The Impact of Pesticides - Academy Publish

contribution in PON1 activity of 17% and 12%, respectively (Chen et al., 2003),while other studies in Caucasian populations reported that PON1 -T108C and M55Lpolymorphisms participated with 23% and 5%, respectively (Brophy et al., 2001).The contribution of polymorphisms in these sites in a Mexican population was 12%and 13%, respectively (Rojas-García et al., 2005). On the other hand, a higharylesterase activity was observed within the PON1 192RR genotype in Mexicanindividuals (Rojas-García et al., 2005), but not in African-American or Caribbeanpopulations (Chen et al., 2003). Finally, in Caucasians populations, PON1 192QQgenotype was the one associated with increased arylesterase activity (Brophy et al.,2001).The differences found in the phenotype-genotype relationship in human populationsmay be due to the modulating effect of a variety of other factors. PON1 activityincreases over time from birth, reaching a plateau between 6 and 15 months of agein humans and at postnatal day 21 in rodents (Costa et al., 2005). No gender-relateddifferences have been found in human populations (Geldmacher-von Mallinckrodtand Diepgen, 1988; Richter et al., 2009). Regarding external factors, cigarettesmoke extract inhibited in vitro human plasma PON1 activity and this effect wasantagonized by antioxidants (Costa et al., 2005), while heavy alcohol drinkers had45% lower activity compared with non-drinkers (Rao et al., 2003). A study in 189white men found a positive correlation between dietary and medicinal intakes ofVitamins C and E and serum PON1 activity; although other studies have shown noassociation (Costa et al., 2005). These data evidenced the importance of evaluatingPON1 phenotype and genotype to provide better information about PON1 status.The wide variability in human plasma PON1 activity has led to the hypothesis thatindividuals with high plasma PON1 activity would be more resistant to OP pesticideeffects than individuals with low activity. The number of articles reporting theinfluence of PON1 polymorphisms on some adverse effects of OP exposure ordegenerative diseases has increased in last decades, and several outstanding reviewshave dealt with the evidence of the relationship between PON1 genotype orphenotype and diseases in several populations worldwide.PON1 and male reproductive toxicityThe presence of PON1 activity in male reproductive system has been poorlyexplored and until recent years, the expression of PON1 was reported in mousetesticular cells (Marsillach et al., 2008) and biopsies of humans (Marsillach et al.,2010). Some reports have related seminal PON1 activity and antioxidant status withsemen quality, suggesting that the reduced PON1 activity may have a role in thepathogenesis of male subfertility (Verit et al., 2009). However, other studies havenot shown such association (Marsillach et al., 2010). Regarding the most studiedPON1 genetic polymorphisms, Q192R and L55M, the 55M allele showed asignificant difference in the distribution between infertile (n=187) and fertile(n=194) men in a case-control study conducted in Slovenia and Q192Rpolymorphism did not. These results suggested that the 55M allele might represent arisk factor for infertility susceptibility in Slovenian men (Volk et al., 2011).Similarly, Lazaros et al. (2011) reported that both, 55M and 192R allele frequencieswere significantly higher in oligospermic respect to normospermic men fromGreece; in addition, men with 55LL/192RR genotype showed lower spermconcentration and motility.Few studies have evaluated the role of PON1 Q192R and L55M polymorphisms asmodulators of the adverse effects of OP exposure on semen quality. Padungtod et al.(1999) showed that Chinese workers from a pesticide factory (n=60; parathion andmethamidophos) carrying the 192QR/RR genotype had significantly lower spermAcademyPublish.org - The Impact of Pesticides65