Research Interests:
Research Interests:
Research Interests:
Research Interests: Neuroscience, Immunohistochemistry, Medicine, Peripheral Nerve Injury, Neuropathic pain, and 15 moreAnimals, Male, Neurons, Clinical Sciences, Rats, Nociception, Allodynia, Neurosciences, Hyperalgesia, Dorsal Horn, Brain stem, Parabrachial Nucleus, Mesencephalon, Ligation, and Pharmacology and pharmaceutical sciences
Neuropathic pain often accompanies the functional deficits associated with spinal cord injury (SCI) and further reduces a patient's quality of life. Clinical and pre-clinical research is beginning to highlight the beneficial role that... more
Neuropathic pain often accompanies the functional deficits associated with spinal cord injury (SCI) and further reduces a patient's quality of life. Clinical and pre-clinical research is beginning to highlight the beneficial role that rehabilitative therapies such as locomotor training can have not only on functional recovery but also on chronic pain management. Our group has previously developed an intensive locomotor training (ILT) treadmill protocol in a rat that reduced SCI neuropathic pain symptoms for at least 3 months. We have extended these findings in the current study to evaluate the ability of regular ILT regimen over a 2 year period post-SCI to maintain neuropathic pain reduction. To assess this, the rat clip compression SCI model (T7/8) was used and treadmill training initiated starting 4 weeks after SCI and continuing through the duration of the study. Results showed continued suppression of SCI neuropathic pain responses (reduced mechanical, heat, and cold hypersensitivity throughout the entire time course of the study. In contrast, non-exercised rats showed consistent and sustained neuropathic pain responses during this period. In addition, prolonged survival and improved locomotor outcomes were observed in rats undergoing ILT as the study longevity progressed. Potential contributory mechanisms underlying beneficial effects of ILT include reduced inflammation and restoration of antinociceptive inhibitory processes as indicated by neurochemical assays in spinal tissue of remaining rats at 2 years post-SCI. The benefits of chronic ILT suggest long-term physical exercise therapy can produce powerful and prolonged management of neuropathic pain, partly through sustained reduction of spinal pathological processes.
Research Interests:
Research Interests:
Research Interests: Pharmacology, Chemistry, Neuropharmacology, Enzyme Inhibitors, Medicine, and 15 moreNeuropathic pain, Amines, Animals, Male, Endocannabinoid System, Nociception, Allodynia, Gabapentin, Neurosciences, Carbamates, Analgesics, Hyperalgesia, Benzamides, Pharmacology and pharmaceutical sciences, and HIV infections
Fluoro-Jade B, a marker of degenerating neurons, was used to label histopathological changes in the rat spinal cord after transient ischemia and ischemic preconditioning (IPC). To characterize postischemic neurodegenerations and... more
Fluoro-Jade B, a marker of degenerating neurons, was used to label histopathological changes in the rat spinal cord after transient ischemia and ischemic preconditioning (IPC). To characterize postischemic neurodegenerations and consequent neurological changes, a particular attention was paid to the standardization of ischemic conditions in animals of both groups. 1. The control ischemic rats were submitted to a reversible occlusion of descending aorta by insertion and subsequent inflation of a 2F Fogarty catheter for 12 min. 2. In the IPC rats, an episode of short 3 min occlusion and 30 min reperfusion preceded the 12 min ischemia. Postischemic motor function testing (ambulation and stepping) was provided repeatedly for evaluation of neurological status 2 h and 24 h after surgery and at the end of postischemic survival, i.e. after 48 h. Fluoro-Jade B staining was used to demonstrate degenerated neurons. In the control rats, neurological consequences of histopathological changes in lumbosacral spinal cord, manifested as paraplegia, were present after 12 min ischemia. Thus, numbers of degenerated Fluoro-Jade B positive cells were visible in gray matter of the most injured L(4)-S(2) spinal cord segments. Slight motor function impairment, consequential from significant decreasing in Fluoro-Jade B-positivity in the L(4)-S(2) spinal cord segments of the IPC rats, was considered the pathomorpfological evidence that IPC induces spinal cord tolerance to ischemia. Our results are consistent with the previously published silver impregnation method for histopathological demonstration of ischemic degeneration.
