Differential effects of alpha- and gamma-tocopherol on low-density lipoprotein oxidation, superoxide activity, platelet aggregation and arterial thrombogenesis.
OBJECTIVE
This study was designed to examine the differential effects of alpha- and gamma-tocopherol on parameters of oxidation-antioxidation and thrombogenesis.


BACKGROUND
Experimental studies have shown that antioxidants, such as vitamin E (alpha-tocopherol), improve atherosclerotic plaque stability and vasomotor function, and decrease platelet aggregation and tendency to thrombus formation.


METHODS
Sprague Dawley rats were fed chow mixed with alpha- or gamma-tocopherol (100 mg/kg/day) for 10 days. A filter soaked in 29% FeCl3 was applied around the abdominal aorta to study the patterns of arterial thrombosis. The aortic blood flow was observed and continuously recorded using an ultrasonic Doppler flow probe. ADP-induced platelet aggregation, low-density lipoprotein oxidation induced by phorbol 12-myristate 13-acetate (PMA)-stimulated leukocytes, superoxide anion generation and superoxide dismutase (SOD) activity were also measured.


RESULTS
Both alpha- and gamma-tocopherol decreased platelet aggregation and delayed time to occlusive thrombus (all p < 0.05 vs. control). Both alpha- and gamma-tocopherol decreased arterial superoxide anion generation, lipid peroxidation and LDL oxidation (all p < 0.05 vs. control), and increased endogenous SOD activity (p < 0.05). The effects of gamma-tocopherol were more potent than those of alpha-tocopherol (p < 0.05).


CONCLUSIONS
This study indicates that both alpha- and gamma-tocopherol decrease platelet aggregation and delay intraarterial thrombus formation, perhaps by an increase in endogenous antioxidant activity. Gamma-tocopherol is significantly more potent than alpha-tocopherol in these effects.
Saldeen
T
T
Department of Forensic Medicine, University of Uppsala, Sweden.
Li
D
D
Mehta
J L
JL
D000818:Animals; D003328:Coronary Thrombosis / Q000097:blood; D015227:Lipid Peroxidation / Q000502:physiology*; D008077:Lipoproteins, LDL / Q000097:blood*; D008297:Male; D010974:Platelet Aggregation / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000097:blood*; D013927:Thrombosis / Q000097:blood*; D014810:Vitamin E / Q000502:physiology*
D008077:Lipoproteins, LDL; D013481:Superoxides; D014810:Vitamin E