The effects of pioglitazone and rosiglitazone on liver function in hypothyroid rats

OBJECTIVES

This study aimed to investigate the antioxidant effect of rosiglitazone (ROG) and pioglitazone (POG) on oxidative damage and dysfunction of hepatic tissue in hypothyroid rats.

METHODS

The male rats were classified into six groups: (1) Control; (2) Hypothyroid, (3) Hypothyroid-POG 10, (4) Hypothyroid-POG 20, (5) Hypothyroid-ROG 2, and (6) Hypothyroid-ROG 4. To induction hypothyroidism in rats, propylthiouracil (PTU) (0.05 %w/v) was added to drinking water. In groups 2-6, besides PTU, the rats were also intraperitoneal administrated with 10 or 20 mg/kg POG or 2 or 4 mg/kg ROG for six weeks. Finally, after deep anesthesia, the blood was collected to measure the serum biochemical markers and hepatic tissue was separated for biochemical oxidative stress markers.

RESULTS

Administration of PTU significantly reduced serum thyroxin concentration, total thiol levels, activity of superoxide dismutase (SOD) and catalase (CAT) enzymes, and increased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (Alk-P) and malondialdehyde (MDA) in the liver. Additionally, our results showed that prescription of POG or ROG for six weeks to hypothyroid rats resulted in an improvement in liver dysfunction (decrease in serum levels of AST, ALT, and ALK-P) through reducing oxidative damage in hepatic tissue (increase in CAT, SOD, or total thiols and decrease in MDA levels).

CONCLUSIONS

The findings of the present study presented that the IP administration of POG and ROG for six weeks improves liver dysfunction induced by hypothyroidism in juvenile rats by reducing oxidative damage.

Nanoselenium improved learning, memory, and brain-derived neurotrophic factor and attenuated nitric oxide, and oxidative stress in the brain of juvenile hypothyroid rats

BACKGROUND

Nanoselenium (Nan S) is a form of selenium element that acts with high absorption and low toxicity. However, few studies have examined the effects of Nan S on cognitive impairment. On the other hand, hypothyroidism is a common disease that causes cognitive disorders. Therefore, this study aimed to investigate the effect of Nan S on memory impairment in rats due to propylthiouracil (PTU) - induced hypothyroidism. The roles of brain-derived neurotrophic factor (BDNF), nitric oxide (NO), and oxidative stress were also challenged.

MATERIALS AND METHODS

The animals were randomly divided into 4 groups: (1) Control group (normal saline), (2) hypothyroid (Hypo) group: where 0.05% PTU was added to drinking water, (3) and (4) Hypo-Nan S 50, Hypo-Nan S 100 in which 50 or 100 µg/ kg of Nan S were injected respectively. After 6 weeks, spatial and avoidance memory was measured by Morris water maze (MWM) and passive avoidance (PA) tests. The animals then underwent deep anesthesia and the serum samples and the hippocampus and cortex were collected to be used for thyroxin and biochemical measurements including malondialdehyde (MDA), NO, thiol, superoxide dismutase (SOD), catalase (CAT), and BDNF.

RESULTS

The rats showed an increase in the escape latency and traveled path in MWM in the Hypo group compare with the Control group and these parameters were decreased in both Hypo-Nan S 50 and Hypo-Nan S 100 groups compared to the Hypo group. The rats of both Hypo-Nan S 50 and Hypo-Nan S 100 groups spent longer time and traveled longer distances in the target area during the probe trial of MWM than the Hypo group. In addition, the latency to enter the dark box in the PA test was lower in the Hypo group than in the Control group, which was significantly improved after Nan S treatment. Furthermore, the hippocampal and cortical lipid peroxide marker (MDA) levels and NO metabolites of the Hypo group were significantly increased and the antioxidant markers (total thiol, SOD, and CAT) were significantly inhibited compared to the Control group. Compared with the Hypo group, Nan S administration could significantly decrease the oxidant factors and increase the activities antioxidant system and concentration of BDNF.

CONCLUSION

It is concluded that Nan S might be able to enhance endogenous antioxidant proteins due to its antioxidant activity, thereby improving BDNF and spatial and avoidance memory in the hypothyroidism-induced memory impairment model however, more studies are still necessary to elucidate the exact mechanism(s).

