 instances there occurred definite increases in the heat production over the basal levels, ranging from 6 to 17% and with an average of 10.5%. This increase reached its maximum in 2 to 4 hours after the injection. In 2 experiments there was no apparent effect. Boiled extracts, in which the growth principle was destroyed, also caused an increased heat production of about the same magnitude (5 to 13%) in 4 rats. The extracts contained some protein and we believe that this increased metabolism may be due to the specific dynamic action of such protein products.
In 18 rats, 7 males and 11 females, frequent metabolic rate determinations were made before, during and after periods of daily administration of the extracts ranging from 15 to 72 days. In these experiments at least 24 hours elapsed after a dose of the extract before a metabolic rate determination was made. In 10 of the rats, 6 females and 4 males, there were significant decreases in the basal metabolic levels ranging from 12 to 39%.
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