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

• Published in: Biology of reproduction Vol. 67; no. 5; pp. 1502 - 1508
• Main Authors: NAGAOSA, Kaz, SHIRATSUCHI, Akiko, NAKANISHI, Yoshinobu
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-11-2002
• Subjects: Animals; Apoptosis - physiology; Biological and medical sciences; Chemokine CCL2 - genetics; Corpus Luteum - cytology; Corpus Luteum - physiology; Estrous Cycle - physiology; Female; Fundamental and applied biological sciences. Psychology; Gene Expression; Macrophages - physiology; Mammalian female genital system; Monocytes - physiology; Morphology. Physiology; Rats; Rats, Inbred Strains; RNA, Messenger - metabolism; Vertebrates: reproduction; Monocyte; Rat; Rodentia; Cytokine; Gene expression; Ovary; Vertebrata; Mammalia; Type specificity; Cell death; Ovulatory cycle; Animal; Female genital system; Corpus luteum; Luteolysis; Monocyte chemoattractant protein 1; Apoptosis; Macrophage
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.102.005009

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.