Oxytocin response to controlled dietary sodium and angiotensin II among healthy individuals

Abstract

Oxytocin, while classically known for its role in parturition, lactation, and social behavior, also has been implicated in the control of sodium homeostasis in animal models. To improve our understanding of oxytocin physiology in humans, we measured basal oxytocin levels under low- and liberal-dietary-sodium conditions and following a peripheral angiotensin II (ANG II) infusion. Ten healthy individuals underwent a 6-day standardized low-sodium diet and a 6-day liberal-sodium diet. Each diet was followed by a graded ANG II infusion for 30-min sequential intervals at doses of 0.3, 1.0, and 3.0 ng·kg·min. Fasting serum oxytocin was assessed before and after ANG II infusion. Basal oxytocin levels (1,498.5 ± 94.7 vs. 1,663.3 ± 213.9 pg/ml, P = 0.51) did not differ after the low- and liberal-sodium diets. Following the ANG II infusion, ANG II levels and mean arterial pressure significantly increased as expected. In contrast, the ANG II infusion significantly lowered oxytocin levels from 1,498.5 ± 94.7 vs. 1,151.7 ± 118.1 pg/ml ( P < 0.001) on the low-sodium diet and from 1,663.3 ± 213.9 vs. 1,095.2 ± 87.4 pg/ml ( P = 0.03) on the liberal-sodium diet. The percent change in oxytocin following the ANG II infusion did not differ by sodium diet (-25 ± 5% vs. -28 ± 7% low- vs. liberal-sodium conditions, P > 0.99). Dietary sodium intake did not affect circulating oxytocin levels among healthy individuals. Systemic oxytocin levels were significantly suppressed following a peripheral ANG II infusion independent of dietary sodium conditions.

Potential of Endogenous Oxytocin in Endocrine Treatment and Prevention of COVID-19

“…Consistently, COVID-19 patients have lower circulating levels of natriuretic peptides ( 118 ) that are under facilitatory regulation of oxytocin ( 119 ). The increased angiotensin II due to reduction of ACE2 ( 120 ) can also reduce circulating oxytocin levels ( 121 ). Consequently, the insufficiency of oxytocin in the brain and blood can make individuals fall in panic, fear and immune-metabolic disorders ( 122 , 123 ), thereby reducing resistance to COVID-19.…”

Cardiovascular protective properties of oxytocin against COVID-19

“…Since ANP is under facilitatory regulation of OXT, its reduction manifests that OXT or OTR signaling is reduced in COVID-19. In addition, systemic OXT levels are significantly suppressed following a peripheral infusion of AT II [ 80 ]. Since AT II is increased due to the reduction of ACE2, which can also reduce OXT secretion in COVID-19 patients.…”

The Predisposition for Type 2 Diabetes Mellitus and Metabolic Syndrome

“…Meta-analyses have also described a positive association with subjects from Middle East, North Africa ( 26 ) or Asia ( 32 ), whereas, among Europeans, the results are more heterogenous ( 33 , 34 ). The number of ACE D variants was correlated with an increase in ACE activity ( 35 ) and angiotensin II signal transduction influences secretion of oxytocin ( 36 , 37 ). Long-term ACE hyperactivity may pre-dispose to insulin hypersecretion and impairment of vessel walls compliance which increase the risk for T2DM and hypertension development ( 38 ).…”