Srikanta Jena

Induction of oxidative stress and inhibition of superoxide dismutase expression in rat cerebral cortex and cerebellum by PTU-induced hypothyroidism and its reversal by curcumin

The present study was carried out to elucidate the effectiveness of curcumin in ameliorating the expression of superoxide dismutase (SOD) in cerebral cortex and cerebellum of rat brain under 6-propyl-2-thiouracil (PTU)-induced hypothyroidism. Induction of hypothyroidism in adult rats by PTU resulted in augmentation of lipid peroxidation (LPx), an index of oxidative stress in cerebellum but not in cerebral cortex. Curcumin-supplementation to PTU-treated (hypothyroid) rats showed significant reduction in the level of LPx in both the regions of brain. The decreased translated products (SOD1 and SOD2) and the unchanged activity of SOD in cerebral cortex of PTU-treated rats were increased on supplementation of curcumin to the hypothyroid rats. Declined translated products of SOD1 and SOD2 in cerebellum of PTU-treated rats were alleviated on administration of curcumin to hypothyroid rats. On the other hand, the decreased activity of SOD in cerebellum of PTU-treated rats was further declined on administration of curcumin to the hypothyroid rats. Results of the present investigation indicate that curcumin differentially modulates the expression of superoxide dismutase in rat brain cortex and cerebellum under PTU-induced hypothyroidism.

Hypothyroidism modulates renal antioxidant gene expression during postnatal development and maturation in rat.

In the present study effects of 6-n-propyl thiouracil (PTU)-induced hypothyroidism on renal antioxidant defence system during postnatal development (from birth to 7, 15 and 30days old) and on adult rats were reported. Hypothyroidism in rats was induced by feeding the lactating mothers (from the day of parturition till weaning, 25days old) or directly to the pups with 0.05% PTU in drinking water. The activities of Cu/Zn-superoxide dismutase (SOD1) and glutathione peroxidase (GPx) were increased in 30days old hypothyroid rats with respect to their respective controls, on the other hand, levels of translated products and activities of Mn-superoxide dismutase (SOD2) and catalase (CAT) were decreased in hypothyroid rats of all age groups as compared to their respective control rats. SOD1 activity remained unchanged in persistent (PTU-treatment from birth to 90days old) hypothyroid rats as compared to euthyroid. However, a decreased activity of SOD1 was recorded in transient (PTU-treatment from birth to 30days then withdrawal till 90days old) hypothyroid rats with respect to control rats. The mRNA level, protein expression and activity of SOD2 and CAT were significantly decreased in persistent hypothyroid rats as compared to euthyroid rats. The activity of GPx was significantly increased in both persistent and transient hypothyroid rats with respect to euthyroid rats. The present study indicates modulation of antioxidant defence status of rat kidney during postnatal development and maturation by hypothyroidism.

Expression of antioxidant genes in renal cortex of PTU-induced hypothyroid rats: effect of vitamin E and curcumin

The present study was undertaken to investigate the effect of vitamin E and curcumin on the expression of antioxidant genes in 6-propyl-2-thiouracil (PTU)-induced hypothyroid rat renal cortex. The levels of lipid peroxidation and protein carbonylation were increased in hypothyroid rat kidney. Co-administration of vitamin E and curcumin to hypothyroid rats resulted in amelioration of lipid peroxidation level, whereas curcumin alone alleviated the protein carbonylation level. The mRNA levels of SOD1 and SOD2 were decreased in hypothyroid rats. Decreased level of SOD1 transcripts was observed in hypothyroid rats supplemented with curcumin alone or co-administrated with vitamin E. Translated products of SOD1 and SOD2 in hypothyroid rats was elevated in response to supplementation of both the antioxidants. Decreased SOD1 and SOD2 activities in hypothyroid rats compared to control were either unaltered or further decreased in response to the antioxidants. Expressions of CAT at transcript and translate level along with its activity were down regulated in hypothyroid rats. Administration of vitamin E to hypothyroid rats resulted in elevated CAT mRNA level. In contrast, expression of CAT protein was elevated in response to both the antioxidants. However, CAT activity was unaltered in response to vitamin E and curcumin. GPx1 and GR mRNA level and the activity of glutathione peroxidase (GPx) were not affected in response to induced hypothyroidism. The activity of GPx was increased in response to vitamin E treatment, whereas decreased GR activity in hypothyroid rats was further declined by the administration of antioxidants. The over all results suggest that vitamin E and curcumin differentially modulate the altered antioxidant defence mechanism of rat kidney cortex under experimental hypothyroidism.

