The effects of vitamin C on hypothyroidism-associated learning and memory impairment in juvenile rats

Tetrabromobisphenol A exerts thyroid disrupting effects but has little overt impact on postnatal brain development and neurobehaviors in mice

Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant. There is evidence showing that TBBPA can exert thyroid disrupting effects in mammals, but different results were also reported, along with inconsistent reports regarding its neurotoxicity. Here, we investigated thyroid disrupting effects and neurotoxicity of TBBPA (5, 50, 500 µg/(kg·day)) to male mice following maternal and direct exposure through drinking water, with the anti-thyroid drug propylthiouracil (PTU) as the positive control. On postnatal day (PND) 15, we expectedly observed severe thyroid compensatory hyperplasia and cerebellar developmental retardation in PTU-treated pups. The highest dose of TBBPA also caused thyroid histological alteration but had no effects on cerebellar development in terms of Purkinje cell morphology and the thickness of the internal granular layer and the molecular layer of the cerebellum. During puberty and adulthood, the thyroid morphological alterations became more pronounced in the TBBPA-treated animals, accompanied by decreased serum thyroid hormone levels. Furthermore, the 50 and 500 µg/(kg·day) TBBPA groups showed a significant decrease in the serum level of serotonin, a neurotransmitter associated with anxiety behaviors. Correspondingly, the highest dose group displayed anxiety-like behaviors in the elevated plus-maze test on PND 35, but this neurobehavioral alteration disappeared on PND 56. Moreover, no changes in neurobehavioral parameters tested were found in TBBPA-treated animals at puberty and adulthood. Altogether, all observations show that TBBPA can exert thyroid disrupting effects but has little overt impact on brain development and neurobehaviors in mice, suggesting that thyroid disruption does not necessarily cause overtly adverse neurodevelopmental outcomes.

Effects of Ocimum basilicum L. Extract on Hippocampal Oxidative Stress, Inflammation, and BDNF Expression in Amnesic Aged Rats

The present study was conducted to investigate the effects of Ocimum basilicum L. (OB) extract on learning and memory impairment in aged rats. Male rats were divided into the following experimental groups: Group 1 (control): including 2 months old rats, Group 2 (aged) including 2 years old rats, Groups 3-5 (aged-OB): including 2 years old rats received 50, 100, and 150 mg/kg OB for 8 weeks by oral gavage. Aging increased the delay to find the platform but, however, decreased the time spent in the target quadrant when tested by Morris water maze (MWM). Aging also reduced the latency to enter the dark chamber in the passive avoidance (PA) test compared to the control group. Moreover, interleukin-6 (IL-6) and malondialdehyde (MDA) levels were raised in the hippocampus and cortex of aged rats. In contrast, thiol levels and enzymatic activity of superoxide dismutase (SOD) and catalase (CAT) significantly reduced. In addition, aging significantly reduced BDNF expression. Finally, OB administration reversed the mentioned effects. The current research showed that OB administration improves learning/memory impairment induced by aging. It also found that this plant extract protects the brain tissues from oxidative damage and neuroinflammation.

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.

Sodium nitroprusside restored lipopolysaccharide-induced learning and memory impairment in male rats via attenuating inflammation and oxidative stress

Inflammation and oxidative stress upset memory. We explored influence of sodium nitroprusside (SNP) on memory deficits resulted from lipopolysaccharide (LPS).Groups include control, LPS, LPS + SNP 1 mg/kg, LPS + SNP 2 mg/kg, and LPS + SNP 3 mg/kg. Morris water maze and passive avoidance tests and biochemical measurements were carried out.In Morris water maze, LPS prolonged time and distance for finding the platform. In probe trial, it diminished time spent and traveled distance in the target zone. Injection of 2 and 3 mg/kg of SNP overturned the effect of LPS. In passive avoidance task, LPS postponed entrance into darkroom and reduced time spent in light room and incremented time spent in darkroom in 3, 24, and 72 h after electrical shock. All three doses of SNP restored the effects of LPS. Biochemical experiments confirmed that LPS elevated interleukin-6 and malondialdehyde concentration and declined total thiol content and superoxide dismutase and catalase activity in the hippocampus and cortex tissues. SNP particularly at a 3 mg/kg dose ameliorated LPS effects on these parameters.SNP attenuated memory disabilities resulting from LPS through modifying inflammation and boosting antioxidant defense.

