Aptidão física, fatores de risco metabólicos e presença de polimorfismo nos receptores adrenérgicos em crianças e adolescentes

Abstract

Resumo: O objetivo deste trabalho foi avaliar a influencia das mutacoes Arg16Gly e Gln27Glu do gene do receptor ƒÀ2-adrenergico (ADRB2), e da mutacao Trp64Arg do gene receptor do ƒÀ3-adrenergico (ADRB3) sobre os fatores de risco para a sindrome metabolica (SMet) em criancas e adolescentes com excesso de peso e comparar suas condicoes metabolicas com aptidao fisica. Foram avaliadas 320 criancas e adolescentes (210 meninos e 110 meninas), de ambos os sexos, com idade entre 10 e 16 anos. Os participantes foram divididos em tres grupos: eutroficos (n=110), excesso de peso (n=110) e excesso de peso com SMet (n=100). Avaliou-se estatura, massa corporal, indice de massa corporal (IMC), IMC-escore Z, circunferencia abdominal (CA), estagio puberal, pressao arterial sistolica (PAS) e diastolica (PAD). O consumo maximo de oxigenio direto (VO2 maximo) foi avaliado pelo metodo de Rampa. Foram dosados glicemia, colesterol total (CT), lipoproteina de alta densidade (HDL-C) e triglicerideos (TG). A SMet foi caracterizada pela presenca de tres ou mais dos seguintes criterios, para idade e genero: HDL-c<45 mg/dl; TG.130 mg/dl; CA.75o; GLI.100 mg/dl; PAS e/ou PAD.90o ou .120/80. A genotipagem das mutacoes Arg16Gly e Gln27Glu do gene ADRB2 e da mutacao Tr64Arg do gene ADRB3 foi desenvolvida pelo metodo de PCR em Tempo Real com Taqman. Utilizaram-se os testes t de student, Mann Whitney, analise de variancia (ANOVA), Kruskall Wallis, Qui-quadrado, Correlacao de Pearson e Correlacao de Spearman, com nivel de significancia de p < 0,05. As frequencias dos polimorfismos Arg16Gly, Gln27Glu e Trp64Arg foram semelhantes entre os grupos eutrofico, excesso de peso e excesso de peso e SMet. A presenca de SMet foi correlacionada diretamente com o polimorfismo Arg16Gly do gene ADRB2 (r=0,284, p=0,032). Quando comparado usual e polimorfico, no grupo excesso de peso observaram-se maiores medias nas variaveis peso (p<0,01), estatura (p<0,01), TG (p=0,05), PAS (p<0,01) e PAD (p<0,01) para as mutacoes Arg16Gly; na mutacao Gln27Glu, maiores CA em meninos (p=0,03) e IMC-escore Z (p=0,02) e CA (p=0,038) em meninas e por fim, na mutacao Trp64Arg nas variaveis IMC (p=0,029), IMC escore-Z (p=0,05) e CA (p=0,02) em meninos e TG (p=0,043) em meninas. Na avaliacao de aptidao fisica, a media do VO2max relativo foi maior em meninas com excesso de peso e sem a presenca do polimorfismo Gln27Glu do gene ADRB2 quando comparada a meninas polimorficas (p=0,047). Os resultados permitiram concluir que a SMet esta relacionada a polimorfismo Gln27Glu do gene ADRB2 em meninas, e a aptidao fisica adequada nao foi fator de protecao em portadores de variantes geneticos. Palavras-chave: excesso de peso, sindrome metabolica, aptidao fisica, polimorfismo, alelo Arg16Gly, alelo Gln27Glu, receptor ƒÀ2-adrenergico, alelo Trp64Arg, receptor ƒÀ3-adrenergico.

Abstract: The objective of this study was to evaluate the influence of changes Arg16Gly and Gln27Glu of the ?2-adrenergic receptor gene (ADRB2) and the Trp64Arg mutation of the ?3-adrenergic receptor (ADRB3) receptor gene on the risk factors for metabolic syndrome (MetS) in children and adolescents with overweight and to compare their metabolic conditions with physical fitness. The study included 320 children and adolescents (210 boys and 110 girls), of both sexes, aged between 10 and 16 years. Participants were divided in three groups: adequate weight (n=110), overweight (n=110) and overweight with MetS (n=100). Height, body mass, body mass index (BMI), BMI Z-score, waist circumference (WC), pubertal stage, systolic blood pressure (SBP) and diastolic (DBP) were evaluated. The maximal direct oxygen (VO2 max) was evaluated by the ramp method. Glucose, total cholesterol (TC), high density lipoprotein (HDL-C) and triglycerides (TG) were measured. The MetS was defined by the presence of three or more of the following criteria for age and gender: HDL-C<45 mg/dL, TG?130 mg/dl, WC?75 percentil; GLI?100 mg/dl, SBP and/or DBP?90 or?120/80. Genotyping of mutations Arg16Gly and Gln27Glu the ADRB2 gene and Tr64Arg the ADRB3 gene mutation was developed by the PCR method with Taqman Real-Time. Used the Student t test, Mann Whitney test, analysis of variance (ANOVA), Kruskal Wallis test, chi-square, Pearson correlation and Spearman correlation, with significance level of p<0.05. The frequencies of polymorphisms Arg16Gly, Gln27Glu and Trp64Arg were similar between normal weight, overweight and excess weight groups and MetS. The presence de Smet was directly correlated with the Arg16Gly polymorphisms (ADRB2) (r=0.284, p=0.032). When compared usual and polymorphic, in excess weight group shows higher average values in weight (p <0.01), height (p<0.01), TG (p=0.05), SBP (p<0.01) and DBP (p<0.01) for Arg16Gly mutations; in mutation Gln27Glu, larger CA in boys (p=0.03) and BMI Z-score (p=0.02) and CA (p=0.038) in girls and finally, the Trp64Arg mutation in variables BMI (p=0.029), BMI Z-score (p=0.05) and CA (p=0.02) in boys and TG (p=0.043) in girls. In the assessment of physical fitness, the mean relative VO2max was higher in overweight girls with and without the presence of Gln27Glu polymorphism of ADRB2 gene polymorphism when compared to girls (p=0.047). The results showed that MetS is related to Gln27Glu polymorphism of ADRB2 gene in girls, and adequate physical fitness was not a protective factor in patients with genetic variants. Keywords: overweight, metabolic syndrome, physical fitness, polymorphism, Arg16Gly allele, Gln27Glu allele, ?2-adrenergic receptor; Trp64Arg allele, ?3-adrenergic receptor.