FRI004 Sex Differences In Oxytocin And Arginine-Vasopressin Levels Around A Standardized Meal In Adults With Obesity
Authors: Wronski Marie-Louis , Sanislow James T , Holman Katherine , Gydus Julia , Muhammed Maged , Smith Sarah , Asanza Elisa , Golden Emily R , Hadaway Natalia , Ehrlich Stefan , Maso Ana Aulinas , Kerem Liya , Davis John M , Nazarloo Hans P , Carter Sue , Plessow Franziska , Lawson Elizabeth Austen 
Published: October 2023

Abstract
Disclosure: M. Wronski: None. J.T. Sanislow: None. K. Holman: None. J. Gydus: None. M. Muhammed: None. S. Smith: None. E. Asanza: None. E.R. Golden: None. N. Hadaway: None. S. Ehrlich: None. A. Aulinas Maso: None. L. Kerem: None. J.M. Davis: None. H.P. Nazarloo: None. S. Carter: None. F. Plessow: None. E.A. Lawson: None.
Objective: Oxytocin (OXT) and arginine-vasopressin (AVP) are neurohormones involved in metabolism that are regulated by gonadal steroid levels. OXT tends to be higher in healthy-weight females than males; levels decrease following a meal with an associated reduction in appetite. In contrast, AVP tends to be lower in healthy-weight females than males; post-prandial AVP response has not been examined. OXT and AVP levels in response to feeding and the impact of sex are important to study in individuals with obesity to improve our understanding of disease pathophysiology and advance treatment. We investigated peripheral OXT and AVP levels in female and male adults with obesity fasting and at three post-prandial time points (TP). Methods: The diverse study sample of 56 non-diabetic adults with obesity (35.71% non-White, 19.64% Hispanic) included 30 premenopausal females and 26 males (age: mean ± SEM = 33.73 ± 0.83 years, range = 18.60 - 45.71 years; BMI: 36.77 ± 0.66 kg/m2, 30.20 - 50.60 kg/m2). We tested sex differences in age and BMI using two-samples t-tests. Plasma samples were collected fasting and 30, 60, and 120 minutes (TP) after a standardized ∼500 kcal meal to measure OXT and AVP levels (using enzyme-linked immunosorbent assays). OXT and AVP levels deviating &gt;3*SD from the hormone-, sex-, and TP-specific mean were excluded prior to log-transformation to approximate normality. Sex differences and meal-related dynamics in OXT and AVP levels were examined using two random-intercept linear mixed effects models with predictors sex, TP, and sex-x-TP interaction, covarying for BMI (false discovery rate across both models). Results: Age and BMI did not differ between sexes (ps ≥ 0.354). Across TPs, female sex significantly predicted lower OXT (F(1,53) = 4.90, FDR-q = 0.031, partial eta squared = 0.08, adjusted mean ± SEM females = 273.95 ± 1.12 pg/mL versus males = 397.61 ± 1.13 pg/mL) and lower AVP (F(1,52) = 5.04, FDR-q = 0.031, partial eta squared = 0.09, adjusted mean ± SEM females = 79.77 ± 1.21 pg/mL versus males = 149.39 ± 1.22 pg/mL). TP and sex-x-TP interaction effects were nonsignificant. Conclusion: In this first study to investigate sex differences and meal-dependent changes in OXT and AVP levels in adults with obesity, we found that levels of both neurohormones were lower in females than males. In contrast to our previous finding of a post-prandial decrease in OXT, associated with change in appetite in healthy-weight females, there was no impact of food intake on OXT or AVP levels in adults with obesity. Our data indicate that in obesity, OXT and AVP levels are sexually dimorphic and postprandial dynamics may be dysregulated.
Presentation: Friday, June 16, 2023