Abstract
Moore and Price 1 injected male and female sex hormones into normal and castrate rats. They concluded that gonadal hormones suppress the functions of the hypophysis in the production of gonad stimulating secretions. Working with the female sex hormone, we wished to learn whether or not this inhibition of the hypophysis extended also to the growth-promoting factor produced by this gland. We therefore injected a very pure and carefully assayed preparation into young rats, and studied their growth curves.
The hormone preparation was obtained from pregnancy urine according to the method previously described, 2 except that no effort was made to obtain crystalline material. It was assayed according to the Coward and Burn method, as repeated by us, 2 and the rat unit found to be 5 gamma. Three litters of young rats, 24 in all, were divided so that equal numbers from each litter would be used in the control and experimental groups. Each group included 12 animals, 6 males and 6 females. The experiment was started immediately after the animals were weaned. The experimental group received 40 units of hormone dissolved in 0.2 cc. of olive oil every other day, the control group the same amount of olive oil only. The animals were weighed every week and their growth plotted.
Results: A small but, we believe, significant difference in the growth rates of the 2 groups was observed. The growth rates were consistent, in no case did any injected animal grow as rapidly as any control animal. The injected group gained 1051 gm. or 211.0%. The non-injected group gained 1348 gm. or 262.3%.
It was observed that the testes of the injected animals appeared much smaller than those of the control group, therefore all animals were autopsied and the sex glands weighed.
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