Transgenerational Effects Of Fenvalerate On The Reproductive Physiology In Male Chickens

To evaluate the transgenerational effects of Fenvalerate (Fen) on reproductive physiology in male chickens,(1)40mature Qingjiaoma male chickens were randomly divided into4groups. The chickens from each group were orally administrated with0.0,0.1,1.0,10mg·kg-1·d-1·BW of Fen for8days, The expression of function genes in gonadal axis were analysed.(2)10adult Qingjiaoma male chickens were orally treated with10mg·kg-1·BW Fen for4weeks and bred with normal hens by artificial insemination to produce offspring (F1), then F1cockerels bred with normal hens to have offspring (F2).1. Effects of Fen at different doses on the expression and function of gonadal axis function genes in adult male chickens1.1Semen quality and testicular histomorphologyThe semen quality was impaired after Fen exposure for8days, sperm abnormality of0.1,1.0and10mg·kg-1·BW Fen-treated groups were significantly increased (P<0.05), but there was no significant differences between different doses. However, Fen didn’t alter the relative weight of testis and diameter of seminiferous tubules significantly.1.2Sex hormoneTwo days Fen exposure at doses of0.1,1.0and10mg·kg-1·BW didn’t effect serum T level significantly. However on the4th day, the serum T level was significant higher in10mg·kg-1Fen than the control (P<0.05), and this difference last till the end of this trial.Two days Fen exposure at doses of0.1,1.0and10mg·kg-1·BW didn’t effect serum E2level significantly. On the4th day, serum E2levels of0.1and1.0mg·kg-1Fen-treatments were significantly lower than the control (P<0.05), but10mg·kg-1Fen-treatment didn’t alter serum E2level significantly. In eighth days, serum E2level in0.1mg·kg-1Fen-treated was significantly lower than10mg·kg-1Fen-treated and control groups (P<0.05), there was no significant difference in1.0and10mg·kg-1Fen-treated groups and control. 1.3The expression of function gene in gonadal axis8days10mg·kg-1Fen treatment significantly increased the mRNA level of GnRHl and ERa in hypothalamus (P<0.05), but the treatmnts of0.1and1.0mg·kg-1Fen did not alter the expression in GnRH1gene significantly. The mRNA level of AR and ERβ of hypothalamus were not altered by Fen treatment (0.1,1.0and10mg·kg-1)1.0mg·kg-1Fen significantly decreased expression of ERβ in pituitary (P<0.05), but0.1and1.0mg·kg-1Fen did not effect the pituitary ERP expression significantly.0.1mg·kg-1Fen significantly increased expression of AR in pituitary (P<0.05),1.0and10.0mg·kg-1Fen did not effect the pituitary AR expression significantly.0.1,1.0and10.0mg·kg-1Fen did not effect the mRNA level of GnRHR1, GnRHR2and ERβ in pituitary.The expression of ERa and AR in testis was markedly upregulated in0.1mg·kg-1Fen-treated group (P<0.05).0.1,1.0and10mg·kg-1Fen-treatment did not influence the expression of ERβ in testis.2. Transgenerational effects of Fen on the male reproductive physiology of chickens2.1Methylation profiles of sperm genomic DNAThe mean methylation levels of CpGs in Steroid17-alpha-hydroxylase (CP17A) gene and membrane-associated progesterone receptor component1(PGRC1) gene, attenuated in response to Fen-treatment (P<0.05). Whereas, the mean methylation level of CpGs in nuclear receptor subfamily5(NR5A1, known as steroidogenic factor1, SF1) gene was increased significantly (P<0.05).Furthermore, Fen-treatment significantly decreased the methylation level at4CpG sites in Activin receptor type-2A Precursor (AVR2A) gene and9CpG sites in CP17A gene (P<0.05) and it increased1CpG site in NR5A1gene (P<0.05). But in prohibitin-2(PHB2) gene, Fen-treatment significantly increased methylation level at1CpG site (P<0.05) and decreased5CpG site (P<0.05). Sperm genomic DNA showed no significant changes in Fen treated group in the mean CpGs methylation level following genes:gonadotropin-releasing hormone receptor (Q9DDC9) gene, gonadotropin-releasing hormone receptor2(Q5EFE0) gene, luteinizing hormone receptor (Q9DER3) gene, estrogen receptor alpha (ESR1) gene, progesterone receptor binding protein (Q9YH14) gene, sex determining region Y box9(SOX9) gene, male hypermethylated region on the Z chromosome (MHM) gene, cytochrome P45011A1(013254), steroidogenic acute regulatory protein (STAR) gene, activin receptor type-2A Precursor (AVR2A) gene.2.2Gonadal development and sexual behavior in the offspring of Fen-treated male chickens2.2.1Development of secondary sex characteristics and testis in male offspringsMale chicken exposure to Fen decreased the development of secondary sex characteristics in its male offspring. The comb length in F1of treatment was significantly shorter than control group from14weeks onwards (P<0.05), wattle and spur length is shorter than control group obviously from16weeks onwards (P<0.05). Relative weight of wattle and testis in F1of treatment at the age of35weeks significantly lower than the control group (P<0.05). However in F2, spur length was significantly shorter than the control group from14weeks onwards (P<0.05), there was no significant difference between control and F2of treatment in development of comb and wattle length. Further, there was no statistic difference between the control and treatment at the age of35weeks.Histological analysis showed that the diameter of seminiferous tubules in F1of treatment was significantly decreased (P<0.01). But in F2, there was no statistic difference on the diameter of the seminiferous tubules between the F2of the Fen-treatment and the control.2.2.2Serum sex hormone level of male offspringsMale chicken exposure to10mg/kg Fen significantly increased the serum E2level in F1and F2cockerels (P<0.05), but did not alter the serum T level in Fl and F2significantly.2.2.3Sexual behaviors of male offspringsResults of female mate choice trial of Fl showed that paternal Fen-treatment decreased the attractive of Fl cockerels to female, female spent less time infront of Fl cockerels compartment than the control (P<0.05). But frequency of crowing, wing flaps, dancing and copulations of Fl cockerels were not different from the control. Frequency of crowing, wing flaps, dancing and copulations were not significantly different between control and F2of treatment.In conclusion,(1) Short-term exposed to Fen adversely effect the semen quality in adult male chicken, disturb the expression of some function genes of gonadal axis,(2) Fen may interfere with the methylation programming of some critical genes in sperm genetic DNA, and cause transgenerational effect on reproductive function.