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KAREN A. SCRIBNER, CLAIRE-DOMINIQUE WALKER, CAREN S. CASCIO, MARY F. DALLMAN, Chronic Streptozotocin Diabetes in Rats Facilitates the Acute Stress Response without Altering Pituitary or Adrenal Responsiveness to Secretagogues, Endocrinology, Volume 129, Issue 1, 1 July 1991, Pages 99–108, https://doi.org/10.1210/endo-129-1-99
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We have used streptozotocin (STZ)-induced diabetes in rats to determine whether this represents a sustained stimulus to the adrenocortical system and whether STZ-diabetic rats are able to mount an acute stress response. Furthermore, we compared pituitary responsiveness to CRF and/or arginine vasopressin, and adrenal responsiveness to ACTH in STZ- us. vehicle-treated rats. We also compared the efficacy of dexamethasone inhibitory feedback in STZ-diabetic and control rats. Our results show that STZ-treated rats chronically hypersecrete corticosterone (B) as evidenced by their decreased thymus weights, their increased urinary B excretion, and their elevated mean plasma B levels during the light hours of the day. Despite the evidence for sustained hypersecretion of B, STZ-treated rats showed greater and more prolonged ACTH and B responses to the acute stress of histamine injection. However, when tested separately, neither pituitary nor adrenal responsiveness to their secretagogues were increased in STZ-diabetic compared to control rats. Dexamethasone inhibition of stress-induced B secretion was tested using two different paradigms: pentobarbitalanesthetized rats were given iv injections of acid saline, and awake rats were given ip injections of histamine. In both experiments the STZ-treated rats were relatively resistant to glucocorticoid inhibition of stress responses. This finding, taken together with the exaggerated ACTH and B responses to stress, strongly suggests that the facilitatory effects of chronic STZdiabetes are a consequence of changes in sensitivity of central neural components of the adrenocortical system to stimulatory and/or inhibitory inputs, in conjunction with changes in glucocorticoid feedback sensitivity.