Increased Responsivity of Adrenals from Reserpine-Treated or Stressed Rats to Steroidogenic Activity of AGTH

Abstract

When preincubated rat adrenal bisects taken from reserpine-treated rats were examined for their ability to respond with increased steroidogenesis in vitro following the addition of ACTH, adenosine 3[image],5[image]-monophosphate (3[image],5[image]-AMP), or glucose-6-P plus triphosphopyridine nucleotide (NADP) no impairment of response was observed. Preincubation with reserpine and acetyl choline did not alter the responses obtained. It has been reported that epididymal fat pads from reserpine-treated rats do not respond to ACTH with the normal increase in release of free fatty acids. In the course of these experiments it was observed that the steroidogenic action of ACTH or 3[image],5[image]-AMP was considerably enhanced in adrenals taken from reserpine-treated rats relative to control rats. This effect was not due to a specific action of reserpine as adrenals from rats treated for 2 days with ACTH or formalin reacted similarly. On the other hand, the steroidogenic action of glucose-6-P and NADP was at a similar level in adrenals from stressed or control rats. This differential response of adrenals from stressed rats to various steroidogenic agents is discussed in terms of current theories on the mechanism of action of ACTH.