Hepatic Acyl CoA Oxidase1 Inhibition Modifies Brain Lipids and Electrical Properties of Dentate Gyrus.

Introduction: Peroxisomes are essential organelles in lipid metabolism. They contain enzymes for ß-oxidation of very long-chain fatty acids (VLCFA) that cannot be broken down in mitochondria. Reduced expression in hepatic acyl-CoA oxidase 1 (ACOX1), a peroxisome ß-oxidation enzyme, followed by modification of the brain fatty acid profile has been observed in aged rodents. These studies have suggested a potential role for peroxisome ß-oxidation in brain aging. This study was designed to examine the effect of hepatic ACOX1 inhibition on brain fatty acid composition and neuronal cell activities of young rats (200-250 g). Methods: A specific ACOX1 inhibitor, 10, 12- tricosadiynoic acid (TDYA), 100 µg/kg (in olive oil) was administered by daily gavage for 25 days in male Wistar rats. The brain fatty acid composition and electrophysiological properties of dentate gyrus granule cells were determined using gas chromatography and whole-cell patch-clamp, respectively. Results: A significant increase in C20, C22, C18:1, C20:1, and a decrease of C18, C24, C20:3n6, and C22:6n3 were found in 10, 12- tricosadiynoic acid (TDYA) treated rats compared to the control group. The results showed that ACOX1 inhibition changes fatty acid composition similar to old rats. ACOX1 inhibition caused hyperpolarization of resting membrane potential, and also reduction of input resistance, action potential duration, and spike firing. Moreover, ACOX1 inhibition increased rheobase current and afterhyperpolarization amplitude in granule cells. Conclusion: The results indicated that systemic inhibition of ACOX1 causes hypo-excitability of neuronal cells. These results provide new evidence on the involvement of peroxisome function and hepatic ACOX1 activity in brain fatty acid profile and the electrophysiological properties of dentate gyrus cells.

Evaluation of the Ankylosing Spondylitis Transcriptome for Oxidative Phosphorylation Pathway: The Shared Pathway with Neurodegenerative Diseases.

Ankylosing spondylitis (AS) is a systemic inflammatory disorder of joints and entheses. Recent studies have reported an increased prevalence of dementia in AS patients. However, data for exploring the association between dementia and AS remain uncertain. In this study, enriched pathways and differentially expressed genes (DEGs) were identified in whole blood transcription data of AS patients obtained from the gene expression omnibus (GEO) database; using gene set enrichment analysis (GSEA) and differential expression analysis. Four pathways, including oxidative phosphorylation, Alzheimer's, Parkinson's, and Huntington's diseases were significantly enriched in AS patients compared to the controls. We identified 22 common genes among the pathways that showed an increasing trend in AS compared to the controls. Five of them including COX7B, NDUFB3, ATP5PF, UQCRB, and NDUFS4 were the most significant genes which were selected for gene expression analysis; using real-time PCR on RNA contents of peripheral blood mononuclear cells (PBMCs) of AS patients and controls (20 samples from each group). The gene expression analysis indicated considerable overexpression of COX7B (p<0.0001) and ATP5J (p=0.0001) genes in AS patients group in comparison to the control samples. The role of oxidative phosphorylation has previously been established in dementia pathogenesis. Given that AS patients have also a remarkably higher prevalence of dementia than the their healthy counterparts, hence our results may propose that the common pathway of oxidative phosphorylation can be regarded as a possible shared contributing factor in the etiopathogenesis of AS and dementia.

Downregulation of ITM2A Gene Expression in Macrophages of Patients with Ankylosing Spondylitis.

OBJECTIVES: Ankylosing spondylitis (AS) is a rheumatic disorder that is mostly determined by genetic and environmental factors. Given the known importance of macrophage in AS pathogenesis, we investigated the transcriptional profile of macrophage cells in the disease. METHODS AND RESULTS: Two approaches of differential expression and subsequently, weighted gene co-expression network analysis was utilized to analyze a publicly available microarray dataset of macrophages. Integral membrane protein 2A (ITM2A) was among the most significant genes with a decreased trend in the common results of both methods. In order to confirm the finding, the expression of ITM2A was evaluated in monocyte-derived (M2-like) and M1 macrophages obtained from 14 AS patients and 14 controls. Macrophages were differentiated from whole-blood separated monocytes by 7 days incubating with macrophage colony-stimulating factor and then macrophages specific markers were verified with the flow cytometer. M1 polarization was induced by IFN-γ and lipopolysaccharide. Finally, relative gene expression analysis by real-time polymerase chain reaction revealed a significant downregulation of the ITM2A gene in both M2 like and M1 macrophages of the AS group compared to the control. CONCLUSION: Since ITM2A plays a critical role in osteo- and chondrogenic cellular differentiation, our finding may provide new insights into AS pathogenesis.