Preventive impacts of vitamin C on memory damage caused by unpredictable chronic mild stress in relation to biochemical parameters in the hippocampus of male rats

The present study focused on examining the impact of vitamin C (Vit C) administration on the function of memory and the status of oxidative stress (OS) in the hippocampal area of the brain using an unpredictable chronic mild stress (UCMS) model in rats. To this end, 50 male Wistar rats (11-12 weeks of age at the start of the study) were assigned to five groups of six animals, including control, UCMS, UCMS + Vit C 50 mg/Kg, UCMS + Vit C 100 mg/Kg, and UCMS + Vit C 400 mg/Kg. The animals received daily intraperitoneal injections of Vit C at a certain time (9 am) before the initiation of a stressor. UCMS, including a progression of typical stressors, was applied for four weeks. Subsequently, using the passive avoidance (PA) and Morris water maze (MWM) tests were performed to investigate learning and memory. Eventually, hippocampal tissues were evaluated in terms of OS criteria. The results revealed that the latency to enter the dark chamber (P < 0. 01 and P < 0.05, PA test) and the time spent in the target quadrant (P < 0.0001, MWM test) were shorter in the UCMS group, while latency to discover the platform was longer (P < 0.05 and P < 0.001, MWM test) compared to the control group. However, UCMS decreased the content of thiol (P < 0.0001), as well as the activities of catalase (P < 0.0001) and superoxide dismutase (P < 0.0001), whereas the concentration of malondialdehyde (P < 0.01) increased in the hippocampal region of the brain in comparison to the control group. Interestingly, Vit C treatment reversed the mentioned effects of UCMS. Therefore, the latency to enter the dark chamber (P < 0. 05 and P < 0.01,1 and 24 h after the shock, PA test, UCMS + Vit C 400) and the time spent in the target quadrant (P < 0. 01 and P < 0.05, MWM test, UCMS + Vit C 400 and UCMS + Vit C 100, respectively) were longer in the UCMS + Vit C groups. Moreover, Vit C increased the content of thiol (P < 0.05, UCMS + Vit C 400), as well as the activity of catalase (P < 0.001, UCMS + Vit C 400) and superoxide dismutase (P < 0.0001, UCMS + Vit C 400, UCMS + Vit C 100), whereas the concentration of malondialdehyde (P < 0. 05 and P < 0.01, UCMS + Vit C 100, UCMS + Vit C 400) decreased in the hippocampal region of the brain in comparison to the UCMS group. Overall, these results suggest that Vit C could reverse UCMS-induced learning and memory impairment possibly through the modulation of brain OS.Key points Memory and learning impairments were induced by unpredictable chronic mild stress (UCMS)Vitamin C could prevent cognitive impairments caused by UCMS in rats by attenuation of oxidative stress in the brain.

Amorphous selenium inhibits oxidative stress injury of neurons in vascular dementia rats by activating NMDAR pathway

Vascular dementia (VD) is one of the most common causes of dementia, taking account for about 20% of all cases. Although studies have found that selenium supplementation can improve the cognitive ability of Alzheimer's patients, there is currently no research on the cognitive impairment caused by VD. This study aimed to investigate the role and mechanism of Amorphous selenium nanodots (A SeNDs) in the prevention of VD. The bilateral common carotid artery occlusion (BCCAO) method was used to establish a VD model. The neuroprotective effect of A SeNDs was evaluated by Morris water maze, Transcranial Doppler TCD, hematoxylin-eosin (HE) staining, Neuron-specific nuclear protein (Neu N) staining and Golgi staining. Detect the expression levels of oxidative stress and Calcium-calmodulin dependent protein kinase II (CaMK II), N-methyl-D-aspartate receptor subunit NR2A, and postsynaptic dense protein 95 (PSD95). Finally, measure the concentration of calcium ions in neuronal cells. The results showed that A SeNDs could significantly improve the learning and memory ability of VD rats, restore the posterior arterial blood flow of the brain, improve the neuronal morphology and dendritic remodeling of pyramidal cells in hippocampal CA1 area, reduce the level of oxidative stress in VD rats, increase the expression of NR2A, PSD95, CaMK II proteins and reduce intracellular calcium ion concentration, but the addition of selective NR2A antagonist NVP-AAMO77 eliminated these benefits. It suggests that A SeNDs may improve cognitive dysfunction in vascular dementia rats by regulating the NMDAR pathway.

