STUDIES IN THE ACTIVATION AND INHIBITION OF ADRENOCORTICOTROPHIN SECRETION

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Abstract
Comparisons have been made in the depletion of adrenal ascorbic acid which resulted from cold, hypertonic saline and bell-ringing, in normal, neurohypophysectomized and reserpine injected male rats. The effects upon ACTH/AAF release of the stimulation ofneurohypophysial hormone release, or its injection, were recorded in normal animals and neurohypophysectomized animals subjected to cold stress. Also, the effects of neurohypophysectomy and reserpine injectionupon the adrenal weights of normal and adrenal-enucleateregeneratc animals were recorded. It was concluded that: 1. The liberation of AAF by the adenohypophysis seems to necessitate the concomitant release of neurohypophysial hormone or something associated with it and it is suggested that the release of ADH by the neurohypophysis results in an “obligatory” release of AAF. 2. The neurohypophysis is involved in the release of ACTH/AAF in response to systemic stresses but not to emotional ones. It is suggested that separate centres within the hypothalamus control, via different pathways, the secretion of AAF by the adenohypophysis. 3. The hypertrophy of the adrenals which results from neurohypophysectomy, and the regeneration of the adrenals after enucleation, are discussed and related to the results of other workers. It is suggestedthat enucleated adrenals regenerate under the influence of a basal secretion of ACTH/AWF, the control of which probably does not involve hypothalamic centres and that the release of a hypertrophy AWFinvolves a hypothalamic centre the stimulation of which depends upon the capacity of the centre/s which stimulate/s AAF release, to meet body requirements.