Optogenetic control of neural differentiation in Opto-mGluR6 engineered retinal pigment epithelial cell line and mesenchymal stem cells.

In retinal degenerative disorders, when neural retinal cells are damaged, cell transplantation is one of the most promising therapeutic approaches. Optogenetic technology plays an essential role in the neural differentiation of stem cells via membrane depolarization. This study explored the efficacy of blue light stimulation in neuroretinal differentiation of Opto-mGluR6-engineered mouse retinal pigment epithelium (mRPE) and bone marrow mesenchymal stem cells (BMSCs). mRPE and BMSCs were selected for optogenetic study due to their capability to differentiate into retinal-specific neurons. BMSCs were isolated and phenotypically characterized by the expression of mesenchymal stem cell-specific markers, CD44 (99%) and CD105 (98.8%). mRPE culture identity was confirmed by expression of RPE-specific marker, RPE65, and epithelial cell marker, ZO-1. mRPE cells and BMSCs were transduced with AAV-MCS-IRES-EGFP-Opto-mGluR6 viral vector and stimulated for 5 days with blue light (470 nm). RNA and protein expression of Opto-mGluR6 were verified. Optogenetic stimulation-induced elevated intracellular Ca2+ levels in mRPE- and BMS-treated cells. Significant increase in cell growth rate and G1/S phase transition were detected in mRPE- and BMSCs-treated cultures. Pou4f1, Dlx2, Eomes, Barlh2, Neurod2, Neurod6, Rorb, Rxrg, Nr2f2, Ascl1, Hes5, and Sox8 were overexpressed in treated BMSCs and Barlh2, Rorb, and Sox8 were overexpressed in treated mRPE cells. Expression of Rho, Thy1, OPN1MW, Recoverin, and CRABP, as retinal-specific neuron markers, in mRPE and BMS cell cultures were demonstrated. Differentiation of ganglion, amacrine, photoreceptor cells, and bipolar and Muller precursors were determined in BMSCs-treated culture and were compared with mRPE. mRPE cells represented more abundant terminal Muller glial differentiation compared with BMSCs. Our results also demonstrated that optical stimulation increased the intracellular Ca2+ level and proliferation and differentiation of Opto-mGluR6-engineered BMSCs. It seems that optogenetic stimulation of mRPE- and BMSCs-engineered cells would be a potential therapeutic approach for retinal degenerative disorders.

Optogenetic control of perforant pathway kindled seizures by photoinhibition of CA3 after insertion of Jaws into CA3 neuronal cells.

Medial temporal lobe epilepsy (MTLE) is among the most common and most drug-resistant types of epilepsies associated with remodeling of the trisynaptic circuit of the hippocampus. The cornu ammonis (CA)3 region, as the "pacemaker" of the circuit, and CA3 â†’ CA1 synapse (Schaffer collaterals) are potential targets for suppression of MTLE. We examined optogenetic manipulation of CA3 neurons in controlling the perforant pathway kindled seizures. One week after implantation of stimulating electrodes in perforant pathway, a recording electrode in CA1, and an optic fiber in CA3, rats underwent rapid kindling procedure. A lentivector with capability to move in retrograde monosynaptic direction and to insert the gene of red light sensitive opsin Jaws in neurons was injected into CA1 of the kindled rats. One week later, the kindled rats were stimulated at afterdischarge (AD) threshold under red light illumination to CA3; and duration of AD (ADD), generalized seizures (S5D), and total seizure behavior (SD) were recorded. Encoding Jaws in CA1, CA3, and entorhinal neuronal cells of the vector injected rats was verified by immunohistochemistry. More than 90% of CA1, CA3, and entorhinal neurons of the counted sections expressed Jaws. Red light (625 nm) illumination to CA3 of the kindled rats expressing Jaws entirely suppressed generalized seizures and significantly diminished ADD and SD. Encoding the light-sensitive chloride pump Jaws in the CA3, is an efficient optogenetic strategy to stop perforant pathway kindled seizures.

