Different paradigms of transcranial electrical stimulation improve motor function impairment and striatum tissue injuries in the collagenase-induced intracerebral hemorrhage rat model.

BACKGROUND: In the horizon of therapeutic restrictions in intracerebral hemorrhage (ICH), recently, non-invasive transcranial electrical stimulation (tES) has achieved considerable prosperities. Translational studies have postulated that transcranial direct current stimulation (tDCS) and the other types of tES remain potentially a novel therapeutic option to reverse or stabilize cognitive and motor impairments. OBJECTIVE: The aim of this study was to comparatively evaluate the effects of the four main paradigms of tES, including tDCS, transcranial alternating (tACS), pulsed (tPCS), and random noise (tRNS) stimulations on collagenase-induced sensorimotor impairments and striatum tissue damage in male rats. METHODS: To induce ICH, 0.5 µl of collagenase was injected into the right striatum of male Sprague Dawley rats. One day after surgery, tES, was applied to the animals for seven consecutive days. Motor functions were appraised by neurological deficit score, rotarod, and wire hanging tests on the day before surgery and postoperative days 3, 7, and 14. After behavioral tests, brain tissue was prepared appropriately to perform the stereological evaluations. RESULTS: The results indicated that the application of the four tES paradigms (tDCS, tACS, tRNS, and tPCS) significantly reversed motor disorders in collagenase-induced ICH groups. Further, the motor function improvement of tACS and tRNS receiving rats in wire-hanging and rotarod tests were higher than the other two tES receiving groups. Structural changes and stereological assessments also confirmed the results of behavioral functions. CONCLUSION: Our findings suggest that in addition to tDCS application in the treatment of ICH, other tES paradigms, especially tACS and tRNS may be considered as add-on therapeutic strategies in stroke.

The effect of chronic stress and its preconditioning on spatial memory as well as hippocampal LRP1 and RAGE expression in a streptozotocin-induced rat model of Alzheimer's disease.

According to available evidence, prolonged or chronic exposure to stress is detrimental to various brain structures, including the hippocampus. The current study examined the expression of two critical blood-brain barrier receptors required for amyloid-beta clearance to understand better the mechanism by which chronic stress impairs learning and memory in patients with Alzheimer's disease (AD). Rats were randomly assigned to one of two groups in this study: experiment 1 and experiment 2. Each main group was then divided into four subgroups. Rats were bilaterally injected with streptozotocin (STZ, 3 mg/kg, twice) using the intracerebroventricular (ICV) technique to induce the Alzheimer's model. Additionally, they were subjected to foot shock (1 mA, 1 Hz) for 10 s every 60 s (1 h/day) for ten consecutive days prior to and following STZ injection. The Morris Water Maze (MWM) test was used to assess spatial learning and memory. Real-time PCR was used to determine Low-density lipoprotein receptor-related protein-1 (LRP1) and receptor for advanced glycation end-products (RAGE) mRNA levels in the hippocampus. Moreover, the animals' body weights were determined as physiological parameters in all groups. The results indicated that 10-day chronic electric foot shock stress reduced body weight, impaired spatial learning and memory, decreased hippocampal LRP1 mRNA expression, and increased hippocampal RAGE mRNA expression in a rat AD model. It can be concluded that chronic stress in conjunction with AD alters the expression of LRP1 and RAGE in the hippocampus. The findings pave the way for scientists to develop novel treatment strategies for AD.

Astrocyte swelling in hepatic encephalopathy: molecular perspective of cytotoxic edema.

Hepatic encephalopathy (HE) may occur in patients with liver failure. The most critical pathophysiologic mechanism of HE is cerebral edema following systemic hyperammonemia. The dysfunctional liver cannot eliminate circulatory ammonia, so its plasma and brain levels rise sharply. Astrocytes, the only cells that are responsible for ammonia detoxification in the brain, are dynamic cells with unique phenotypic properties that enable them to respond to small changes in their environment. Any pathological changes in astrocytes may cause neurological disturbances such as HE. Astrocyte swelling is the leading cause of cerebral edema, which may cause brain herniation and death by increasing intracranial pressure. Various factors may have a role in astrocyte swelling. However, the exact molecular mechanism of astrocyte swelling is not fully understood. This article discusses the possible mechanisms of astrocyte swelling which related to hyperammonia, including the possible roles of molecules like glutamine, lactate, aquaporin-4 water channel, 18 KDa translocator protein, glial fibrillary acidic protein, alanine, glutathione, toll-like receptor 4, epidermal growth factor receptor, glutamate, and manganese, as well as inflammation, oxidative stress, mitochondrial permeability transition, ATP depletion, and astrocyte senescence. All these agents and factors may be targeted in therapeutic approaches to HE.

