Protective Effect of PPARγ Agonists on Cerebellar Tissues Oxidative Damage in Hypothyroid Rats

Exploring the molecular mechanisms of PPARγ agonists in modulating memory impairment in neurodegenerative disorders

Neurodegenerative diseases are characterized by progressive memory impairment and cognitive decline. This review aims to unravel the molecular mechanisms involved in the enhancement of memory function and mitigation of memory impairment through the activation of PPARγ agonists in neurodegenerative diseases. The findings suggest that PPARγ agonists modulate various molecular pathways involved in memory formation and maintenance. Activation of PPARγ enhances synaptic plasticity, promotes neuroprotection, suppresses neuroinflammation, attenuates oxidative stress, and regulates amyloid-beta metabolism. The comprehensive understanding of these molecular mechanisms would facilitate the development of novel therapeutic approaches targeting PPARγ to improve memory function and ultimately to alleviate the burden of neurodegenerative diseases. Further research, including clinical trials, is warranted to explore the efficacy, safety, and optimal use of specific PPARγ agonists as potential therapeutic agents in the treatment of memory impairments associated with neurodegenerative diseases.

Omega-3 fatty acids supplementation prevents learning and memory impairment induced by chronic ethanol consumption in adolescent male rats through restoration of inflammatory and oxidative responses

OBJECTIVE

Ethanol (Eth) intake is known to cause numerous detrimental effects on the structure and function of the brain, and it is commonly used as a psychostimulant drug by adolescents. Conversely, omega-3 (O3) can reduce the risk of cognitive decline and promote the maintenance of neurophysiological functions. In this study, we investigated the protective effects of O3 on behavioral alterations, oxidative stress, and interleukin-6 (IL-6) levels induced by chronic Eth intake during adolescence in rats.

MATERIALS AND METHODS

Adolescent male rats (21 days old) were divided as follows: (1) Vehicle, (2) Eth (Eth in drinking water [20%]), (3-5) Eth + O3 (50/100/150 mg/kg), and (6) O3 (150 mg/kg). After 5 weeks, Morris water maze (MWM) and passive avoidance (PA) tests were performed, and the hippocampal and cortical levels of oxidative stress markers and inflammatory indices were measured.

RESULTS

Adolescent Eth intake impairs learning and memory function in MWM and PA tests (groups × day, p < 0.05 and p < 0.001, respectively). It was shown that Eth induced oxidative stress and neuroinflammation. O3 improved learning and impairment induced by Eth by reducing the adverse effects of Eth on the oxidant/antioxidant balance in the hippocampi (for malondialdehyde [MDA]/thiol: p < 0.01, p < 0.001, respectively) and for superoxide dismutase (SOD)/catalase (CAT): p < 0.01 and p < 0.05, respectively). Furthermore, we found that O3 prevented the Eth-induced increase of hippocampal IL-6 (p < 0.001).

CONCLUSION

O3 supplementation acts as an effective approach to prevent learning and memory impairments induced by chronic Eth consumption during adolescence. In this respect, the antioxidant and anti-inflammatory properties of O3 seem to be the main underlying mechanisms of neuroprotection.

Ascorbic Acid Supplementation Improves Adolescent Stress-induced Cognitive Impairment Through Restoration of Behavioral, Biochemical and Electrophysiological Alterations in Male Rats

The present research study aimed to investigate the role of Ascorbic acid (AA) on synaptic plasticity, learning, and memory impairment induced by unpredicted chronic mild stress (CUMS) in adolescent male rats. Adolescent male rats were divided into: 1) vehicle, 2) CUMS, 3-5) CUMS plus various doses of AA by oral gavage (CUMS-10/100/400 mg/kg), and 6) AA400 mg/kg by oral gavage. In Morris Water Maze, the time latency decreased, while the time spent in the target quadrant increased in CUMS group treated with AA at the dose of 400 mg/kg. In passive avoidance, the latency of entering into the dark chamber decreased in CUMS group treated with AA (400 mg/kg). In biochemical test results, nitrite and MDA significantly decreased, while thiol content, SOD, and catalase activity in CUMS group that received AA400mg/kg was increased. IL-10, BDNF and Ki67 increased, while TNF-a and AChE activity were decreased in CUMS group treated with AA simultaneously. The results of our study showed that chronic stress during adolescence could cause learning and memory disorders as well as synaptic plasticity. In addition, we showed that AA can prevent this problem by reducing oxidative stress, inflammation, increasing the amount of BDNF, and neurogenesis.