The Lentiviral Vector Pseudotyped by Modified Rabies Glycoprotein Does Not Cause Reactive Gliosis and Neurodegeneration in Rat Hippocampus

Background: A human immunodeficiency virus type 1 (HIV-1)-based lentiviral vector (LV) pseudotyped by a variant of rabies envelope glycoprotein, FUG-B2, has previously been prepared and used in transfection of hippocampal CA1 ("Cornu Ammonis" area 1) neurons. This study aimed to verify reactive gliosis and neuronal damage after injection of the vector into the rat hippocampus. Methods: HEK 293T cells were transfected with transfer (fck-Jaws-GFP-ER2), envelope (FUG-B2), and packaging (pMDLg/pRRE, pRSV-Rev) plasmids, and the vector was injected into CA1 of the rat hippocampus. After one week, transduction efficiency, and the number of neuronal and astroglial cells were determined in CA1 and CA3 by double staining of the brain slices. Results: Hippocampal cells were successfully transfected as 92.7% of CA1 and 95.8% of CA3 neuronal cells expressed GFP. The frequency of neuronal and astroglial cells in CA1 and CA3 of the vector-injected rats remained unchanged compared to those in the control and the saline-injected rats. Furthermore, no morphological change was found in hippocampal astrocytes and neuronal cells. Conclusion: The HIV-1-based LV pseudotyped by FUG-B2 is safe and does not cause neuroinflammation and neuronal loss once directly delivered into the rat hippocampus.

Calcium Channel Blockade Ameliorates Endoplasmic Reticulum Stress in the Hippocampus Induced by Amyloidopathy in the Entorhinal Cortex.

Entorhinal cortex (EC) is one of the first cerebral regions affected in Alzheimer's disease (AD). The pathology propagates to neighboring cerebral regions through a prion-like mechanism. In AD, intracellular calcium dyshomeostasis is associated with endoplasmic reticulum (ER) stress. This study was designed to examine hippocampal ER stress following EC amyloidopathy. Aß1-42 was bilaterally microinjected into the EC under stereotaxic surgery. Rats were daily treated with 30 µg of isradipine, nimodipine, or placebo over one week. Passive avoidance and novel object recognition (NOR) tasks were performed using shuttle box and NOR test, respectively. GRP78/BiP and CHOP levels were measured in the hippocampal dentate gyrus (DG) by western blot technique. The glutathione (GSH) level and PDI activity were also assessed in the hippocampus by colorimetric spectrophotometer. Aß treated group developed passive avoidance and novel recognition memory deficit compared to the control group. However, treatment with calcium channel blockers reversed the impairment. BiP and CHOP level increased in the hippocampus following amyloidopathy in the EC. PDI activity and GSH level in the hippocampus decreased in the Aß treated group, but calcium channel blockers restored them toward the control level. In conclusion, memory impairment due to EC amyloidopathy is associated with ER stress related bio-molecular changes in the hippocampus, and treatment with L-type calcium channel blockers may prevent the changes and ultimately improve cognitive performance.

Photothrombotically induced unilateral selective hippocampal ischemia in rat.

INTRODUCTION: The vulnerability of hippocampal formation to ischemic insult has been documented in both humans and animal models. Ischemic injury induction through photothrombosis is an invasive and reproducible model of ischemic stroke which provides the ability to induce ischemia selectively in any desired area. In this study, we describe a method to induce selective unilateral hippocampal ischemia in rat through modified photothrombotic model. METHODS: Male wistar rats (n = 66) were subjected to stereotaxic surgery to insert a guide cannula just above the ascending part of hippocampal fissure. After recovery femoral vein was cannulated and rats were mounted in stereotaxic frame to optical fiber insertion in guide cannula and illumination of hippocampal fissure for 25 min. Rose Bengal dye was slowly injected through femoral vein during the first two-minute of illumination. Twenty-four hours later, infarct volume and histological change were evaluated in rat hippocampus. Cognitive function was also evaluated 48 h after ischemia induction. RESULTS: This procedure caused significant neuronal necrosis and infarct formation in the right hemisphere hippocampus. The infarct size was consisted in different subjects and was paralleled to cognitive impairment. The mean volume of infarction was 6.5% which affected whole right hippocampus and caused significant cognitive impairment compared to sham group (P < 0.001). DISCUSSION: The method described in this study provides the ability of selective hippocampal ischemia induction and study of hippocampal injury consequences following ischemia or other neurodegenerative disease that affect hippocampus.