Insulin-Like Growth Factor 2 (IGF-2) Regulates Neuronal Density and IGF-2 Distribution Following Hippocampal Intracerebral Hemorrhage.

BACKGROUND: The insulin-like growth factor 2 (IGF-2) is a growth factor and anti-inflammatory cytokine that plays a crucial role in memory consolidation. However, the precise role of this factor in acute brain damage is still unclear. The present study aimed to evaluate the variations in hippocampal IGF-2 distribution on different days and investigate the effect of recombinant IGF-2 on memory cell density, and IGF-2 distribution following acute hippocampal damage resulting from intracerebral hemorrhage (ICH). METHODS: ICH was induced by injection of 100 µL of autologous blood into the left hippocampus of 72 male Sprague-Dawley rats. Recombinant IGF-2 was injected into the damaged hippocampus 30 min post-induction of ICH in the ICH-IGF-2 group. Then, on postoperative days 1, 3, 7, and 14, samples of brain tissue were collected to perform histopathological and immunohistochemical examinations. RESULTS: The stereological study indicated that the volume of the hippocampus and the number of neurons had a significant reduction, and the infarct volume had a significant increase following ICH. Following the injection of IGF-2, a significant improvement was observed in stereological studies. Immunohistochemical data showed that IGF-2 distribution increased in the hippocampus on different days after ICH, and IGF-2 injection led to a dramatic reduction in this distribution. CONCLUSIONS: In summary, the gradual increase of endogenous IGF-2 as growth and anti-inflammatory factor following hemorrhagic stroke reveals a critical role of this factor in brain recovery after injury. Moreover, the injection of IGF-2 can prevent cell death and alleviate the damage caused by the hemorrhagic stroke.

An Experimental Study on Spinal Cord µ-Opioid and α2-Adrenergic Receptors mRNA Expression Following Stress-Induced Hyperalgesia in Male Rats.

BACKGROUND: Intense stress can change pain perception and induce hyperalgesia; a phenomenon called stress-induced hyperalgesia (SIH). However, the neurobiological mechanism of this effect remains unclear. The present study aimed to investigate the effect of the spinal cord µ-opioid receptors (MOR) and α2-adrenergic receptors (α2-AR) on pain sensation in rats with SIH. METHODS: Eighteen Sprague-Dawley male rats, weighing 200-250 g, were randomly divided into two groups (n=9 per group), namely the control and stress group. The stress group was evoked by random 1-hour daily foot-shock stress (0.8 mA for 10 seconds, 1 minute apart) for 3 weeks using a communication box. The tail-flick and formalin tests were performed in both groups on day 22. The real-time RT-PCR technique was used to observe MOR and α2-AR mRNA levels at the L4-L5 lumbar spinal cord. Statistical analysis was performed using the GraphPad Prism 5 software (San Diego, CA, USA). Student's t test was applied for comparisons between the groups. P<0.05 was considered statistically significant. RESULTS: There was a significant (P=0.0014) decrease in tail-flick latency in the stress group compared to the control group. Nociceptive behavioral responses to formalin-induced pain in the stress group were significantly increased in the acute (P=0.007) and chronic (P=0.001) phases of the formalin test compared to the control group. A significant reduction was also observed in MOR mRNA level of the stress group compared to the control group (P=0.003). There was no significant difference in α2-AR mRNA level between the stress and control group. CONCLUSION: The results indicate that chronic stress can affect nociception and lead to hyperalgesia. The data suggest that decreased expression of spinal cord MOR causes hyperalgesia.

Different paradigms of transcranial electrical stimulation induce structural changes in the CA1 region of the hippocampus in a rat model of Alzheimer's disease.

