Butyrylcholinesterase and obesity in individuals with the CHE2 C5+ and CHE2 C5− phenotypes

Cholinesterases and the fine line between poison and remedy

Acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) are related enzymes found across the animal kingdom. The critical role of acetylcholinesterase in neurotransmission has been known for almost a century, but a physiological role for butyrylcholinesterase is just now emerging. The cholinesterases have been deliberately targeted for both therapy and toxicity, with cholinesterase inhibitors being used in the clinic for a variety of disorders and conversely for their toxic potential as pesticides and chemical weapons. Non-catalytic functions of the cholinesterases (ChEs) participate in both neurodevelopment and disease. Manipulating either the catalytic activities or the structure of these enzymes can potentially shift the balance between beneficial and adverse effect in a wide number of physiological processes.

Butyrylcholinesterase Deficiency Promotes Adipose Tissue Growth and Hepatic Lipid Accumulation in Male Mice on High-Fat Diet

Despite numerous reports of relationships between weight gain and butyrylcholinesterase (BChE), this enzyme's role in the genesis of obesity remains unclear, but recent research points to strong links with ghrelin, the "hunger hormone." The availability of BChE knockout (KO) mice provides an opportunity to clarify the causal relationship between BChE and obesity onset. We now find that young KO mice have abnormally high plasma ghrelin levels that slowly decline during long-term high-fat feeding and ultimately drop below those in wild-type mice. On such a diet, the KO mice gained notably more weight, more white fat, and more hepatic fat than wild-type animals. In addition to a greater burden of hepatic triglycerides, the livers of these KO mice show distinctly higher levels of inflammatory markers. Finally, their energy expenditure proved to be lower than in wild-type mice despite similar activity levels and increased caloric intake. A gene transfer of mouse BChE with adeno-associated virus vector restored nearly all aspects of the normal phenotype. Our results indicate that BChE strongly affects fat metabolism, has an important impact on fat accumulation, and may be a promising tool for combating obesity.

Serum Cholinesterase Is Inversely Associated with Body Weight Change in Men Undergoing Routine Health Screening

OBJECTIVE

The purpose of this study is to investigate the relationships between serum cholinesterase and body weight change, in addition to incident obesity defined as a body mass index (BMI) of 25 kg/m(2) or greater.

METHODS

A retrospective 5-year follow-up study was conducted. The crude incidence and hazard ratios (HRs) of obesity adjusted for the BMI and other confounders were calculated for cholinesterase quartiles in 1,412 men and 921 women. Partial correlation coefficients (PCCs) were calculated between cholinesterase and changes in the BMI during the 5-year follow-up period adjusted for age and other confounders and the change in the BMI were compared among cholinesterase quartiles in 1,223 men and 681 women.

RESULTS

During the 5-year follow-up period, 149 men (10.6%) and 65 women (7.1%) developed obesity. The adjusted HRs of obesity decreased, although the crude incidence of obesity increased along the quartiles of cholinesterase in men. The adjusted HRs of obesity for the first (lowest), second and third quartiles of cholinesterase were 2.02 (p=0.006), 1.45 (p=0.122), and 1.28 (p=0.265), respectively compared with the highest quartile in men. The PCC between the baseline level of cholinesterase and change in the BMI was -0.16 (p<0.001) in men. The mean changes in BMI for 5 years were 0.31 kg/m(2), 0.17 kg/m(2), 0.01 kg/m(2) and -0.04 kg/m(2), respectively in the first, second, third and fourth quartiles of cholinesterase in men (p=0.005). Neither incident obesity nor weight gain was significantly associated with cholinesterase in women.

CONCLUSION

The serum cholinesterase level was inversely associated with body weight change, as well as incident obesity, after adjusted for the BMI in men.

