EFFECT OF SOME PREPARATIONS OF ADRENOCORTICOTROPHIC HORMONE ON THE COLOUR OF BUFO ARENARUM HENSEL

Abstract

SUMMARY In view of recent claims that intermedin and adrenocorticotrophic hormone (ACTH) are identical or closely related, a comparative study of their action on skin colour and the adrenals of the toad, Bufo arenarum Hensel, has been carried out. 1. Intermedin and ACTH darken the skin of the pale, hypophysectomized toad, but, weight for weight, intermedin is far more active than ACTH. Both preparations are more active than those of the pressor and oxytocic principles of the posterior pituitary. The melanotrophic action of ACTH does not depend on the presence of the adrenals or the sex of the toad. 2. Treatment with formaldehyde or boiling with sodium hydroxide, which are known to destroy the activity of the adrenocorticotrophic hormone, do not affect the action of ACTH on the skin; the latter treatment may even increase it. Boiling ACTH with acid does not affect its action on the colour of the skin. 3. Unlike ACTH, intermedin does not prevent atrophy of the adrenals after hypophysectomy or the development of asthenia. 4. It is concluded that the adrenocorticotrophic and chromatophorotrophic actions of the hypophysis are produced by two different substances.