The memory impairment by hypothyroidism in mice is dependent on time-of-day and sex

Hypothyroidism is an endocrine-metabolic disorder, and as such it compromises a wide range of physiological functions. Memory deficits and, the most recently described, circadian rhythm disruption are among the impairments caused by thyroid dysfunctions. However, although highly likely, there is no evidence connecting these two effects of hypothyroidism. Here, we hypothesized the time-of-day interferes with the memory deficit caused by hypothyroidism. C57BL/6 J mice from both sexes were subjected to novel object recognition (NOR) task during the rest and active phases, corresponding to ZT 2-4 and 14-16, respectively (ZT: Zeitgeber time; ZT 0: lights on at 07:00 am). First, we showed that neither sex nor ZT altered object recognition memory (ORM) in euthyroid mice. Next, animals were divided into control (euthyroid) and hypothyroid [induced with methimazole (0.01%) and perchlorate (0.1%) treatment in the drinking water for 21 days] groups. Under euthyroid conditions, male and female mice recognized the novel object regardless of the time-of-day. However, hypothyroidism impaired ORM at rest phase (ZT 2-4) in both sexes. Surprisingly, in the active phase (ZT 14-16), the hypothyroid males performed the NOR, though a longer time to execute the task was required. In contrast, female hypothyroid mice showed a greater impairment in ORM. Our results suggest that hypothyroidism may disrupt the circadian rhythm in brain areas related to mnemonic processes since in euthyroid condition ORM is not affected by the time-of-day. Furthermore, our findings in an animal model indicate a pronounced deleterious effect of hypothyroidism in women.

Nanowarming improves survival of vitrified ovarian tissue and follicular development in a sheep model

Tissue cryopreservation has allowed long term banking of biomaterials in medicine. Ovarian tissue cryopreservation in particular helps patients by extending their fertility window. However, protection against tissue injury during the thawing process has proven to be challenging. This is mainly due to the heterogenous and slow distribution of the thermal energy across the vitrified tissue during a conventional warming process. Nanowarming is a technique that utilizes hyperthermia of magnetic nanoparticles to accelerate this process. Herein, hyperthermia of synthesized PEGylated silica-coated iron oxide nanoparticles was used to deter the injury of cryopreserved ovarian tissue in a sheep model. When compared to the conventional technique, our findings suggest that follicular development and gene expression in tissues warmed by the proposed technique have been improved. In addition, Nanowarming prevented cellular apoptosis and oxidative stress. We therefore conclude that Nanowarming is a potential complementary candidate to increase efficiency in the ovarian cryopreservation field.

Protective effects of cinnamon on acetylcholinesterase activity and memory dysfunction in diabetic rats

OBJECTIVES

Regarding neurocognitive and immunomodulatory properties of cinnamon (Cinn) we aimed to investigate whether cinnamon regulates acetylcholinesterase (AChE) activity, and oxidative abnormalities with concomitant memory dysfunction in streptozotocin (STZ)-induced diabetes.

METHODS

Forty-seven male adult rats were divided into seven groups (n=8 animals): Control group: in these non-diabetic rats only saline 0.9% NaCl was gavaged, Diabetic (Dia) group: diabetic rats in them saline 0.9% NaCl was gavaged for six weeks. Dia-Cinn 100, Dia-Cinn 200, and Dia-Cinn 400, Dia-Met groups: in these diabetic rats the extract (100, 200, 400 mg/kg respectively) or metformin (300 mg/kg) was gavaged for six weeks. Passive avoidance performance, AChE enzyme activity, and oxidative indicators were examined among the groups.

RESULTS

Vs. the control group, blood glucose level and stay time in the dark were remarkably increased in Dia group whereas the latency time was decreased. Meanwhile, antioxidant levels (superoxide dismutase, catalase, and thiols) noticeably decreased in the Dia group compared to the Control group. On the other hand, Cinn extract espicailly at the highest dose recovered the changes similar to those found in the metformin-treated group.