Folic Acid Ameliorates Anxiety- and Depressive-Like Behavior Induced by Nicotine Withdrawal Through Restoration of Behavioral and Biochemical Alterations in Adolescent Male Rats

BACKGROUND

The present study aimed to assess the efficacy of folic acid (FA) on withdrawal following nicotine (Nic) administration in adolescent male rats.

AIMS AND METHODS

Adolescent male rats were divided into two groups: (1) vehicle and (2) Nic (Nic-2 mg/kg), and were under treatment from 21 to 42 days of age. After that, they continued the experiment without treatment and returned to a regular diet, except for one of those who received Nic. The rats were divided into four groups where they were treated with different doses of FA (5, 10, and 15 mg/kg) and bupropion (Bup) by oral gavage, and the final group included normal rats that received only FA (15 mg/kg) from 42 days of age for three weeks during which withdrawal occurred.

RESULTS

Results showed that adolescent Nic exposure exacerbated the behavioral indices of anxiety- and depression-like behaviors, while FA attenuated the effects of Nic withdrawal on anxiety and depression as well as Bup. In support, the biochemical results demonstrated a balance between oxidant and antioxidant mediators in addition to the increase and decrease of serotonin and monoamine oxidase (MAO) activity in cortical tissue. TNF-α as an inflammatory agent was decreased, whereas IL-10 as an anti-inflammatory parameter was increased.

CONCLUSIONS

The present findings suggest anxiety and depression caused by Nic withdrawal were attenuated by FA more likely through the reduction activity of MAO, the important enzyme responsible for serotonin metabolism along with balance between oxidant/antioxidant and pro-inflammatory/anti-inflammatory mediators. However, various mechanisms might be involved, which requires further investigation.

IMPLICATIONS

Nic withdrawal-induced depression and anxiety like behavior in rats followed by neuro-oxidative damage and neuro-inflammation. FA supplementation as well as Bup improved cognitive disorders induced by Nic withdrawal by increasing neuro-inflammation and neuro-oxidative damage.

Eltroxin and Hesperidin mitigate testicular and renal damage in hypothyroid rats: amelioration of oxidative stress through PPARγ and Nrf2/HO-1 signaling pathway

BACKGROUND

Thyroid hormones (THs) regulate growth, development and function of different tissues. Hypothyroidism is a common clinical disorder characterized by deficiency in THs and adversely affects the development and functions of several organs. This work aimed to investigate the ameliorative effect of eltroxin (ELT), a hypothyroidism medication, and hesperidin (HSP), a flavonoid, against testicular and renal toxicity in hypothyroid rats. Twenty-four rats were divided into four groups and treated orally for 12 weeks. Group I (control), group II (hypothyroidism) received 20 mg/kg carbimazole (CBZ), group III received CBZ and 0.045 mg/kg ELT, and group IV received CBZ and 200 mg/kg HSP.

RESULTS

CBZ administration induced biochemical and histopathological changes in testis and kidney. Co-administration of ELT or HSP significantly (P < 0.05) ameliorated THs, reduced urea and creatinine while raised follicle stimulating hormone (FSH), Luteinizing hormone (LH), and testosterone in serum. Testicular and renal malondialdehyde level as a lipid peroxidation indicator, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were significantly (P < 0.05) decreased while glutathione content, glutathione peroxidase, and glutathione-s-transferase activities were significantly (P < 0.05) increased. The histopathological changes were also diminished. Decreased mRNA and protein expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and peroxisome proliferator-activated receptor gamma(PPARγ) in hypothyroid rats were up-regulated after ELT or HSP treatment.

