Serum lipidomics reveals early differential effects of gastric bypass compared with banding on phospholipids and sphingolipids independent of differences in weight loss.

BACKGROUND/OBJECTIVES: Circulating phospholipids and sphingolipids are implicated in obesity-related comorbidities such as insulin resistance and cardiovascular disease. How bariatric surgery affects these important lipid markers is poorly understood. We sought to determine whether Roux-en-Y gastric bypass (RYGB), which is associated with greater metabolic improvement, differentially affects the phosphosphingolipidome compared with adjustable gastric banding (AGB). SUBJECTS/METHODS: Fasting sera were available from 59 obese women (body mass index range 37-51 kg m-2; n=37 RYGB and 22 AGB) before surgery, then at 1 (21 RYGB, 12 AGB) and 3 months follow-up (19 RYGB, 12 AGB). HPLC-MS/MS was used to quantify 131 lipids from nine structural classes. DXA measurements and laboratory parameters were also obtained. The associations between lipids and clinical measurements were studied with P-values adjusted for the false discovery rate (FDR). RESULTS: Both surgical procedures rapidly induced weight loss and improved clinical profiles, with RYGB producing better improvements in fat mass, and serum total cholesterol, low-density lipoprotein-cholesterol (LDL-C) and orosomucoid (FDR <10%). Ninety-three (of 131) lipids were altered by surgery-the majority decreasing-with 29 lipids differentially affected by RYGB during the study period. The differential effect of the surgeries remained statistically significant for 20 of these lipids after adjusting for differences in weight loss between surgery types. The RYGB signature consisted of phosphatidylcholine species not exceeding 36 carbons, and ceramides and sphingomyelins containing C22 to C25 fatty acids. RYGB also led to a sustained increase in unsaturated ceramide and sphingomyelin species. The RYGB-specific lipid changes were associated with decreases in body weight, total and LDL-C, orosomucoid and increased HOMA-S (FDR <10%). CONCLUSIONS: Concomitant with greater metabolic improvement, RYGB induced early and sustained changes in phosphatidylcholines, sphingomyelins and ceramides that were independent of greater weight loss. These data suggest that RYGB may specifically alter sphingolipid metabolism, which, in part, could explain the better metabolic outcomes of this surgical procedure.

Equal BMD after daily or triweekly exercise in growing rats.

The purpose of this study was to examine the efficacy of continuous resistance training (3 days/wk) compared to interrupted resistance training where 20-24 h separated an exercise bout (i. e. 6 days/wk) for enhancing bone mineral density (BMD) in growing male rats. The total volume of work performed per week between the two resistance training programs was equivalent by design. Young male rats were randomly divided into Control (Con, n=9), 3 days/wk resistance trained group (RT3, n=9), and 6 days/wk resistance trained group (RT6, n=9). The RT3 and RT6 groups were conditioned to climb a vertical ladder with weights appended to their tail for a total of 6 wks. After 6 wks, BMD (assessed via DXA) from the left tibia was significantly greater for RT3 (0.242+/-0.004 g/cm (2)) and RT6 (0.244+/-0.004 g/cm (2)) compared to Con (0.226+/-0.003 g/cm (2)). Further, serum osteocalcin (oc, in ng/ml) was significantly greater for RT3 (75.8+/-4.4) and RT6 (73.5+/-3.8) compared to Con (53.4+/-2.4). There was no significant difference in BMD or serum OC between RT3 and RT6 groups. The results indicate that both resistance training programs were equally effective in elevating bone mineral density in young, growing rats.

Interrupted resistance training and BMD in growing rats.

A resistance training program, where the exercise was uninterrupted (UT, i.e. continuous repetitions) was compared against another resistance training program where the exercise was interrupted (IT, i.e. 2 exercise sessions during a training day) for enhancing bone modeling and bone mineral density (BMD) in maturating animals. The total volume of work performed between the two resistance training programs was equivalent by design. Young male rats (approximately 8 weeks old) were randomly divided into Control (Con, n=8), UT (n=8) and IT (n=7) resistance trained groups. The UT and IT groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/week for 6 weeks. After the 6 week training regimen (Mean+/-SD), tibial BMD (assessed via DXA) was significantly greater for UT (0.237+/-0.008 g/cm(2)) and IT (0.238+/-0.005 g/cm(2)) compared to Con (0.223+/-0.004 g/cm(2)). Further, serum osteocalcin (OC) was significantly greater for UT (45.65+/-2.83 ng/ml) and IT (46.33+/-4.60 ng/ml) compared to Con (37.86+/-4.04 ng/ml). There was no significant difference in BMD or serum OC between UT and IT groups. The results indicate that both resistance training programs were equally effective in elevating BMD in growing animals.