Localization of bradykinin B-2 receptor in the follicles of porcine ovary and increased expression of matrix metalloproteinase-3 and-20 in cultured granulosa cells by bradykinin treatment

We have recently shown that not only bradykinin, but also all components fo r the production of bradykinin, can be detected within the follicle of porc ine ovaries. To elucidate the relevance of the intrafollicular bradykinin-p roducing system to its physiological role, we investigated the distribution of bradykinin receptor (B2R) mRNA and the protein in porcine ovaries. A cD NA encoding porcine B2R was first cloned from a porcine uterus cDNA library . The receptor mRNA was scarcely detected in the ovary by Northern blot ana lysis. Polymerase chain reaction analysis with total RNAs isolated from the ovary and from granulosa cells of small and large follicles demonstrated t he ovarian expression of B2R mRNA. The B2R protein was detected by Western blot analysis in extracts of isolated granulosa cells. In situ hybridizatio n of B2R mRNA and immunohistochemical analysis of the protein revealed that the receptor is expressed in the theca and granulosa cells of all growing follicles. The effect of bradykinin on the expression of some matrix metall oproteinase (MMP) genes was examined using isolated granulosa cells. Bradyk inin treatment induced MMP-3 and MMP-20 gene expression to an extreme degre e. The expression of MT1-MMP was also affected by bradykinin treatment. The se results suggest that MMPs play a role in follicle rupture during ovulati on. The present study provides new information regarding the mechanisms of bradykinin-induced ovulation in porcine ovaries.