CONCLUSIONS

ELT and HSP showed antioxidant and anti-inflammatory effects against CBZ-induced testicular and renal toxicity, and these effects may be promoted via activating Nrf2/HO-1 and PPARγ signaling pathways.

One Incremental Stride for Doxycycline, One Substantial Advancement for Thyroid Eye Disease

The aim of this study is to assess the effectiveness of a 12-week doxycycline treatment for thyroid eye disease (TED), an autoimmune condition associated with thyroid dysfunction. In this randomized controlled clinical trial, 82 patients were randomly assigned at a 1:1 ratio to receive doxycycline (50 mg) or to undergo no treatment. Various metrics, including margin reflex distance (MRD1 and MRD2), eyelid aperture, levator muscle function, lagophthalmos, proptosis, ocular motility, diplopia, and Graves' ophthalmopathy-specific quality-of-life (GO-QOL) scale scoring were assessed. Exclusion criteria were uncontrolled systemic diseases, tetracycline allergies, pregnancy, lactation, or age below 18. The mean age was 51.6 years (SD), 87.8% of participants were female, and all were Caucasians. By week 12, the doxycycline group exhibited a significant improvement rate based on MRD2 (from 4 to 15 participants with physiological findings), clinical activity score (from 7 to 35 participants with non-active disease), and GO-QOL (from 51.22% to 70.73% of participants with a good life quality). Doxycycline showcased anti-inflammatory and immunomodulatory effects in treating TED, suggesting its potential efficacy for TED and other orbit inflammatory conditions. However, these results warrant further validation through future research involving extended follow-up periods and larger cohorts.

Feeding metformin during pregnancy and lactation periods improved learning and memory impairment in the rat offspring exposed to febrile seizure: Role of oxidative stress and inflammatory response

BACKGROUND

Many clinical evidences have reported the higher risk of seizure in young children and infants after exposure to hyperthermia, which more likely can cause brain damage and affect cognitive function, so, many researches were focused on prevention or treatment of febrile seizure (FS) with minimal adverse effects. Considering the potential effects of oxidative stress as a prominent trigger in FS, and demonstrating the anti-oxidant effects of metformin, the present study aimed to investigate the protective effect of metformin administration in prenatal and lactation periods in rat pups exposed to hyperthermia by which induced seizure.

METHOD AND MATERIALS

Pregnant rats were divided into six groups: (1) vehicle: pregnant rats received normal saline during pregnancy and lactation; (2) FS: pregnant rats received normal saline during pregnancy and lactation; (3-5) FS-Met50/100/150 mg/kg: pregnant rats received different doses of metformin including 50, 100 and 150 mg/kg during pregnancy and lactation; (6) Met150 mg/kg: pregnant rats received Met150 mg/kg during pregnancy and lactation. The male pups born to mothers received in all FS groups exposed to hyperthermia. All experimental groups were allowed to grow up, and after the lactation period, they were subjected for behavioural tests and biochemical analysis.

RESULTS

According to the present findings, the prenatal and lactation exposure to the highest dose of metformin demonstrated significant difference with FS group in both behavioural and biochemical test analyses. Although the remaining doses of metformin were also effective, the much better results were reported with the highest dose of metformin (150 mg/kg). Interestingly, the highest dose of metformin administered alone demonstrated better result than vehicle in probe trial test.

CONCLUSION

Considering the present research and related study in relation to metformin in ameliorating the epilepsy symptoms, there are numerous evidences on positive effect of metformin on seizure. Although the exact mechanism is unclear, the anti-oxidant effect of metformin is strongly supported.

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.

