Acute paraquat exposure determines dose-dependent oxidative injury of multiple organs and metabolic dysfunction in rats: impact on exercise tolerance.
This study investigated the pathological morphofunctional adaptations related to the imbalance of exercise tolerance triggered by paraquat (PQ) exposure in rats. The rats were randomized into four groups with eight animals each: (a) SAL (control): 0.5 ml of 0.9% NaCl solution; (b) PQ10: PQ 10 mg/kg; (c) PQ20: PQ 20 mg/kg; and (d) PQ30: PQ 30 mg/kg. Each group received a single injection of PQ. After 72 hours, the animals were subjected to an incremental aerobic running test until fatigue in order to determine exercise tolerance, blood glucose and lactate levels. After the next 24 h, lung, liver and skeletal muscle were collected for biometric, biochemical and morphological analyses. The animals exposed to PQ exhibited a significant anticipation of anaerobic metabolism during the incremental aerobic running test, a reduction in exercise tolerance and blood glucose levels as well as increased blood lactate levels during exercise compared to control animals. PQ exposure increased serum transaminase levels and reduced the glycogen contents in liver tissue and skeletal muscles. In the lung, the liver and the skeletal muscle, PQ exposure also increased the contents of malondialdehyde, protein carbonyl, 8-hydroxy-2'-deoxyguanosine, superoxide dismutase and catalase, as well as a structural remodelling compared to the control group. All these changes were dose-dependent. Reduced exercise tolerance after PQ exposure was potentially influenced by pathological remodelling of multiple organs, in which glycogen depletion in the liver and skeletal muscle and the imbalance of glucose metabolism coexist with the induction of lipid, protein and DNA oxidation, a destructive process not counteracted by the upregulation of endogenous antioxidant enzymes.
Department of Structural Biology, Federal University of Alfenas, Alfenas, MG, Brazil.
Rômulo D
RD
Novaes
Department of Animal Biology, Federal University of Viçosa, Viçosa, MG, Brazil.
Reggiani V
RV
Gonçalves
Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil.
Marli C
MC
Cupertino
Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil.
Eliziária C
EC
Santos
Department of Nutrition and Health, Federal University of Viçosa, Viçosa, MG, Brazil.
Solange M
SM
Bigonha
Department of Anatomy, Federal University of Alfenas, Alfenas, MG, Brazil.
Geraldo J M
GJ
Fernandes
Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil.
Izabel R S C
IR
Maldonado
Department of Physical Education, Federal University of Viçosa, Viçosa, MG, Brazil.
Antônio J
AJ
Natali
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017079:Exercise Tolerance / Q000187:drug effects* / Q000502:physiology; D006540:Herbicides / Q000008:administration & dosage* / Q000633:toxicity; D019344:Lactic Acid / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D009102:Multiple Organ Failure / Q000139:chemically induced* / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D010269:Paraquat / Q000008:administration & dosage* / Q000633:toxicity; D011897:Random Allocation; D017208:Rats, Wistar
D000975:Antioxidants; D001786:Blood Glucose; D006540:Herbicides; D019344:Lactic Acid; D010269:Paraquat
liver; lung; oxidative stress; pathology; skeletal muscle