RESUMO
Paternal germline exposure to organophosphorous pesticides (OP) has been associated with reproductive failures and adverse effects in the offspring. Methyl-parathion (Me-Pa), a worldwide-used OP, has reproductive adverse effects and is genotoxic to sperm, possibly via oxidative damage. This study investigated the stages of spermatogenesis susceptible to be targeted by Me-Pa exposure that impact on spermatozoa function and their ability to fertilize. Male mice were exposed to Me-Pa (20 mg/kg bw, i.p.) and spermatozoa from epididymis-vas deferens were collected at 7 or 28 days post-treatment (dpt) to assess the effects on maturing spermatozoa and spermatocytes, respectively. Spermatozoa were examined for DNA damage by nick translation (NT-positive cells) and SCSA (%DFI), lipoperoxidation (LPO) by malondialdehyde production, sperm function by spontaneous- and induced-acrosome reactions (AR), mitochondrial membrane potential (MMP) by using the JC-1 fluorochrome, and fertilization ability by an in vitro assay and in vivo mating. Alterations on DNA integrity (%DFI and NT-positive cells) in spermatozoa collected at 7 and 28 dpt, and decreases in sperm quality and induced-AR were observed; reduced MMP and LPO were observed at 7 dpt only. Negative correlations between LPO and sperm alterations were found. Altered sperm functional parameters evaluated either in vitro or in vivo were associated with reduced fertilization rates at both times. These results show that Me-Pa exposure of maturing spermatozoa and spermatocytes affects many sperm functional parameters that result in a decreased fertilizing capacity. Oxidative stress seems to be a likely mechanism of the detrimental effects of Me-Pa exposure in male germ cells.
Assuntos
Reação Acrossômica/efeitos dos fármacos , Inseticidas/toxicidade , Metil Paration/toxicidade , Espermatogênese/efeitos dos fármacos , Espermatozoides/efeitos dos fármacos , Animais , Quebras de DNA de Cadeia Simples/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Feminino , Fertilização/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos ICR , Estresse Oxidativo/efeitos dos fármacos , Exposição Paterna , Distribuição Aleatória , Motilidade dos Espermatozoides/efeitos dos fármacos , Estatísticas não Paramétricas , Fatores de TempoRESUMO
Pesticide exposure, including organophosphorous (OP) insecticides, has been associated with poor semen quality, and paraoxonase (PON1), an enzyme involved in OP deactivation, may have a role on their susceptibility, due to PON1 polymorphisms. Our objective was to evaluate the role of PON1Q192R polymorphism on the susceptibility to OP toxicity on semen quality and DNA integrity in agricultural workers. A cross-sectional study was conducted in farmers with Mayan ascendancy from southeastern Mexico chronically exposed to pesticides; mostly OP. Fifty four agricultural workers (18-55 years old) were included, who provided semen and blood samples. Semen quality was evaluated according to WHO, sperm DNA damage by in situ-nick translation (NT-positive cells), PON1Q192R polymorphism by real-time PCR and serum PON1 activity by using phenylacetate and paraoxon. Two OP exposure indexes were created: at the month of sampling and during 3 months before sampling, representing the exposure to spermatids-spermatozoa and to cells at one spermatogenic cycle, respectively. PON1 192R and 192Q allele frequencies were 0.54 and 0.46, respectively. Significant associations were found between OP exposure at the month of sampling and NT-positive cells and sperm viability in homozygote 192RR subjects, and dose-effect relationships were observed between OP exposure during 3 months before sampling and sperm quality parameters and NT-positive cells in homozygote 192RR farmers. This suggests that cells at all stages of spermatogenesis are target of OP, and that there exists an interaction between OP exposure and PON1Q192R polymorphism on these effects; farmers featuring the 192RR genotype were more susceptible to develop reproductive toxic effects by OP exposure.
Assuntos
Doenças dos Trabalhadores Agrícolas/induzido quimicamente , Doenças dos Trabalhadores Agrícolas/genética , Arildialquilfosfatase/genética , DNA/efeitos dos fármacos , Inseticidas/toxicidade , Compostos Organofosforados/toxicidade , Sêmen/efeitos dos fármacos , Adolescente , Adulto , Doenças dos Trabalhadores Agrícolas/epidemiologia , Consumo de Bebidas Alcoólicas/epidemiologia , Arildialquilfosfatase/metabolismo , Estudos Transversais , Dano ao DNA , Frequência do Gene , Genótipo , Humanos , Marcação In Situ das Extremidades Cortadas , Modelos Lineares , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Exposição Ocupacional/efeitos adversos , Polimorfismo Genético/efeitos dos fármacos , Polimorfismo Genético/genética , Fumar/epidemiologia , Transtornos Relacionados ao Uso de Substâncias/epidemiologiaRESUMO
Lead (Pb) alters sperm chromatin condensation (CC) and the mechanisms are investigated. During spermatogenesis, protamines replace histones and disulfide bonds formation during epididymal maturation condense the chromatin. We evaluated sperm Pb uptake in testis and epididymis and the effects on CC in mice (0.06% Pb(2+)/16 weeks/drinking water). Spermatozoa from caput epididymis (CP) and cauda epididymis-vas deferens (CE-VD) were obtained and CC was measured by SCSA. Lead levels in spermatozoa from CP were lower than those from CE-VD, and correlated with a decreased CC, while Pb in CE-VD spermatozoa correlated with an increased CC. Lead accumulation into the nucleus was observed and Pb binding to nuclear sulfhydryl groups decreased chromatin decondensation in vitro. Our results suggest that spermatozoa take up Pb during testicular development and epididymal transport and alter CC, depending of the timing of Pb incorporation into the sperm nucleus, which finally may interfere with the chromatin decondensation process after fertilization.