One of the prominent sign of Alzheimer's disease (AD) is structural changes in the hippocampus. Recently, the new methods used to treat this disease is transcranial electrical stimulation (tES). This study evaluated the effect of four primary standards of tES, including tDCS, tACS, tRNS, and tPCS on beta-amyloid 25-35 (Aß25-35)-induced structural changes in the CA1 region of hippocampus in male rats. For this purpose, rats weighing 250-275 g were selected, the cannula was embedded reciprocally into the hippocampi. Aß25-35 (5 µg/ 2.5 ml/ day) was infused reciprocally for four continuous days.Then, animals were then given tES for 6 days.Subsequently, structural changes in the hippocampal CA1 were evaluated using the stereological method. Aß25-35 resulted in loss of neurons (P < 0.01) and decreased hippocampal volume (P < 0.05). However, the administration of tES paradigms prevented these changes. The results proposed that through the improvement of hippocampal cell number and volume, tES paradigms can retain efficiency in remediating structural impairments in AD. From this, it can be concluded that other tES paradigms besides tDCS can also be considered for the treatment of AD.

Therapeutic effects of nanosilibinin in valproic acid-zebrafish model of autism spectrum disorder: Focusing on Wnt signaling pathway and autism spectrum disorder-related cytokines.

In this study, we delved into the intricate world of autism spectrum disorder (ASD) and its connection to the disturbance in the Wnt signaling pathway and immunological abnormalities. Our aim was to evaluate the impact of silibinin, a remarkable modulator of both the Wnt signaling pathway and the immune system, on the neurobehavioral and molecular patterns observed in a zebrafish model of ASD induced by valproic acid (VPA). Because silibinin is a hydrophobic molecule and highly insoluble in water, it was used in the form of silibinin nanoparticles (nanosilibinin, NS). After assessing survival, hatching rate, and morphology of zebrafish larvae exposed to different concentrations of NS, the appropriate concentrations were chosen. Then, zebrafish embryos were exposed to VPA (1 µM) and NS (100 and 200 µM) at the same time for 120 h. Next, anxiety and inattentive behaviors and the expression of CHD8, CTNNB, GSK3beta, LRP6, TNFalpha, IL1beta, and BDNF genes were assessed 7 days post fertilization. The results indicated that higher concentrations of NS had adverse effects on survival, hatching, and morphological development. The concentrations of 100 and 200 µM of NS could ameliorate the anxiety-like behavior and learning deficit and decrease ASD-related cytokines (IL1beta and TNFalpha) in VPA-treated larvae. In addition, only 100 µM of NS prevented raising the gene expression of Wnt signaling-related factors (CHD8, CTNNB, GSK3beta, and LRP6). In conclusion, NS treatment for the first 120 h showed therapeutic effect on an autism-like phenotype probably via reducing the expression of pro-inflammatory cytokines genes and changing the expression of Wnt signaling components genes.

Monitoring Alzheimer's disease via ultraweak photon emission.

In an innovative experiment, we detected ultraweak photon emission (UPE) from the hippocampus of male rat brains and found significant correlations between Alzheimer's disease (AD), memory decline, oxidative stress, and UPE intensity. These findings may open up novel methods for screening, detecting, diagnosing, and classifying neurodegenerative diseases, particularly AD. The study suggests that UPE from the brain's neural tissue can serve as a valuable indicator. It also proposes the development of a minimally invasive brain-computer interface (BCI) photonic chip for monitoring and diagnosing AD, offering high spatiotemporal resolution of brain activity. The study used a rodent model of sporadic AD, demonstrating that STZ-induced sAD resulted in increased hippocampal UPE, which was associated with oxidative stress. Treatment with donepezil reduced UPE and improved oxidative stress. These findings support the potential utility of UPE as a screening and diagnostic tool for AD and other neurodegenerative diseases.

Comparison of the efficacy of human umbilical cord mesenchymal stem cells conditioned medium and platelet-rich plasma on the hippocampus of STZ-induced rat model of Alzheimer's disease: A behavioral and stereological study.

