Endocrine and paracrine-autocrine regulation of the human corpus luteum during the mid-luteal phase

Human corpora lutea undergo an extremely rapid period of growth, development and regression during the course of non-fertile cycles. The tissue consists of steroidogenic (parenchymal) and non-steroidogenic (stromal) cells. In women and other primates, steroid hormone production by corpora lutea depends on the presence of pituitary-derived LH. Nevertheless, there is also intra-luteal regulation of steroid synthesis. Steroidogenic luteal cells and non-steroidogenic cells interact via endocrine and paracrine pathways, and by contact-dependent pathways (gap junctions). Thus, hormones and locally produced factors including steroids, growth factors, cytokines, reactive oxygen species and nitric oxide may modulate luteal lifespan. The factors regulating regression and rescue of the corpus luteum are not understood completely. This review describes the expression of two representative intragonadal peptides that may influence luteal regression (interleukin 1 beta) and luteal rescue (steroidogenic acute regulatory protein).