Expression And Distribution Of Dnmt1 And MeCP2 In Hypothalamus During The Puberty Onset Of Ewes

Puberty,the transition period for animal from young stage to reproductive stage,is the time for first estrus and ovulation of female animal representing the reproductive ability.Mechanism of puberty onset is extremely complex and still not fully understood.Futhermore,previous studies on puberty onset mainly focused on rodents and primate,studies in livestock are still rather less.The present study was conducted to explore mechanism of puberty onset in ewes in view of DNA methylation.First,we detected mRNA expression of DNA methyltransferases 1(Dnmt1),methylated CPG binding proteins(Methyl-CpG),Gonadotropin-releasing hormone(GnRH)and KiSS-1 gene in hypothalamus during puberty onset of ewes using qRT-PCR.Second,we investigated the distribution relationship between Dnmt1,MeCP2 and GnRH,KiSS-1 in hypothalamus using immunofluorescence double labeling method.The qRT-PCR results indicated that KiSS-1,Dnmt1,GnRH,MeCP2 were expressed in hypothalamus of ewes,it was also noted that GnRH and KiSS-1 expression significantly increased during puberty onset while the expression of MeCP2 significantly decreased as at puberty and pre-puberty.The results from immunofluorescence double-labeling method demonstrated that Dnmt1 and MeCP2 were both distributed in the POA and ARC of the ewe hypothalamus,while they were co-expressed in the ARC respectively with GnRH and Kisspeptin neurons.The number of positive cells for co-expression in ARC increased significantly with the puberty onset.In POA,Dnmt1 and MeCP2 were also co-expressed with GnRH and Kisspeptin,and expression of GnRH was higher compared to Kisspeptin.The number of positive cells for co-expression decreased during puberty onset.In the current study,expression and distribution of Dnmt1,MeCP2,GnRH and Kisspeptin in the hypothalamus of ewes during puberty onset were investigated.The results showed that Dnmt1,MeCP2,GnRH and Kisspeptin were expressed in hypothalamus of ewes.Furthermore,Dnmt1 and MeCP2 were coexpressed with GnRH and Kisspeptin in ARC and POA of hypothalamus.These results inciated that Dnmt1 and MeCP2 may participate in the regulation of puberty onset of ewes by regulating the expression of GnRH and Kisspeptin in hypothalamus.