Introduction: Alzheimer's disease (AD) is accompanied by progressive cognitive disorders and memory loss. This study aims to determine the combined effects of conditioned medium of human umbilical cord mesenchymal stem cells (CM) and platelet-rich plasma (PRP) on AD model rats. Methods: Forty-eight male Sprague Dawley rats were classified into 6 groups: Control, Sham, AD, and three treatment groups. AD was induced by streptozotocin(STZ; 3 mg/kg, intracerebroventricular (ICV)) and the treatment groups received injections of CM [(200 µl, intraperitoneally (i.p.), and/or PRP (100 µl, intravenously(i.v)] for 8 days. Behavioral tests (Morris water maze and novel objective recognition) were used to assess learning ability and memory. At the end of the behavioral tests, the rats were sacrificed and their brain was entirely removed, sectioned, and stained with cresyl violet. The hippocampus volume and number of neurons were evaluated by stereological techniques. Results: In the AD group, the discrimination ratio, time spent in the target zone, volume of Cornu Ammonis1 (CA1) and Dentate Gyrus (DG), and the number of pyramidal and granular cells decreased significantly compared to the Sham group. The mentioned parameters increased in the CM and CM+PRP groups compared to the AD group (p < 0.01). PRP did not have any noticeable effect on the examined parameters. Conclusions: CM may be beneficial in the treatment of AD as it led to better improvement in STZ-induced learning and memory impairments as well as the structure of the hippocampus.

The medial prefrontal cortex to the medial amygdala connections may affect the anxiety level in aged rats.

BACKGROUND: Aging changes brain function and behavior differently in male and female individuals. Changes in the medial prefrontal cortex (mPFC)-medial amygdala (MeA) connectivity affect anxiety-like behavior. OBJECTIVES: Therefore, this study aimed to investigate the effect of aging and sex on the mPFC-MeA connection and its association with the level of anxiety-like behavior. METHODS: We divided the Wistar rats into the male and female young rats (2-3-month-old) and male and female old rats (18-20 months old). First, the open field test (OFT) was performed, and then 80 nl of Fluoro-Gold (FG) was injected by stereotaxic surgery in the right or left MeA. After 10 days, the animals were perfused, their brain removed, coronal sections cut, and the number of FG-labeled cells in the right and left mPFC of each sample was estimated. RESULTS: Based on our results, old animals revealed less anxiety-like behavior than young ones, and young females were less anxious than young males, too. Interestingly, MeA of old male rats received more fibers from the bilateral mPFC than young ones. Also, this connection was stronger in the young females than young males. Altogether, the present study indicated that old individuals had less anxiety-like behavior and stronger mPFC-MeA connection, and young female rats were less anxious and had a stronger connection of mPFC-amygdala than males of the same age. CONCLUSION: Thus, it seems that there is a negative relationship between anxiety levels based on the rat's performance in the OFT apparatus and the mPFC-MeA connection.

Effect of chronically electric foot shock stress on spatial memory and hippocampal blood brain barrier permeability.

Maintaining blood-brain barrier (BBB) contributes critically to preserving normal brain functions. According to the available evidence, intense or chronic exposure to stress would potentially affect different brain structures, such as the hippocampus, negatively. The purpose of this study was to define the relationship between the BBB permeability of the hippocampus and the performance of spatial learning and memory under chronically electric foot shock stress. Sixteen rats were divided into the control and stress groups equally. Animals in the stress group were exposed to foot shock (1 mA, 1 Hz) for 10-s duration every 60 s (1 h/day) for 10 consecutive days. The anxiety-related behavior, spatial learning, and memory were assessed by an Open Field (OF) and the Morris Water Maze (MWM) respectively. The hippocampal BBB permeability was determined by Evans blue penetration assay. Our results demonstrated that the stress model not only increased locomotor activities in the OF test but reduced spatial learning and memory in MWM. Moreover, these effects coincided with a significant increase in hippocampal BBB permeability. In sum, the stress model can be used in future studies focusing on the relationship between stress and BBB permeability of the hippocampus.

Simultaneous transcranial and transcutaneous spinal direct current stimulation to enhance athletic performance outcome in experienced boxers.

Transcranial direct current stimulation (tDCS) is among the rapidly growing experimental approaches to enhance athletic performance. Likewise, novel investigations have recently addressed the effects of transcutaneous spinal Direct Current Stimulation (tsDCS) on motor functions such as reduced reaction time. The impact of tDCS, and tsDCS might be attributed to altered spontaneous neural activity and membrane potentials of cortical and corticomotoneuronal cells, respectively. Given the paucity of empirical research in non-invasive brain stimulation in sports neuroscience, especially in boxing, the present investigation studied the effects of neuromodulation on motor and cognitive functions of professional boxers. The study sample comprised 14 experienced male boxers who received random sequential real or sham direct current stimulation over the primary motor cortex (M1) and paraspinal region (corresponding to the hand area) in two sessions with a 72-h interval. Unlike sham stimulation, real stimulation improved selective attention and reaction time of the experienced boxers [enhanced selective attention (p < 0.0003), diminished right hand (p < 0.0001) and left hand reaction time (p < 0.0006)]. Meanwhile, the intervention left no impact on the participants' cognitive functions (p > 0.05). We demonstrated that simultaneous stimulation of the spinal cord and M1 can improve the performance of experienced boxers through neuromodulation. The present study design may be extended to examine the role of neurostimulation in other sport fields.

