Root Ganglion Research Articles

Rhizotomy and endoscopic discectomy for chronic low back pain and acute radiculopathy in a stiff-person syndrome - case report

INTRODUCTION: Stiff Person Syndrome (SPS) is a rare neurological disorder, first described in 1956 by Moersch and Woltman. The clinical picture has an insidious onset of classic findings of episodic painful spasms, hyperreflexia, axial muscle stiffness, progressing slowly to the proximal limb muscles. Painful hyperlordosis due to lumbar spine stiffness is a diagnostic characteristic of SPS. CASE REPORT: Male, 69 years old, with SPS for 40 years, referred by the neurologist to the spine surgeon because of failure to conservative management of chronic low back pain, progressively acute leg and gait impairment. Physical examination is difficult to perform in SPS because it triggers spasms. MRI presented zygoapophyseal joint, intervertebral discs and muscle degeneration, including a L4L5 cranial migrated herniated disc. Once there were no other effective ways to manage his axial and radicular pain, it was decided to perform percutaneous transforaminal endoscopic discectomy for L4L5 decompression, L3 to S1 dorsal ganglion root medial branch ablative radiofrequency rhizotomy to relieve facet pain and L2 dorsal sensory ganglion pulsed radiofrequency rhizotomy for modulation of chronic low back pain. One year postoperative follow up, the patient has showed improvement in the VAS and SF-36. CONCLUSION: Chronic pain reported by a patient must be addressed in the biological, psychological and social dimensions. Understanding the multidimensionality of the factors involved with pain allows planning less aggressive and highly efficient strategies in uncommon and off label patients, as in the case of SPS.

Complex regional pain syndrome of the knee after conventional radiofrequency ablation of the genicular nerves treated successfully with dorsal root ganglion stimulation: A case report

BackgroundRadiofrequency (RF) treatment of the genicular nerves offers pain relief in patients suffering from chronic knee pain including persistent post‐surgical knee pain (PPSP). We present the first case report of the development of complex regional pain syndrome (CRPS) in a chronic knee pain patient after an RF ablation of the genicular nerves that was successfully treated with dorsal root ganglion (DRG) stimulation.Case PresentationThe patient developed increased pain, sympathetic and dysmorphic changes of the index knee 10 weeks after RF treatment for PPSP. Diagnosis of CRPS type II was made using positive clinical findings and the Budapest diagnostic tool. Laboratory workup and PET‐CT were negative. The patient was refractory to usual care and she was treated successfully with dorsal ganglion root stimulation.ConclusionsComplex regional pain syndrome is a possible complication of RF ablation of the genicular nerves in patients with chronic knee pain, and DRG stimulation may be a treatment option. Physicians should be aware of this complication, especially when patients have a medical history of CRPS.

“HERPES ZOSTER – CASE REPORT”

Herpes zoster (HZ) commonly referred as shingles is reactivation of varicella zoster. Herpes zoster is usually seen in older age group whereas varicella zoster is seen in younger age group. Reactivation of varicella zoster from dorsal root of ganglion results in HZ. The clinical features include painful vesicular rash along the affected dermatome and pain may persist even after skin lesions heal. Complication of HZ are Post Herpetic Neuralgia, Ramsay hunt syndrome. Antiviral drugs are the main treatment of choice. We report a case of Herpes zoster in a 65-year-old female patient and highlights on clinical features complications and various treatment modalities.

High‑glucose microenvironment promotes perineural invasion of pancreatic cancer via activation of hypoxia inducible factor 1α.

Pancreatic cancer (PC) is one of the most lethal diseases, with a 5-year survival rate of <9%. Perineural invasion (PNI) is a common pathological hallmark of PC and is correlated with a poor prognosis in this disease. Hyperglycemia has been shown to promote the invasion and migration of PC cells; however, the effect of hyperglycemia on the PNI of PC and its underlying mechanism remains unclear. In the present study, Western blotting was utilized to detect the expression of hypoxia inducible factor 1α (HIF1α) and nerve growth factor (NGF). Transwell and wound-healing assays were performed to detect the influence of hyperglycemia on the invasion and migration ability of PC cells. An in vitro PC-dorsal root ganglion (DRG) co-culture system and an in vivo PNI sciatic nerve-infiltrating tumor model were used to evaluate the severity of PNI in hyperglycemic conditions. In the results, hyperglycemia promoted the invasion/migration ability and elevated the expression of NGF in PC by upregulating HIF1α. Moreover, in vitro short-term hyperglycemia caused little damage on the DRG axons and accelerated both the PNI of the PC and the outgrowth of the DRGs by increasing the expression of NGF via activation of HIF1α. Indeed, in vivo long-term hyperglycemia promoted the infiltration and growth of PC, and then disrupted the function of the sciatic nerve in a HIF1α-dependent manner. In conclusion, a high-glucose microenvironment promotes PNI of PC via activation of HIF1α.