Research Interests:
Research Interests:
Research Interests: Neuroscience, Psychology, Long Term Potentiation, Medicine, Hippocampus, and 15 morecyclic AMP, Chronic Disease, Animals, Male, Fear conditioning, CREB, Phosphodiesterase Inhibitors, Rats, Memory Disorders, Maze Learning, Cognition disorders, Hippocampal formation, Brain injuries, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Pain, Calcium, Immunohistochemistry, Medicine, Gene expression, and 15 morePeripheral Nerve Injury, Neuropathic pain, Animals, Male, Behavior change, Nociception, Pain Measurement, Nerve Injury, Dorsal Horn, Lumbosacral Region, Motor Neurons, Psychology and Cognitive Sciences, Ligation, Medical and Health Sciences, and Cold Temperature
Development of chronic pain has been attributed to dysfunctional GABA signaling in the spinal cord. Direct pharmacological interventions on GABA signaling are usually not very efficient and often accompanied by side effects due to the... more
Development of chronic pain has been attributed to dysfunctional GABA signaling in the spinal cord. Direct pharmacological interventions on GABA signaling are usually not very efficient and often accompanied by side effects due to the widespread distribution of GABA receptors in CNS. Transplantation of GABAergic neuronal cells may restore the inhibitory potential in the spinal cord. Grafted cells may also release additional analgesic peptides by means of genetic engineering to further enhance the benefits of this approach. Conopeptides are ideal candidates for recombinant expression using cell-based strategies. The omega-conopeptide MVIIA is in clinical use for severe pain marketed as FDA approved Prialt in the form of intrathecal injections. The goal of this study was to develop transplantable recombinant GABAergic cells releasing conopeptide MVIIA and to evaluate the analgesic effect of the grafts in a model of peripheral nerve injury-induced pain. We have engineered and characterized the GABAergic progenitors expressing MVIIA. Recombinant and nonrecombinant cells were intraspinally injected into animals after the nerve injury. Animals were tested weekly up to 12 weeks for the presence of hypersensitivity, followed by histochemical and biochemical analysis of the tissue. We observed beneficial effects of the grafted cells in reducing hypersensitivity in all grafted animals, especially potent in the recombinant group. The level of pain-related cytokines was reduced in the grafted animals and correlation between these pain markers and actual behavior was indicated. This study demonstrated the feasibility of recombinant cell transplantation in the management of chronic pain.
Research Interests:
The most frequently reported use of medical marijuana is for pain relief. However, its psychoactive component Δ9-tetrahydrocannabinol (THC) causes significant side effects. Cannabidiol (CBD) and β-caryophyllene (BCP), two other cannabis... more
The most frequently reported use of medical marijuana is for pain relief. However, its psychoactive component Δ9-tetrahydrocannabinol (THC) causes significant side effects. Cannabidiol (CBD) and β-caryophyllene (BCP), two other cannabis constituents, possess more benign side effect profiles and are also reported to reduce neuropathic and inflammatory pain. We evaluated the analgesic potential of CBD and BCP individually and in combination in a rat spinal cord injury (SCI) clip compression chronic pain model. Individually, both phytocannabinoids produced dose-dependent reduction in tactile and cold hypersensitivity in male and female rats with SCI. When co-administered at fixed ratios based on individual A50s, CBD and BCP produced enhanced dose-dependent reduction in allodynic responses with synergistic effects observed for cold hypersensitivity in both sexes and additive effects for tactile hypersensitivity in males. Antinociceptive effects of both individual and combined treatment ...
