Synergistic but not additive effect between ACPA and lithium in the dorsal hippocampal region on spatial learning and memory in rats: Isobolographic analyses

The effect of olanzapine on spatial memory impairment, depressive-like behavior, pain perception, and BDNF and synaptophysin expression following childhood chronic unpredictable mild stress in adult male and female rats

Chronic unpredictable mild stress (CUMS) method has been introduced as a rodent model of depression. On the other hand, olanzapine, as an antipsychotic, can induce antidepressant and antipsychotic effects. Also, olanzapine may improve cognitive functions. Both CUMS and olanzapine can also affect the expression level of brain-derived neurotrophic factor (BDNF) and synaptophysin, the molecular factors involved in synaptic function, and learning and memory. In this study, we investigated the effect of olanzapine on locomotor activity (using open field test), pain threshold (using hot plate), depressive-like behavior (using forced swim test), spatial learning and memory (using Morris water maze), and BDNF and synaptophysin hippocampal expression (using real-time PCR) in both male and female CUMS rats. CUMS was performed for three consecutive weeks. Olanzapine was also injected intraperitoneally at the dose of 5 mg/kg. Our data showed that olanzapine can reverse the effects of CUMS on behavioral functions and BDNF and synaptophysin expression levels in the hippocampus of both males and females. It was also shown that olanzapine effects on spatial memory, pain perception, and BDNF and synaptophysin level were stronger in females than males. In conclusion, we suggested that the therapeutic effects of olanzapine in CUMS rats may be closely related to the function of BDNF and synaptophysin. Also, the therapeutic effects of olanzapine may be stronger in females. Therefore, and for the first time, we showed that there may be a sex difference in the effects of olanzapine on behavioral and molecular changes following CUMS.

The Interaction Effect of Sleep Deprivation and Treadmill Exercise in Various Durations on Spatial Memory with Respect to the Oxidative Status of Rats

Sleep deprivation (SD) has deleterious effects on cognitive functions including learning and memory. However, some studies have shown that SD can improve cognitive functions. Interestingly, treadmill exercise has both impairment and improvement effects on memory function. In this study, we aimed to investigate the effect of SD for 4 (short-term) and 24 (long-term) hours, and two protocols of treadmill exercise (mild short-term and moderate long-term) on spatial memory performance, and oxidative and antioxidant markers in the serum of rats. Morris Water Maze apparatus was used to assess spatial memory performance. Also, SD was done using gentle handling method. In addition, the serum level of catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) was measured. The results showed that 24 h SD (but not 4 h) had negative effect on spatial memory performance, decreased SOD, CAT, and GSH-Px level, and increased MDA level. Long-term moderate (but not short-term mild) treadmill exercise had also negative effect on spatial memory performance, decreased SOD, CAT, and GSH-Px level, and increased MDA level. Interestingly, both protocols of treadmill exercise reversed spatial memory impairment and oxidative stress induced by 24 h SD. In conclusion, it seems that SD and treadmill exercise interact with each other, and moderate long-term exercise can reverse the negative effects of long-term SD on memory and oxidative status; although, it disrupted memory function and increased oxidative stress by itself.

Dose-dependent manner of luteolin in the modulation of spatial memory with respect to the hippocampal level of HSP70 and HSP90 in sleep-deprived rats

Sleep deprivation (SD) induces a variety of deleterious effects on different cognitive functions such as memory. Elevated neuroinflammation, oxidative stress, and apoptosis, and decreased synaptic plasticity and antioxidant capacity are involved in the deleterious effects of SD on memory. On the other hand, luteolin (a flavonoid compound) has antioxidant, neuroprotective, and anti-inflammatory properties. Also, Heat shock protein 70 (HSP70) and Heat shock protein 90 (HSP90) can be involved in modulating memory. In this study, we aimed to assess the effects of SD and luteolin on spatial learning and memory using Morris Water Maze apparatus in rats, with respect to the level of HSP70 and HSP90 in the hippocampus. Luteolin was injected intracerebroventricular (i.c.v.) at the doses of 0.5, 1, and 2 µg/rat. The results showed that SD impaired spatial memory, while luteolin dose-dependently restored SD-induced spatial memory impairment. SD increased the expression level of HSP90 in the hippocampus, whereas luteolin dose-dependently reversed the effect of SD. Furthermore, SD decreased the expression level of HSP70 protein in the hippocampus, while luteolin dose-dependently reversed the effect of SD. In conclusion, HSP70 and HSP90 may be involved in the deleterious effect of SD on memory, and in the improvement effect of luteolin on memory. This is a novel study reporting novel data and we suggest further detailed studies to better understand the interactions between SD, luteolin, and Heat shock proteins.

The Effect of NeuroAid (MLC901) on Cholestasis-Induced Spatial Memory Impairment with Respect to the Expression of BAX, BCL-2, BAD, PGC-1α and TFAM Genes in the Hippocampus of Male Wistar Rats