PPARγ activation improved learning and memory and attenuated oxidative stress in the hippocampus and cortex of aged rats

Oxidative stress has an important role in brain aging and its consequences include cognitive decline and physiological disorders. Peroxisome proliferator-activated receptor-γ (PPARγ) activation has been suggested to decrease oxidative stress. In the current research, the effect of PPARγ activation by pioglitazone(Pio) on learning, memory and oxidative stress was evaluated in aged rats. The rats were divided into five groups. In the Control group, vehicle (saline-diluted dimethyl sulfoxide (DMSO)) and saline were injected instead of Pio and scopolamine (Sco), respectively. In the Sco group, the vehicle was injected instead of Pio and the rats were injected by Sco 30 min before the behavioral tests. In the Sco-Pio 10, Sco-Pio 20, and Sco-Pio 30 groups, 10, 20, and 30 mg/kg Pio was injected and finally, the rats were injected with Sco 30 min before the behavioral tests. Morris water mater maze(MWM) and passive avoidance(PA) tests were carried out, and finally, the hippocampus and cortex were removed for biochemical assessments. The results showed that the highest dose of Pio decreased the traveling time and distance during 5 days of learning and increased the time and distance in the target area on the probe day of MWM. The highest dose of Pio also prolonged the delay time for entering the dark and total time spent in the light while decreasing the total time spent in and the number of entries into the dark in PA test. Pio especially, in the medium and highest doses, decreased MDA while increasing thiol, superoxide dismutase, and catalase in the hippocampus and cortex. It is concluded that PPARγ activation by Pio as an agonist improved learning and memory in aged rats probably by attenuating oxidative stress in the hippocampus and cortex.

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).

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.

Regulation of Neuroinflammatory Signaling by PPARγ Agonist in Mouse Model of Diabetes

Many relevant studies, as well as clinical practice, confirm that untreated diabetes predisposes the development of neuroinflammation and cognitive impairment. Having regard for the fact that PPARγ are widely distributed in the brain and PPARγ ligands may regulate the inflammatory process, the anti-inflammatory potential of the PPARγ agonist, pioglitazone, was assessed in a mouse model of neuroinflammation related with diabetes. In this regard, the biochemical and molecular indicators of neuroinflammation were determined in the hippocampus and prefrontal cortex of diabetes mice. The levels of cytokines (IL-1β, IL-6, and TNF) and the expression of genes (Tnfrsf1a and Cav1) were measured. In addition, behavioral tests such as the open field test, the hole-board test, and the novel object recognition test were conducted. A 14-day treatment with pioglitazone significantly decreased IL-6 and TNFα levels in the prefrontal cortex and led to the downregulation of Tnfrsf1a expression and the upregulation of Cav1 expression in both brain regions of diabetic mice. Pioglitazone, by targeting neuroinflammatory signaling, improved memory and exploratory activity in behavioral tests. The present study provided a potential theoretical basis and therapeutic target for the treatment of neuroinflammation associated with diabetes. Pioglitazone may provide a promising therapeutic strategy in diabetes patients with muffled of behavioral activity.

Nitric oxide and thyroid carcinoma: A review

Thyroid carcinoma is the most common endocrine cancer in the world, and its incidence has been steadily increasing in recent years. Despite its relatively good prognosis, therapies have not improved greatly in recent years. Therefore, exploring new therapies for thyroid carcinoma represents an unmet need. Nitric oxide (NO) is a short-term endogenous signaling molecule that plays a vital role in various physiological and pathological processes and is synthesized by nitric oxide synthase (NOS). Many studies have been conducted over the past decades to explain its correlation to cancer. NO exerts a wide range of effects on cancer, involving angiogenesis, apoptosis, cell cycle, invasion, and metastasis. It also serves a dual function by promoting and halting tumor development simultaneously. The relationship between NO and thyroid carcinoma has been intensively studied and discussed. This paper reviews the role and molecular mechanism of NO in thyroid carcinoma and discusses potentials of prevention and treatment of thyroid carcinoma.

