Effect of pretreatment with intracerebroventricular injection of minocycline on morphine‐induced memory impairment in passive avoidance test: Role of P‐ CREB and c‐Fos expression in the dorsal hippocampus and basolateral amygdala regions

Changes in the hippocampal level of tau but not beta-amyloid may mediate anxiety-like behavior improvement ensuing from exercise in diabetic female rats

BACKGROUND

In the present study, we investigated the effect of high-intensity interval training (HIIT) on cognitive behaviors in female rats with a high-fat diet + streptozotocin (STZ)-induced type 2 diabetes.

METHODS

Twenty-four female rats were divided into four groups randomly (n = 6): control (C), control + exercise (Co + EX), diabetes mellitus (type 2) (T2D), and diabetes mellitus + exercise (T2D + EX). Diabetes was induced by a two-month high-fat diet and a single dose of STZ (35 mg/kg) in the T2D and T2D + EX groups. The Co + EX and T2D + EX groups performed HIIT for eight weeks (five sessions per week, running on a treadmill at 80-100% of VMax, 4-10 intervals). Elevated plus maze (EPM) and open field test (OFT) were used for assessing anxiety-like behaviors, and passive avoidance test (PAT) and Morris water maze (MWM) were applied for evaluating learning and memory. The hippocampal levels of beta-amyloid (Aβ) and Tau were also assessed using Western blot.

RESULTS

An increase in fasting blood glucose (FBG), hippocampal level of Tau, and a decrease in the percentage of open arm time (%OAT) as an index of anxiety-like behavior were seen in the female diabetic rats which could be reversed by HIIT. In addition, T2D led to a significant decrease in rearing and grooming in the OFT. No significant difference among groups was seen for the latency time in the PAT and learning and memory in the MWM.

CONCLUSIONS

HIIT could improve anxiety-like behavior at least in part through changes in hippocampal levels of Tau.

Diosgenin normalization of disrupted behavioral and central neurochemical activity after single prolonged stress

Introduction: Post-traumatic stress disorder (PTSD) is a chronic mental illness triggered by traumatic experiences such as wars, natural disasters, or catastrophes, and it is characterized by anxiety, depression and cognitive impairment. Diosgenin is a steroidal sapogenin with known neuroprotective and antioxidant properties. This study aimed to assess the pharmacological potential of diosgenin in a single prolonged stress (SPS) model of PTSD, plus other behavioral models along with any consequent alterations in brain neurochemistry in male mice. Methodology: SPS was induced by restraining animals for 2 h, followed by 20 min of forced swim, recuperation for 15 min, and finally, exposure to ether to induce anesthesia. The SPS-exposed animals were treated with diosgenin (20, 40, and 60 mg/kg) and compared with the positive controls, fluoxetine or donepezil, then they were observed for any changes in anxiety/depression-like behaviors, and cognitive impairment. After behavioral screening, postmortem serotonin, noradrenaline, dopamine, vitamin C, adenosine and its metabolites inosine and hypoxanthine were quantified in the frontal cortex, hippocampus, and striatum by high-performance liquid chromatography. Additionally, animal serum was screened for changes in corticosterone levels. Results: The results showed that diosgenin reversed anxiety- and depression-like behaviors, and ameliorated cognitive impairment in a dose-dependent manner. Additionally, diosgenin restored monoamine and vitamin C levels dose-dependently and modulated adenosine and its metabolites in the brain regions. Diosgenin also reinstated otherwise increased serum corticosterone levels in SPS mice. Conclusion: The findings suggest that diosgenin may be a potential candidate for improving symptoms of PTSD.

Fisetin provides neuroprotection in pentylenetetrazole-induced cognition impairment by upregulating CREB/BDNF

OBJECTIVES

Fisetin is a flavonoid molecule known to be neuroprotective by its multiple mechanisms. The present study was designed to explore the effect of fisetin in the pentylenetetrazole (PTZ) kindling-induced cognitive dysfunction in mice.