CONCLUSIONS

These findings proposed that the cinnamon hydro-ethanolic extract promotes memory recovery in diabetic conditions through the atteuation of the AChE activity and oxidative injury.

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).

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.

The effects of vitamin D on learning and memory of hypothyroid juvenile rats and brain tissue acetylcholinesterase activity and oxidative stress indicators

Apart from a role as a key regulator of calcium/phosphate homeostasis, vitamin D (Vit D) is suggested to be a potential player in nervous system growth and function. This study aimed to assess the impacts of Vit D administration on memory impairment, oxidative damage, and acetylcholinesterase (AchE) overactivity in hypothyroid juvenile rats. The animals were randomly grouped as (1) Control; (2) Hypothyroid; (3) Hypothyroid-Vit D100, and (4) Hypothyroid-Vit D 500. Propylthiouracil (PTU) was added to their drinking water (0.05%) for 6 weeks, and Vit D (100 or 500 IU/kg) treatment was performed daily by gavage. Morris water maze (MWM) and passive avoidance (PA) tests were performed. The brains were removed under deep anesthesia, then the hippocampal and cortical tissues were separated to assess biochemical parameters. Hypothyroidism was significantly associated with learning and memory impairment in MWM and PA tests. Hypothyroidism was also accompanied by an elevation in AChE activity and malondialdehyde (MDA) content and a reduced level of thiol content and superoxide dismutase (SOD) activity in the brain. Treatment with Vit D recovered hypothyroidism-induced cognitive impairment and improved memory performance in MWM and PA tasks. On the other hand, Vit D alleviated AChE activity and MDA level, whereas increased SOD activity and thiol content in the hippocampal and cortical tissues. In conclusion, these outcomes suggest an association between the oral administrations of Vit D and learning and memory improvement of hypothyroid rats, which was accompanied by decreasing AChE activity and brain tissue oxidative damage.

Oxidative Stress in Autism Spectrum Disorder-Current Progress of Mechanisms and Biomarkers

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. Existing data suggest that early diagnosis and intervention can improve ASD outcomes. However, the causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. More mechanisms and biomarkers of autism have been found with the development of advanced technology such as mass spectrometry. Many recent studies have found a link between ASD and elevated oxidative stress, which may play a role in its development. ASD is caused by oxidative stress in several ways, including protein post-translational changes (e.g., carbonylation), abnormal metabolism (e.g., lipid peroxidation), and toxic buildup [e.g., reactive oxygen species (ROS)]. To detect elevated oxidative stress in ASD, various biomarkers have been developed and employed. This article summarizes recent studies about the mechanisms and biomarkers of oxidative stress. Potential biomarkers identified in this study could be used for early diagnosis and evaluation of ASD intervention, as well as to inform and target ASD pharmacological or nutritional treatment interventions.

Hesperidin Preserves Cognitive Functions and Hippocampus Histological Architecture in Albino Wistar Rats Subjected to Stress Through Enhancement of Brain-Derived Neurotrophic Factor

Hesperidin (HSD) is a natural compound with antioxidant potential. On the other hand, chronic stress had been linked to impaired cognitive functions as it affects many neurotransmitters and brain regions such as the hippocampus. The current study was conducted to examine the effect of HSD on learning and memory after chronic mild stress. Albino Wistar rats were subjected to chronic mild stress with HSD administered as supplements. HSD was found to decrease hippocampal amyloid beta and malondialdehyde levels, in addition, to preserve cognitive functions together with preserving hippocampus histological architecture. In conclusion, the present study sheds the light on the potential of HSD to ameliorate the deleterious effects of chronic mild stress on cognitive functions through brain-derived neurotrophic factor enhancement and reduction in Aβ formation in addition to activation of the antioxidant pathway.

