The expression of MMP family members in bovine follicles before and after LH surge and in luteal tissue

Abstract

Matrix metalloproteinases (MMP) and their endogenous tissue inhibitors (TIMP) are implicated in tissue remodelling in the ovary. The aim of this study was to characterize the mRNA patterns of the collagenase-1 (MMP-1), gelatinase A (MMP-2), MT1-MMP (MMP-14), MMP-19 and tissue inhibitor of metalloproteinases-1 (TIMP-1), and -2 (TIMP-2) after FSH follicle stimulation and GnRH induced ovulation. Follicles were classified in 5 groups: before GnRH, 3–5h after GnRH (during LH), 10h after GnRH, 20h after GnRH and 25h after GnRH (periovulation). The CL were classified into 4 stages of oestrous cycle: Days 1–2, 3–4, 5–7 and 8–12. Real time RT-PCR was applied to investigate mRNA expression. In follicles, MMP-1 mRNA increased (p<0.001) after GnRH and remained high. In contrast, MMP-2 mRNA was downregulated (p<0.05) after GnRH until the periovulatoy period (p<0.05). MMP-14 and MMP-19 mRNA did not change significantly (p>0.05) throughout the whole experiment. TIMP-1 mRNA was unregulated (p<0.05) 3–5h and 10h after GnRH injection, decreased to low level 20h after GnRH to increase again during periovulation (p<0.05). TIMP-2 mRNA increased (p<0.05) 3–5h and 10h after GnRH followed by maximal downregulation (p<0.05) at 20h and 25h after GnRH (periovulation). In CL, MMP-1 mRNA was high between Days 1–7 but declined significantly on Days 8–12 (p<0.01). MMP-2, MMP-14 and MMP-19 transcripts did not change (p>0.05) throughout the investigated periods. Luteal TIMP-1 mRNA was high between Days 1–7 and decreased (p<0.01) afterwards. In contrast, TIMP-2 mRNA expression increased significantly (p<0.05) on days 3–4 and stayed unchanged afterwards. These data show that mRNA of MMP and TIMP are distinctively expressed during induced ovulation and in the early CL. The strong upregulation of MMP-1 and TIMP-1 in the follicle during and after the LH surge suggests that they may be involved in ovulation of bovine follicle. Their constantly high mRNA level in the CL of Days 1–7 may be associated with CL formation (angiogenesis) and function.