Pioglitazone improves skeletal muscle functions in reserpine-induced fibromyalgia rat model

BACKGROUND

Fibromyalgia (FM) is characterized by musculoskeletal pain, fatigue, sleep and memory disturbance. There is no definitive cure yet for FM-related health problems. Peroxisome proliferator-activated receptor's (PPAR's) activation is associated with insulin sensitisation and improved glucose metabolism. PPAR-γ was reported to alleviate FM allodynia. Limited data are discussing its effect on motor disorders.

OBJECTIVE

To investigate the potential effect of PPAR-γ agonists (pioglitazone, as one member of thiazolidinediones (TZD)) on motor dysfunction in reserpine-induced FM in a rat model.

MATERIALS AND METHODS

Thirty-six male Wistar rats were divided into negative control (n = 9) and reserpine-induced FM (n = 27) groups. The latter was subdivided into three equal subgroups (n = 9), positive control (untreated FM model), pioglitazone-treated and GW9662-treated. We evaluated muscle functions and activity of chloramphenicol acetyltransferase, superoxide dismutase, malondialdehyde, and serum levels of interleukin-8 and monocyte chemoattractant protein-1.

RESULTS

Pioglitazone significantly relieved fatigue, improved muscle performance, reduced inflammatory cytokines and enhanced antioxidant's activity, while GW9662, a known PPAR-γ antagonist, aggravated the FM manifestations in the rat model.

CONCLUSION

PPAR-γ agonists show a promising role against FM-associated motor dysfunctions.

Thymoquinone Ameliorate Hepatorenal Toxicity Associated With Propylthiouracil-Induced Hypothyroidism in Juvenile Rats

BACKGROUND

An increasing number of studies suggest that hypothyroidism may lead to hepatorenal toxicity. This study examined whether thymoquinone (TQ), the main active Nigella sativa constituent, could prevent the detrimental influences of hepatorenal toxicity of hypothyroidism during the juvenile period in rats.

METHODS

The male rats were randomly divided into four groups (n = 7), including control, propylthiouracil (PTU), PTU-TQ 5 mg/kg, and PTU-TQ 10 mg/kg. PTU was dissolved in drinking water at a concentration of 0.05% and administered for six weeks. In the PTU-TQ5 and PTU-TQ10 groups, animals received PTU plus 5 mg/kg and 10 mg/kg of the TQ (i.p.) for six weeks, respectively. The rats were evaluated after TQ treatment by measuring serum markers of liver and kidney function tests as well as oxidative stress biomarkers in liver and kidney tissues.

RESULTS

Administration of TQ (5 and 10 mg/kg) decreased oxidative stress damage in liver and kidney tissue in hypothyroidism rats with improvement in activities of antioxidant enzymes and a decrease in MDA in both liver and kidney homogenates. Furthermore, TQ treatment significantly inhibited the elevation of serum biochemical markers of liver and kidney function associated with this hepatorenal toxicity.

CONCLUSION

These results suggest that the protective effect of TQ in hypothyroidism-induced hepatorenal toxicity in rats is attributed to its ability to reduce oxidative stress in hepatic and renal tissues. However, more studies are recommended to investigate the exact mechanism (s) for the effect of TQ on hepatorenal outcomes of hypothyroidism in human subjects.

Dose-dependent effects of prenatal exposure of pioglitazone, the PPARγ agonist, on the hippocampus development and learning and memory performance of rat offspring