METHODS

Kindling was established by the intraperitoneal administration of PTZ in a subconvulsive dose (25 mg/kg). Mice were administered fisetin (5, 10, and 20 mg/kg, p.o.) to study its probable cognition-enhancing effect. The kindled mice were evaluated for cognition using behavioral tests-elevated plus maze and passive avoidance response. Then, the oxidative stress markers, gene expressions and neurotransmitters levels were estimated in the hippocampus and cortex of mice.

RESULTS

Passive avoidance response and elevated plus maze paradigms showed that fisetin administration improved the cognitive function in kindled mice. The increased levels of lipid peroxidation and protein carbonyl were modulated upon fisetin administration through increasing the levels of antioxidants (reduced glutathione, glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase) in the hippocampus and cortex of kindled mice. Upregulated gene expressions of cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) were observed in the hippocampus and cortex of fisetin-administered mice which play a crucial role in cognitive function. Furthermore, alterations of neurotransmitter levels (dopamine, GABA, and glutamate) and acetylcholinesterase (AchE) were ameliorated by fisetin administration in the hippocampus and cortex of kindled mice.

CONCLUSION

Our findings suggest a therapeutic potential of fisetin against cognitive dysfunction associated with PTZ-induced kindling.

Ameliorating age-dependent effects of resveratrol on VPA-induced social impairments and anxiety-like behaviors in a rat model of Neurodevelopmental Disorder

Although anxiety disorders, as well as difficulties in social interaction, are documented in children with autism spectrum disorder (ASD) as a neurodevelopmental disorder, the effectiveness of potential therapeutic procedures considering age and sex differences is under serious discussion. The present study aimed to investigate the effect of resveratrol (RSV) on anxiety-like behaviors and social interaction in juvenile and adult rats of both sex in a valproic acid (VPA)-induced autistic-like model. Prenatal exposure to VPA was associated with increased anxiety, also causing a significant reduction in social interaction in juvenile male subjects. Further administration of RSV attenuated VPA-induced anxiety symptoms in both sexes of adult animals and significantly increased the sociability index in male and female juvenile rats. Taken together, it can be concluded that treatment with RSV can attenuate some of the harsh effects of VPA. This treatment was especially effective on anxiety-like traits in adult subjects of both sexes regarding their performance in open field and EPM. We encourage future research to consider the sex and age-specific mechanisms behind the RSV treatment in the prenatal VPA model of autism.

High-Intensity Interval Training-Induced Hippocampal Molecular Changes Associated with Improvement in Anxiety-like Behavior but Not Cognitive Function in Rats with Type 2 Diabetes

(1) Background: Exercise exerts many neuroprotective effects in diabetes-induced brain disorders. In this study, we investigated the effect of high-intensity interval training (HIIT) on brain molecular changes and cognitive and anxiety-like behaviors in rats with type 2 diabetes. (2) Methods: Twenty-eight adult male rats were divided into four groups (n = 7): control (C), exercise + control (C+EX), diabetes (DM), and diabetes + exercise (DM+EX). Diabetes was induced using a two-month high-fat diet and a single dose of streptozotocin (35 mg/kg) in the DM and DM+EX groups. After, the C+EX and DM+EX groups performed HIIT for eight weeks (five sessions per week, running at 80-100% of VMax, 4-10 intervals) on a motorized treadmill. Then, the elevated plus maze (EPM) and open field test (OFT) were performed to evaluate anxiety-like behaviors. The Morris water maze (MWM) and shuttle box were used to assess cognitive function. The hippocampal levels of beta-amyloid and tau protein were also assessed using Western blot. (3) Results: The hippocampal levels of beta-amyloid and tau protein were increased in the DM group, but HIIT restored these changes. While diabetes led to a significant decrease in open arm time percentage (%OAT) and open arm enters percentage (%OAE) in the EPM, indicating anxiety-like behavior, HIIT restored them. In the OFT, grooming was decreased in diabetic rats, which was restored by HIIT. No significant difference between groups was seen in the latency time in the shuttle box or for learning and memory in the MWM. (4) Conclusions: HIIT-induced hippocampal molecular changes were associated with anxiety-like behavior improvement but not cognitive function in rats with type 2 diabetes.

