title: The dynamics of physical exercise-induced increases in thalamic and abdominal temperatures are modified by central cholinergic stimulation.
abstract: Evidence has shown that brain and abdominal (T abd) temperatures are regulated by distinct physiological mechanisms. Thus, the present study examined whether central cholinergic stimulation would change the dynamics of exercise-induced increases in T abd and thalamic temperature (T thal), an index of brain temperature. Adult male Wistar rats were used in all of the experiments. Two guide cannulae were implanted in the rats, one in the thalamus and the other in the right lateral cerebral ventricle, to measure T thal and to centrally inject a cholinergic agonist, respectively. Then, a temperature sensor was implanted in the abdominal cavity. On the day of the experiments, the rats received an intracerebroventricular injection of 2 μL of 10(-2)M physostigmine (Phy) or a vehicle solution (Veh) and were subjected to treadmill running until volitional fatigue occurred. T thal was measured using a thermistor connected to a multimeter, and T abd was recorded by telemetry. Phy injection delayed the exercise-induced increases in T thal (37.6 ± 0.2°C Phy vs 38.7 ± 0.1°C Veh at the 10th min of exercise) and in T abd. Despite the delayed hyperthermia, Phy did not change the rats' physical performance. In addition, the more rapid exercise-induced increase in T thal relative to Tabd in the rats treated with Veh was abolished by Phy. Collectively, our data indicate that central cholinergic stimulation affects the dynamics of exercise-induced increases in T thal and T abd. These results also provide evidence of the involvement of cholinoceptors in the modulation of brain heat loss during physical exercise.
authors: Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: William Coutinho
authors: WC
authors: Damasceno
authors: Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Washington
authors: W
authors: Pires
authors: Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Milene Rodrigues Malheiros
authors: MR
authors: Lima
authors: Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors: Nilo Resende Viana
authors: NR
authors: Lima
authors: Exercise Physiology Laboratory, Department of Physical Education, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address: samuelwanner@eeffto.ufmg.br.
authors: Samuel Penna
authors: SP
authors: Wanner
mesh_terms: D034841:Abdominal Cavity / Q000502:physiology*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D010805:Physical Conditioning, Animal; D010830:Physostigmine / Q000494:pharmacology*; D017208:Rats, Wistar; D013788:Thalamus / Q000502:physiology*
chemical_list: D002800:Cholinesterase Inhibitors; D010830:Physostigmine
keywords: Fatigue; Hyperthermia; Physostigmine; Thalamus; Thermoregulation; Treadmill running