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Integrity of paraventricular nucleus is critical for thermoregulation adjustments during exercise
Author(s) -
Guimarães Juliana Bohnen,
Wanner Samuel Penna,
Coimbra Cândido Celso
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.991.3
Subject(s) - thermoregulation , hyperthermia , endocrinology , medicine , hypothalamus , vasodilation , chemistry , core temperature , thermal management of electronic devices and systems , lesion , surgery , mechanical engineering , engineering
Exercise induced‐hyperthermia results from the imbalance between heat production and dissipation, being capable of interfering on performance. Anatomical and physiological evidences support that the paraventricular nucleus of hypothalamus (PVN) is involved in central pathways modulating the sympathetic activity of thermoregulatory effectors, including the rat's tail vasodilation that is crucial for heat dissipation during exercise. The aim of this study was to verify the participation of PVN on thermoregulatory adjustments during exercise. Male Wistar rats (250–350 g) were submitted to bilateral electrolytic lesion of PVN (n=4) and with control rats were performed sham surgery (n=6). Core body temperature (Tb) and tail skin temperature (Ts) were continuously measured during exercise (18/min, 5% inclination) until fatigue. Ts was taken as an index of vasodilation and heat dissipation. Time to fatigue was 33.4% lower in PVN‐lesioned rats. However, heat storage rate was higher in PVN‐lesioned rats than control (10.4 ± 1.8 cal/min, PVN‐lesioned rats vs. 4.1 ± 0.2 cal/min, control; p<0.05). We also observed a higher threshold for tail vasodilation in PVN‐lesioned rats (0.6 ± 0.0 ° C PVN‐lesioned vs. 0.3 ± .0.0 °C, control; p<0.05). Our results indicate that integrity of PVN interferes with heat balance during exercise by altering heat dissipation. Support: CNPq, FAPEMIG, CAPES.