MESSENGER-RIBONUCLEIC-ACID ENCODING MONOCYTE CHEMOATTRACTANT PROTEIN-1 IS EXPRESSED BY THE OVINE CORPUS-LUTEUM IN RESPONSE TO PROSTAGLANDIN-F2-ALPHA

To investigate expression of monocyte chemoattractant protein-1 (MCP-1 ) in the ovine corpus luteum, a partial cDNA was produced by reverse t ranscription-polymerase chain reaction. This cDNA was 89% identical to that reported for bovine MCP-1 mRNA. In experiment 1, steady-state co ncentrations of mRNA encoding MCP-1 were measured in pools of luteal t issue collected on Days 3, 6, 9, 12, and 15 of the estrous cycle (estr us = 0; n = 4/day). There were no differences in mRNA concentrations f or MCP-1 among any of the days studied (p = 0.43). In experiment 2, mi dluteal-phase corpora lutea were collected from ewes at 0 (untreated), 2, 4, 8, and 16 h after administration of a luteolytic dose of prosta glandin F-2 alpha (PCF2 alpha; n = 4/time point). Concentrations of MC P-1 mRNA were undetectable in untreated controls, were detectable at 2 h post-treatment, had increased 4 and 8 h after administration of PCF 2 alpha when compared to those at 2 h (p < 0.05), and were decreased 1 6 h after administration of PGF(2 alpha) when compared to those at 4 h (p < 0.05). In situ hybridization for MCP-1 mRNA combined with immuno cytochemical labeling of tissue inhibitor of metalloproteinase-1 (TIMP -1) in large luteal cells was used to determine whether the steroidoge nic cells that have PCF2 alpha receptors express MCP-1 mRNA in respons e to PCF2 alpha. Messenger RNA encoding MCP-1 and TIMP-1 were not colo calized, indicating that MCP-1 was not expressed by large steroidogeni c luteal cells during luteolysis.