Bradykinin, a 9-amino acid peptide, is a biologically active peptide that is released from kininogens by a proteolytic cleavage of kallikreins .
This peptide plays important roles in a number of biological processes, including cardiovascular homeostasis, pain
production, and inflammation . With respect to events associated with reproductive organs, bradykinin has been
implicated in ovulation and embryo implantation .
The bradykinin receptor B2 cDNA clone encoded a 364-amino acid protein that had the characteristics of a
7-transmembrane domain G protein-coupled receptor.
General function
Receptor
Comment
Cellular localization
Plasma membrane
Comment
Ovarian function
Ovulation, Follicle rupture
Comment
Atsushi Kimura et al 2001 reported localization of Bradykinin B2 Receptor in the Follicles of Porcine Ovary and Increased Expression
of Matrix Metalloproteinase-3 and -20 in Cultured Granulosa Cells by
Bradykinin Treatment.
The authors have recently shown that not only bradykinin, but also all components for the production of bradykinin, can be
detected within the follicle of porcine ovaries. To elucidate the relevance of the intrafollicular bradykinin-producing
system to its physiological role, the authors investigated the distribution of bradykinin receptor (B2R) mRNA and the protein in
porcine ovaries. A cDNA encoding porcine B2R was first cloned from a porcine uterus cDNA library. The receptor
mRNA was scarcely detected in the ovary by Northern blot analysis. Polymerase chain reaction analysis with total
RNAs isolated from the ovary and from granulosa cells of small and large follicles demonstrated the ovarian
expression of B2R mRNA. The B2R protein was detected by Western blot analysis in extracts of isolated granulosa
cells. In situ hybridization 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 metalloproteinase (MMP) genes was examined using isolated granulosa cells. Bradykinin treatment induced
MMP-3 and MMP-20 gene expression to an extreme degree. The expression of MT1-MMP was also affected by
bradykinin treatment. These results suggest that MMPs play a role in follicle rupture during ovulation. The present study
provides new information regarding the mechanisms of bradykinin-induced ovulation in porcine ovaries.