It is known that pioglitazone, defined as a PPARγ agonist, has neuron-protective properties in nervous system disorders. The aim of this study is to investigate the effects of pioglitazone administration at different doses during prenatal period on the neurons, glial cells and learning-memory levels in the hippocampus of rat offspring. Pregnant rats were divided into three groups; Low-Dose Pioglitazone (LDP), High-Dose Pioglitazone (HDP) and control (C) (n = 3). Pregnant rats in the HDP and LDP groups were given pioglitazone at 30 mg/kg and 5 mg/kg doses, respectively, by gavage once a day during their pregnancy. No procedure was applied to the rats in the control group. Morris water tank test was applied to offspring obtained from postnatal 24th to 28th day. The offspring were sacrificed on the 29th postal day and their brain tissues removed. Stereological, histopathological and immunohistochemical techniques were used to analyze brain tissues. As a result of the analysis, it was observed that there were delays in learning and memory, the number of pyramidal neurons decreased, and the density of cells stained with glial fibrillar acidic protein (GFAP) positive increased in the HDP group compared to the other groups (p < 0.05). No significant difference was found between the LDP and control groups in terms of these parameters (p > 0.05). Our results showed that pioglitazone administered in the prenatal period had an effect on the hippocampus development and learning and memory performance of rats, depending on the dose.

Neuronal Nitric Oxide Inhibitor 7-Nitroindazole Improved Brain-Derived Neurotrophic Factor and Attenuated Brain Tissues Oxidative Damage and Learning and Memory Impairments of Hypothyroid Juvenile Rats

Hypothyroidism-associated learning and memory impairment is reported to be connected to oxidative stress and reduced levels of brain-derived neurotrophic factor (BDNF). The effects of neuronal nitric oxide inhibitor 7-nitroindazole (7NI) on brain tissues oxidative damage, nitric oxide (NO), BDNF and memory impairments in hypothyroid juvenile rats were investigated. Male Wistar juvenile rats (20 days old) were divided into five groups, including Martinez et al. (J Neurochem 78 (5):1054-1063, 2001). Control in which vehicle was injected instead of 7NI, (Jackson in Thyroid 8 (10):951-956, 1998) Propylthiouracil (PTU) where 0.05% PTU was added in drinking water and vehicle was injected instead of 7NI, (Gong et al. in BMC Neurosci 11 (1):50, 2010; Alva-Sánchez et al. in Brain Res 1271:27-35, 2009; Anaeigoudari et al. in Pharmacol Rep 68 (2): 243-249, 2016) PTU-7NI 5, PTU-7NI 10 and PTU-7NI 20 in which 5, 10, or 20 mg/kg7NI was injected intraperitoneally (i.p.). Following 6 weeks, Morris water maze (MMW) and passive avoidance learning (PAL) tests were used to evaluate the memory. Finally, the hippocampus and the cortex of the rats were removed after anesthesia by urethane to be used for future analysis. The escape latency and traveled path in MWM test was increased in PTU group (P < 0.001). PTU also reduced the latency to enter the dark box of PAL and the time spent and the distance in the target quadrant in MWM test (P < 0.001 and P < 0.01). Treatment with 7NI attenuated all adverse effects of PTU (P < 0.05 to P < 0.001). PTU lowered BDNF and thiol content and superoxide dismutase (SOD) and catalase (CAT) activities in the brain but increased malondialdehyde (MDA) and nitric oxide (NO) metabolites. In addition, 7NI improved thiol, SOD, CAT, thiol, and BDNF but attenuated MDA and NO metabolites. The results of the current study showed that 7NI improvement in the learning and memory of the hypothyroid juvenile rats, which was accompanied with improving of BDNF and attenuation of NO and brain tissues oxidative damage.

The effects of the combination of Cyperus rotundus, Crocus sativus, Piper nigrum, and Boswellia serrata on learning and memory deficit and oxidative damage in brain tissue of hypothyroid rats