The Effects of Buthotus schach Scorpion Venom on Electrophysiological Properties of Magnocellular Neurons of Rat Supraoptic Nucleus.

Bothutous Schach (BS) scorpion venom consists of several polypeptides that could modulate ion channels. In this study, the effects of BS crude venom on passive and active electrophysiological properties of rat neurons in supraoptic nucleus (SON) of hypothalamus was investigated using whole-cell patch clamp technique. The results showed that bath application of BS venom produced significant change in passive properties of SON neurons, namely a decrease in resting membrane potential and an increase in input resistance of the cells. Also, significant change in active properties of SON neurons was shown after bath application of BS venom; including a decrease in the number of evoked action potential along with an increase in half width and decay time of action potential and a significant decrease in after-hyperpolarization amplitude. Finally, a decreased latency to the first spike accompanied by a lower current threshold to elicit the first spike was shown compared with the values before venom application. These effects are possibly through blocking different ion channels including potassium channels. Further experiments using different fractions of the venom is required to specify venom effects on various ion channels.

Neuroprotective effect of monophosphoryl lipid A, a detoxified lipid A derivative, in photothrombotic model of unilateral selective hippocampal ischemia in rat.

Finding a neuroprotective strategy to rescue patients suffering from acute brain damage is of great interest. Monophosphoryl lipid A (MPL) is a derivative of lipopolysaccharide (LPS) that lacks many of the endotoxic properties of the parent molecule, and yet has similar protective effect. Here, we report the first evidence that MPL preconditioning, similar to LPS preconditioning, can induce neuroprotection against cerebral ischemia. MPL (0.5, 1, 5 µg/rat) was injected unilaterally into the left cerebral ventricle of male rats, and 48 h later, rats were subjected to ipsilateral selective hippocampal ischemia using a modified version of the photothrombotic method. The neuroprotective effects of MPL and LPS were evaluated by measuring infarct size and assessing cognitive function. The expression level of some inflammatory and anti-inflammatory cytokines involving in TLR4 signaling pathway was also measured. Cognitive impairment and infarct size were obvious in control group receiving normal saline intracerebroventricularly and then selective hippocampal ischemia, compared to the sham group. Immunologic preconditioning with MPL or LPS significantly reduced infarct size and improved cognitive function. Additionally, immunologic preconditioning resulted in inflammatory mediators, NF-κB and TNF-α, down-regulation but anti-inflammatory mediators, IRF3, IFN-ß, and TGF-ß, up-regulation. Our data showed that both MPL and LPS preconditioning may reprogram the TLR4 signaling pathway to produce a cytokine profile which eventually leads to neuroprotection against ischemia injury. MPL, unlike LPS, is safe and well tolerated in clinic, thus it could be considered as a new approach in prevention or even treatment of cerebral ischemic insult consequences.

Optogenetics: Control of Brain Using Light

Neuronal cells communicate with each other by producing electrical signals or action potentials (APs). Different ion channels, including Na+, K+ and Ca2+ channels, are involved in generation of AP. Once an AP is generated in the soma, it travels down entire the axon length toward its terminal in a self-generating fashion that ultimately conveys information between neurons in the neural circuit. Depending on the neurotransmitter, each neuron inhibits or excites other neurons in a certain network. For instance, glutamate released from glutamatergic neurons, opens AMPA and NMDA channels permitting influx of Na+/Ca2+, which leads to postsynaptic depolarization. On the other hand, GABA released from GABAergic neurons results in Cl- influx and postsynaptic hyperpolarization. One of the major challenges in neuroscience is how actions of individual cells in the brain could underlie a certain behavior such as attention, food consumption, aggression, cognition, and movement...

Forced exercise attenuates neuropathic pain in chronic constriction injury of male rat: an investigation of oxidative stress and inflammation.

