ON TESTIS AND EPlDlDYMlS OF RATS - Pondicherry University ...

as compared to the corresponding groups of control animals. Increased production of'
reactive oxygen species. decreased levels of antioxidants as well as the activities of'
antioxidant enzymes and increased levels of lipid peroxidation reflected that testis are
In oxidative stress.
Increased production of superoxide anion in the hepatic and brain tissues of
rats after exposure to TCDD has been reponed (Hassoun r! ul., 2001). TCDD
increased the production of reactive oxygen species in mitochondria1 and microsomal
fractions of rat testis (Latchoumycandane er ul., 2002 c). Nitric oxide has been shown
to react with superoxide anion to produce peroxynitrite, which actively react with
glutathione, cysteine, deoxyribose and thiolsl thioethers (Sikka, 2001). It has been
reported that acute exposure of TCDD in mice decreased the levels of glutathione and
a-tocopherol in hepatic tissues (Slezack el a[.. 1999). Glutathione is important in the
regulation of the cellular redox state and a decline in its cellular level in TCDDtreated
rats is considered to be indicative of increased oxidative stress. The reduction
in testicular glutathione levels in TCDD-treated rats might be in part attributed to the
inhibition of glutathione reductase activity, which is responsible for regcneration of
glutathione from its oxidised form Sikka (2001) showed that glutathione reductase is
inactivated by superoxide anion. Therefore, reduced superoxide dismutase activity in
testis might have enhanced flux of superoxide radicals that potentially could damage
glutathione rcductase and decrease glutathione content in testis. In addition, decrease
in glutathione level might reflect a direct reaction between glutathione and free
radicals generated by TCDD. This is consistent with function of glutathione of
scavenging oxidants by binding to them covalently. Furthermore. a regression of thc
antioxidant recycling mechanism duc to a decrease in ascorbic acid level in 'l'CI)Vtreated
rats might contributed to a decline in glutathione level in testis. This is in
accordance with the position of glutathione at the end of the cycling mechanism.
which includes vitamin E and vitamin C (Shindo er ul.. 1994).
Ascorbic acid is the most important free radical scavenger within membranes
and lipoproteins. Alpha-tocopherol is a well-known chain breaking antioxidant; its