Research Interests:
Research Interests:
doi: 10.3389/fphys.2012.00167 Predifferentiated GABAergic neural precursor transplants for alleviation of dysesthetic central pain following excitotoxic spinal cord injury
Therapeutic strategies targeting phantom limb pain (PLP) provide inadequate pain relief; therefore, a robust and clinically relevant animal model is necessary. Animal models of PLP are based on a deafferentation injury followed by... more
Therapeutic strategies targeting phantom limb pain (PLP) provide inadequate pain relief; therefore, a robust and clinically relevant animal model is necessary. Animal models of PLP are based on a deafferentation injury followed by autotomy behavior. Clinical studies have shown that the presence of pre-amputation pain increases the risk of developing PLP. In the current study, we used Sprague-Dawley male rats with formalin injections or constriction nerve injury at different sites or time points prior to axotomy to mimic clinical scenarios of pre-amputation inflammatory and neuropathic pain. Animals were scored daily for PLP autotomy behaviors, and several pain-related biomarkers were evaluated to discover possible underlying pathological changes. Majority displayed some degree of autotomy behavior following axotomy. Injury prior to axotomy led to more severe PLP behavior compared to animals without preceding injury. Autotomy behaviors were more directed toward the pretreatment insul...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Chronic neuropathic pain represents clinically challenging state with poor response to current treatment options. Long-term management of chronic pain is often associated with the development of tolerance, addiction and other side... more
Chronic neuropathic pain represents clinically challenging state with poor response to current treatment options. Long-term management of chronic pain is often associated with the development of tolerance, addiction and other side effects, reducing the therapeutic value of treatment. Alternative strategies based on cell therapy and gene manipulation, balancing the inhibitory and excitatory events in the spinal cord, may provide sustained pain relief in the long term. Transplantation of GABAergic cells has been successfully used to enhance inhibition and to restore physiological spinal pain processing. However, since the underlying mechanism of chronic pain development involves changes in several pain signaling pathways, it is essential to develop an approach targeting several components of pain signaling. Recombinant cell therapy offers the possibility to deliver additional analgesic substances to the restricted area in the nervous system. The current study explores the analgesic po...
Research Interests:
Research Interests:
Research Interests:
Research Interests: Regeneration, Stem Cells, Spinal Cord Injury, Medicine, Neuroplasticity, and 15 moreTransplantation, Animals, Spinal Cord, Male, Bone marrow, Mesenchymal Stem Cell, Clinical Sciences, Bone Marrow Transplantation, Rats, Wistar Rats, Neurotrauma, Spinal Cord Injuries, Neurosciences, Motor activity, and Recovery of Function
Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. However, most of the clinically potent CB1 receptor-active drugs derived from cannabis are considered concerning due to psychotomimetic side... more
Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. However, most of the clinically potent CB1 receptor-active drugs derived from cannabis are considered concerning due to psychotomimetic side effects. Selective CB receptor ligands that do not induce CNS side effects are of clinical interest. The venoms of marine snail Conus are a natural source of various potent analgesic peptides, some of which are already FDA approved. In this study we evaluated the ability of several Conus venom extracts to interact with CB1 receptor. HEK293 cells expressing CB1 receptors were treated with venom extracts and CB1 receptor internalization was analyzed by immunofluorescence. Results showed C. textile (C. Tex) and C. miles (C. Mil) samples as the most potent. These were serially subfractionated by HPLC for subsequent analysis by internalization assays and for analgesic potency evaluated in the formalin test and after peripheral nerve injury. Intrathecal injection of C. Tex and C. Mil subfractions reduced flinching/licking behavior during the second phase of formalin test and attenuated thermal and mechanical allodynia in nerve injury model. Treatment with proteolytic enzymes reduced CB1 internalization of subfractions, indicating the peptidergic nature of CB1 active component. Further HPLC purification revealed two potent antinociceptive subfractions within C. Tex with CB1 and possible CB2 activity, with mild to no side effects in the CB tetrad assessment. CB conopeptides can be isolated from these active Conus venom-derived samples and further developed as novel analgesic agents for the treatment of chronic pain using cell based or gene therapy approaches.
Research Interests:
Research Interests:
Research Interests:
Paclitaxel is a chemotherapeutic agent that causes peripheral neuropathy (PIPN) as a side effect of cancer treatment. Severely affected patients need to terminate chemotherapy, diminishing their chance of survival. The underlying causes... more
Paclitaxel is a chemotherapeutic agent that causes peripheral neuropathy (PIPN) as a side effect of cancer treatment. Severely affected patients need to terminate chemotherapy, diminishing their chance of survival. The underlying causes of PIPN are unclear, but epidermal, unmyelinated axons have been shown to be the first to degenerate. We previously utilized a zebrafish in vivo model to show that the epidermal matrix-metalloproteinase 13 (MMP-13) induces degeneration of unmyelinated axons, whereas pharmacological inhibition of MMP-13 prevented axon degeneration. The precise functions by which MMP-13 is regulated and affects axons, however, remained elusive. In this study, we assessed mitochondrial damage and reactive oxygen species (ROS) formation as possible inducers of MMP-13, and we analyzed MMP-13-dependent damage. We show that the small ROS, H2O2, is increased in keratinocytes following treatment with paclitaxel. Epidermal mitochondrial damage appears to be a source of ROS lea...
