Resistance exercise prevents impaired homocysteine metabolism and hepatic redox capacity in Walker-256 tumor-bearing male Wistar rats.
OBJECTIVE
The aim of this study was to investigate changes in homocysteine (Hcy) metabolism and redox balance in response to exercise treatment in a tumor-bearing rat model.


METHODS
Male Wistar rats were exposed, or not, to a resistance exercise program 6 wk before inoculation with Walker-256 tumor cells or vehicle. After application, rats maintained their routine for 12 d and were then sacrificed for plasma and liver analyses.


RESULTS
Impaired Hcy metabolism was evident after 12 d of tumor cell inoculation as demonstrated by significantly increased (P < 0.05) plasma total homocysteine (tHcy) concentration (53%) and decreased plasma cysteine, methionine, and vitamin B12 concentrations. Decreased hepatic cystathionine β-synthase (CBS) and betaine-homocysteine S-methyltransferase mRNA levels were found in tumor-bearing rats but not in controls. Tumor inoculation also decreased levels of liver reduced glutathione (GSH) and increased hepatic oxidative stress compared with non-tumor controls. However, resistance exercise prevented the tumor-impaired transsulfuration pathway as demonstrated by the decreased plasma tHcy, hepatic CBS expression, and increased GSH in tumor-exercised versus tumor-sedentary rats. Remarkably, all measures of liver oxidative stress were suppressed by exercise training. Tumor weight was unchanged between groups.


CONCLUSIONS
Resistance exercise prevented tHcy accumulation and liver oxidative damage caused by Walker-256 tumor cell inoculation; the modulatory effects of resistance exercise on Hcy metabolism appear to be at the level of transsulfuration pathway.
Department of Physical Education, Faculty of Physical Education and Sport, State University of Londrina, Londrina, Paraná, Brazil. Electronic address: Deminice@ig.com.br.
Rafael
R
Deminice
Department of Physical Education, Faculty of Physical Education and Sport, State University of Londrina, Londrina, Paraná, Brazil.
Camila de Souza
Cde S
Padilha
Laboratory of Free Radicals and Pathophysiology, State University of Londrina, Londrina, Paraná, Brazil.
Fernando
F
Borges
Laboratory of Nutrition and Metabolism, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirão Preto, Sao Paulo, Brazil.
Lilian Eslaine Costa Mendes
LE
da Silva
Laboratory of Nutrition and Metabolism, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirão Preto, Sao Paulo, Brazil.
Flávia Troncon
FT
Rosa
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.
Jason Lorne
JL
Robinson
Laboratory of Free Radicals and Pathophysiology, State University of Londrina, Londrina, Paraná, Brazil.
Rubens
R
Cecchini
Laboratory of Free Radicals and Pathophysiology, State University of Londrina, Londrina, Paraná, Brazil.
Flávia Alessandra
FA
Guarnier
Department of Physical Education, Faculty of Physical Education and Sport, State University of Londrina, Londrina, Paraná, Brazil.
Fernando Trevisan
FT
Frajacomo
D000818:Animals; D002279:Carcinoma 256, Walker / Q000378:metabolism* / Q000628:therapy*; D005978:Glutathione / Q000378:metabolism; D006710:Homocysteine / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010805:Physical Conditioning, Animal / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar
D006710:Homocysteine; D005978:Glutathione
Exercise; Homocysteine; Liver; Oxidative stress; Tumor; Walker-256