Gestational diabetes mellitus (GDM) decreases butyrylcholinesterase (BChE) activity and changes its relationship with lipids

Many conditions interfere with butyrylcholinesterase (BChE) activity, e.g., pregnancy or presence of the BCHE gene variant -116A can decrease activity whereas obesity and types I and II diabetes mellitus can increase activity. In this study, we examined BChE activity, -116A and 1615A BCHE gene variants, and anthropometric and biochemical variables associated with diabetes in patients with gestational diabetes mellitus (GDM) and in healthy pregnant women. BChE activity was measured spectrophotometrically using propionylthiocholine as substrate and genotyping of the -116 and 1615 sites of the BCHE gene was done with a TaqMan SNP genotyping assay. Three groups were studied: 150 patients with GDM, 295 healthy pregnant women and 156 non-pregnant healthy women. Mean BChE activity was significantly lower in healthy pregnant women than in women from the general population and was further reduced in GDM patients. BChE activity was significantly reduced in carriers of -116A in GDM patients and healthy pregnant women. Although GDM patients had a significantly higher mean body mass index (BMI) and triglycerides than healthy pregnant women, they had lower mean BChE activity, suggesting that the lowering effect of GDM on BChE activity was stronger than the characteristic enhancing effect of increased BMI and triglycerides.

Effects of physical exercise on butyrylcholinesterase in obese adolescents

The aim of the present study was to evaluate the effect of a 12 week program of physical exercise (PE) on butyrylcholinesterase (BChE) in obese adolescents. This study compared obese adolescents (N = 54) before and after PE, regarding the relative intensity (RI) and activity of different molecular forms (G1, G2, G4 and G1-ALB) of BChE found in plasma. Waist circumference (WC) and lipid profile were also assessed before and after PE. It was shown that before PE, mean plasma BChE activity was significantly higher in obese than in non-obese adolescents and that it was significantly reduced after PE, becoming similar to that found in non-obese adolescents. Lipid profile and WC also changed in response to PE. These results are consistent with studies that found a correlation between BChE and lipid metabolism and suggest that PE may have led to a physiological regularization of plasma BChE activity. Although mean BChE activity of each isoform was significantly reduced by PE, their RI did not change. This is in accordance with a previous suggestion that this proportion is maintained under factors such as obesity, and may therefore be important for BChE functions.

Obesity and variants of the GHRL (ghrelin) and BCHE (butyrylcholinesterase) genes

Ghrelin coded by the GHRL gene is related to weight-gain, its deactivation possibly depending on its hydrolyzation by butyrylcholinesterase (BChE) encoded by the BCHE gene, an enzyme already associated with the body mass index (BMI). The aim was to search for relationships between SNPs of the GHRL and BCHE genes with BChE activity, BMI and obesity in 144 obese and 153 nonobese Euro-Brazilian male blood donors. In the obese individuals, a significant association with higher BChE activity, in the 72LM+72MM; –116GG genotype class (GHRL and BCHE genes, respectively) was noted. No significant differences were found otherwise, through comparisons between obese and control individuals, of genotype and allele frequencies in SNPs of the GHRL gene (Arg51Gln and Leu72Met), or mean BMI between 72LL and 72LM+72MM genotypes. Although there appears to be no direct relationship between the examined GHRL SNPs and BMI, the association of the 72M SNP with higher BChE activity in obese subjects probably points to a regulatory mechanism, thereby implying the influence of the GHRL gene on BChE expression, and a consequential metabolic role in the complex process of fat utilization.

Molecular forms of butyrylcholinesterase and obesity

This study compared obese (N = 134) and unobese (N = 92) male blood donors, regarding the relative intensity (RI) and activity of different molecular forms (G1, G2, G4 and G1-ALB) of butyrylcholinesterase (BChE, EC 3.1.1.8) found in plasma, thereby searching for an association between these variables with obesity and SNPs of exons 1 and 4 of the BCHE gene. It was shown that obese and unobese individuals do not differ in the RI of each BChE band, even when classifying the sample into three genotypes of exons 1 and 4 of the BCHE gene (-116GG/539AA, -116GG/539AT, -116GA/539AT). Although the mean BChE activity of each band was significantly higher in obese than in unobese blood donors, the proportions of BChE bands were maintained, even under the metabolic stress associated to obesity, thereby leading to infer that this proportion is somehow regulated, and may therefore be important for BChE functions.

