The role of CA1 α-adrenoceptor on scopolamine induced memory impairment in male rats

Introduction: Similarities in the memory impairment between Alzheimer patients and scopolamine treated animals have been reported. In the present study, the possible role of α-adrenergic receptors of the dorsal hippocampus on scopolamine state-dependent memory in adult male Wistar rats was evaluated. Methods: The animals were bilaterally implanted with chronic cannulae in the CA1 regions of the dorsal hippocampus, trained in a step-through type inhibitory avoidance task, and tested 24 h after training to measure step-through latency. Results: Post-training intra-CA1 administration of scopolamine (0.5 and 2μg/rat) dose-dependently reduced the step-through latency, showing an amnestic response. Amnesia produced by post-training scopolamine (2 μg/rat) was reversed by pre-test administration of the scopolamine (0.5 and 2 μg/rat) that is due to a state-dependent effect. Pre-test intra-CA1 injection of α1-adrenoceptor agonist, phenylephrine (0.25, 0.5 μg/rat) in the dose range that we used, could not affect memory impairment induced by post-training injection of scopolamine (2 μg/rat). However intra-CA1 pretest injection of α2-adrenoceptor agonist, clonidine (0.5 μg/rat) improved post-training scopolamine (2 μg/rat) intra-CA1 injection induced retrieval impairment. Furthermore, pre-test intra-CA1 microinjection of phenylephrine (0.25 and 0.5 μg/rat) or clonidine (0.25 and 0.5 μg/rat) with an ineffective dose of scopolamine (0.25 μg/rat), synergistically improved memory performance impaired by post-training scopolamine (2 μg/rat). Our results also showed that, pre-test injection of α1-receptor antagonist prazosin (1, 2 μg/rat) or α2-receptors antagonist yohimbine (1, 2 μg/rat) before effective dose of scopolamine (2 μg/rat) prevented the improvement of memory by pre-test scopolamine. Conclusion: These results suggest that α1- and α2-adrenergic receptors of the dorsal hippocampal CA1 region may play an important role in scopolamine-induced amnesia and scopolamine state-dependent memory

An overview of cognitive aspects of β-carbolines

    Mind-altering drugs, especially plants, have fascinated human and always occupied man’s attention .Among the plants used by humans, those able to alter the mind and the mood have drawn special consideration. Actually, due to their amazing effects, these drugs, have occupied much of the researchers’ time and efforts towards attempts to understand their mechanism, and, hence, to understand human thoughts, behavior, cognitive aspects, sensations and etc. The fact is plants could have beneficial properties to treat mental disease and have some effects on cognitive function. Now we know that plants by originating directly from nature are not less toxic than synthetic drugs. The manner of poisoning with plants can be divided into unintentional or intentional ingestion of plant material and substance abuse. This review article deals with β-carboline, which has effect on CNS

The involvement of hippocampal CA3 TRP channels in anxiety and avoidance memory consolidation in rats tested in elevated plus maze

    In the current study, we assessed the role of transient receptor potential (TRP) channels on avoidance memory and anxiety states in CA3 area of the hippocampus. We explored the anxiety and avoidance memory states using test-retest protocol in the elevated plus maze to understand whether TRP channels can affect the above mentioned states in CA3 area. To investigate the consolidation phase of memory, the drugs were injected into the CA3 region before the test. Our data showed that the application of SKF-96365 did not alter anxiety-like behaviors but induced avoidance memory impairment. It was revealed that CA3 TRP channels could affect the avoidance memory consolidation and their role must be considered in future research

The effect of crocin on total sleep-deprivation induced amnesia in male Wistar rats