Vitamin D3 administration prevents memory deficit and alteration of biochemical parameters induced by unpredictable chronic mild stress in rats

The present study aimed to investigate the effects of vitamin D3 (Vit D) administration on memory function, hippocampal level of amyloid-beta (Aβ), brain-derived neurotrophic factor (BDNF) and oxidative stress status in a rat model of unpredictable chronic mild stress (UCMS). Vit D was intraperitoneally administered at doses of 100, 1000, and 10,000 IU/kg. Animals were subjected to UCMS for a total period of 4 weeks. Memory function was assessed using morris water maze (MWM) and passive avoidance (PA) tests. Biochemical markers were measured to reveal the status of oxidative stress and antioxidant defense system. In addition, the levels of Aβ and BDNF were measured in hippocampal region. In the UCMS group, latency to find the platform was greater and the time spent in target quadrant (MWM test) as well as the latency to enter the dark compartment (PA test), were less than the vehicle group. Hippocampal malondialdehyde (MDA) and Aβ concentrations in the UCMS group were higher than the vehicle group. Hippocampal level of thiol and BDNF plus the activities of catalase and superoxide dismutase (SOD) were reduced in UCMS group compared to the control subjects (i.e. vehicle group). Interestingly, Vit D treatment supplementation reversed the mentioned effects of UCMS. Our findings indicated that Vit D administration improves UCMS-induced impairment of learning and memory through prevention of adverse effects on Aβ, BDNF and oxidative stress parameters.

Protective effects of vitamin D on learning and memory deficit induced by scopolamine in male rats: the roles of brain-derived neurotrophic factor and oxidative stress

The beneficial effects of vitamin D (vit D) on central nervous system disorders have been suggested. In the current research, the protective effects of vit D on learning and memory deficit induced by scopolamine, oxidative stress criteria, brain-derived neurotrophic factor (BDNF), and nitric oxide (NO) in the brain were investigated. Rats were divided into five groups, including (1) Control, (2) Scopolamine (2 mg/kg), (3-5) Scopolamine + Vit D (100, 1000, and 10,000 IU/kg) groups. Vit D administrated for 2 weeks and in the third week scopolamine co-administrated with vit D and behavioral tests, including Morris water maze (MWM) and passive avoidance (PA) tests, were carried out. The cortical and hippocampal tissues were analyzed for BDNF, catalase (CAT), and superoxide dismutase (SOD) activities, thiol content, NO metabolites, and malondialdehyde (MDA) concentration. Scopolamine injection significantly impaired rats' performance on the MWM and PA test. It further enhanced the MDA and nitrite level while decreased thiol content and BDNF levels and SOD and CAT activities in the brain. Administration of both 1000 and 10,000 IU/kg vit D improved cognitive outcome in MWM and PA tests. In addition, vit D elevated thiol content, SOD and CAT activities, and BDNF levels, while reduced nitrite and MDA concentration. Vit D also increased the levels of vit D and calcium in the serum. The results demonstrated that vit D has protective effects on scopolamine-associated learning and memory impairment by improving BDNF levels and attenuating NO and brain tissue oxidative damage.

The protective effect of vitamin supplementation (E and E + C) on passive avoidance learning and memory during exposure to 900 MHz RFW emitted from BTS

Deleterious effects of exposure to electromagnetic radiation on public health have been widely studied. This study was conducted to evaluate the protective effect of vitamin supplementation (E or E + C) on passive avoidance learning (PAL) and memory in rats subjected to 900 MHz radiofrequency waves (RFW). Thirty adult male Sprague-Dawley rats (190 ± 20 g) were randomly divided into six groups as: control I (vehicle), control II (vitamin E 250 mg/kg), control III (vitamin E 100 mg/kg + l-ascorbic acid 200 mg/kg), and three exposed groups to RFW as: sham-exposed, treatment I (vitamin E), and treatment II (vitamin E + C). The duration of exposure was 30 continuous days (4 h/day). The PAL was evaluated on the last day by the shuttle box. Learning and memory of animals demonstrated as the duration of remaining within the light area, which is called the light time (LT). The sham-exposed group showed a significant decrease in LT on the learning, consolidation, and retention days compared to other groups (p < 0.05). Pretreatment with vitamins (E and E + C) could protect PAL against adverse effects of RFW, and the administration of vitamin E + C improved PAL performance in control III compared to control I and treatment II groups (p < 0.05). Administration of vitamin E + C to exposed group (treatment II) caused a significant increase in LT on the learning (p = 0.013), consolidation, and retention (p = 0.009) sessions compared to the treatment group I (vitamin E). Long-term exposure to 900 MHz RFW impaired PAL and memory, and pretreatment of vitamin (E or E + C) prevented these effects, which may be a new potential mechanism against side effects of RFW.

