Growth hormone activity of the anterior pituitary lobe of the male rat at various ages.

Abstract

WITHIN the past few years several reports have dealt with the relationship between the age of an animal and the pituitary content of growth hormone. Pigs1,2, ox3, and the rat4,5 have been examined. In general, it has been found that although the total amount of growth hormone in the pituitary gland increases greatly with age, the concentration of the hormone in the gland tends to remain fairly constant. The present work on the male rat supports this concept, but also indicates that relative to body-weight there may be a decreased amount of total growth hormone in the anterior lobe as the animal advances in age. This latter relationship has likewise been found in the larger species which have been examined, but previous evidence5 on the rat has indicated a lack of correlation between the total pituitary growth hormone/body-weight ratio and age.