The Effects of Social Support and Oxytocin Administration on Physiological Stress Reactivity in Essential Hypertension

To test a psychopharmacological intervention strategy which may provide new insights into the mechanisms underlying the physiological hyperreactivity to stress observed in hypertension, we plan to test the effects of the neuropeptide oxytocin and social support on the neurobiological and psychological responsiveness to social stress. The study population for this project consists of 80 hypertensive and 80 normotensive non-smoking medication-free men. We expect exogenous oxytocin administration to enable hypertensives to effectively take advantage of the provided social support. Thereby, oxytocin may enhance the effect of social support on reducing the previously observed physiological hyperreactivity to stress in essential hypertensives.

Background Data on psychobiological stress reactivity in essential hypertension demonstrated physiological hyperreactivity to acute psychosocial stress in hypertensives as compared to normotensive controls in terms of sympathetic nervous system and hypothalamus-pituitary-adrenal axis activity, blood lipids, and coagulation activity. Moreover, we found lower perceived social support in hypertensives as compared to normotensives, with the highest physiological stress responses in hypertensives with low perceived social support.. In addition, the collaborating group of Prof. Heinrichs demonstrated that OT and social support interact to reduce neuroendocrine responses to stress in normotensive individuals. Given these findings and given the aforementioned hypothesized role for OT in physiological stress reactivity, particularly in hypertension, it seems promising to investigate the combined effects of OT and social support provision on physiological stress reactivity in essential hypertensives as compared to normotensives. Objective The proposed project will provide new information on neuroendocrine mechanisms underlying the observed physiological hyperreactivity to stress in essential hypertension. Moreover, stress reactivity of intermediate biological risk factors has not yet been investigated in experiments studying the effects of the acutely provided social support, either in healthy individuals or in hypertensives. The results of this project may provide important information for the development of effective interdisciplinary prevention and intervention strategies for essential hypertension Methods The methodological approach of social stress induction by the TSST used in our previous hypertension study will be translated to the planned project and we will repeatedly collect blood and saliva samples to measure neuroendocrine reactivity in terms of cortisol, epinephrine, and norepinephrine, as well as continuously measuring of heart rate and blood pressure. Blood pressure will be measured at each sampling timepoint as well as twice during the TSST (during the speech and during mental arithmetics). As our recent findings suggest strong associations between social support and heightened coagulation activity in healthy subjects before and after social stress, and as we found higher lipid and coagulation reactivity to psychosocial stress in hypertensives with catecholamine stress changes predicting elevated lipid stress reactivity, we plan to additionally measure biological risk factors for CHD.