Individual behavioral and neuroendocrine changes are correlated with blood-pressure elevations during conflict alone and combined with high-salt diet in baboons

Abstract

Blood pressure, behavioral, and neuroendocrine measures were obtained from adult male baboons during consecutive experimental phases consisting of daily food reinforcement sessions (baseline, 3 weeks), daily food/shock conflict sessions (2 weeks), and enhanced dietary salt added to the daily conflict protocol (3 weeks). Within-session systolic blood pressure (SBP) increased by an average of 5% ± 1% above baseline during conflict and was accompanied by increases in plasma renin activity, urinary free Cortisol, urinary catecholamines, water intake and body weight, and by decreases in urinary sodium excretion in most animals. Behavioral performances of escape from aversive discriminative stimuli and pausing during danger portions of conflict trials increased, while earned food reinforcers decreased. A strong correspondence was found between the degree of individual BP increase during conflict stress and the degree of change in individual stress indexes. Daily dietary salt further elevated SBP by 10% ± 3% above baseline. Those animals that displayed the greatest changes in physiological and behavioral stress indexes during conflict alone displayed the greatest SBP response during the added high-salt diet. Individuals who are stress-sensitive across a variety of behavioral and physiological systems may be more susceptible to other hypertensinogenic variables.