Vitamin C protects against chronic social isolation stress-induced weight gain and depressive-like behavior in adult male rats

Objective. Considering the importance of ghrelin in stress-induced hyperphagia and a role of antioxidants in decreasing body weight, in the present study, the effect of vitamin C (VitC) on ghrelin secretion and food intake following chronic social isolation (CIS) was evaluated in rats.Methods. Thirty two male Wistar rats (200-220g) were randomly divided into: control, VitC, CIS, and CIS + VitC groups. Animals received VitC (500 mg/kg/day)/saline by gavage for 3 weeks. For 24 h cumulative and post 18-20 h fasting food intake, fasting plasma ghrelin level, and body weight were measured. Gastric histopathology was also evaluated.Results. Results showed a marked increase in fasting plasma ghrelin and food intake in stressed rats compared to controls. VitC prevented the increases in stressed rats. Histological assessment indicated a positive effect of VitC on gastric glandular cells compared to control, an effect that might partially be a reason of significant increase of plasma ghrelin levels in VitC rats. Elevated plasma ghrelin in VitC group was even higher than that one in stressed group, whereas there were no significant changes in the food intake. Assessment of the percentage of changes in body weight during 21 days showed a significant increase in stressed rats compared to controls. Vitamin C treatment prevented this increase. Stressed rats also displayed depression-like behavior as indicated by sucrose test, whereas VitC ameliorated it.Conclusions. The data of the present study indicate that VitC may overcome ghrelin-induced hyperphagia and improve the abnormal feeding and depressive behavior in CIS rats.

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.

Modulation of glutamate levels and Na+,K+-ATPase activity contributes to the chrysin memory recovery in hypothyroidism mice

Abnormalities in the thyroid hormones, like in hypothyroidism, are closely related to dementia and Alzheimer's disease demonstrating the main symptom of these disorders: memory deficit. In this study we evaluated the effect of chrysin on deficit spatial and aversive memories and the contribution of glutamatergic, cholinergic pathways and Na⁺, K⁺-ATPase activity on hippocampus and prefrontal cortex in hypothyroid adult female mice C57BL/6. Hypothyroidism was induced by the continuous exposure to 0.1% methimazole (MTZ) in drinking water for 31 days. The exposure to MTZ was associated to low plasma levels of thyroid hormones (TH) compared to the control group on the 32nd. Subsequently, euthyroid and MTZ-induced hypothyroid mice received (intragastrically) either vehicle or chrysin (20 mg/kg) once a day for 28 consecutive days. After treatments mice performed the following behavioral assessments: open-field test (OFT), morris water maze (MWM) and passive avoidance test. Additionally, plasma TH levels were measured again, as well as glutamate levels, Na⁺,K⁺-ATPase and acetylcholinesterase (AChE) activities were analyzed in the hippocampus and prefrontal cortex of mice. Mice with hypothyroidism showed a deficit of spatial and aversive memory and chrysin treatment reversed these deficits. It also reduced the levels of glutamate and decreased Na⁺,K⁺-ATPase activity in both cerebral structures in the hypothyroid mice compared with the euthyroid ones, with the exception of glutamate in the hippocampus, which was a partial reversal. AChE activity was not altered by treatments. Together, our results demonstrate that chrysin normalized hippocampal glutamate levels and Na⁺,K⁺-ATPase activity, which could be involved in the reversal of memory deficit.

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

Abstract. 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.

The effects of aminoguanidine on hippocampal cytokines, amyloid beta, brain-derived neurotrophic factor, memory and oxidative stress status in chronically lipopolysaccharide-treated rats

INTRODUCTION

In the present study, the effects of aminoguanidine (AMG) on hippocampal cytokines, amyloid beta (Aβ), brain-derived neurotrophic factor, oxidative stress status and memory in chronically lipopolysaccharide (LPS) treated rats were investigated.