In the present study, the impact of a combination of four memory-enhancer herbs on cognitive impairment and brain tissue oxidative damage due to hypothyroidism was evaluated. Propylthiouracil (PTU; 0.05%) was administrated in drinking water. Rats were treated with a combination of four herbal products (Cyperus rotundus, Crocus sativus, Piper nigrum, and Boswellia serrata) mixed with honey at two doses (640 and 1,280 mg/kg) or donepezil (0.5 mg/kg), for 6 weeks. Memory performance on the Morris water maze (MWM) and avoidance behavior in passive avoidance was impaired by hypothyroidism, and brain tissue oxidative damage occurred. Herbal combination and donepezil significantly improved memory impairment, reduced malondialdehyde concentration, and nitric oxide metabolites while increased the thiol contents and catalase and superoxide dismutase enzymes activity in the brain. Our findings suggest that the mixture of herbal products improves learning and memory deficits caused by hypothyroidism, probably by reducing the brain tissue oxidative damage. PRACTICAL APPLICATIONS: Learning and memory impairment is a common feature of thyroid hormones deficiency. Several studies are showing that hypothyroidism in juvenile and mature rats induces significant cognitive impairment. Likewise, in humans, a close relationship between thyroid hormone deficiency and cognitive impairment has been reported. We used a mixture of herbal products, including Cyperus rotundus, Crocus sativus, Piper nigrum, and Boswellia serrata, to treat hypothyroidism-induced memory impairment. All these herbs are widely used as a food additive across the world. In Iranian traditional medicine, this herbal combination traditionally used to treat cognitive impairments. Numerous studies have indicated that these herbs show neuroprotective and memory-enhancing properties. Our finding indicated that a traditionally used herbal combination could potentially use as a treatment of cognitive impairment induced by thyroid hormone deficiency.

Regulation of nitric oxide production in hypothyroidism

Hypothyroidism is a common endocrine disorder that predominantly occurs in females. It is associated with an increased risk of cardiovascular diseases (CVD), but the molecular mechanism is not known. Disturbance in lipid metabolism, the regulation of oxidative stress, and inflammation characterize the progression of subclinical hypothyroidism. The initiation and progression of endothelial dysfunction also exhibit these changes, which is the initial step in developing CVD. Animal and human studies highlight the critical role of nitric oxide (NO) as a reliable biomarker for cardiovascular risk in subclinical and clinical hypothyroidism. In this review, we summarize the recent literature findings associated with NO production by the thyroid hormones in both physiological and pathophysiological conditions. We also discuss the levothyroxine treatment effect on serum NO levels in hypothyroid patients.

Neuroprotective and long term potentiation improving effects of vitamin E in juvenile hypothyroid rats

Protective effects of vitamin E (Vit E) on long term potentiation (LTP) impairment, neuronal apoptosis and increase of nitric oxide (NO) metabolites in the hippocampus of juvenile rats were examined. The rats were grouped (n=13) as: (1) control; (2) hypothyroid (Hypo) and (3) Hypo-Vit E. Propylthiouracil (PTU) was given in drinking water (0.05%) during 6 weeks. Vit E (20 mg/ kg) was daily injected (IP). To evaluate synaptic plasticity, LTP from the CA1 area of the hippocampus followed by high frequency stimulation to the ipsilateral Schafer collateral pathway was carried out. The cortical and hippocampal tissues were then removed to measure NO metabolites. The brains of 5 animals in each group were removed for apoptosis study. The hypothyroidism status decreased the slope, 10-90% slope and amplitude of field excitatory post synaptic potential (fEPSP) compared to the control group (P<0.01-P<0.001). Injection of Vit E increased the slope, 10-90% slope and amplitude of the fEPSP in the Hypo-Vit E group in comparison to the Hypo group (P<0.05-P<0.01). TUNEL positive neurons and NO metabolites were higher in the hippocampus of the Hypo rats, as compared to those in the hippocampus of the control ones (P<0.001). Treatment of the Hypo rats by Vit E decreased apoptotic neurons (P<0.01-P<0.001) and NO metabolites (P<0.001) in the hippocampus compared to the Hypo rats. The results of the present study showed that Vit E prevented the LTP impairment and neuronal apoptosis in the hippocampus of juvenile hypothyroid rats.

