The neurohypophysial peptide oxytocin (OT) and OT-like hormones facilitate reproduction in all vertebrates at several levels. The major site of OT gene expression is the magnocellular neurons of the hypothalamic paraventricular and supraoptic nuclei. In response to a variety of stimuli such as suckling, parturition, or certain kinds of stress, the processed OT peptide is released from the posterior pituitary into the systemic circulation. Such stimuli also lead to an intranuclear release of OT. Moreover, oxytocinergic neurons display widespread projections throughout the central nervous system. However, OT is also synthesized in peripheral tissues, e.g., uterus, placenta, amnion, corpus luteum, testis, and heart. The OT receptor is a typical class I G protein-coupled receptor that is primarily coupled via Gq proteins to phospholipase C-β. The high-affinity receptor state requires both Mg2+ and cholesterol, which probably function as allosteric modulators. The agonist-binding region of the receptor has bee...

The Oxytocin Receptor System: Structure, Function, and Regulation

The Neuroendocrine Basis of Social Recognition

Neuroendocrine basis of social recognition.

During the past 20 years, evidence has accumulated to suggest that the neuropeptide vasopressin (VP) enhances memory by acting on central mechanisms, and that oxytocin (OT) has amnestic effects. In this review, the evidence for the memory hypothesis with respect to VP is considered and alternative interpretations evaluated. A critical approach has been adopted; negative findings, design considerations and problems with the various hypotheses are given prominence. It is concluded that the memory hypothesis fails to provide an adequate account, and some alternative theories and suggestions are discussed. It is speculated that the peptide may affect behaviour by two distinct mechanisms: peripheral action may involve reinforcement mechanisms, but its central role may be to modulate arousal level, especially in stressful situations.

A critique of the vasopressin-memory hypothesis

We have recently shown that an entire oxytocin (OT) system, a peptide and its cognate receptors, is synthesized in the heart. In fetal and newborn hearts, OT exists in its extended three-amino acid form, OT-Gly-Lys-Arg (OT-GKR). OT translocates glucose transporter type 4 to the plasma membrane in human endothelial cells. Therefore, we hypothesized that the cardiac OT/OT-GKR system may be involved in the regulation of myocardial glucose uptake in physiological conditions and during metabolic stress such as hypoxia. Primary cultures of neonatal rat cardiomyocytes (CM) and cardiac progenitor cells expressing ATP-binding cassette efflux transporter G2 transporter (stem cell marker) were studied. OT (10 nm) increased basal glucose uptake in CM to 4.0 ± 0.2 fmol/mg protein, with OT-GKR (10 nm) elevating it to 5.3 ± 0.4 fmol/mg protein (P < 0.001) in comparison with 2.2 fmol/mg in control cells. OT had a moderate synergistic effect with 0.1 mm 2,4-dinitrophenol, augmenting basal glucose uptake to 5.5 ± 0.5 fmol/...

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Oxytocin increases glucose uptake in neonatal rat cardiomyocytes.

Vasopressin analogs: Sedative properties and passive avoidance behavior in rats

Passive avoidance behavior: Opposite effects of oxytocin analogs with agonist and antagonist properties

Actions of neurohypophysial hormone analogues on perfused isolated rat caudal artery

Synthesis and properties of the N α -glycyl-glycyl-glycyl-8-lysine-vasopressin and its des-glycinamide derivative

Synthese d'analogues de la vasopressine ne contenant pas le reste glycinamide en position 9 et differents en position 1 et/ou 8. Activite biologique

Běla Kupková

Papers

Vasopressin analogs: Sedative properties and passive avoidance behavior in rats

Passive avoidance behavior: Opposite effects of oxytocin analogs with agonist and antagonist properties

Actions of neurohypophysial hormone analogues on perfused isolated rat caudal artery

Synthesis and properties of the N α -glycyl-glycyl-glycyl-8-lysine-vasopressin and its des-glycinamide derivative

Vasopressin analogues with effect on central nervous system: Synthesis and biological properties