Serpinin in the Skin.

The serpinins are relatively novel peptides generated by proteolytic processing of chromogranin A and they are comprised of free serpinin, serpinin-RRG and pGlu-serpinin. In this study, the presence and source of these peptides were studied in the skin. By Western blot analysis, a 40 kDa and a 50 kDa protein containing the sequence of serpinin were detected in the trigeminal ganglion and dorsal root ganglia in rats but none in the skin. RP-HPLC followed by EIA revealed that the three serpinins are present in similar, moderate amounts in rat dorsal root ganglia, whereas in the rat skin, free serpinin represents the predominant molecular form. There were abundant serpinin-positive cells in rat dorsal root ganglia and colocalization with substance P was evident. However, much more widespread distribution of the serpinins was found in dorsal root ganglia when compared with substance P. In the skin, serpinin immunoreactivity was found in sensory nerves and showed colocalization with substance P; as well, some was present in autonomic nerves. Thus, although not exclusively, there is evidence that serpinin is a constituent of the sensory innervation of the skin. The serpinins are biologically highly active and might therefore be of functional significance in the skin.

The Anti-Inflammatory and Anti-Pruritus Mechanisms of Huanglian Jiedu Decoction in the Treatment of Atopic Dermatitis.

Atopic dermatitis (AD) is a common chronic skin disease driven by a T-cell-mediated immune response, with inflammation and pruritus being its main clinical manifestations. Huanglian Jiedu decoction (HLJDT), which is an ancient Chinese medicine herbal formula derived from Wai-Tai-Mi-Yao, is a potentially effective treatment for AD. We aimed to clarify the anti-inflammatory and anti-pruritus mechanisms of HLJDT in AD treatment. We performed immunohistochemistry, Western blotting, reverse transcriptase-polymerase chain reaction, Luminex-based direct multiplex immunoassay, enzyme-linked immunosorbent assays, and flow cytometry to address the abovementioned aims. HLJDT significantly reduced clinical symptoms and ear swelling in AD-like mice by inhibiting the production of cytokines [histamine, interleukin (IL)-3, IL-4, IL-5, IL-13, IL-17A, IL-31, and IL-33], substance P (SP), transient receptor potential cation channel subfamily V member 1 (TRPV-1), and gastrin-releasing peptide (GRP). Additionally, HLJDT significantly suppressed the protein expression levels and positive cell percentage of CD28, CD80, CD86, CD207, CD326, MHCII, and OX40 in the lymphoid nodes. Moreover, HLJDT significantly suppressed mRNA and protein expression of tyrosine–protein kinase (JAK1), histamine H4 receptor, and IL-4Rα, as well as the protein expression of GRP, SP, and TRPV-1 in the root ganglion. Our findings indicate that HLJDT can treat AD by regulating the antigen presentation function of dendritic cells, weakening T-lymphocyte activation, and subsequently exerting anti-inflammatory and anti-pruritus effects.

Abstract 1450: Neural communication to peripheral tumors regulates cancer cell activity

