Determination of cell type specificity and estrous cycle dependency of monocyte chemoattractant protein-1 expression in corpora lutea of normally cycling rats in relation to apoptosis and monocyte/macrophage accumulation.
In regressive corpora lutea, apoptosis of luteal cells, expression of monocyte chemoattractant protein-1 (MCP-1), and accumulation of monocytes/macrophages occur. However, whether these three events are correlated and what cell type expresses MCP-1 have yet to be determined. To clarify these issues, we performed histochemical examinations to determine the localization and the numbers of MCP-1 mRNA-containing cells, apoptotic cells, and monocytes/macrophages in corpora lutea of normally cycling rats. We found that the Mcp-1 gene is expressed in nonapoptotic steroidogenic luteal cells. Corpora lutea that contained MCP-1 mRNA-expressing cells increased in number at estrus together with those containing apoptotic luteal cells. When individual corpora lutea at estrus were analyzed, those with many MCP-1-expressing cells contained few apoptotic cells, and vice versa. These results collectively suggest the following pathway for apoptosis- and MCP-1-dependent regression of the corpus luteum: 1) luteal cells are induced to undergo apoptosis at estrus, and the activation of Mcp-1 gene expression follows in nonapoptotic luteal cells; 2) monocytes/macrophages are chemoattracted by MCP-1 toward corpora lutea containing apoptotic luteal cells; and 3) monocytes/macrophages invade corpora lutea and eliminate apoptotic luteal cells by phagocytosis.
Nagaosa
Kaz
K
Graduate School of Natural Science and Technology. Graduate School of Medical Science, Kanazawa University, Takara-machi, Kanazawa, Ishikawa 920-0934, Japan.
Shiratsuchi
Akiko
A
Nakanishi
Yoshinobu
Y
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D018932:Chemokine CCL2 / Q000235:genetics*; D003338:Corpus Luteum / Q000166:cytology / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D018932:Chemokine CCL2; D012333:RNA, Messenger