Potential role of oxytocin in cell to cell communication in the corpus luteum.

Although oxytocin (OT) was identified in the human and primate corpus luteum (CL) over a decade ago, a definitive role for this peptide has not been elucidated. Several in vitro models have been utilized to examine the most obvious role for OT in luteal function, that of its effect on progesterone (P) production. Using dispersed cells in short term incubations, cultured cells and microdialysis procedures utilizing intact tissue, variable effects of OT on P production have been obtained. We therefore hypothesized that OT may have other role(s) in this tissue. The follicle cells remaining after a successful ovulation has occurred undergo rapid luteinization and the tissue is extensively remodeled to form the CL. At this time, in most species, two types of luteal cells have been identified based on their morphology, biochemistry and size. Both cell types produce P, however only one cell type responds to the long distance modulator LH. Since both cell types appear to be needed for the overall synthesis of P in adequate quantities required for the preparation of the endometrium "information trafficking" must occur between the two cell types. Our recent studies have shown the presence of gap junctions and connexin-43, E-cadherin, an adhesion molecule and ZO-1 protein associated with tight junctions in the baboon and human CL. The effect of OT on connexin-43 in the baboon CL has been examined.