Dysfunctional γ-aminobutyric acid (GABA)-ergic inhibitory neurotransmission is hypothesized to underlie chronic neuropathic pain. Intraspinal transplantation of GABAergic neural progenitor cells (NPCs) may reduce neuropathic pain by... more
Dysfunctional γ-aminobutyric acid (GABA)-ergic inhibitory neurotransmission is hypothesized to underlie
chronic neuropathic pain. Intraspinal transplantation of GABAergic neural progenitor cells (NPCs) may reduce
neuropathic pain by restoring dorsal horn inhibition. Rat NPCs pre-differentiated to a GABAergic phenotype
were transplanted into the dorsal horn of rats with unilateral chronic constriction injury (CCI) of the sciatic
nerve. GABA signaling in antinociceptive effects of NPC grafts was tested with the GABAA receptor antagonist
bicuculline (BIC), GABAB receptor antagonist CGP35348 (CGP) and GABA reuptake inhibitor SKF 89976A (SKF).
NPC-treated animals showed decreased hyperalgesia and allodynia 1–3 week post-transplantation; vehicleinjected
CCI rats continued displaying pain behaviors. Intrathecal application of BIC or CGP attenuated the antinociceptive
effects of the NPC transplantswhile SKF injection induced analgesia in control rats. Electrophysiological
recordings in NPC treated rats showed reduced responses of wide dynamic range (WDR) neurons to
peripheral stimulation compared to controls. A spinal application of BIC or CGP increased wind-up response
and post-discharges of WDR neurons in NPC treated animals. Results suggest that transplantation of GABAergic
NPCs attenuate pain behaviors and reduce exaggerated dorsal horn neuronal firing induced by CCI. The effects of
GABA receptor inhibitors suggest participation of continuously released GABA in the grafted animals.
chronic neuropathic pain. Intraspinal transplantation of GABAergic neural progenitor cells (NPCs) may reduce
neuropathic pain by restoring dorsal horn inhibition. Rat NPCs pre-differentiated to a GABAergic phenotype
were transplanted into the dorsal horn of rats with unilateral chronic constriction injury (CCI) of the sciatic
nerve. GABA signaling in antinociceptive effects of NPC grafts was tested with the GABAA receptor antagonist
bicuculline (BIC), GABAB receptor antagonist CGP35348 (CGP) and GABA reuptake inhibitor SKF 89976A (SKF).
NPC-treated animals showed decreased hyperalgesia and allodynia 1–3 week post-transplantation; vehicleinjected
CCI rats continued displaying pain behaviors. Intrathecal application of BIC or CGP attenuated the antinociceptive
effects of the NPC transplantswhile SKF injection induced analgesia in control rats. Electrophysiological
recordings in NPC treated rats showed reduced responses of wide dynamic range (WDR) neurons to
peripheral stimulation compared to controls. A spinal application of BIC or CGP increased wind-up response
and post-discharges of WDR neurons in NPC treated animals. Results suggest that transplantation of GABAergic
NPCs attenuate pain behaviors and reduce exaggerated dorsal horn neuronal firing induced by CCI. The effects of
GABA receptor inhibitors suggest participation of continuously released GABA in the grafted animals.
Research Interests:
The histological assessment of spinal cord tissue in three dimensions has previously been very time consuming and prone to errors of interpretation. Advances in tissue clearing have significantly improved visualization of fluorescently... more
The histological assessment of spinal cord tissue in three dimensions has previously been very time consuming and prone to errors of interpretation. Advances in tissue clearing have significantly improved visualization of fluorescently labelled axons. While recent proof-of-concept studies have been performed with transgenic mice in which axons were prelabeled with GFP, investigating axonal regeneration requires stringent axonal tracing methods as well as the use of animal models in which transgenic axonal labeling is not available. Using rodent models of spinal cord injury, we labeled axon tracts of interest using both adeno-associated virus and chemical tracers and performed tetrahydrofuran-based tissue clearing to image multiple axon types in spinal cords using light sheet and confocal microscopy. Using this approach, we investigated the relationships between axons and scar-forming cells at the injury site as well as connections between sensory axons and motor pools in the spinal ...
