Background: It has been shown â?? mostly in animal models - that circadian clock genes are expressed in granulosa\ncells and in corpora luteum and might be essential for the ovulatory process and steroidogenesis.\nObjective: We sought to investigate which circadian clock genes exist in human granulosa cells and whether their\nexpression and activity decrease during aging of the ovary.\nStudy design: Human luteinized granulosa cells were isolated from young (age 18â??33) and older (age 39â??45)\npatients who underwent in-vitro fertilization treatment. Levels of clock genes expression were measured in these\ncells 36 h after human chorionic gonadotropin stimulation.\nMethods: Human luteinized granulosa cells were isolated from follicular fluid during oocyte retrieval. The mRNA\nexpression levels of the circadian genes CRY1, CRY2, PER1, PER2, CLOCK, ARNTL, ARNTL2, and NPAS2 were analyzed by\nquantitative polymerase chain reaction.\nResults: We found that the circadian genes CRY1, CRY2, PER1, PER2, CLOCK, ARNTL, ARNTL2, and NPAS2, are expressed in\ncultured human luteinized granulosa cells. Among these genes, there was a general trend of decreased expression in\ncells from older women but it reached statistical significance only for PER1 and CLOCK genes....\nConclusions: This preliminary report indicates that molecular circadian clock genes exist in human luteinized\ngranulosa cells. There is a decreased expression of some of these genes in older women. This decline may\npartially explain the decreased fertility and steroidogenesis of reproductive aging.
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