Growth and Bone Changes in Rats Injected With Alkaline Anterior Pituitary Extracts. ∗

Some 175 rats, ranging in weight from 30 to 350 gm. were employed in testing the potency of alkaline anterior pituitary lobe extracts over short periods of time. The method of preparing the extract as described by Evans and Simpson 1 was adopted. In rats weighing between 30 and 100 gm. the presence of the growth hormone could not be detected. However, in animals weighing from 175 to 300 gm., growth stimulating powers were observed. With animals 200 to 225 gm. in weight, after 12 days of injection (the dose being 1 cc. daily intraperitoneally) the experimental rats gained at an average of 2.1 gm. per diem over the control rats. After 14 days of treatment with 1 cc. doses intraperitoneally daily, injected animals weighing between 250 and 300 gm. gained remarkably in weight, averaging 2.7 gm. daily over the control animals.

Periosteal bone growth studies of rats were made by including madder in the diet. Madder was shown by Kölliker to be deposited only in zones of osteoblastic activity, staining newly growing bone red. The skulls and mandibles were used as test bones. In young animals periosteal activity was so great that after feeding madder for 2 weeks the bones were diffusely stained pink and made comparative studies impossible. However, in rats over 175 gm., periosteal bone formation was found to be limited to discrete zones of ossification when madder was fed throughout the experiment. The older the animal, the smaller and more discrete became the ossification zones and the less intensely did they stain. Rats which had received the alkaline extract for 2 weeks showed in the same areas as in the controls a greater activity in periosteal bone formation evidenced by a laying down of more madder.