BDNF Val66Met polymorphism and serum concentrations of BDNF with smoking in Thai males.

Many studies have suggested that brain-derived neurotrophic factor (BDNF) is involved in the reward system of addiction, and that nicotine may induce alterations in BDNF gene expression and its protein level within the mesocorticolimbic system. We investigated the BDNF levels and biochemical-hematological parameters of smoker and non-smoker groups, and examined the association of the Val66Met BDNF gene polymorphism with BDNF serum levels and cigarette smoking. The study sample comprised 311 Thai volunteers (200 smokers; 111 non-smokers). The levels of serum BDNF and biochemical-hematological parameters were determined. The Val66Met BDNF polymorphism was genotyped by the polymerase chain reaction-restriction fragment length polymorphism technique. The smoker group had significantly higher serum BDNF levels than the non-smoker group (8.3 vs 6.5 ng/mL, P < 0.05). BDNF concentrations correlated positively with hemoglobin, hematocrit, red blood cell count, white blood cell count, platelet count, number of cigarettes smoked, and thiocyanate level (P < 0.05). No association was found between the BDNF Val66Met genotype and the serum BDNF level. The BDNF Val66Met polymorphism was not significantly associated with the smoking status of the Thai males in this study. Cigarette smoking may be one factor that determines the serum BDNF level, but the BDNF Val66Met polymorphism probably does not influence susceptibility to smoking among Thai males.

Association of HTTLPR and 5-HT2A T102C polymorphisms with smoking characteristics and anthropometric profiles of Thai males.

Nicotine increases serotonin release in the brain. Gene polymorphisms in the serotonergic system have been suggested to be associated with smoking behavior. We investigated a possible association between two polymorphisms in the serotonergic system - HTTLPR of a serotonin transporter gene and 5-HT(2A) at position T102C - with biochemical and anthropometric parameters, and with cigarette smoking in an investigation of 200 smokers and 111 non-smokers. The two polymorphisms, HTTLPR and 5-HT(2A) at position T102C, were genotyped by PCR-RFLP. They were not significantly associated with smoking status in these Thai males. Among the smokers, thiocyanate concentrations and quantity of cigarettes smoked (cigarette pack-years) were significantly higher for individuals with LL/LS genotypes than SS genotypes of 5-HTTLPR (all P < 0.05), whereas "age at starting smoking" and "duration of smoking" were not significantly different between these two genotypes. Moreover, anthropometric variables, comprising triceps skinfold thickness, arm circumference, waist circumference, hip circumference, and waist-to-hip ratio, were significantly higher for the CC/TC genotypes of 5-HT(2A) than the TT genotype (all P < 0.05), except for body mass index. HTTLPR and 5-HT(2A) T102C polymorphisms were not significantly associated with smoking status among Thai males; however, the HTTLPR polymorphism among smokers appears to be an indicator of increased smoking intensity consisting of cigarette pack-years and thiocyanate concentrations. The 5-HT(2A) T102C polymorphism plays a role in the anthropometric profiles, triceps skinfold thickness, arm circumference, waist circumference, hip circumference, and waist-to-hip ratio, but not smoking status in Thai subjects.