Effect of nicorandil on the spatial arrangement of primary motor cortical neurons in the sub-acute phase of stroke in a rat model.

INTRODUCTION: Ischemic stroke remains a major cause of disability and death worldwide. The density and the spatial distribution of the primary motor (M1) cortical neurons are important in signal transmission and control the movement-related functions. Recently, the neuroprotective effect of nicorandil in cerebral ischemia was described through its anti-apoptosis, antioxidant and anti-inflammatory properties. This study aimed to determine the effects of nicorandil on the neurobehavioral outcome, infarct size, and density, and spatial distribution of M1 cortical neurons after cerebral ischemia. METHODS: Thirty Sprague-Dawley rats were randomly divided into three groups. Sham underwent surgery without middle cerebral artery occlusion (MCAO) and drug. The MCAO and treatment groups after MCAO received saline or nicorandil 2, 24, 48, and 72 h after the induction of brain ischemia. Neurobehavioral tests were performed, brains removed, sectioned, and stained by 2,3,5-triphenyltetrazolium chloride (TTC) to estimate the size of the infarction and Nissl staining to evaluate the numerical density, mean area, and the distribution pattern of M1 cortical neurons, using Voronoi spatial tessellation. RESULTS: Although nicorandil treatment significantly decreased the neurological deficits and density of neuronal neighbors, it could not preserve the normal regular spatial distributions of M1 cortical neurons after MCAO. It also could not significantly improve motor function or reduce ischemic lesion size. CONCLUSIONS: Treatment using the present dose of nicorandil during sub-acute ischemic stroke could not increase neuronal density or preserve the normal regular spatial distributions after MCAO. However, it had beneficial effects on neurobehavioral and motor function and somewhat reduced ischemic lesion size.

Ameliorative Effects of Different Transcranial Electrical Stimulation Paradigms on the Novel Object Recognition Task in a Rat Model of Alzheimer Disease.

BACKGROUND: Treatment of Alzheimer as a disease that is associated with cognitive impairment has been associated with some restrictions. Recently, researchers have focused on non-pharmacological treatments, including non-invasive stimulation of the brain by transcranial electrical stimulation (tES). Four main paradigms of transcranial electrical current include transcranial direct current stimulation (tDCS), transcranial alternative current stimulation (tACS), transcranial random noise stimulation (tRNS), transcranial pulse current stimulation (tPCS). The tDCS is a possible new therapeutic option for patients with cognitive impairment, including Alzheimer disease. MATERIALS AND METHODS: The study was done on Sprague-Dawley male rats weighing 250-270 g. to develop Alzheimer's model, the cannula was implanted bilaterally into the hippocampus. Aß 25-35 (5µg/ 2.5µl/day) was microinjected bilaterally for 4 days. Then, an electrical stimulation paradigm was applied to the animal for 6 days. Animal cognitive capacity was evaluated on day 11 and 12 by novel object recognition (NOR) test. RESULTS: Our results showed that application of tDCS; tACS; tRNS and tPCS reversed beta-amyloid-induced impairment (P<0.05). The tRNS Group spent total exploration time around the objects compared to other groups (P<0.05). There was no significant difference between the four different paradigms in discrimination ratio and the percentage of total exploration time. CONCLUSION: The results of this study showed that the use of multiple sessions of different tES paradigms could improve Aß-induced memory impairment in the NOR test. Therefore, based on evidence, it can be expected that in addition to using tDCS, other stimulatory paradigms may also be considered in the treatment of AD.

Transcranial direct current stimulation to enhance athletic performance outcome in experienced bodybuilders.