Combination therapy with interferon-gamma as a potential therapeutic medicine in rat's glioblastoma: A multi-mechanism evaluation

BACKGROUND

This study assessed the effects of single or combined administration of temozolomide (TMZ) and interferon-gamma (IFN-ᵞ) on anxiety-like behaviors, balance disorders, learning and memory, TNF-α, IL-10, some oxidant and antioxidants factors with investigating the toll-like receptor-4 (TLR4) and p-CREB signaling pathway in C6-induced glioblastoma of rats.

METHODS

40 male Sprague-Dawley rats bearing intra-caudate nucleus (CN) culture medium or C6 inoculation were randomly divided into five groups as follows: Sham, Tumor, TMZ, IFN-ᵞ and a TMZ + IFN-ᵞ combination. The open-field test (OFT), elevated plus maze (EPM), rotarod, and passive avoidance test (PAT) were done on days 14-17. On day 17 after tumor implantation, brain tissues were extracted for histopathological evaluation. TNF-α, IL-10, SOD, GPX, TAC, MDA, the protein level of TLR4 and p-CREB was measured.

RESULTS

Combination therapy inhibited the growth of the tumor. Treatment groups alleviated tumor-induced anxiety-like behaviors and improved imbalance and memory impairment. SOD, GPX, and TAC decreased in the tumor group. The combination group augmented GPX and TAC. MDA decreased in treatment groups. TMZ, IFN-ᵞ reduced tumor-increased TNF-α and IL-10 level. The combination group declined TNF-α level in serum and IL-10 level in serum and brain. Glioblastoma induced significant upregulation of TLR4 and p-CREB in the brain which inhibited by IFN-ᵞ and TMZ+ IFN-ᵞ.

CONCLUSION

The beneficial effects of TMZ, IFN-ᵞ, and TMZ+ IFN-ᵞ on neurocognitive functioning of rats with C6-induced glioblastoma may be mediated via modulating oxidative stress, reduced cytokines, and the downregulation of expression of TLR4 and p-CREB. Combination treatment appears to be more effective than single treatment.

Mouse Model of Weak Depression Exhibiting Suppressed cAMP Signaling in the Amygdala, Lower Lipid Catabolism in Liver, and Correlated Gut Microbiota

To establish a mouse model of weak depression, we raised 6-week-old C57BL/6N mice in single (SH) or group housing (GH) conditions for 2 weeks. The SH group showed less social interaction with stranger mice, learning disability in behavioral tests, and lower plasma corticosterone levels. The cecal microbiota of the SH group showed significant segregation from the GH group in the principal coordinate analysis (PCoA). Transcriptome analysis of the amygdala and liver detected multiple differentially expressed genes (DEGs). In the amygdala of SH mice, suppression of the cyclic adenine monophosphate (cAMP) signal was predicted and confirmed by the reduced immunoreactivity of phosphorylated cAMP-responsive element-binding protein. In the liver of SH mice, downregulation of beta-oxidation was predicted. Interestingly, the expression levels of over 100 DEGs showed a significant correlation with the occupancy of two bacterial genera, Lactobacillus (Lactobacillaceae) and Anaerostipes (Lachnospiraceae). These bacteria-correlated DEGs included JunB, the downstream component of cAMP signaling in the amygdala, and carnitine palmitoyltransferase 1A (Cpt1a), a key enzyme of beta-oxidation in the liver. This trans-omical analysis also suggested that nicotinamide adenine dinucleotide (NAD) synthesis in the liver may be linked to the occupancy of Lactobacillus through the regulation of nicotinamide phosphoribosyltransferase (NAMPT) and kynureninase (KYNU) genes. Our results suggested that SH condition along with the presence of correlated bacteria species causes weak depression phenotype in young mice and provides a suitable model to study food ingredient that is able to cure weak depression.

