Abstract
Summary
Pituitary GH activity was estimated by the tibial epiphyseal cartilage test in hypophysectomized rats. Experimental animals were exposed to 5 different stimuli. Splenectomy evoked a transient decrease in pituitary GH which was followed by a rise in GH activity apparent within 60 minutes of operation. Formalin injections similarly produced an elevation of pituitary GH activity at 30 to 60 minutes after injection. Ringing a doorbell in the animal's cage intermittently for 30 minutes also elevated pituitary GH. Exposure to a temperature of 3°C for 60 minutes produced a depletion of pituitary GH. A biphasic response was observed in fasting, that is an initial depletion, return to base line, and finally depletion observable 64-88 hours after onset of the fast. It was concluded that a variety of apparently unrelated stimuli could alter the GH content of the pituitary. Taken together with other evidence it appears that GH secretion in the rat is very labile and influenced by a variety of stresses as well as by alterations in the supply of available carbohydrate.
Get full access to this article
View all access options for this article.