Invited Speaker

Oxytocin: Old Hormone, New Drug
Jolanta Gutkowska
Canada

We have recently uncovered the entire functional Oxytocin (OT) system in rat and human heart. Following this discovery, OT, traditionally associated with reproductive functions, was recently revisited and several new functions in cardiovascular regulation have been revealed. These functions include stimulation of cardioprotective mediators, nitric oxide (NO) and atrial natriuretic peptide. Oxytocin’s cardiovascular actions include: i) natriuresis, ii) lowering of blood pressure, iii) negative inotropic and chronotropic effects, iv) parasympathetic neuromodulation, v) vasodilatation, triggered by the NO pathway, that is also implicated in endothelial cell growth, vi) anti-inflammatory activity, vii) antioxidant activity, and viii) metabolic and anti-hypertrophic effects. In addition, we showed abundance of oxytocin in the early developing heart, indicating the possible role in the heart development. Furthermore, we have shown oxytocin capacity to generate functional cardiomyocytes from rat and mouse embryonic stem cells. Most potent inducer of cardiac differentiation is an extended form of oxytocin, OT-Gly-Lys-Arg, abundantly expressed in the fetal heart. Mesenchymal cells transfected with OT-Gly-Lys-Arg are resistant to apoptosis and present also endothelial cell markers. Oxytocin increases glucose uptake in cultured cardiomyocytes, in normal, hypoxic, and even in conditions of insulin resistance. In an experimentally-induced myocardial infarction in rats, continuous in vivo oxytocin delivery improves the cardiac healing process, cardiac work, reduces inflammation, and stimulates angiogenesis. Therefore, in pathological conditions, oxytocin and its elongated form OT-Gly-Lys-Arg plays an anti-inflammatory and cardio-protective role, improves vascular and metabolic functions, thus present potential for therapeutic use.