The Effect of Oral Mucosal Mesenchymal Stem Cells on Pathological and Long-Term Outcomes in Experimental Traumatic Brain Injury

Background

Neuroprotective effects of stem cells have been shown in some neurologic diseases. In this study, the effect of oral mucosal mesenchymal stem cells (OMSCs) on traumatic brain injury (TBI) was evaluated in long term.

Materials and Methods

TBI was induced by Marmarou's method. The number of 2 × 10⁶ OMSCs was intravenously injected 1 and 24 h after the injury. Brain edema and pathological outcome were assessed at 24 h and 21 days after the injury. Besides, long-term neurological, motor, and cognitive outcomes were evaluated at days 3, 7, 14, and 21 after the injury.

Results

OMSCs administration could significantly inhibit microglia proliferation, and reduce brain edema and neuronal damage, at 24 h and 21 days after the injury. Neurological function improvement was observed in the times evaluated in OMSCs group. Cognitive and motor function dysfunction and anxiety-like behavior were prevented especially at 14 and 21 days after the injury in the treatment group.

Conclusion

According to the results of this study, OMSCs administration after TBI reduced brain edema and neuronal damage, improved neurologic outcome, and prevented memory and motor impairments and anxiety-like behavior in long term.

The effect of early handling on anxiety-like behaviors of rats exposed to valproic acid pre-and post-natally

INTRODUCTION

Autism spectrum disorder (ASD) is a complex, behaviorally defined disorder of the immature brain as a result of genetic and environmental risk factors, such as prenatal exposure to valproic acid (VPA). This syndrome is known for its high prevalence. On the other hand, postnatal manipulations have been shown to affect brain development, cortical neuroscience, and pituitary-adrenal activity. In early handling (EH) procedure, pups are removed from their mother on a daily basis from birth to lactation, are physically touched, and exposed to the (a) new environment. In the present study, the effect of EH on anxiety-like behaviors in rats exposed pre- and post-natally to valproic acid was investigated.

METHODS

Pregnant Wistar rats were randomly separated into six groups which are prenatal saline, Prenatal VPA, Prenatal VPA + EH and postnatal saline, Postnatal VPA, Postnatal VPA + EH. VPA administration was performed either on ED12.5 (600 mg/kg, i.p.) or PD 2-4 (400 mg/kg, s.c.). In the groups receiving EH, pups underwent physical handling from PD 1 to 21. On postnatal day 21 all offspring were weaned and the behavioral tests were performed on 30 and 31 days of age. Elevated plus maze and open field tests were used to investigate anxiety-like behaviors.

RESULTS

The results revealed that intraperitoneal injection of valrpoic acid (600 mg.kg) during pregnancy significantly reduced OAT% in males (p < 0.01) and females in a non-significant manner (p > 0.05). In comparison, rearing counts of prenatal VPA groups significantly increased in female sex (p < 0.05) in the EPM test. Following postnatal VPA administration (400 mg/kg), decrease in the time spent in central zone occurred in female rats in the open filed (p < 0.05), as well as a significant increase in the number of grooming of the male sex (p < 0.05). Applying Early Handling to male and female Wistar rats receiving prenatal VPA significantly reversed the OAT% fall (p < 0.05). EH in postnatally VPA exposed animals significantly decreased the OAT% and OAE% criteria, while increasing the locomotor activity of the female sex (p < 0.05). Compared with the postnatal VPA group, no significant change was reported in the EPM performance of postnatal VPA + EH group in neither of sexes (p > 0.05).

CONCLUSION

The findings of this study suggest that injections of valproic acid during pregnancy lead to anxiety-like behaviors in male offspring, which EH can improve (attenuate) to some extent. VPA injections on the second to the fourth day of infancy did not have a profound effect on anxiety level. Further behavioral studies need to be performed using other devices to investigate anxiety-like behaviors and to determine the mechanisms involved in these behaviors.