Abstract Transcriptomics and sequencing analyses of tumors from patients provide invaluable information about the cells present in the tumor microenvironment (TME); however, nerves, whose cell bodies are absent from most peripheral TMEs, have eluded such approaches. Recent emerging data highlight the functional importance of innervation in the TME and its contribution to tumor progression, metastasis, and treatment resistance. The Exoneural Platform developed at Cygnal Therapeutics allows for investigation of complex biology in the context of multi-cell culture conditions in vitro and in vivo. As part of this platform, we have developed tools for rapid and selective manipulation of different cell types with the ability to monitor multiple cell specific read-outs. Here, we used a combination of approaches including RNA-seq, bioinformatics, immunohistochemistry, and microscopy to investigate the role of synaptic function in cancer biology. Transcriptomics analyses on co-cultures revealed a direct interaction between nerves and cancer cells based on cell type specific gene expression and ligand - receptor interaction assessment. Both neurons and cancer cells showed a profound shift in their gene expression profile when cultured together. This differential gene expression was reversed if neurons were ablated, pointing to the reversibility of this change and, potentially, the disease state itself. Examination for presence and function of synaptic proteins showed that synaptic proteins, such as PSD95 and synapsin1, were expressed in co-cultures, and in many cases, a co-localization of pre - and post - synaptic markers was observed. Selective stimulation of dorsal ganglion root (DRG) neurons, co-cultured with cancer cells, resulted in a robust and acute increase of cytosolic calcium in cancer cells. Bioinformatic image analysis confirmed that this calcium influx in cancer cells directly correlated with proximity and density of neurites to cancer cells. A calcium response was not observed if DRGs and cancer cells were cultured in two separate chambers between which media can freely travel, confirming that close proximity is required for this interaction. Pharmacological and genetic knock down of key synaptic proteins resulted in changes in cancer cell calcium influx and affected proliferation and gene expression. Bioinformatics analyses, based on public and proprietary data, have identified the synaptic pathway as a major contributing node that influences cancer cell biology in the context of several cancer types. These data collectively point to the importance of exoneural biology, and more specifically, synaptic biology in cancer. More importantly, these results are likely to suggest new oncology targets that have not been identified or pursued previously. Citation Format: Monica Thanawala, Chih-Chieh Wang, Jesse G. Turner, Kai-Chih Huang, Lexiang Ji, Alison Miller, Alexandria Fink, Shan Lou, Alexandra B. Lantermann, Hongyue Dai, John A. Wagner, Grazia Piizi, Jonathan B. Hurov, Pearl Huang, Amir M. Sadaghiani. Neural communication to peripheral tumors regulates cancer cell activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1450.

Benefits of telemedicine in diagnosis of herpes zoster ophthalmicus with timely management and follow-up

Sir, Herpes Zoster is caused by the viral reactivation of Varicella Zoster virus, that enters the cutaneous nerve endings during an earlier episode of chicken pox and travels to the Dorsal Root Ganglia and remains latent. It is characterized by the occurrence of vesicular lesions grouped along the Single Dermatome innervated by Dorsal Root of Sensory Ganglion. Herpes Zoster Ophthalmicus (HZO) is involvement of the ophthalmic division of the fifth cranial nerve. It is the second most common type of Herpes Zoster (HZ), after Thoracic Zoster [1]. We present here, a case of Herpes Zoster in a young girl involving Supraorbital, Maxillary and Mandibular of the Trigeminal nerve. Timely diagnosis of HZO was made. The lesion on the tip of the nose (Hutchinson’s sign) alerted the involvement of Nasociliary nerve and to arrange immediate Ophthalmology consultation. Tele-Dermatology helped in reducing waiting time, fast delivery of care and prevention of visual disability [2]. The patient was monitored, motivated and treated, that could happen because of tele- dermatology. Dramatic improvement in the patient was observed in a very short time. The use of tele-dermatology, especially in times of the COVID – 19 pandemic is invaluable. The patient was a girl aged 12-years, presented through telemedicine with 3 days of lesions on the face mimicking acne. On close examination, there were a few Vesicular Lesions among multiple lesions and there was involvement of tip of the nose. Patient also complained of eye pain. This helped us to consider HZO. Prompt immediate treatment with anti-virus was initiated. It was possible to do continuous monitoring with the help of Tele-Medicine and without the patient having to leave the house in COVID era. Patient was advised to consult an Ophthalmologist for further evaluation. As it was essential, for examination of the eye parameters, patient had to attend in person. This one visit was not through Tele-Medicine. Patient was informed on day-1 of treatment that the condition may initially worsen under proper adequate treatment with a graphic representation (Fig. 1) and then decrease later. And this happened in our case, as seen in the six consecutive photographs as indicated below with date and time of the photographs by the patient, which are presented to illustrate the natural progression of disease under proper adequate treatment. This helped in avoiding panic to the patient. The lesions as seen in the pictures became aggressive in two days which means, the eye could have been affected more but for the immediate treatment given. Patient could get treatment from home by consulting online through out, thereby reducing the risk of venturing to a clinic in COVID situation. Except for one visit to the Ophthalmologist which was inevitable. Ocular Manifestations – Ocular manifestations affect about 50% of patients with HZO and can be isolated. This proportion reaches 80% in case of appearance of the Hutchinson Sign. The latter reflects the involvement of the nasociliary branch and is characterized by eruption on the side and on the tip of the nose [3]. Eye examination showed that there was congestion generalized in Conjunctiva. Corneal sensation was reduced, Iris anterior chamber, Pupil, lens, Fundus and extra ocular movements were normal. Immediate treatment was instituted after counselling about the treatment. The patient was advised Valacyclovir 1000 mg, 3 times a day for 7 days along with adequate fluid intake. For relief of pain, patient was given Pregabalin, Tremedol 25 mg and Gabapentin 6%W/W+Lidocaine 5%W/W smooth locally. Eye treatment As per Ophthalmologists advice, Polyethylene glycol 400 0.4% + Propylene glycol 0.3% five times a day and Acyclovir eye ointment a day was prescribed to the patient. All the pictures were taken by the patient and shared with the doctor, during the course of the treatment helping in regular monitoring have been presented (1a – 1f). In this case, Telemedicine gave the scope of reducing waiting time, providing correct diagnosis, enabling faster delivery of care, enabling tele based access to monitor the patient’s condition, counselling, management, monitoring with good end result. Key Takeaways • The importance of (Hutchinson’s sign) involvement of the tip of nose is emphasized. • Counselling the patient with regard to the possibility of worsening of the visible symptoms while under appropriate and adequate treatment, should be given with the help of a graphic representation (Fig. 2). • Prompt referral to Ophthalmologist is necessary. • The consultant and the patient should be conscious of associated potential Vision threatening complications and the need for prompt treatment to protect from visual complications.

