Cytokines and the hypothalamic-pituitary-ovarian-endometrial axis.

Recently, the demarcating boundaries that allowed separation of the fields of reproductive biology, endocrinology, immunology and neurobiology have faded. The missing link that now ties these disciplines together is the understanding that the language by which cells communicate within these diverse systems is unanimous. This language is the network of products collectively called cytokines. The effect of these factors spans from the hypothalamus to the endometrium and is undoubtedly involved in the maintenance of the delicate balance within the hypothalamic-pituitary-gonadal-endometrial axis. Orchestrated networks of these cytokines also seem to be linked to the steroid hormone signals, an essential feature for maintenance of normal menstrual cycles. Evidence in favour of these emerging concepts is discussed. Major emphasis is placed on interferons, interleukins, tumour necrosis factor, transforming growth factors and colony-stimulating factors.