The effect of GABA-B receptors in the basolateral amygdala on passive avoidance memory impairment induced by MK-801 in rats

MK-801 (dizocilpine) is a potent non-competitive N-methyl-[D]-aspartate (NMDA) receptor antagonist that affects cognitive function, learning, and memory. As we know, NMDA receptors are significantly involved in memory function, as well as GABA (Gamma-Aminobutyric acid) receptors. In this study, we aimed to discover the effect of GABA-B receptors in the basolateral amygdala (BLA) on MK-801-induced memory impairment. We used 160 male Wistar rats. The shuttle box was used to evaluate passive avoidance memory and locomotion apparatus was used to evaluate locomotor activity. MK-801 (0.125, 0.25, and 0.5 μg/rat), baclofen (GABA-B agonist, 0.0001, 0.001, and 0.01 μg/rat) and phaclofen (GABA-B antagonist, 0.0001, 0.001, and 0.01 μg/rat) were injected intra-BLA, after the training. The results showed that MK-801 at the dose of 0.5 μg/rat, baclofen at the doses of 0.001 and 0.01 μg/rat, and phaclofen at the doses of 0.001 and 0.01 μg/rat, impaired passive avoidance memory. Locomotor activity did not alter in all groups. Furthermore, the subthreshold dose of both baclofen (0.0001 μg/rat) and phaclofen (0.0001 μg/rat) restored the impairment effect of MK-801 (0.5 μg/rat) on memory. Also, both baclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 μg/rat) and phaclofen (0.0001 μg/rat) potentiated the impairment effect of MK-801 (0.125 and 0.25 μg/rat) on passive avoidance memory. In conclusion, our results indicated that BLA GABA-B receptors can alter the effect of NMDA inactivation on passive avoidance memory.

HDAC2 hyperexpression alters hippocampal neuronal transcription and microglial activity in neuroinflammation-induced cognitive dysfunction

Background

Inflammation can induce cognitive dysfunction in patients who undergo surgery. Previous studies have demonstrated that both acute peripheral inflammation and anaesthetic insults, especially isoflurane (ISO), are risk factors for memory impairment. Few studies are currently investigating the role of ISO under acute peri-inflammatory conditions, and it is difficult to predict whether ISO can aggravate inflammation-induced cognitive deficits. HDACs, which are essential for learning, participate in the deacetylation of lysine residues and the regulation of gene transcription. However, the cell-specific mechanism of HDACs in inflammation-induced cognitive impairment remains unknown.

Methods

Three-month-old C57BL/6 mice were treated with single versus combined exposure to LPS injected intraperitoneally (i.p.) to simulate acute abdominal inflammation and isoflurane to investigate the role of anaesthesia and acute peripheral inflammation in cognitive impairment. Behavioural tests, Western blotting, ELISA, immunofluorescence, qRT-PCR, and ChIP assays were performed to detect memory, the expressions of inflammatory cytokines, HDAC2, BDNF, c-Fos, acetyl-H3, microglial activity, Bdnf mRNA, c-fos mRNA, and Bdnf and c-fos transcription in the hippocampus.

Results

LPS, but not isoflurane, induced neuroinflammation-induced memory impairment and reduced histone acetylation by upregulating histone deacetylase 2 (HDAC2) in dorsal hippocampal CaMKII⁺ neurons. The hyperexpression of HDAC2 in neurons was mediated by the activation of microglia. The decreased level of histone acetylation suppressed the transcription of Bdnf and c-fos and the expressions of BDNF and c-Fos, which subsequently impaired memory. The adeno-associated virus ShHdac2, which suppresses Hdac2 after injection into the dorsal hippocampus, reversed microglial activation, hippocampal glutamatergic BDNF and c-Fos expressions, and memory deficits.

Conclusions

Reversing HDAC2 in hippocampal CaMKII⁺ neurons exert a neuroprotective effect against neuroinflammation-induced memory deficits.