Anti-apoptotic and neurogenic properties in the hippocampus as possible mechanisms for learning and memory improving impacts of vitamin D in hypothyroid rats during the growth period

The current study was designed to investigate the protective effects of Vitamin D (VD) on hippocampal neurogenesis, apoptosis, and subsequent hippocampal-dependent learning and memory performance in hypothyroid juvenile rats. Twenty eight male Wistar rats were randomly divided into four groups as; control, Hypothyroid (Hypo), Hypo-VD100 and Hypo-VD500. Hypothyroidism was induced by giving 0.05 % propylthiouracil (PTU), and VD (100 or 500 IU/kg) treatment was performed daily by gavage. At the end of treatment, Morris water maze (MWM) was carried out and evaluated hippocampal neurogenesis, apoptosis, and dark neurons (DNs). Our results revealed that the escape latency and the traveled distance to find the platform in the Hypo group were significantly longer but the time spent and distance traveled in the target area in probe trial was lower than the control group. Hypothyroidism was accompanied by a marked decrease in hippocampal neurogenesis, and a significant increase in the number of apoptotic neurons and DNs compared to the control group. VD decreased escape latency and the traveled distance to find the platform but increased the time spent and distance traveled in the target area in probe trial than the Hypo group. VD also increased neurogenesis, reduced apoptosis and DNs production compared to the Hypo group. In conclusion, these results support a role for VD in the restoring hippocampal neurogenesis impairment, reducing neuronal apoptosis, and DNs in hypothyroid rats as well as raise the possibility that VD may contribute as a therapeutic approach to improve the learning and memory deficits associated with hypothyroidism.

The effects of curcumin in learning and memory impairment associated with hypothyroidism in juvenile rats: the role of nitric oxide, oxidative stress, and brain-derived neurotrophic factor

The effect of curcumin (Cur) on cognitive impairment and the possible role of brain tissue oxidative stress, nitric oxide (NO) levels, and brain-derived neurotrophic factor (BDNF) were investigated in juvenile hypothyroid rats. The juvenile rats (21 days old) were allocated into the following groups: (1) control; (2) hypothyroid (0.05% propylthiouracil (PTU) in drinking water); (3-5) hypothyroid-Cur 50, 100, and 150, which in these groups 50, 100, or 150 mg/kg, Cur was orally administered by gavage during 6 weeks. In the hypothyroid rats, the time elapsed and the traveled distance to locate the hidden platform in the learning trials of Morris water maze (MWM) increased, and on the probe day, the amount of time spent in the target quadrant and the distance traveled in there was decreased. Hypothyroidism also decreased the latency and increased the time spent in the darkroom of the passive avoidance (PA) test. Compared with the hypothyroid group, Cur enhanced the performance of the rats in both MWM and PA tests. In addition, Cur reduced malondialdehyde concentration and NO metabolites; however, it increased thiol content as well as the activity of catalase (CAT) and superoxide dismutase enzymes in both the cortex and hippocampus. Cur also increased hippocampal synthesis of BDNF in hypothyroid rats. The beneficial effects of Cur cognitive function in juvenile hypothyroid rats might be attributed to its protective effect against oxidative stress and potentiation of BDNF production.

Thymoquinone improved redox homeostasis in the heart and aorta of hypothyroid rats

OBJECTIVES

Propylthiouracil (PTU) is a common drug that is used in medicine for treating hyperthyroidism. Furthermore, hypothyroidism can also be induced with PTU. Considering the antioxidant effects of thymoquinone (TMQ), this study was designed to find out whether TMQ could counteract the oxidative damage in the heart and aorta tissues induced by hypothyroidism in rats.

METHODS

Animals were arranged into four groups: (1) Control, (2) PTU, (3) PTU-TMQ 5, and (4) PTU-TMQ 10. Hypothyroidism was induced in rats by giving 0.05% PTU in drinking water. PTU and TMQ (5 and 10 mg/kg, ip) treatments were done for 42 days. Finally, the animals were sacrificed and the serum of the rats was collected for thyroxine level assessment. The heart and aorta tissues were also removed for biochemical oxidative stress markers measurement.

RESULTS

A lower serum thyroxine level was observed after PTU treatment compared to the control group. Hypothyroidism also was accompanied by a decrease of thiol content, and superoxide dismutase (SOD), and catalase (CAT) activities in the heart and aorta tissues while increased malondialdehyde (MDA). Furthermore, a significant reduction in oxidative damage was noted in the heart and aorta following the administration of TMQ (5 and 10 mg/kg) which was indicated by the reduction in MDA and improved activities of SOD, CAT, and thiol.

CONCLUSION

In this study, TMQ was found to improve oxidative damages in the heart and aorta tissues of hypothyroid rats.

Cardiovascular protective effects of PPARγ agonists in hypothyroid rats: protection against oxidative stress

Hypothyroidism disturbs redox homeostasis and takes part in cardiovascular system dysfunction. Considering antioxidant and cardio-protective effects of PPAR-γ agonists including pioglitazone (POG) and rosiglitazone (RSG), the present study was aimed to determine the effect of POG or RSG on oxidants and antioxidants indexes in the heart and aorta tissues of Propylthiouracil (PTU)-induced hypothyroid rats.

