Relative efficacies of alpha-tocopherol, n-acetyl-serotonin and melatonin in reducing non-enzymatic lipid peroxidation of rat testicular microsomes and mitochondria

GAVAZZA, M.; ANGEL CATALA

Mol Cell Biochem

Springer

Año: 2009 vol. 321 p. 37 - 43

0300-8177

In this study, we examined the relative efficacies of á-tocopherol, N-acetyl-serotonin and melatonin in reducing ascorbate-Fe2+ lipid peroxidation of rat testicular microsomes and mitochondria. Special attention was paid to the changes produced on the highly polyunsaturated fatty acids C20:4 n6 and C22:5 n6. The lipid peroxidation of testicular microsomes or mitochondria produced a significant decrease of C20:4 n6 and C22:5 n6. Both long chain polyunsaturated fatty acids were protected when the antioxidants were incorporated either in microsomes or mitochondria. By comparison of the IC 50 values obtained between á-tocopherol and both indolamines, it was observed that á-tocopherol was the most efficient antioxidant against the lipid peroxidation induced by ascorbate-Fe++ under experimental conditions in vitro, IC50 values from the inhibition of a-tocopherol on the chemiluminescence were higher in microsomes (0.14 mM) than in mitochondria (0.08 mM). The protective effect observed by a-tocopherol in rat testis mitochondria was higher compared with microsomes, associated with the higher amount of [C20:4 n6] + [C22:5 n6] in microsomes that in mitochondria. Melatonin and N-acetyl-serotonin showed to be more effective in inhibiting the lipid peroxidation in mitochondria that in microsomes.  Thus, a concentration 1 mM of both indolamines was sufficient to inhibit in approximately 70 % the light emission in mitochondria, whereas a greater dose 10 times (10 mM) was necessary to produce the same effect in microsomes. It is proposed that the vulnerability to lipid peroxidation of rat testicular microsomes and mitochondria in the presence of both indolamines is different because of the different proportion of PUFAs in these organelles.