Study On The Effect Of Timed Artificial Insemination On The Secretion Of Luteal Steroid Hormones In Gilts During Early Pregnancy

Timed artificial insemination(TAI)technology is the use of exogenous hormones to regulate the sow’s estrus and ovulation time,so as to realize the technology of insemination and breeding of the pigs within a specific time,which is of great significance to the modern pig industry.The corpus luteum can secrete progesterone,which plays a key role in the establishment and maintenance of pregnancy.In order to explore the effect of TAI procedure on the secretion of luteal steroid hormones in gilts in early pregnancy,12 gilts in good physical condition were selected and randomly divided into 4 groups.The experimental group was treated with the TAI program of Altrenogest+PMSG+GnRH(APG),and slaughtered on the 16th and 25th day of pregnancy(D16-APG group and D25-APG group);the control group did not use any hormones Treatment,slaughtered on the 16th and 25th day of pregnancy(group D16-C and group D25-C).Collect blood and corpus luteum as the research object,first detect the concentration of serum P4,E2,LH and FSH;In order to explore its mechanism of action,the expression of transcription factors JUN,JUNB,FOS,EGR1,EGR2,EGR3,ERK1/2 and JNK were detected based on the detection of the expression of luteal steroid hormone synthase STAR,CYP11A1 and 3βHSD.The results show:(1)The levels of P4,E2,and LH in the D16-APG were higher than the D16-C(P<0.05);The levels of P4,E2 and FSH in the D25-APG were higher than the D25-C(P<0.05);However,there was no difference in FSH concentration between D16-APG and D16-C group(P>0.05),and there was no difference in LH concentration between D25-APG and D25-C group(P>0.05).(2)At the 16th day of pregnancy,the protein levels of CYP11A1 and 3βHSD in the D16-APG group were higher than the D16-C group(P<0.05),but the STAR protein levels in the D16-APG group were not significantly different from those in the D16-C group(P>0.05);At the 25th day of pregnancy,the protein levels of CYP11A1,STAR and 3βHSD in the D25-APG group were significantly higher than those in the D25-C group(P<0.05).(3)On the 16th day of pregnancy,the relative expression levels of JUNB,FOS and EGR2 genes in the D16-APG group were higher than the D16-C group(P<0.05),but the relative expression levels of JUN,EGR1 and EGR3 genes in the D16-APG group Compared with the D16-C group,there was no difference(P>0.05);at the 25th day of pregnancy,the expression of JUN,FOS,JUNB,EGR1,EGR2,and EGR3 genes in the D25-APG group was higher than the D25-C group(P<0.05).(4)On the 16th day of pregnancy,the relative expression levels of NARS、MPP2 and GNA11 genes in the D16-APG group were higher than the D16-C group(P<0.05),on the 25th day of pregnancy,the expression of NARS、MPP2 and GNA11 genes in the D25-APG group was higher than the D25-C group.On the 16th day of pregnancy,timed insemination treatment increased the expression of ERK1/2 and its phosphorylated protein,and on the 25th day of pregnancy(P<0.05),it increased the expression of ERK1/2 and JNK and their respective phosphorylated proteins(P<0.05).In summary,Altrenogest+PMSG+GnRH TAI treatment can affect the expression of transcription factors such as JUN,FOS,EGR1 through the ERK1/2 and JNK pathways in the early pregnancy.And promote the synthesis of luteinizing steroid hormone by mediating the transcription and expression of luteinizing steroid hormone synthase.