Introduction: In recent years, Crocin has been used for its pharmacological functions, such as memory and learning enhancement. The aim of the present study was to assess the effect of Crocin on total sleep deprivation (TSD)-induced amnesia in male Wistar rats. Materials and Methods: The water box apparatus was used to induce sleep deprivation followed by Y- maze task as an index of learning and memory (the percentage of time in the novel arm during the retention phase was reported as an index of memory performances). The rats were divided into 12 groups, 8 rats in each group, including four control groups, four sham groups, and four TSD groups. Each group received saline and Crocin at doses of 1, 5 or 15 mg/kg twice a day. Results: The findings revealed that TSD for 24 h impaired memory function. In addition, the intra-peritoneal injection of Crocin at all doses (1, 5 and 15 mg/kg) did not change the percentage of time spent in the novel arm of Y-maze in sham of TSD, whereas it abolished the responses induced by the TSD groups. Conclusion: The findings showed a close interaction between the Crocin and SD. Based on the findings, Crocin seems to possess a modulatory effect on SD-induced amnesia

Precondition of right frontal region with anodal tDCS can restore the fear memory impairment induced by ACPA in male mice

Fear memory and learning cause behavioural patterns such as fight or flight responses, which increase survival probability, but unfit processing of fear memory and learning can lead to maladaptive behaviours and maladies such as phobias, Post-Traumatic Stress Disorder (PTSD) and anxiety disorders. The growing prevalence of these maladies shows the need to quest novel methods for their treatment. We used anodal transcranial direct current stimulation (tDCS) on the right frontal region as a precondition neuromodulator and arachidonylcyclopropylamide (ACPA), a selective CB1 cannabinoid receptor agonist, as a fear memory impairing agent to assess their effects on contextual and auditory fear conditioning (reliable model for fear studies). Right frontal anodal tDCS (0.2 mA for. 20 minutes) 24 hours before the train did not alter contextual and auditory learning and memory in short-term (24 hrs after the training phase). Moreover, intraperitoneal pre-train injection of ACPA (0.1 mg/kg) alone, decreased both contextual and auditory learning and memory in short- but not long-term. Right frontal anodal tDCS improved short-term contextual fear memory in subthreshold doses of ACPA. On the other hand, right frontal anodal tDCS in long-term improved (lower doses of ACPA) and restored (higher doses of ACPA) both fear memories. These findings showed that, aforementioned approach could cause durable learning and memory improvements. Also this combined modality could be useful for fear extinction training and maladies which inflict amnesia

The Effect of ICV Administration of PI3K on Memory

Introduction: Brain insulin receptors (IRs) have been suggested as an important regulatory factor for cognitive functions but the involvement of IR signaling in memory deficit associated with neurodegenerative conditions is not yet explored.  Among the diverse signaling pathways of IR, PI-3 kinase and (MAP) kinase pathways in brain have been suggested for learning and memory functions. The phosphoinositide3-kinase (PI3K) complex plays important roles in virtually all cells of the body. The enzymatic activity of PI3Kto phosphorylate phosphoinositides in the membrane is mediated by a group of catalytic and regulatory subunits. Among those, the class I catalytic subunits, p110α, p110β,p110γ,and p110δ have recently drawn attention in the neuroscience field due to their specific dysregulation in diverse brain disorders. The present study was planned to investigate the effect of PI3K on memory.Materials and Methods: The animals were injected bilaterally with ICV water (control group), ICV PI3k (1,10 and 100 ng/rat) on days 1 and 3 after surgery.  The learning and memory performance was assessed two weeks after the first dose of drugs by using step-through passive avoidance paradigm (0.3 mA, 3seconds) and open field test. The results revealed that The ICV administration   of PI3K (P<0.05) altered inhibitory avoidance acquisition. PI3K at dose 1 ng/rat decreased the step- through latency during the retention test.Results: data showed that PI3K at dose of 1 ng/rat decreased the step- through latency during the retention test. In addition, the results showed that PI3K at dose 10 ng/rat increased locomotor activity. Conclusion: Finally, our data indicated that PI3K has critical role in memory consolidation and locomotor activity.

