Expression of monocyte chemoattractant protein-1 in the bovine corpus luteum around the time of natural luteolysis

Monocyte chemoattractant protein (MCP-1) is a specific chemoattractant for monocytes/macrophages that could have a role in the influx of macrophages i nto the corpus luteum (CL) during structural luteolysis, In this study, rev erse transcription-polymerase chain reaction and in situ hybridization were used to investigate MCP-1 mRNA expression in CL collected from 18 heifers between Days 15 and 20 of the estrous cycle, There was expression of mRNA e ncoding MCP-1 in luteal tissue from ail cows; however, expression was great er in animals that had undergone luteolysis at the time of CL collection as compared to animals in which the Ct was still functional. Similarly, in si tu hybridization showed greater expression of mRNA encoding MCP-1 in CL aft er functional luteolysis, There was also evidence of increased MCP-1 mRNA e xpression in an animal with a functional Ce where the systemic concentratio n of prostaglandin F-2 alpha metabolite was high at the time of tissue coll ection, T lymphocyte populations, identified by immunohistochemistry, had a distribution similar to that of cells expressing MCP-1 mRNA within the CE, but other cell types were also involved. These results demonstrate an incr ease in MCP-1 mRNA after functional luteolysis in the cow, which may be rel ated to the influx of macrophages that occurs at this time.