Adrenocorticotrophin in relation to the diabetogenic activity of growth-hormone preparations: further observations.

Abstract

As previously reported [Reid, 1953a], ACTH preparations do not readily enhance the diabetogenic potency (in cats) of purified preparations of growth hormone (GH), in contrast to that of crude ox-pituitary extracts. It is now postulated that crude extracts are rich in a 'co-factor' which enables, or helps, ACTH to enhance the diabetogenic activity of GH. Some evidence has been found for the presence of such a 'co-factor' in crude chorionic gonadotrophin, in semipurified LH, and in crude 'albumin fractions' obtained as by-products in the isolation of GH from crude extracts. It was previously shown that the effectiveness of different ACTH preparations, in enhancing the diabetogenic potency of crude GH preparations, bore little relation to their activity in the Sayers test (ascorbic acid depletion). It now appears that this lack of correlation is not attributable to differences in the rate of absorption after injection into cats. The diabetogenic potency of an alkaline pituitary extract was found to be enhanced when a preparation of ox 'crude corticotropin' (containing some GH), or of pig GH, was given concurrently at an acidic pH so that its intrinsic diabetogenic activity was low. This ' ACTH-like activity' was not found with purified ox GH under these conditions.