BACKGROUND AND OBJECTIVE: Initial peripheral/central nerve injuries, such as chronic constriction injury (CCI)/spinal cord injury, are often compounded by secondary mechanisms, including inflammation and oxidative stress, which may lead to chronic neuropathic pain characterized by hyperalgesia or allodynia. On the other hand, exercise as a behavioral and non-pharmacological treatment has been shown to alleviate chronic neuropathic pain. Therefore, this study was conducted to examine whether or not exercise reduces neuropathic pain through modifying oxidative stress and inflammation in chronic constriction injury of the sciatic nerve. MATERIALS AND METHODS: Wistar male rats weighing 200±20 g were randomly divided into five groups (normal, sham, CCI, pre-CCI exercise, and post-CCI exercise group). Sciatic nerve of anesthetized rats was loosely ligated to induce CCI, and they were then housed in separate cages. The rats ran on treadmill at a moderate speed for 3 weeks. Mechanical allodynia and thermal hyperalgesia were determined using von Frey filament and plantar test, respectively. Tumor necrosis factor-alpha (TNF-α) assayed in the cerebrospinal fluid, malondialdehyde, and total antioxidant capacity were measured in the serum using Western blot test, thiobarbituric acid, and ferric reducing ability of plasma (FRAP), respectively. RESULTS: The mechanical allodynia (P=0.024) and thermal hyperalgesia (P=0.002) in the CCI group were higher than those in the sham group. Exercise after CCI reduced (P=0.004) mechanical allodynia and thermal hyperalgesia (P=0.025) compared with the CCI group. Moreover, the level of FRAP in the CCI group was (P=0.001) lower than that in the sham group, and post-CCI exercise reversed FRAP amount toward the control level (P=0.019). The amount of malondialdehyde did not differ between groups. Level of TNF-α increased in the CCI group (P=0.0002) compared with sham group and post-CCI exercise could reverse it toward the level of control (P=0.005). CONCLUSION: Post CCI-exercise but not pre CCI-exercise reduces CCI-induced neuropathic pain. One of the possible involved mechanisms is increasing the total antioxidant capacity and reducing the amount of TNF-α.

Anxiolytic-Like and Sedative Effects of Alcea Aucheri (Boiss.) Alef. Flower Extract in the Laboratory Rat.

The present study was conducted to investigate the possible anxiolytic and sedative of an acute administration and 4-day repeated dosing of an aqueous extract of flowers of Alcea aucheri (Boiss.) Alef. (EFA)in rats subjected to the elevated plus-maze (EPM), open-field, and horizontal wire tests. All drugs were administered intraperitoneally. Phytochemical screening confirmed the presence of phenolic compounds, flavonoids, and polysaccharides in the extract. Repeated dosing of EFA (at dose of 35 mg/kg) significantly increased percentage of time spent on open arms and of open arms entries, and also decreased percentage of time spent on closed arms and of closed arms entries; compared with saline control, 24 h after treatment. In addition, repeated dosing of EFA (at dose of 175 mg/kg) significantly increased open arm activity 48 h after treatment, versus saline group. This effect was also observed following acute administration of EFA at 175 mg/kg. In open field, acute administration of EFA at doses of 17.5, 35, 70, 175, 350, and 700 mg/kg induced a statistically significant and dose-dependent decrease in locomotor activity, compared with saline control. ED50 value for EFA-induced decrease in locomotor activity was 194 mg/kg. Furthermore, unlike diazepam; EFA didn´t decrease the percent of the rats grasping the wire. These data suggest that Alcea aucheri extract may have anxiolytic and sedative properties and some of the components in the extract such as phenolic compounds may have contributed to the observed effects.

Systems Biomedicine of Rabies Delineates the Affected Signaling Pathways.

The prototypical neurotropic virus, rabies, is a member of the Rhabdoviridae family that causes lethal encephalomyelitis. Although there have been a plethora of studies investigating the etiological mechanism of the rabies virus and many precautionary methods have been implemented to avert the disease outbreak over the last century, the disease has surprisingly no definite remedy at its late stages. The psychological symptoms and the underlying etiology, as well as the rare survival rate from rabies encephalitis, has still remained a mystery. We, therefore, undertook a systems biomedicine approach to identify the network of gene products implicated in rabies. This was done by meta-analyzing whole-transcriptome microarray datasets of the CNS infected by strain CVS-11, and integrating them with interactome data using computational and statistical methods. We first determined the differentially expressed genes (DEGs) in each study and horizontally integrated the results at the mRNA and microRNA levels separately. A total of 61 seed genes involved in signal propagation system were obtained by means of unifying mRNA and microRNA detected integrated DEGs. We then reconstructed a refined protein-protein interaction network (PPIN) of infected cells to elucidate the rabies-implicated signal transduction network (RISN). To validate our findings, we confirmed differential expression of randomly selected genes in the network using Real-time PCR. In conclusion, the identification of seed genes and their network neighborhood within the refined PPIN can be useful for demonstrating signaling pathways including interferon circumvent, toward proliferation and survival, and neuropathological clue, explaining the intricate underlying molecular neuropathology of rabies infection and thus rendered a molecular framework for predicting potential drug targets.

