Stress-Induced Secretion of Adrenocorticotropin, Corticosterone, and Prolactin in Experimentally and Genetically Hypertensive Rats

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Abstract
Plasma levels of immunoreactive ACTH, corticosterone (CS), and PRL in two-kidney, one clip (2K1C) hypertensive SABRA, hypertension-prone (SBH), hypertension-resistant (SBN), and normotensive SABRA rats were compared under both quiescent conditions and after acute (2 min) cold water stress. Serum levels of CS were higher in 2K1C hypertensive compared with normotensive SABRA rats under both quiescent and stressful conditions. Circulating levels of ACTH and PRL were similar in both groups under quiescent conditions. Resting circulating levels of CS were higher in the SBH rats compared with SABRA or SBN rats. Serum PRL levels were similar in SBH and SABRA rats under both quiescent and stressful conditions. Resting PRL levels in the SBN rats were lower compared with the SABRA rats. Resting serum levels of ACTH and CS in the SBN rats were similar to those found in the SABRA rats. After stress exposure serum ACTH and CS levels were elevated in all groups. Serum PRL levels in SBN rats were not affected by stress, unlike the marked elevation seen in the other groups. Our study demonstrates increased secretion of CS in both 2K1C hypertensive and SBH rats under quiescent conditions. Both 2K1C hypertensive and SBH rats have normal hormonal capacity to respond to stress. SBN rats exhibited reduced PRL secretion under both quiescent and stressful conditions. It is suggested that abnormal activity of the hypothalamicpituitary-adrenal system may play a role in the pathogenesis of 2K1C and genetic hypertension as well as in resistance to hypertension.