Comparison of 5-HT3 or 5-HT4 agents function into the prelimbic area on passive avoidance memory consolidation

     Growing evidence suggests that serotonin plays an important role in learning and memory and all its receptors might be implicated in this process. The present study aimed at investigating and comparing the possible involvement of 5-HT3 and 5-HT4 receptor (R) agonists/antagonists upon consolidation of inhibitory avoidance memory in the pre-limbic (PL) area. Bilateral intra-PL microinjections of m-CPBG (m-Chlorophenylbiguanide hydrochloride: a selective 5-HT3R agonist; 0.1 μg/rat), Y-25130 (a selective 5-HT3R antagonist; 0.1 μg/rat), RS67333 (a potent and highly selective 5-HT4R partial agonist; 0.5 μg/rat) and RS23597-190 (a selective 5-HT4R antagonist; 0.5 μg/rat) were performed immediately after training. The step-through inhibitory avoidance (IA) task was used to memory assessment in adult male Sprague-Dawley rats. Our data revealed that the post-training intra-PL microinjection of m-CPBG relative to saline and Y-25130 decreased inhibitory avoidance memory consolidation in the PL area. On the contrary, RS67333 increased IA memory consolidation in comparison to saline and RS23597-190. In addition, there was also a significant difference between the effects of m-CPBG and RS67333 on IA memory consolidation in the PL area. M-CPBG induced reduction of IA memory consolidation, while RS67333 increased it. However, Y-25130 compared to RS23597-190 did not show any significant difference. All above interventions did not alter locomotor activity. This study indicated that local direct agonist activation of 5-HT3Rs induced the reduction of IA memory consolidation, opposed to the local direct agonist activation of 5-HT4Rs, which mediated enhancement of IA memory consolidation. It can be proposed that 5-HT3Rs in comparison to 5-HT4Rs may be inversely involved in modulation of IA memory consolidation in the PL

Effectiveness of Transcranial Direct Current Stimulation (tDCS) on Methamphetamine Craving

Introduction: Transcranial Direct-Current Stimulation is one of the most challenging version of non-invasive brain stimulation. Although it has promised effects on drug-cravings, it has not been approved by FDA as an intervention.The purpose of this study was to investigate the effectiveness of tDCS on reducingmethamphetamine craving.Method: This study was a quasi-experimental design with the pre-test, post-test and control group. The statistical population included all the methamphetamine users who were referred to the HematPayrovan Institute for treatment in 2019. The sample population were 60 males assigned randomly into two groups of experimental and control group. We applied 20 minutestDCS (2 Ma, Anode F4/Cathode FP1) for experimental group. Data were collected using the Individual Student Assessment Plan (ISAP), The Leeds Dependence Questionnaire (LDQ), and Desires for drug questionnaire (DDQ). The data were analyzed through multivariate analysis of covariance (MANCOVA).Results: The result showed that t DCS significantly decreases methamphetamine craving in the experimental group (P<0.03).Discussion: This finding has important implications pertaining the education and mental health of methamphetamine users. Based on the results, repeated DLPFC stimulation could be a promising approach for therapeutic intervention in decreasing methamphetamine craving

Role of 5-HT1 receptors of accumbens shell arena upon ACPA-induced anxiolytic-like behaviors in rat

     Cannabinoids induce diverse responses on anxiolytic–like behaviors. Moreover some studies postulated that there is a close relationship between this system and serotonergic system upon cognitive process formation. Thus the aim of present study is investigation the possible role of 5-HT1 receptor on anxiolytic–like behaviors induced by ACPA in the elevated plus maze task (EPM). In the present study rats weighting 250–300g upon surgery bilateral guide cannulae were implanted to allow microinjection of ACPA (agonist CB1 receptor), CP94253 Hcl(agonist 5-HT1 receptor) alone and them interaction in the AcbSh.The data showed pretest AcbSh infusion of ACPA at doses of0.0002, 0.002, 0.02 and 0.2 μg/rat increased and decreased the percentage of open-arms time (%OAT) and percentage of Enclosed-arms time (%CAT), respectively as compared to control groups. Pretest AcbSh infusion ofCP94253 Hcl at doses of 5, 0.5 and 0.05 ng/rat, did not alter anxiety-like behaviors. In addition intra-AcbSh microinjection of subthreshold dose of CP94253 Hcl did not alter ACPA-induced anxiolytic-like behaviors. Our data suggest that activation of AcbSh 5-HT1 receptor did not involve in ACPA-induced behaviors in the EPM task.