Calcium channel blockade attenuates abnormal synaptic transmission in the dentate gyrus elicited by entorhinal amyloidopathy.

Entorhinal-hippocampal network is one of the earliest circuits which is affected by Alzheimer's disease (AD). There are numerous data providing the evidence of synaptic deficit in the dentate gyrus (DG) of AD animal model. However, there is little known about how entorhinal cortex (EC) amyloidophaty affects each excitatory and/or inhibitory transmission in the early stage of AD. On the other hand, it is believed that calcium dyshomeostasis has a critical role in the etiology of AD. Here, the effect of the EC amyloid pathogenesis on excitatory or inhibitory post synaptic currents (EPSC and IPSC, respectively) in the DG granule cells and then the possible neuroprotective action of L-type calcium channel blockers (CCBs), nimodipine and isradipine, were examined. The amyloid beta (Aß) 1-42 was injected bilaterally into the EC of male rats and one week later, synaptic currents in the DG granule cells were assessed by whole cell patch clamp. EPSCs were evoked by stimulating the perforant pathway. Voltage clamp recording showed profound decrease of evoked EPSC amplitude and paired pulse facilitation in the DG granule cells of Aß treated rats. Furthermore, AMPA/NMDA ratio was significantly decreased in the Aß treated animals. On the other hand, amplitude of IPSC currents was significantly increased in the DG granule cells of these animals. These modifications of synaptic currents were partially reversed by daily intracerebroventricular administration of isradipine or nimodipine. In conclusion, our results suggest that Aß in the EC triggers decreased excitatory transmission in the DG with substantial decrement in AMPA currents, leading to a prominent activity of inhibitory circuits and increased inhibition of granule cells which may contribute to the development of AD-related neurological deficits in AD and treatment by CCBs could preserve normal synaptic transmission against Aß toxicity.

Facilitation of Hippocampal Kindling and Exacerbation of Kindled Seizures by Intra-CA1 Injection of Quinine: A Possible Role of Cx36 Gap Junctions.

BACKGROUND: GABAergic interneurons in the hippocampal CA1 area are mutually communicated by gap junctions (GJs) composed of connexin36 (Cx36). We examined the role of Cx36 in CA1 in manifestation of kindled seizures and hippocampal kindling in rats. METHODS: Quinine, as the specific blocker of Cx36, was injected into CA1, and kindled seizures severity was examined 10 min afterward. Moreover, quinine was injected into CA1 once daily, and the rate of CA1 kindling was recorded. RESULTS: Quinine 0.5 and 1 mM caused 2- and 3.5-fold increase in the duration of total seizure behavior and generalized the seizures. Primary and secondary afterdischarges (AD) were also significantly increased. Quinine 0.1 mM augmented the rate of kindling and the growth of secondary AD. CONCLUSION: Cx36 GJs in CA1 are the main components of hippocampal inhibitory circuit. Any interruption in this path by pathologic or physical damages can trigger hippocampal hyperexcitability and facilitate epileptogenesis.

Assessment of the Optimal Stimulus Pattern to Achieve Rapid Dorsal Hippocampal Kindling in Rats.

INTRODUCTION: Although hippocampus is the most famous brain area involved in temporal lobe epilepsy, hippocampal kindling (HK) develops very slowly. Hence, rapid kindling is usually preferred to the traditional kindling and it is widely used. In this article we aimed at finding the optimal stimulus pattern, which yields the fastest HK rate. METHODS: Stimulus patterns with different duration (2, 3, 5 and 10 s) and inter-train interval (ITI) (5, 10 and 30 min) as well as number of trains in 24 h (8 and 12) were exerted to rats' dorsal hippocampus. The stimuli were continued until appearance of 3 consecutive generalized seizures or maximum 7 days stimulations. RESULTS: While the protocol with train duration of 10 s and ITI of 30 min caused the fastest kindling rate and the most growth of afterdischarges, the protocol with train duration of 5 s and ITI of 5 min was the most time-consuming protocol among protocols tested. DISCUSSION: Rapid HK develops with a time course of days compared to weeks in traditional kindling. Train duration and inter-train interval are key factors for rapid HK. Among the patterns, 12 trains/24h of 50Hz monophasic square wave with 10 s duration and 30 min interval between trains, is the best stimulus pattern for eliciting rapid dorsal HK.