1541-P: Sympathetic Nervous System Activity in Response to Food Ingestion Is Impacted by Obesity

Studies have shown that sympathetic nervous system activity (SNSA) may differ in obese (OB) compared to lean individuals. In addition, increased (SNSA) has been observed after ingestion of food. However, it remains unclear whether obesity alters post-meal (SNSA). We tested the hypothesis that (SNSA) is increased post-meal in OB individuals. We used a dual strategy to assess SNSA: i) a whole-body PET radiotracer ([11C]MRB) in combination with CT imaging (PET-CT). [11C]MRB binds to norepinephrine (NE) transporter allowing measurement of NE release from SNS. ii) Skeletal muscle microneurography to measure muscle sympathetic nerve activity (MSNA). Participants underwent two PET-CT and MSNA visits: fasting and mixed meal test (MMT). We ​​examined 5 subjects, 3F/2M, age 41±7 years (2 OB) and 3 normal weight (NW). During the MSNA fasting visit, RR intervals were longer at 15 minutes (P=0.03), while opposite findings were observed with MMT, which diminished between 15 until 60 minutes indicating increased heart rate (HR). We also observed increased total MSNA area/burst at 60 min after MMT (P<0.02). No statistically significant differences in MSNA were observed between OB and NW. PET-CT of deltoid muscle (n=4, 2 OB and 2 NW) showed changes in distribution volume ratio (DVR) between days (MMT - fasting) were correlated with BMI (R2=0.71, P=0.16). DVR changes in both NW were reduced, while both OB were increased (P=0.01), suggesting that OB had less endogenous NE competing with [11C]MRB to bind at the NE transporter compared to NW. These preliminary data suggest that MSNA increases following MMT in both NW and OB subjects which may be further impacted by obesity. Disclosure T.J.Chung: None. J.Deajon-jackson: None. J.Bini: None. H.Song: None. E.Sanchez rangel: None. C.W.Yeckel: None. J.J.Hwang: None. N.Stachenfeld: None. R.Belfort-deaguiar: Research Support; Fractyl Health, Inc., Silver Palate Kitchens. Funding National Institute of Diabetes and Digestive and Kidney Diseases (1R56DK129344)