ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P444

Effects of intranasal atrial natriutetic peptide (ANP) and insulin on sleep-associated pituitary-adrenal inhibition in elderly humans

Manfred Hallschmid1, Christian Bendict1, Sophie Spielmann2, Rick Schicke2, Werner Kern2, Jan Born1 & Hendrik Lehnert2

1Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany; 2Department of Medicine I, University of Lübeck, Lübeck, Germany.

Introduction: In elderly humans sleep disturbances are associated with an impaired nocturnal inhibition of the hypothalamo–pituitary–adrenal (HPA) axis and chronic diseases like metabolic syndrome and depression. Recent experiments in young and healthy subjects demonstrated that intranasal ANP inhibited stimulated cortisol secretion during wakefulness whereas administration of intranasal insulin in the evening reduced cortisol levels in the morning after undisturbed sleep.

Methods: In a double-blind, placebo controlled experiment 19 healthy elderly (mean age 70.8 years, nine women, ten men) were treated in randomized order with intranasal ANP (1 mg) or insulin (160 IU) or placebo (saline solution) at 22.30 hours. Sleep was assessed by polysomnography and blood samples were drawn in close intervals for determination of cortisol, ACTH and blood glucose. Furthermore mood and memory as well as caloric intake in the morning after experimental nights were investigated.

Results: The cortisol nadir values were lower in subjects treated with ANP or Insulin, but differences between experimental groups were statistically not significant (mean±S.E.M cortisol nadir (μg/dl): placebo: 2.26±0.17; ANP: 1.99±0.21; Insulin: 2.10±0.18). No changes of mood, memory and caloric intake were detected.

Conclusion: In this sample of healthy elderly our data do not support the hypothesis that intranasal ANP or insulin improves inhibition of nocturnal HPA-activity in aged humans.

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