Stress-Induced Secretion of Acth and Corticosterone During Development of Spontaneous Hypertension in Rats

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Abstract
Plasma ACTH and corticosterone response to ether inhalation was examined in spontaneously hypertensive rats (SHR) and in normotensive Wistar-Kyoto (WKY) and Wistar control rats at 4, 8, 12 and 16 weeks of age. In SHR, blood pressure rose to hypertensive levels (above 150 mm Hg) between 5 and 8 weeks, whereas, in control animals, it did not exceed 140 mm Hg. Maximum plasma ACTH concentrations were measured 5 min after exposure to ether and plasma corticosterone values attained their maximum at 20 min. Stress-induced ACTH release was significantly elevated in SHR at 4 and 6 weeks. At 16 weeks of age, no difference in the ACTH response between the three strains could be detected. Correspondingly, 4-week-old SHR showed a more pronounced corticosterone release than Wistar and WKY, whereas 16-week-old SHR and control rats responded similarly. Hypothalamo-pituitary-adrenocortical response to ether stress is thus markedly enhanced in SHR during early development of hypertension.