A functional selective effect of oxytocin secreted under restraint stress in rats

Autor(es)

Bel, Ivaldo Jesus Almeida ^[1] ; Brasil, Taiz Francine Silva ^[1] ; Fortaleza, Eduardo Albino Trindade ^[1] ; Antunes-Rodrigues, Jose ^[2] ; Correa, Fernando Morgan Aguiar ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Pharmacol, Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, Ribeirao Preto, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: European Journal of Pharmacology; v. 904, AUG 5 2021.
• Citações Web of Science: 0

Resumo

Restraint stress (RS) is an unavoidable stress model that triggers activation of the autonomic nervous system, endocrine activity, and behavioral changes in rodents. Furthermore, RS induces secretion of oxytocin into the bloodstream, indicating a possible physiological role in the stress response in this model. The presence of oxytocin receptors in vessels and heart favors this possible idea. However, the role of oxytocin secreted in RS and effects on the cardiovascular system are still unclear. The aim of this study was to analyze the influence of oxytocin on cardiovascular effects during RS sessions. Rats were subjected to pharmacological (blockade of either oxytocin, vasopressin, or muscarinic receptors) or surgical (hypophysectomy or sinoaortic denervation) approaches to study the functional role of oxytocin and its receptor during RS. Plasma levels of oxytocin and vasopressin were measured after RS. RS increased arterial pressure, heart rate, and plasma oxytocin content, but not vasopressin. Treatment with atosiban (a Gi biased agonist) inhibited restraint-evoked tachycardia without affecting blood pressure. However, this effect was no longer observed after sinoaortic denervation, homatropine (M2 muscarinic antagonist) treatment or hypophysectomy, indicating that parasympathetic activation mediated by oxytocin secreted to the periphery is responsible for blocking the increase in tachycardic responses observed in the atosiban-treated group. Corroborating this, L-368,899 (oxytocin antagonist) treatment showed an opposite effect to atosiban, increasing tachycardic responses to restraint. Thus, this provides evidence that oxytocin secreted to the periphery attenuates tachycardic responses evoked by restraint via increased parasympathetic activity, promoting cardioprotection by reducing the stress-evoked heart rate increase. (AU)

• Processo FAPESP: 16/25502-7 - Efeitos cardiovasculares, comportamentais, neuroendócrinos e morfofuncionais evocados pelo estresse agudo por restrição em ratos: envolvimento da via ocitocinérgica
• Beneficiário: Ivaldo de Jesus Almeida Belém Filho
• Modalidade de apoio: Bolsas no Brasil - Doutorado