Effects of Aerobic Physical Training on Thermoregulatory Adjustments During Physical Exercise in Spontaneously Hypertensive Rats

This study aimed to investigate the effects of physical training on thermoregulatory adjustments during running exercise and its effects on brain neuronal nitric oxide synthase (n‐NOS) expression. Male spontaneously hypertensive (SHR) and normotensive Wistar rats (NWR) at 8‐weeks age old were divided into four groups: untrained NWR (NWR‐U), trained NWR (NWR‐T), untrained SHR (SHR‐U) and trained SHR (SHR‐T). Experimental procedures were approved by the CEUA‐UFMG (#21/2015). Aerobic exercise training was performed on a treadmill running for 8 weeks. On the day of the experiments, the rats were subjected to a constant‐speed (60% of V máx ) protocol until fatigue at 25°C. Tail skin temperature (T s ) and abdominal temperature (T a ) were measured every minute throughout the exercise trials. The preoptic area (POA) and paraventricular nuclei (PVN) of hypothalamus was collected to quantification of n‐NOS(ser852) by western blot. During exercise, the SHR‐U group showed greater increase in T a compared to with NWR‐U group from the 16 th min until the 23 th min (min 23: 1.62 ± 0.15 °C vs. 1.21 ± 0.12 °C, p<0.05) and lower T s from the 1 th until the 16 th min of exercise (min 16: 0.09 ± 0.95 °C vs. 1.39 ± 0.41 °C, p<0.05). Physical training in SHRs group did not change T a response during exercise (fatigue: SHR‐T: 1.54 ± 0.29 °C vs. SHR‐U: 1.70 ± 0.18 °C, p<0.05) but caused a greater increase in T s in SHR‐T group (min 12: −0.54 ± 0.93 °C vs. −2.64 ± 0.80 °C, p<0.05). Physical training in NWR group did not change T a response during exercise (fatigue: NWR‐T: 1.62 ± 0.26 °C vs. NWR‐U: 1.71 ± 0.26 °C, p<0.05) but caused a greater increase in T s in NWR‐T group (fatigue: 3.65 ± 0.38 °C vs. 1.60 ± 0.47 °C, p<0.05). The p‐nNOS expression in APO was lower in SHR‐U group when compared to the NWR‐U (0.06 ± 0.01 u.a. vs. 0.09 ± 0.01 u.a., p<0.05). Physical training increased the p‐nNOS expression in the APO in the SHR group (0.10 ± 0.01 u.a. vs. 0.06 ± 0.01 u.a., p<0.05). The p‐nNOS expression in PVN was similar between SHR‐U and NWR‐U groups (SHR‐U: 1.10 ± 0.19 u.a vs. NWR NT: 0.94 ± 0.13 u.a., p>0.05). Physical training increased p‐NOS expression in the APO in both SHR group (1.58 ± 0.17 u.a. vs. 1.10 ± 0.19 u.a., p<0.05) and NWR group (1.56 ± 0.25 u.a vs. 0.94 ± 0.13 u.a., p<0.05). We conclude that physical training increases the efficiency of thermoregulatory control during exercise in hypertensive animals, which can be explained, at least in part, to an increase in the activity of neuronal nitric oxide synthase in trained animals. Support or Funding Information Fapemig, Capes, and CNPq. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .