Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic
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NEUROSCIENCE
Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic neuronal activation Lucas Rios Drummond 1 & Helton Oliveira Campos 1 & Paulo Marcelo de Andrade Lima 1 & Cletiana Gonçalves da Fonseca 2 & Ana Cançado Kunstetter 2 & Quezia Teixeira Rodrigues 1 & Raphael Escorsim Szawka 1 & Antônio José Natali 3 & Thales Nicolau Prímola-Gomes 3 & Samuel Penna Wanner 2 & Cândido Celso Coimbra 1 Received: 31 May 2020 / Revised: 5 September 2020 / Accepted: 6 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study aimed to evaluate the physical exercise-induced neuronal activation in brain nuclei controlling thermoregulatory responses in hypertensive and normotensive rats. Sixteen-week-old male normotensive Wistar rats (NWRs) and spontaneously hypertensive rats (SHRs) were implanted with an abdominal temperature sensor. After recovery, the animals were subjected to a constant-speed treadmill running (at 60% of the maximum aerobic speed) for 30 min at 25 °C. Core (Tcore) and tail-skin (Tskin) temperatures were measured every minute during exercise. Ninety minutes after the exercise, the rats were euthanized, and their brains were collected to determine the c-Fos protein expression in the following areas that modulate thermoregulatory responses: medial preoptic area (mPOA), paraventricular hypothalamic nucleus (PVN), and supraoptic nucleus (SON). During treadmill running, the SHR group exhibited a greater increase in Tcore and an augmented threshold for cutaneous heat loss relative to the NWR group. In addition, the SHRs showed reduced neuronal activation in the mPOA (< 49.7%) and PVN (< 44.2%), but not in the SON. The lower exercise-induced activation in the mPOA and PVN in hypertensive rats was strongly related to the delayed onset of cutaneous heat loss. We conclude that the enhanced exercise-induced hyperthermia in hypertensive rats can be partially explained by a delayed cutaneous heat loss, which is, in turn, associated with reduced activation of brain areas modulating thermoregulatory responses. Keywords SHR . Body temperature . Hypertension . Medial preoptic area . Paraventricular nucleus of hypothalamus and supraoptic nucleus
Introduction Blood pressure regulation involves a complex interplay between various elements of an integrated neurohumoral system, including the renin-angiotensin-aldosterone system, the * Lucas Rios Drummond [email protected] 1
Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG 31270-901, Brazil
2
Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
3
Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil
natriuretic peptides, the endothelium, the sympathetic nervous system, and the immune system [54,
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