METHODS

The rats were divided into five groups and were treated: (1) Control (Saline), (2) LPS (1 mg/kg), (3-5) LPS- AMG50, LPS-AMG100, and LPS-AMG150 (AMG 50, 100 and 150 mg/kg 30 min before LPS injection). The treatment started five weeks prior to the behavioral experiments and continued during the behavioral tests (LPS injection two hours before each behavioral evaluation). Finally, the tissue was removed for biochemical measurements.

RESULTS

The escape latency in Morris water maze test and the latency to enter the dark compartment in passive avoidance test in LPS group were significantly greater than the control group (P < 0.001), while, in LPS-AMG 100 and LPS-AMG150 groups they were less than LPS group (P < 0.001). Malondialdehyde (MDA), NO metabolites of hippocampal and cortical tissues and interleukin-6 (IL-6), Aβ and tumor necrosis factor-α (TNFα) concentration in the hippocampus of LPS group were higher than control group (P < 0.001-P < 0.05). However, in LPS-AMG 100 and LPS-AMG150 group they were lower than LPS group (P < 0.001-P < 0.05). The thiol content and the activities of catalase (CAT) and superoxide dismutase (SOD) in both cortical and hippocampal tissues of LPS group were reduced compared to the control group (P < 0.001-P < 0.05). These factors enhanced in LPS-AMG 100 and LPS-AMG150 groups compared to LPS (P < 0.001-P < 0.05). The hippocampal content of brain-derived neurotrophic factor (BDNF) in LPS group was significantly lower compared to the control group (P < 0.001). All treated groups had higher BDNF content in comparison to LPS group (P < 0.01-P < 0.001).

CONCLUSION

The findings indicated that the protective effects of AMG against LPS-induced memory were accompanied by decreasing of inflammatory cytokines, Aβ, oxidative stress and increasing of anti-inflammatory mediators and BDNF.

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.

Feeding Vitamin C during Neonatal and Juvenile Growth Improves Learning and Memory of Rats

We investigated the effects of feeding vitamin C (Vit C) during neonatal and juvenile growth on learning and memory of rats. Rats after delivery were randomly divided into four groups and treated. Group 1, control group, received normal drinking water. Groups 2-4 received Vit C 10, 100, and 500 mg/kg, respectively, from the first day. After 8 weeks, 10 male offspring of each group were randomly selected and tested in the Morris water maze (MWM) and passive avoidance (PA) tests. Finally, the brains were removed for biochemical measurement. In MWM, 10-500 mg/kg Vit C reduced the latency and traveled distance and increased time spent in the target quadrant. In PA, 10 and 100 mg/kg of Vit C increased the latency; 10-500 mg/kg of Vit C decreased the malondialdehyde (MDA) in the brain tissues and increased thiol and catalase (CAT) activity compared to the control group. We showed that feeding rats Vit C during neonatal and juvenile growth has positive effects on learning and memory.

The effects of vitamin E on brain derived neurotrophic factor, tissues oxidative damage and learning and memory of juvenile hypothyroid rats

The effects of vitamin E (Vit E) on brain derived neurotrophic factor (BDNF) and brain tissues oxidative damage as well as on learning and memory impairments in juvenile hypothyroid rats were examined. The rats were grouped as: (1) Control; (2) Propylthiouracil (PTU); (3) PTU-Vit E and (4) Vit E. PTU was added to their drinking water (0.05%) during 6 weeks. Vit E (20 mg/kg) was daily injected (IP). Morris water maze (MWM) and passive avoidance (PA) were carried out. The animals were deeply anesthetized and the brain tissues were removed for biochemical measurements. PTU increased the escape latency and traveled path in MWM (P < 0.001). It also shortened the latency to enter the dark compartment of PA as well as the time spent in the target quadrant in probe trial of MWM (P < 0.01-P < 0.001). All the effects of PTU were reversed by Vit E (P < 0.01-P < 0.001). PTU administration attenuated thiol and BDNF content as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in the brain tissues while increased molondialdehyde (MDA). Moreover, Vit E improved BDNF, thiol, SOD and CAT while diminished MDA. The results of the present study showed that Vit E improved BDNF and prevented from brain tissues oxidative damage as well as learning and memory impairments in juvenile hypothyroid rats.