MATERIALS AND METHODS

The animals were divided into six groups: (1) Control; (2) propylthiouracil (PTU), (3) PTU-POG 10, (4) PTU-POG 20, (5) PTU-RSG 2, and (6) PTU-RSG 4. Hypothyroidism was induced in rats by giving 0.05% propylthiouracil (PTU) in drinking water for 42 days. The rats of PTU-POG 10 and PTU-POG 20 groups received 10 and 20 mg/kg POG, respectively, besides PTU, and the rats of PTU-RSG 2 and PTU-RSG 4 groups received 2 and 4 mg/kg RSG, respectively, besides PTU. The animals were sacrificed, and the serum of the rats was collected to measure thyroxine level. The heart and aorta tissues were also removed for the measurement of biochemical oxidative stress markers.

RESULTS

Hypothyroidism was induced by PTU administration, which was indicated by lower serum thyroxine levels. Hypothyroidism also was accompanied by a decrease of catalase (CAT), superoxide dismutase (SOD) activities, and thiol concentration in the heart and aorta tissues while increased level of malondialdehyde (MDA). Interestingly, administration of POG or RSG dramatically reduced oxidative damage in the heart and aorta, as reflected by a decrease in MDA and increased activities of SOD, CAT, and thiol content.

CONCLUSION

The results of this study showed that administration of POG or RSG decreased oxidative damage in the heart and aorta tissues induced by hypothyroidism in rats.

Folic acid attenuated learning and memory impairment via inhibition of oxidative damage and acetylcholinesterase activity in hypothyroid rats

Hypothyroidism has been reported to be associated with cognitive decline. Considering the role of folic acid (FA) in cognitive performance, the present study was designed to investigate the effects of FA on hypothyroidism-induced cognitive impairment, oxidative damage, and alterations in acetylcholinesterase (AChE) activity in rat model of propylthiouracil (PTU)-induced hypothyroidism. In this study, PTU (0.05% in drinking water) and FA (5, 10, and 15 mg/kg, oral gavage) were administered for the rats during 7 weeks. Then, behavioral performance was tested using Morris water maze (MWM) and passive avoidance (PA) tasks. Finally, oxidative stress indicators and AChE activity were assayed in the brain tissues. The impairing effect of hypothyroidism on cognitive performance was markedly alleviated by FA especially at higher doses. In the MWM test, FA reduced escape latency and travelled distance, compared to the non-treated hypothyroid group. In the PA test, latency to enter dark chamber was significantly enhanced by FA compared to the non-treated hypothyroid group (p < 0.05-p < 0.001). Besides, FA attenuated AChE activity and malondialdehyde level but it increased activity of superoxide dismutase enzyme and total thiol content (p < 0.05-p < 0.001). In conclusion, our findings revealed that FA could improve learning and memory ability in hypothyroid rats. The observed protective effects may have been mediated through regulation of oxidative stress and AChE activity.

Combination of tea polyphenols and proanthocyanidins prevents menopause-related memory decline in rats via increased hippocampal synaptic plasticity by inhibiting p38 MAPK and TNF-α pathway

OBJECTIVE

Many studies have examined the beneficial effects of tea polyphenols (TP) and proanthocyanidins (PC) on the memory impairment in different animal models. However, the combined effects of them on synaptic, memory dysfunction and molecular mechanisms have been poorly studied, especially in the menopause-related memory decline in rats.

METHODS

In this rat study, TP and PC were used to investigate their protective effects on memory decline caused by inflammation. We characterized the learning and memory abilities, synaptic plasticity, AMPAR, phosphorylation of the p38 protein, TNF-ɑ, structural synaptic plasticity-related indicators in the hippocampus.

RESULTS

The results showed that deficits of learning and memory in OVX + D-gal rats, which was accompanied by dendrites and synaptic morphology damage, and increased expression of Aβ1-42 and inflammation. The beneficial effects of TP and PC treatment were found to prevent memory loss and significantly improve synaptic structure and functional plasticity. TP+PC combination shows more obvious advantages than intervention alone. TP and PC treatment improved behavioral performance, the hippocampal LTP damage and the shape and number of dendrites, dendritic spines and synapses, reduced the burden of Aβ and decreased the inflammation in hippocampus. In addition, TP and PC treatment decreased the expressions of Iba-1, TNF-α, TNFR1, and TRAF2.

CONCLUSIONS

These results provided a novel evidence TP combined with PC inhibits p38 MAPK pathway, suppresses the inflammation in hippocampus, and increase the externalization of AMPAR, which may be one of the mechanisms to improve synaptic plasticity and memory in the menopause-related memory decline rats.