The effects of nicotine on metabolic rate

Changes of body composition in patients with BMI 23-50 after tailored one anastomosis gastric bypass (BAGUA): influence of diabetes and metabolic syndrome

BACKGROUND

The use of bariatric surgery to treat diabetes mellitus (DM) requires procedures developed for morbid obese in patients with normal and over-weight. Therefore, we started tailoring one anastomosis gastric bypass (BAGUA) adapted to each patient. This study analyzes changes in body composition (BC) of patients with BMI 23-50 after BAGUA as well as influence of DM and MS.

METHODS

We studied 79 (37 diabetic and 42 non-diabetic) patients (BMI 23-50) who completed all evaluation appointment (preoperative, 10 days, 1, 3, 6, and 12 months) after tailored BAGUA for obesity, diabetes, or diabesity. Patients were classified according to BMI (23-29, 30-34, 35-50) and bearing or not diabetes. Variables are components of BC as well as DM and MS.

RESULTS

Preoperatively, mean values of weight varied 37 kg (78-115 kg), muscle mass (MM) 8 kg (54-62 kg), while fat mass (FM) 30 kg (22-53 kg). Basal metabolism (BM) was higher in diabetic. After surgery, percentage (%) of excess weight loss (%EWL) ranged from 76 % (BMI 35-50) to 128 % (BMI 23-29), FM 56 % (BMI 23-29) to 65 % (BMI 35-50), without differences bearing DM. MM 12 % (non-diabetics BMI 30-34) to 17 % (diabetics BMI 35-50) and visceral fat (VF) 50 % (diabetics BMI 30-34) to 56 % (non-diabetics BMI 35-50).

CONCLUSIONS

After tailored BAGUA, MM maintains steady while FM is highly reduced and variable. BM is reduced in all groups. Diabetics lose less weight and VF but more MM than non-diabetic patients. Preoperative presence of MS influences the changes in BC.

Nicotine enantiomers and oxidative stress

Nicotine affects a variety of cellular processes ranging from induction of gene expression to secretion of hormones and modulation of enzymatic activities. The objective of this study was to characterize the toxicity of nicotine enantiomers as well as their ability to induce oxidative stress in an in vitro model using Chinese hamster ovary (CHO) cells. Colony formation assay has demonstrated that (-)-nicotine is the more toxic of the enantiomers. At 6 mM concentrations, (-)-nicotine was found to be approximately 28- and 19-fold more potent than (+)-, and (+/-)-nicotine (racemic), respectively. Results also indicated that the toxicity of (+/-)-nicotine is higher than that of (+)-nicotine. (-)-Nicotine at a 10 mM concentration substantially decreased glutathione (GSH) levels (46% decrease). In addition, a 3-fold increase in malondialdehyde (MDA) level was evident in cells after exposure to 10 mM (-)-nicotine. Increased lactate dehydrogenase (LDH) activities in the media demonstrated that cellular membrane integrity was disturbed in nicotine treated cells. In the presence of superoxide dismutase (SOD) and catalase (CAT), the LDH activities returned to control value in 24 h with all concentrations of (-)-, (+)-, and (+/-)-nicotine. The decreases in LDH activities in the presence of the radical scavenging enzymes SOD and CAT suggest that membrane damage may be due to free radical generation.

Nicotine administration reduces neuropeptide Y and neuropeptide Y mRNA concentrations in the rat hypothalamus: NPY may mediate nicotine's effects on energy balance

Neuropeptide Y (NPY) is synthesized in arcuate (ARC) neurons which project principally to the paraventricular nucleus (PVN). NPY injected into the PVN causes hyperphagia, reduced energy expenditure and eventually obesity, effects which are opposed by nicotine. We aimed to investigate whether nicotine's effects on energy balance might be mediated by inhibition of hypothalamic NPYergic neurons. Nicotine or saline was given for 1 or 12 days using osmotic minipumps, and additional groups of rats were food-restricted to the intake of the nicotine-treated groups to allow for the effects of hypophagia on hypothalamic NPY. One day's nicotine treatment (12 mg/kg/day) reduced food intake by 30% (P < 0.001) and body weight by 2% (P < 0.01 vs. controls). NPY mRNA levels were significantly reduced by 40% (P < 0.05) and NPY concentrations fell significantly by 33% in the ARC and PVN (both P < 0.01). Matched food restriction also reduced NPY levels significantly in the ARC and PVN (P < 0.02 vs. controls) but had no effect on NPY mRNA. 12 days' nicotine treatment (12 mg/kg/day) lowered cumulative food intake by 8% (P = 0.02) and body weight by 10% (P < 0.05). NPY mRNA levels rose by 40% (P < 0.05), while NPY levels again fell in the ARC and PVN (both P < 0.05). Food restriction, which induced weight loss comparable with that during nicotine treatment, increased NPY mRNA to levels that were 100% above controls (P < 0.01) and also significantly higher than in the nicotine-treated group (P < 0.05). Food restriction also reduced NPY peptide levels in the PVN (P < 0.02), but did not affect those in the ARC. In addition, 12 days' nicotine treatment significantly reduced plasma insulin levels compared with controls (P < 0.05). We suggest that nicotine may inhibit NPY synthesis in the hypothalamus, independently of any effects due to altered energy balance. Reduced activity of NPYergic neurons in the ARC-PVN projection may mediate the effects of nicotine on energy balance.