Proceedings of 'The Neurohypophysial Peptide Systems', Satellite symposium, Spa-Liège 6-11 September 1992

A great part of the neurohypophysial jigsaw puzzle has taken shape... and now ? This Satellite Symposium of the 9th International Congress of Endocrinology was held at a very appropriate time ! The characterization of three important types of neurohypophysial peptide receptors had then been recently reported. New pharmacological tools had become available to investigate further biological significance of vasopressin- and oxytocin-mediated actions. A few weeks before the meeting, the increasing importance of local paracrine circuits mediated by neurohypophysial signals was brought into focus by the clear demonstration of an intra-uterine circuit with a potential implication in the initiation of labour. Now, we have all returned to our laboratories, armed with new knowledge and inspired by new questions. This is the natural fate of scientific life. If the physiological importance of the oxytocinergic and vasopressinergic V2 systems has been supported by the recent discoveries, may we claim the same with regard to the vasopressinergic V1 pathways ? We were reminded of their importance in the regulation of the vascular tone, but what about the significance of the wide-spread distribution of different V1-subtype receptors ? Although analogies with other peptide systems have to be made with caution, do we in fact not observe similar evolutionary phenomena like those recently evidenced for other hormonally-related tissue growth factors ? Whatever it is, it seems more and more obvious that the precise significance of the V1 system will appear rather from studies about its implication in developmental biology and in paracrine/autocrine signaling, than from studies based on the classical neuroendocrine model of cell-to-cell communication. In any case, much work remains to be carried out before we will get a definitive answer.