Abstract
The neurons secreting oxytocin (OXY) and vasopressin (AVP) are located mainly in the supraoptic, paraventricular, and suprachiasmatic nucleus of the brain. Oxytocinergic and vasopressinergic projections reach several regions of the brain and the spinal cord. Both peptides are released from axons, soma, and dendrites and modulate the excitability of other neuroregulatory pathways. The synthesis and action of OXY and AVP in the peripheral organs (eye, heart, gastrointestinal system) is being investigated. The secretion of OXY and AVP is influenced by changes in body fluid osmolality, blood volume, blood pressure, hypoxia, and stress. Vasopressin interacts with three subtypes of receptors: V1aR, V1bR, and V2R whereas oxytocin activates its own OXTR and V1aR receptors. AVP and OXY receptors are present in several regions of the brain (cortex, hypothalamus, pons, medulla, and cerebellum) and in the peripheral organs (heart, lungs, carotid bodies, kidneys, adrenal glands, pancreas, gastrointestinal tract, ovaries, uterus, thymus). Hypertension, myocardial infarction, and coexisting factors, such as pain and stress, have a significant impact on the secretion of oxytocin and vasopressin and on the expression of their receptors. The inappropriate regulation of oxytocin and vasopressin secretion during ischemia, hypoxia/hypercapnia, inflammation, pain, and stress may play a significant role in the pathogenesis of cardiovascular diseases.
Highlights
Laboratory of Centre for Preclinical Research, Chair and Department of Experimental and Clinical Physiology, Citation: Szczepanska-Sadowska, E.; Wsol, A.; Cudnoch-Jedrzejewska, A.; Żera, T
Sivukhina et al reported no significant differences in OXY-positive neuron expression in paraventricular nucleus (PVN) and supraoptic nucleus (SON) in the brains of patients, who died from chronic heart failure [173]
In the rat model of heart failure induced by pressure overloading of the left ventricle lasting four weeks, chronic stimulation of PVN neurons in adult Sprague Dawley rats resulted in several beneficial effects, such as a decrease in blood pressure and heart rate, a reduction of cellular hypertrophy, a reduction of fibrosis, a reduction of IL-1β concentration, and an improvement of the LV function [222]
Summary
Oxytocin (Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2; OXY) and arginine vasopressin (Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2; AVP) are nonapeptides, differing only in two aminoacids [1,2,3]. OXY and AVP are synthesized mainly in the hypothalamus as preprohormones, namely preprooxytocin and preprovasopressin They are processed along the axonal projections to the posterior lobe of the pituitary, where they are stored in secretory vesicles and released to the peripheral circulation as final products [4]. The secretion of oxytocin and vasopressin is enhanced by hyperosmolality, reduction of the circulating blood volume, hypotension, hypoxia, stress, and hyperthermia [17,39,40,41,42,43,44,45,46] The effects of these signals are associated with the activation of multiple receptors and transmitting pathways. The abundant innervation of oxytocinergic and vasopressinergic neurons enables the precise adjustment of the central and systemic secretion of OXY and AVP to specific physiological conditions and changes in the internal and external environment (see below and [34,35,36,37,38])
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