| ObjectiveAcetochlor ,amide herbicide, is one of the three mostly common used herbicides in China. For its weeding effect and low toxicity, acetochlor consumption has been rising. For a long time, acetochlor was considered to be very secure. However, recent domestic and foreign epidemiological investigations as well as animal experiments demonstrate that acetochlor is an environmental endocrine disruptor, which would produce a wide range of effects to organism.This study investigated reproductive endocrine disruption effect of acetochlor by observing its impact on male mouse reproductive organs and reproductive functions, and provided basis for the evaluation of toxilogical effect of acetochlor and its potential damage to human reproductive system as well as for the making of related laws and residue standard.Methods48 Male Kunming mice of clean grade, weighing (18±2)g were purchased from experimental animal centre, Jilin University. Mice were fed by ordinary diet and conducted adaptive feeding for one week. Afterwards, mice were randomly divided into blank control group, and hight, medium and low exposure dose groups, and 12 for each group, that were exposed to 0 (solvent corn oil), 75,225, 750mg/kg(body weight) acetochlor respectively. All mice were administrated once a day for 90 consecutive days.After exposure, mice were sacrificed and determined serum testosterone levels while testicles were extracted and homogenized. Cell enzyme activities, cell cycle, cell apoptosis changes were measured. Sperm abnormality and pathological changes were also studied.Data were analyzed by SPSS13.0. Normality and homogeneity of variance were determined. And All variance were expressed as x±s. Apply ANOVA for multi-group comparisons, P<0.05 were considered significant.Results1. effect of acetochlor on male mouse genital organ coefficient. Organ coefficient decreased in low dose group while increased a bit in medium and high dose groups but no significance was observed compared with control group(P>0.05); similar result were observed in epididymis, where organ coefficient decreased in low dose group while increased in medium and high group but no significance was observed(P>0.05).2. effect of acetochlor on male mouse testicle serum testosterone levels Serum testosterone level increased as exposure dose increased but no significance were observed (P>0.05). This indicated that acetochlor had impact on testosterone level in mouse serum, but had yet to yield significance.3. effect of acetochlor on male mouse testicular cell enzymes As exposure dose increased, LDH and SDH activities decreased in testicular tissues where LDH activity in medium and high dose group were significantly higher than in control and low dose group (P<0.05). No significance was observed between low dose group and control group (P>0.05). SDH activities were significantly higher in the three exposure groups than in control group (P<0.05). SDH activity in high dose group was obviously higher than in any other group (P<0.05). No significance was observed in low and medium dose group (P>0.05).4. effect of acetochlor on cell cycle and cell apoptosis of male mouse testicle Cell percentage in G0/G1 phase of each exposure dose group were lower than in control group where low and high dose group were significantly different compared with control group (P<0.05). No significance was observed within the exposure dose groups (P>0.05). Compared with control, cell percentage in S phase of each exposure dose group increased and significances were all significant (P<0.05). No significance was observed within the exposure dose groups (P>0.05). Cell percentage in G2/M of each exposure dose group was lower than in control group but no significance was observed (P>0.05). This indicated that acetochlor could have impact on cell cycle.Cell apoptosis result demonstrated that cell apoptosis in each exposure does group increased, where significance was observed in low and high dose group compared with control group (P<0.05). Cell apoptosis in high exposure does group were obviously increased and were significantly higher than in medium exposure does group (P<0.05). This indicated that acetochlor could render testicular cell apoptosis rate increase or decrease apoptotic cells cleavage capability. This was more obvious when under large dose exposure.5. effect of acetochlor on DNA damage of mouse testicular cell Severity of DNA damage increased with the increased of exposure dose. Significance were observed between the three exposure dose group and control group (P<0.05). In addition, high exposure dose group was also significantly different compared with low and medium dose group (P<0.05). This indicated that acetochlor could lead damage to genetic material in mouse testicular tissues.6. effect of acetochlor on male mouse sperm abnormality Sperm abnormality rate increased as exposure dose increased and significances were significant compared with control group (P<0.05). Differences among every two groups were also significant (P<0.05). This indicated that acetochlor could increase mouse sperm abnormality rate increase and was in dose-dependent manner. 7. pathological changes in mouse testicular tissue As exposure dose increased, mouse seminiferous epithelium thinned, and seminiferous tubule atrophy, collapse were also observed. Germ cells of each grade and supporting cells decreased, and were arrayed disorderly. Mature sperm amount declined or even disappeared. Interstitial edema and congestion occurred at the same time.ConclusionThis study indicated that, long time exposure to environmental endocrine disruptor-acetochlor could cause male mouse testicles pathological damage, sperm abnormality increased, serum testosterone level decrease, testicular enzyme of LDH and SDH activity decrease, testicular cell cycle disorder and cell apoptosis rate increase. Acetochlor has some reproductive toxicity on male mouse.
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