Effects of PPAR-γ agonist, pioglitazone on brain tissues oxidative damage and learning and memory impairment in juvenile hypothyroid rats

Aim: The effect of peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist pioglitazone on the brain tissues oxidative damage and learning and memory impairment in the juvenile hypothyroid rats was evaluated. Main methods: Rats were classified as: ( 1 ) Control; (2) Propylthiouracil (PTU); (3) PTU-Pio 10 and (4) PTU-Pio 20. PTU was given in drinking water (0.05%) during 6 weeks. Pioglitazone (10 or 20 mg/kg) was daily injected intraperitoneally. Passive avoidance (PA) and Morris water maze (MMW) were conducted. Later, the animals were sacrificed and the brain tissues were removed for biochemical measurements. Key funding: The results indicated that in the MWM escape latency as well as traveled path increased in the PTU group as compared to the control group. Also, the time spent in the target quadrant in the probe test of MWM and step-through latency in the PA test were decreased in the PTU group as compared to the control group. Pioglitazone reversed all the negative behavioral effects of hypothyroidism. Administration of PTU attenuated thiol and superoxide dismutase (SOD), and catalase (CAT) activities in the brain tissues, whereas increased malondialdehyde (MDA) and nitric oxide (NO) metabolites. PPARγ agonist improved thiol, SOD and CAT, while diminished MDA concentration. Significance: Our finding in the present study indicated that PPARγ agonist pioglitazone prevented the brain tissues from oxidative damage and learning and memory impairments in juvenile hypothyroid rats.

Beneficial effects of pioglitazone, a selective peroxisome proliferator-activated receptor-γ agonist in prenatal valproic acid-induced behavioral and biochemical autistic like features in Wistar rats

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder in children. It is diagnosis by two main behavioral phenotypes i.e. social-communication impairments and repetitive behavior. ASD is complex disorder with unsolved etiology due to multiple genes involvement, epigenetic mechanism and environmental factors. Valproic acid (VPA), a teratogen is known to induce characteristic features related to ASD in rodents. Numerous studies suggest the potential therapeutic effects of peroxisome proliferator-activated receptor-gamma (PPAR-γ) in different brain disorders. This research evaluates the utility of selective agonist of PPAR-γ, pioglitazone in prenatal VPA induced experimental ASD symptomatology in Wistar rats. The prenatal administration of VPA has induced social impairment, repetitive behavior, hyperlocomotion, anxiety and low exploratory activity in rats. Also, prenatal VPA-treated rats have shown higher levels of oxidative stress (increased in thiobarbituric acid reactive species, and decreased in reduced glutathione level) and inflammation (increased in interleukin-6, tumor necrosis factor-alpha and decreased in interleukin-10) in the cerebellum, brainstem and prefrontal cortex. Treatment with pioglitazone significantly attenuated the prenatal VPA-induced social impairment, repetitive behavior, hyperactivity, anxiety and low exploratory activity. Furthermore, pioglitazone also reduced the prenatal VPA-induced oxidative stress and neuroinflammation in aforementioned brain regions. Hence, it may be concluded that pioglitazone may provide neurobehavioral and biochemical benefits in prenatal VPA-induced autistic phenotypes in rats.

Thymoquinone reverses learning and memory impairments and brain tissue oxidative damage in hypothyroid juvenile rats

In this study, the effect of thymoquinone (TQ) on propylthiouracil (PTU)-induced memory impairment was investigated in juvenile rats. The rats were grouped into control, Hypo, Hypo-TQ5 and Hypo-TQ10. Propylthiouracil increased latency time in the Morris water maze test and decreased delay in entering the dark compartment in the passive avoidance test. Both 5 mg/kg and 10 mg/kg doses of TQ decreased latency time in the Morris water maze test and increased delay in entering the dark compartment in a passive avoidance test. The PTU also increased malondialdehyde and nitric oxide metabolites in the brain while reduced the thiol content and superoxide dismutase and catalase activities and serum T4 level. Both doses of TQ decreased malondialdehyde and nitric oxide metabolites in the brain while enhanced the thiol content and superoxide dismutase and catalase activities and serum T4 level. The results of the present study showed that TQ protected against PTU-induced memory impairments in rats.