Cholestasis is a bile flow reduction that is induced following Bile Duct Ligation (BDL). Cholestasis impairs memory and induces apoptosis. Apoptosis consists of two pathways: intrinsic and extrinsic. The intrinsic pathway is modulated by BCL-2 (B cell lymphoma-2) family proteins. BCL-2 (a pro-survival BCL-2 protein) has anti-apoptotic effect, while BAD (BCL-2-associated death) and BAX (BCL-2-associated X), the other members of BCL-2 family have pro-apoptotic effect. Furthermore, TFAM (mitochondrial transcriptional factor A) is involved in transcription and maintenance of mitochondrial DNA and PGC-1α (peroxisome proliferator-activated receptor γ coactivator-1α) is a master regulator of mitochondrial biogenesis. On the other hand, NeuroAid is a Traditional Chinese Medicine with neuroprotective and anti-apoptosis effects. In this study, we evaluated the effect of cholestasis on spatial memory and expression of BCL-2, BAD, BAX, TFAM, and PGC-1α in the hippocampus of rats. Additionally, we assessed the effect of NeuroAid on cholestasis-induced cognitive and genetic alterations. Cholestasis was induced by BDL surgery and NeuroAid was injected intraperitoneal at the dose of 0.4 mg/kg. Furthermore, spatial memory was evaluated using Morris Water Maze (MWM) apparatus. The results showed cholestasis impaired spatial memory, increased the expression of BAD and BAX, decreased the expression of TFAM and PGC-1α, and did not alter the expression of BCL-2. Also, NeuroAid decreased the expression of BAD and BAX and increased the expression of TFAM, PGC-1α, and BCL-2. In conclusion, cholestasis impaired spatial memory and increased the expression of pro-apoptotic genes. Also, cholestasis decreased the expression of TFAM and PGC-1α. Interestingly, NeuroAid restored the effects of cholestasis.

Effects of Treadmill Exercise on the Expression Level of BAX, BAD, BCL-2, BCL-XL, TFAM, and PGC-1α in the Hippocampus of Thimerosal-Treated Rats

Thimerosal (THIM) induces neurotoxic changes including neuronal death and releases apoptosis inducing factors from mitochondria to cytosol. THIM alters the expression level of factors involved in apoptosis. On the other hand, the anti-apoptotic effects of exercise have been reported. In this study, we aimed to discover the effect of three protocols of treadmill exercise on the expression level of mitochondrial transcription factor A (TFAM), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), BCL-2-associated death (BAD), BCL-2-associated X (BAX), BCL-XL, and BCL-2 (a pro-survival BCL-2 protein) in the hippocampus of control and THIM-exposed rats. Male Wistar rats were used in this research. Real-time PCR was applied to assess genes expression. The results showed that THIM increased the expression of pro-apoptotic factors (BAD and BAX), decreased the expression of anti-apoptotic factors (BCL-2 and BCL-XL), and decreased the expression of factors involved in mitochondrial biogenesis (TFAM and PGC-1α). Treadmill exercise protocols reversed the effect of THIM on all genes. In addition, treadmill exercise protocols decreased the expression of BAD and BAX, increased the expression of BCL-2, and increased the expression of TFAM and PGC-1α in control rats. In conclusion, THIM induced a pro-apoptotic effect and disturbed mitochondrial biogenesis and stability, whereas treadmill exercise reversed these effects.

The effect of alpha-2 adrenergic receptors on memory retention deficit induced by rapid eye movement sleep deprivation

Objective(s):

Evidence shows that sleep deprivation (SD) disrupts the formation of hippocampus-related memories. Moreover, α2 adrenergic receptors that are wildly expressed in the CA1 hippocampal region have a significant role in modulating both sleep and memory formation. In the present research, we wanted to investigate the effect of stimulation and blockage of CA1 α2 adrenergic receptors by clonidine (an agonist of α2 adrenergic receptor) and yohimbine (an antagonist of α2 adrenergic receptor), respectively, on memory retention impairment induced by REM SD (RSD) in rats.

Materials and Methods:

Multiple platform apparatus were used to induce RSD, and the passive avoidance task was used to assess memory consolidation. Clonidine and yohimbine were injected intra-CA1.

Results:

The results showed that RSD (for 24 and 36, but not 12 hr) decreased memory retention, with no effect on locomotion. Post-training intra-CA1 infusion of a subthreshold dose of yohimbine (0.001 μg/rat) did not alter, while clonidine (0.1 μg/rat) restored memory retention impairment induced by RSD (24 and 36 hr). Also, none of the interventions did not influence locomotor activity.

Conclusion:

Our data strongly showed that CA1 α2 adrenergic receptors have a critical role in RSD-induced memory retention impairment.

The effect of alpha lipoic acid on passive avoidance and social interaction memory, pain perception, and locomotor activity in REM sleep-deprived rats

BACKGROUND

Evidence shows the vital role of sleep in the modulation of cognitive functions. Sleep deprivation (SD) can disrupt learning and memory processes. SD also affects pain perception and locomotor activity. Furthermore, alpha lipoic acid (ALA) may induce antioxidant and neuroprotective effects. ALA affects memory processes, pain subthreshold, and locomotor activity. The goal of the present study was to investigate the effect of REM (rapid-eye movement) SD and ALA on social and passive avoidance memory, locomotor activity, and pain perception.

METHODS

Multiple-platform apparatus was used to induce REM SD for 24 h. Three-chamber paradigm test, the shuttle box, locomotion apparatus, and hot plate were used to assess social interaction memory, passive avoidance memory, locomotor activity, and pain perception, respectively. ALA was injected intraperitoneally at the doses of 35 and 70 mg/kg.

RESULTS

24 h REM SD impaired both types of memory. In addition, ALA (35 mg/kg) reversed REM SD-induced memory impairments. However, ALA (70 mg/kg) impaired social memory with no effect on REM SD-induced memory impairments. ALA (70 mg/kg) also decreased pain subthreshold in REM SD rats.

CONCLUSION

REM SD impairs social interaction and passive avoidance memory. Furthermore, ALA may exhibit a dose-dependent manner in some cognitive tasks. ALA can induce a therapeutic effect at one dose, and an impairment effect at another dose (lower or higher), while the cognitive task and the conditions are equal.