The treatment of spinal cord injury (SCI)-induced neuropathic pain presents a challenging healthcare problem. The lack of available robust pharmacological treatments underscores the need for novel therapeutic methods and approaches. Due... more
The treatment of spinal cord injury (SCI)-induced neuropathic pain presents a challenging healthcare problem. The lack of available robust pharmacological treatments underscores the need for novel therapeutic methods and approaches. Due to the complex character of neuropathic pain following SCI, therapies targeting multiple mechanisms may be a better choice for obtaining sufficient long-term pain relief. Previous studies in our lab showed analgesic effects using combinations of an NMDA antagonist peptide [Ser1]histogranin (SHG), and the mu-opioid peptides endomorphins (EMs), in several pain models. As an alternative to drug therapy, this study evaluated the analgesic potential of these peptides when delivered via gene therapy. Lentiviruses encoding SHG and EM-1 and EM-2 were intraspinally injected, either singly or in combination, into rats with clip compression SCI 2 weeks following injury. Treated animals showed significant reduction in mechanical and thermal hypersensitivity, com...
Research Interests:
The heat shock protein 70 (HSP70) is a key component of the stress response induced by various noxious conditions such as heat, oxygen stress, trauma and infection. In present study we have assessed the consequences of the compression of... more
The heat shock protein 70 (HSP70) is a key component of the stress response induced by various noxious conditions such as heat, oxygen stress, trauma and infection. In present study we have assessed the consequences of the compression of lower lumbar and sacral nerve roots caused by a multiple cauda equina constrictions (MCEC) on HSP70 immunoreactivity (HSP70-IR) in the dog. Our data indicate that constriction of central processes evokes HSP70 up-regulation in the spinal cord (L7, S1-Co3) as well as in the corresponding dorsal root ganglion cells (DRGs) (L7-S1) two days following injury. A limited number of bipolar or triangular HSP-IR neurons were found in the lateral collateral pathway (LCP) as well as in the pericentral region (lamina X) of the spinal cord. In contrast, a high number of HSP70 exhibiting motoneurons with fine processes appeared in the ventral horn (laminae VIII-IX) of lumbosacral segments. Concomitantly, close to them a few lightly HSP70-positive neuronal somata o...
Research Interests:
Distal sensory neuropathies are a hallmark of HIV infections and can result in persistent and disabling pain despite advances in antiretroviral therapies. HIV-sensory neuropathic (HIV-SN) pain may be amenable to cannabinoid treatment, but... more
Distal sensory neuropathies are a hallmark of HIV infections and can result in persistent and disabling pain despite advances in antiretroviral therapies. HIV-sensory neuropathic (HIV-SN) pain may be amenable to cannabinoid treatment, but currently available agonist treatments are limited by untoward side effects and potential for abuse in this patient population. Fatty acid amide hydrolase (FAAH) inhibitors may offer an alternative approach by inhibiting the degradation of endocannabinoids with purportedly fewer untoward CNS side effects. In order to evaluate this potential approach in the management of HIV-SN pain, the recombinant HIV envelope protein gp120 was applied epineurally to the rat sciatic nerve to induce an HIV-SN-like pain syndrome. Two distinct FAAH inhibitory compounds, URB597 and PF-3845 were tested, and contrasted with standard antinociceptive gabapentin or vehicle treatment, for attenuation of tactile allodynia, cold allodynia, and mechanical hyperalgesia. Both FAAH inhibitors markedly reduced cold and tactile allodynia with limited anti-hyperalgesic effects. Peak antinociceptive effects produced by both agents were more modest than gabapentin in reducing tactile allodynia with similar potency ranges. URB597 produced comparable cold anti-allodynic effects to gabapentin, and the effects of both FAAH inhibitors were longer lasting than gabapentin. To assess the contribution of cannabinoid receptors in these antinociceptive effects, CB1 antagonist AM251 or CB2 antagonist SR144528 were tested in conjunction with FAAH inhibitors. Results suggested a contribution of both CB1- and CB2-mediated effects, particularly in reducing tactile allodynia. In summary, these findings support inhibition of endocannabinoid degradation as a promising target for management of disabling persistent HIV-SN pain syndromes.