Curcumin differentially regulates the expression of superoxide dismutase in cerebral cortex and cerebellum of l-thyroxine (T4)-induced hyperthyroid rat brain

The present investigation was aimed to elucidate the effect of curcumin on lipid peroxidation (LPx) and superoxide dismutase (SOD) in l-thyroxine (T4)-induced oxidative stress in cerebral cortex and cerebellum of rat brain. Elevated level of LPx in cerebral cortex declined to control level on supplementation of curcumin to T4-treated rats. On the other hand, unaltered LPx level in T4-treated rats showed a significantly decreased level of LPx on supplementation of curcumin. The increased activity of SOD and translated products of SOD1 and SOD2 in cerebral cortex of T4-treated rats was ameliorated on supplementation of curcumin. The decreased activity of SOD and protein expression of SOD1 in cerebellum of T4-treated rats were ameliorated on administration of curcumin. On the other hand, SOD2 expression was not influenced either by T4-treated or by curcumin supplementation to T4-treated rats. Results of the present investigation reveal that the regulation of expression of SOD by curcumin in different regions (cerebral cortex and cerebellum) of rat brain is different under hyperthyroidism.

Age-Related Changes in Antioxidant Enzymes of Rat Kidney and Oxidative Stress Parameters with Special Reference to Methylation of the Catalase Promoter

Oxidative stress plays an important role in etiology of age-associated decline in renal physiological functions. The purpose of the present study was to determine the profiles of antioxidant enzymes (AOEs) and oxidative stress parameters in rat kidney from birth to old age with a particular reference to catalase promoter methylation. Results revealed that the levels of oxidative stress indices (lipid peroxides and protein carbonyls) were significantly higher, while levels of small antioxidants (reduced glutathione and ascorbic acid) were significantly lower in kidneys of old rats than that of adult ones. Also the results suggest lack of a correlation among the expression levels of antioxidant enzymes and their respective activity levels in rat kidney with relation to aging process. For example, when SOD1 activity was significantly low in old age than adult ones, its mRNA and protein levels were higher in old age. On the contrary, SOD2 activity and its mRNA level were higher in old age in comparison to adult rats without any alteration in its translated products. GPx activity and its mRNA did not change in old age in comparison to adult ones. Although GR activity remained unaltered during aging, its mRNA level was reduced in old age than in adult ones. On the other hand, CAT activity and levels of its mRNA and protein were reduced in old rats than that of adult ones. The methylation level in CpG dinucleotides of CAT promoter (from −268 to +52) was higher in old rats than in adult ones and was inversely proportional to its expression. The results suggest that (i) rates of prooxidant generation exceed the overall antioxidant defenses during aging in kidney and (ii) emphasize important role of methylation in the expression of CAT during aging.

REMOVED: Hypothyroidism impairs antioxidant defence system and histoarchitecture of cerebral cortex of rat brain during postnatal development

This article has been removed: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our‐business/policies/article‐withdrawal)The investigation was carried out to evaluate alterations in histoarchitecture, oxidative stress parameter (lipid peroxidation, LPx) and antioxidant enzyme activities in cerebral cortex of rat brain in response to 6-n-propyl 2-thiouracil (PTU)-induced hypothyroidism during postnatal development (from birth to 7, 15 and 30 days old). Hypothyroidism in rats was induced by feeding the lactating mothers (from the day of parturition till weaning, 25 days old) or directly to the pups with 0.05% PTU in drinking water. A significant decrease in level of LPx was seen in 7 and 30 days old PTU-treated rats with respect to their controls. Significantly decreased activities of superoxide dismutase (SOD) and catalase (CAT) along with the translated products of SOD1 and SOD2 were observed in 7, 15 and 30 days old PTU-treated rats as compared to their respective controls. However, increase in translated product of CAT was seen in all age groups of PTU-treated rats. Histological sections of 30 days hypothyroid rats clearly exhibited a decline in neuronal migration with neurons packed together in the hypothyroid group as compared to the control. These results suggest that deprivation of thyroid hormone modulates antioxidant defence status as well as the histoarchitecture of rat brain cerebral cortex during postnatal development.