Changes in interleukin-1β mRNA expression in the rat ovary during the estrous cycle in response to lipopolysaccharide

Abstract

The changes in interleukin-1 (IL-1) β mRNA expression and the number of macrophages were studied in the ovary during the estrous cycle in rats and after intraperitoneal injection of lipopolysaccharide (LPS, 2 mg/body) 2 hours before autopsy. IL-1β mRNA expression was very low in the ovary, and there was no statistically significant change during the estrous cycle. Hybridization signals of IL-1β mRNA were localized intensely in the thecal layer, moderately in the corpora lutea, and slightly in granulosa cells of the ovary during the cycle. The number of macrophages seen mainly in the hilum and interstitium significantly increased on proestrus compared with other estrous days. LPS significantly increased IL-1β mRNA expression on each day with the highest response to LPS at 1500 h on proestrus, and caused an increase in the number of macrophages in the ovary within 2 hours. These results indicate that IL-1β mRNA expressions are low during the estrous cycle in rats, and proestrus is the day of maximal IL-1β synthesis in response to LPS. The increase in IL-1β synthesis caused by LPS might be due to at least the influx of macrophages into the ovary.