Abstract
Although oxytocin has been recognized as a product of the corpus luteum in numerous
species, including nonhuman primate and women, for some time, its precise role in
luteal physiology has remained obscure. However, with the recent observations that
the steroidogenic activity of the large and small cells is increased in the presence
of LH when these cells are in intimate contact has led to the hypothesis that cell-to-cell
communication must occur between these cells. Cell-to-cell communication is possible
via several mechanisms, including paracrine/autocrine and intercellular crosstalk
via gap junctions. Substantial morphological and immunohistological evidence using
antibodies to gap-junction specific proteins, the connexins, indicates the presence
of gap junctions in corpora lutea. Our recent studies indicate that oxytocin affects
the expression of the gap-junction protein connexin-43 and that the gonadotropins
are intimately involved in this action. The synthesis of oxytocin and the oxytocin
receptor is influenced by the gonadotropins and locally produced prostaglandins. Oxytocin
stimulates estradiol synthesis, which may affect the expression of the gap-junction
protein connexin-43, allowing interaction between the large cells and small cells
of the corpus luteum. With the ubiquitous presence of oxytocin and its receptor, and
the presence of gap junctions in the corpora lutea of numerous species, it is concluded
that oxytocin is involved in not only paracrine/autocrine interaction but also may
be of significant importance in intercellular crosstalk in the corpus luteum.
Keywords:
Corpus luteum - cell-to-cell communication - oxytocin - human - nonhuman primate