Butyrylcholinesterase and diabetes mellitus in the CHE2 C5- and CHE2 C5+ phenotypes

OBJECTIVE:To investigate the relationship between butyrylcholinesterase (BChE) activities (total and band specific) and diabetes mellitus. SUBJECTS AND METHODS: BChE activities (BChEA, AC 4/5, AC OF and RC5) were analyzed in 101 type 1 (DM1) and in 145 type 2 (DM2) diabetic patients, in relation to phenotype, weight and incidence of metabolic syndrome (MS) in these patients. The C4/5 and C5 complex were separated from other molecular forms (C OF) using an acid agar gel. RESULTS: The BChE activity (BChEA) and the absolute activities of C4/5 (AC4/5) and C OF (AC OF) showed a high positive correlation coefficient to weight in the CHE2 C5- group, while the relative activity of C5 complex (RC5) showed a negative correlation to weight. CONCLUSIONS: The present study suggests that the positive correlation of the BChE activities to diabetes mellitus and to insulin resistance may depend on the CHE2 locus variability. High values of BChE activities were associated with insulin resistance only in CHE2 C5- diabetic patients, while in CHE2 C5+ diabetic patients, the presence of C5 complex, especially in a relatively high proportion, leads to less fat storage and better protection against metabolic syndrome.

Serum butyrylcholinesterase is strongly associated with adiposity, the serum lipid profile and insulin resistance

OBJECTIVE

We investigated the association between the serum butyrylcholinesterase (BChE) activity and parameters of adiposity, insulin resistance and the serum lipid profile, including the serum levels of triglyceride (TG), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) in Japanese patients with type 2 diabetes and non-diabetic subjects.

PATIENTS AND METHODS

A total of 259 Japanese subjects [171 patients with type 2 diabetes (age 60.4+/-11.9 years, BMI 25.0+/-4.4) and 88 non-diabetic subjects (age 54.2+/-15.0 years, BMI 25.8+/-4.7)] were enrolled in the study. To assess the hepatic fat content, the ratio of the CT attenuation value of the liver to that of the spleen (L/S ratio) was calculated.

RESULTS

Serum BChE activity was significantly correlated with various indices of adiposity, including the waist circumference, L/S ratio, visceral fat area (VFA), subcutaneous fat area (SFA) and BMI, and also with the TG, HDL-C, LDL-C and HOMA-R, in the entire subject population. Even after adjustment for five variables, namely, age, gender, HbA1c, CRP and serum ferritin (the serum levels of ferritin and CRP have been reported to be associated with adiposity and insulin resistance), the serum BChE activity was still correlated with the waist circumference, L/S ratio, VFA, SFA, BMI, TG, HDL-C, LDL-C and HOMA-R. Furthermore, changes in the serum BChE activity were associated with changes in the L/S ratio, VFA and SFA at 1 year after the baseline.

CONCLUSIONS

These results indicate that the serum BChE activity is associated with parameters of adiposity, the serum lipid profile and the degree of insulin resistance.

Butyrylcholinesterase activity and metabolic syndrome in obese patients

Total butyrylcholinesterase activity (EC 3.1.1.8) was previously suggested as a marker for metabolic syndrome. The present study examined total butyrylcholinesterase activity and the relative and absolute activities of two butyrylcholinesterase electrophoretic bands (C(4/5) and C(OF) in 99 obese individuals (body mass index > or = 30 kg/m2) presenting the CHE2 C5- phenotype of the CHE2 gene. Anthropometric, hormonal and biochemical variables already associated with metabolic syndrome were also examined. The data from these obese individuals of the CHE2 C5- phenotype show that total butyrylcholinesterase activity and the absolute activities of the C(4/5) and C(OF) electrophoretic bands are associated with metabolic syndrome and with variables related to it. These butyrylcholinesterase activities do not behave as independent risk factors for metabolic syndrome, but can be considered as secondary markers for this syndrome in obese individuals with the CHE2 C5- phenotype.