Transcranial direct current stimulation (tDCS) is currently under investigation as a promising technique for enhancement of athletic performance through modulating cortical excitability. Through consecutive randomization, 12 experienced bodybuilders were randomly assigned to two arms receiving either sham or real tDCS over the primary motor cortex (leg area) and left temporal cortex (T3) for 13 minutes in the first session. After 72 hours, both groups received the inverse stimulation. After the brain stimulation, cerebral hemodynamic response (using frontopolar hemoencephalography) was examined upon taking three computer-based cognitive tasks i.e. reasoning, memory and verbal ability using the Cambridge Brain Science-Cognitive Platform. Subsequently, the bodybuilders performed knee extension exercise while performance indicators including one-repetition maximum (1RM), muscular endurance (SEI), heart rate (ECG), motivation (VAS), surface electromyography over quadriceps femoris muscle (sEMG) and perceived exertion (RPE) were evaluated. The real tDCS vs. sham group showed decreased RPE and HR mean scores by 14.2% and 4.9%, respectively. Regarding muscular strength, endurance, and electrical activity, the 1RM, SEI, and sEMG factors improved by 4.4%, 16.9%, and % 5.8, respectively. Meanwhile, compared to sham, real tDCS did not affect the athletes' motivation. Incidentally, it turned out that subjects who underwent T3 anodal stimulation outperformed in memory (p = 0.02) and verbal functions (0.02) as well as their corresponding frontopolar hemodynamic response [(memory HEG (p = 0.001) and verbal HEG (p = 0.003)]. Our findings suggest that simultaneous tDCS-induced excitation over the M1 leg area and left temporal area may potentially improve the overall athletic performance in experienced bodybuilders (Trial registration: IRCT20181104041543N1, Registered on 4 Nov. 2018, retrospectively registered).

Different fibrillar Abeta 1-42 concentrations induce adult hippocampal neurons to reenter various phases of the cell cycle.

In Alzheimer's disease (AD) cell cycle reentry precedes neuronal death, which could be induced by many cytotoxic factors. It is believed that beta amyloid (Abeta), the major component of extracellular plaques in AD, is potent in inducing neurons to reenter cell cycle. In AD brains, neurons expressing cell cycle markers are reported in many brain regions without any plaque formation, although very low levels of Abeta may still be detected. In the other side, because cell cycle reentry is not an immediate cause of apoptosis, neurons may remain in cell cycle phases for some time prior to their final death. In this study we examined if very low concentrations of Abeta 1-42 (picomolar) can trigger the adult neurons to reenter the cell cycle, and the effect of different Abeta concentrations on neuronal progression through different cell cycle phases. Primary adult neurons were treated with Abeta 1-42 at 2 x 10(-6), 2 x 10(-5), 2 x 10(-4), 0.5 and 2.5 microM concentrations. Cyclin D1 and cyclin B1 (the markers for G1 and G2 phases of the cell cycle, respectively) and apoptosis were assessed. Treatment with Abeta at 2.5 microM induced apoptosis. At lower levels however, Abeta promoted neurons entering G1 and G2 phases without apoptosis, with 0.5 microM of Abeta inducing neurons into G2, and 2 x 10(-5,) 2 x 10(-4) into G1 phases. Our results suggested that lower concentrations of Abeta induced neurons to reenter the cell cycle, and different concentrations had differential abilities to promote neurons into various cell cycle phases or trigger their death.

Culturing adult rat hippocampal neurons with long-interval changing media.

BACKGROUND: Primary cultures of embryonic neurons have been used to introduce a model of neurons in physiological and pathological conditions. However, age-related cellular events limit this method as an optimal model in adult neurodegenerative diseases studies. Besides, short-interval changing media in previous cultures decreases the effectiveness of this model. As an example of this matter, we can refer to the study on some special neuronal secreted factors or the influence of some experimental materials on neurons. Meanwhile, short-interval changing media could remove the effects of some released factors from the environment. In this study, the method for isolation and culturing adult rat hippocampal neurons with long-intervals medium changing has been described. METHODS: The hippocampal neurons of adult male rats were cultured. We used Neurobasal A/B27 culture medium, papain (2 mg/ml), trypsin 0.25% and collagenase (1 mg/ml) for neuronal isolation, OptiPrep density gradient for separation of neurons from other cell types and also debris and FGF2 (10 ng/ml) for increasing neuronal survival and regeneration. RESULTS: The neuronal sprouting and viability were increased by using papain and mild triturating (P<0.05). Adult neuronal culturing and their regeneration were impossible without FGF2. It was shown that adding new fresh medium every 4 days and exchanging half of it every 8 days had no detrimental effect on neuronal viability. CONCLUSION: This investigation shows the possibility of culturing adult neuronal cells and their maintaining in long-interval media. It could be happened because of adult neurons rely significantly on the neighboring cells secreted factors for living and making synaptic connections. This model is very useful in physiological and pathological studies which need stable conditions of neuronal culture in a long period of time.