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Psychology, Pregnancy, Female, Animals, Spinal Cord, and 19 moreMale, Reaction Time, Temperature, Embryonic Stem Cells, Neurons, Clinical Sciences, Experimental, Rats, Analysis of Variance, Time Factors, Sciatica, Experimental Neurology, Action Potentials, Laminectomy, Neurosciences, Pain Measurement, Hyperalgesia, Pain Threshold, and Gamma-Aminobutyric Acid
Research Interests:
Chronic constriction injury (CCI) of the sciatic nerve in rats evokes c-Fos expression at spinal cord level. Using immunohistochemical methods we studied changes in c-Fos expression in the brain stem area, which is suggested as one of the... more
Chronic constriction injury (CCI) of the sciatic nerve in rats evokes c-Fos expression at spinal cord level. Using immunohistochemical methods we studied changes in c-Fos expression in the brain stem area, which is suggested as one of the major targets of projection neurons in the superficial dorsal horn laminae, i.e., the parabrachial area. During the first week following injury, the animals developed tactile allodynia. At this time we found an increase of c-Fos positive neurons in the parabrachial area, mainly in the pontine part where the group of c-Fos immunoreactive neurons was present in the dorsal part of lateral parabrachial subnuclei. The number of c-Fos positive neurons gradually decreased up to 14 days following CCI. The specific activation of brain stem neurons during onset of mechanical allodynia could underlie the changes in central nociceptive processing following peripheral nerve injury.
Research Interests:
Research Interests:
Research Interests: Animal Behavior, Immunohistochemistry, Spinal Cord Injury, Cell therapy, Cell Differentiation, and 22 moreMolecular and cellular biology, Humans, Cellular and Molecular Neurobiology, Female, Animals, Spinal Cord, Male, Statistical Significance, Bone marrow, Mesenchymal Stem Cell, Nerve Regeneration, Middle Aged, White matter, Rats, Adult, Functional Recovery, Wistar Rats, Spinal Cord Injuries, Neurosciences, Mesenchymal Stromal Cells, Biochemistry and cell biology, and Human Mesenchymal Stem Cells
Research Interests:
A prolonged exposure to vibration stimuli triggers pathological changes with many later manifested symptoms. Early vibration-induced changes are still not very well explored. Therefore, short 30 min vibration period per day with frequency... more
A prolonged exposure to vibration stimuli triggers pathological changes with many later manifested symptoms. Early vibration-induced changes are still not very well explored. Therefore, short 30 min vibration period per day with frequency 60 Hz repeated for 10 days was used, and the retrograde axonal transport from the sciatic nerve, the expression of calcitonin gene-related peptide (CGRP) and parvalbumin (PV) were studied in the dorsal root ganglia (DRGs) corresponding to lower lumbar spinal levels. Repeated vibration markedly decreased (25 and 34%) the accumulation of retrogradely transported Fluorogold to spinal motor neurons, whereas a significant increase (35 and 25%) was seen in the DRG primary sensory neurons corresponding to the L4 and L5 spinal level. Immunohistochemical studies showed a significant reduction of CGRP-positive small-sized neuronal cells in both DRGs. Fluoro-Jade labeling revealed that marked loss of CGRP-imunoreactive DRG sensory neurons is not due to neuronal degeneration. CGRP protein expression determined by Western blot analysis and optical density measurement, and NGF level measured by ELISA have been decreased, markedly only at the L4 DRG. PV protein expression was not affected by short repeated vibrations. Our results indicate that (a) short-lasting repeated vibrations affect the retrograde axonal transport in the DRG sensory neurons differently than in spinal motor neurons; (b) a decreased NGF-dependent CGRP production in the DRG primary sensory neurons plays an important role in early vibration-induced pathological mechanisms.