Anatomical distribution of primary amine oxidase activity in four adipose depots and plasma of severely obese women with or without a dysmetabolic profile.

Abstract

Semicarbazide-sensitive amine oxidase (SSAO), identical to primary amine oxidase or vascular adhesion protein-1, is a membrane enzyme that generates hydrogen peroxide. SSAO is highly expressed at the adipocyte surface, and its plasma levels increase with type 2 diabetes. Since visceral adipose tissue (AT) is more tightly associated with obesity complications than subcutaneous (SC) abdominal fat, we compared SSAO activity in plasma and 4 distinct AT locations in 48 severely obese women (body mass index (BMI), averaging 54±11kg/m2), with or without a dysmetabolic profile. Higher glucose and triacylglycerol levels vs lower high-density lipoprotein (HDL)-cholesterol characterized dysmetabolic women (DYS; n=25) from non-dysmetabolic (NDYS; n=23), age- and weight-matched subjects. SC, mesenteric (ME), omental (OM), and round ligament (RL) fat locations were collected during bariatric surgery. SSAO capacity to oxidize up to 1mM benzylamine was determined in AT and plasma with radiometric and fluorimetric methods. Plasma SSAO was higher in the DYS group. SSAO activity was higher in fat than in plasma, when expressed as radiolabeled benzaldehyde per milligram of protein. In ATs from DYS women, protein content was 10% higher, and basal hydrogen peroxide release lower than in NDYS subjects, except for RL location. The SSAO affinity towards benzylamine did not exhibit regional variation and was not altered by a dysmetabolic profile (K m averaging 184±7μM; n=183). Although radiometric and fluorimetric methods gave different estimates of oxidase activity, both indicated that AT SSAO activity did not vary according to anatomical location and/or metabolic status in severely obese women.