Relationship between PON-1 enzymatic activity and risk factors for pesticide poisoning in farmers from the Cienega, Jalisco, Mexico

Abstract

Paraoxonase-1 (PON-1) is an enzyme that hydrolyzes organophosphate pesticides. The presence of polymorphisms in PON-1 (L55M and Q192R) decreases its enzyme activity and increases the risk of central nervous system (CNS) toxicity in occupationally exposed farmers, leading to chronic degenerative diseases and death. We studied 103 farmers in the region of Cienega Jalisco, Mexico, which were exposed mainly to organophosphate pesticides. We used serum and plasma samples to assay PON-1 activity and perform polymorphism analysis (L55M and Q192R) using qPCR and TaqMan probes, respectively. For both polymorphisms, there was high percentage of heterozygosity (55 LL = 0.19, LM = 0.75, MM = 0.06; 192 QQ = 0.12, QR = 0.72, RR = 0.16), while the allelic frequencies were more balanced (L = 0.56, M = 0.44; Q = 0.48, R = 0.52). There were no significant differences in enzyme activity of L55M polymorphism genotypes (LL = 179.27; LM = 192.11; MM = 122.11; QQ = 135.74; QR = 187.90; RR = 209; p > 0.05). But there was a slight decrease in enzyme activity for the Q192R polymorphism genotypes. The genotype and alcohol consumption associated with slight increases in enzyme activity. However, genotype and tobacco consumption did not have a significant effect on PON-1 activity (µU/mL) (p > 0.05). Overall, alcohol and tobacco consumption affected PON-1 enzyme activity (µU/mL) up to 21.1%. The data obtained in this study reveal that PON-1 activity is affected by genetic variants such as Q192R and alcohol consumption. This may influence the susceptibility of populations to organophosphate poisoning.