Non-Identity of Intermedin and Adrenocorticotrophic Hormone

Abstract

IT has been reported by Johnsson and Högberg¹ and Sulman² that some purified preparations of pituitary adrenocorticotrophic hormone have a strong dispersing action on the melanocytes of Rana temporaria and Hyla arborea, like the pituitary melanotropic hormone (intermedin), and from this and other arguments¹ they infer the identity of these hormones. However, later observations by Geschwindt et al. ³, Morris⁴ and Lock⁵ do not seem to be consistent with the hypothesis of Johnsson and Högberg¹ and Sulman², as (a) the melanotropic action of adrenocorticotrophic hormone could be separated from the corticotrophic, and (b) the treatment with 0.1 N alkali destroys the latter action to a large extent but leaves relatively unaffected or even potentiates the melanophore expanding action. If Johnsson and Högberg¹ and Sulman's² assumption were correct, highly purified preparations of intermedin would prevent, like adrenocorticotrophic hormone, the changes in the adrenals following hypophysectomy and restore the glands to their normal structure. In the toad Bufo arenarum Hensel, thirty days after complete removal of the pituitary, the adrenals appear atrophied, as the trabeculæ become thinner and the cortical cells lose most of the osmiophilic droplets (Fig. 1) observed in the normal controls (Fig. 2). If fifteen days after the hypophysectomy a daily injection of 100 µgm./100 gm. toad weight of adrenocorticotrophic hormone (from Armour and Co., lot J–80211) is started and continued for the following fifteen days, then the adrenals show again the thick trabecular structure and the cortical cells loaded with medium- and large-sized osmiophilic granula (Fig. 3). In the toads similarly injected with intermedin (LRW ₁ extract of Landgrebe et al. ⁶), the conditions of the adrenals (Fig. 4) is the same as in the hypophysectomized non-injected toads, which proves that intermedin cannot replace the action of adrenocorticotrophic hormone on the adrenals.