Effects of Post-Weaning Chronic Stress on Nociception, Spinal Cord µ-Opioid, and α2-Adrenergic Receptors Expression in Rats and Their Offspring.

Stressful situations can change biological process in human and animal, and some of these changes may transfer to the next generations. We used a communication box to induce chronic electrical foot-shock stress in rats. Tail flick latency and formalin test were done to determine the level of pain sensation. Real-time RT-PCR was used to measure the level of spinal cord µ-opioid (MOR) and α2-adrenergic receptors (α2-AR) mRNA. We demonstrate that chronic stress can change nociception and leads to hyperalgesia. Moreover, spinal cord MOR mRNA level decreased following chronic stress. We did not observe any significant changes in the level of spinal cord α2-AR mRNA between stressed and non-stressed rats. In addition, non-stressed sons of stressed mothers showed hyperalgesia compared to the control group. They showed lesser level of MOR mRNA level in comparison to the control rats. Furthermore, stressed sons of stressed mothers illustrated more hyperalgesia than the other stressed groups. We indicate that chronic stress can reduce spinal cord MOR mRNA level and lead to hyperalgesia. Additionally, these changes can transfer to offspring.

Effect of Recombinant Insulin-like Growth Factor-2 Injected into the Hippocampus on Memory Impairment Following Hippocampal Intracerebral Hemorrhage in Rats.

BACKGROUND: Insulin-like growth factor 2 (IGF-2) is a growth factor and an anti-inflammatory cytokine that plays a pivotal role in memory. In this study, we examined the effect of recombinant IGF-2 on memory impairment due to intracerebral hemorrhage (ICH). Avoidance and recognition memory, locomotor activity, neurological deficit score (NDS), and the level of the IGF-2 gene expression were evaluated. MATERIALS AND METHODS: To induce ICH, 100 µL of autologous blood was injected into the left hippocampus of male Sprague Dawley rats. Recombinant IGF-2 was injected into the damaged hippocampus 30 minutes after the induction of ICH. Then, over two weeks, NDS, locomotor activity, passive avoidance, and novel object recognition (NOR) test were evaluated. Finally, the level of IGF-2 gene expression was evaluated by using the real-time polymerase chain reaction technique. RESULT: Our results indicated that recombinant IGF-2 injection significantly increased step-through latency (P<0.001) and total time spent in the dark box (P<0.01). However, no significant difference was seen in recognition memory and NDS. Locomotor activity did not significantly change in any group. A significantly reduced level of IGF-2 was observed after two weeks (P<0.05). CONCLUSION: The results of this study show that a single dose of recombinant IGF-2 injection can influence hippocampus-dependent memories. Importantly, IGF-2 did not change locomotor activity and NDS after two weeks, which probably represents its specific function in memory.

Fibrillar beta-amyloid (Abeta) (1-42) elevates extracellular Abeta in cultured hippocampal neurons of adult rats.

Alzheimer's disease (AD) is a chronic disorder with progressive neurodegeneration associated with aging and is characterized by fibrillar beta-amyloid (Abeta) deposits in the brain. Although the increased production of Abeta seems to play a noticeable role in AD pathogenesis and its progression, all the mechanisms which are involved in this extracellular Abeta elevation are not known completely. In the present study, we used adult hippocampal neuronal culture as an in vitro model which is favorable for adult neurodegenerative diseases' studies. We introduced a toxic concentration for fibrillar Abeta1-42 in adult neurons which was much lower from the toxic concentration in embryonic neurons. To determine the effect of fibrillar Abeta1-42 which is the most toxic part of amyloid plaques, on extracellular Abeta1-40, as the main part of betaAPP proteolysis products, we treated the neurons with fibrillar Abeta1-42 at nontoxic concentrations of 2 x 10(-6), 2 x 10(-5) and 2 x 10(-4) microM and measured extracellular Abeta1-40. Our findings show that even very low levels of fibrillar Abeta1-42 can contribute to subsequent extracellular Abeta elevation in a dose dependent manner. These results suggest that even low levels of fibrillar Abeta may have deleterious actions if it remains in extracellular space for a period of time.