Chemokine receptor CXCR7 non-cell-autonomously controls pontine neuronal migration and nucleus formation

Long distance tangential migration transports neurons from their birth places to distant destinations to be incorporated into neuronal circuits. How neuronal migration is guided during these long journeys is still not fully understood. We address this issue by studying the migration of pontine nucleus (PN) neurons in the mouse hindbrain. PN neurons migrate from the lower rhombic lip first anteriorly and then turn ventrally near the trigeminal ganglion root towards the anterior ventral hindbrain. Previously we showed that in mouse depleted of chemokine receptor CXCR4 or its ligand CXCL12, PN neurons make their anterior-to-ventral turn at posteriorized positions. However, the mechanism that spatiotemporally controls the anterior-to-ventral turning is still unclear. Furthermore, the role of CXCR7, the atypical receptor of CXCL12, in pontine migration has yet to be examined. Here, we find that the PN is elongated in Cxcr7 knockout due to a broadened anterior-to-ventral turning positions. Cxcr7 is not expressed in migrating PN neurons en route to their destinations, but is strongly expressed in the pial meninges. Neuroepithelium-specific knockout of Cxcr7 does not recapitulate the PN phenotype in Cxcr7 knockout, suggesting that CXCR7 acts non-cell-autonomously possibly from the pial meninges. We show further that CXCR7 regulates pontine migration by modulating CXCL12 protein levels.

Ganglion-Specific Sensitivity of P2X3 Receptors to Leu-Enkephalin

In this study, several properties of modulation of P2X3 currents by an endogenous opioid, leu-enkephalin (LEK), in neurons of the dorsal root and nodose ganglia (DRGs and NGs, respectively) were compared. P2X3-mediated currents were recorded using a patch-clamp technique in the whole-cell configuration. P2X3 receptors in DRG neurons were found to be more sensitive to LEK application compared to NG neurons; complete suppression of the corresponding currents required lower concentrations of LEK and rose more quickly. Short-term preapplication of naloxone (a nonselective opioid receptor antagonist) on NG neurons did not alter the effect of the tested opioid on P2X3 currents, while it dramatically enhanced LEK-induced inhibition in DRG neurons. This fact may be indicative of the existence of specific intracellular pathways involved in opioid-induced modulation of P2X3 receptors of different peripheral ganglia in vertebrates.

Anatomical variations of the ciliary ganglion with an emphasis on the location in the orbit.

The ciliary ganglion is of outmost physiological importance, due to its involvement in pupillary light reflex circuits. The ciliary ganglion may be damaged during surgical procedures. Therefore, the aim of the study was to examine the anatomical variations of the ganglion with an emphasis in location in the orbit. Anatomical variations of the parasympathetic root of the ganglion were also examined and classified. 40 orbits were dissected. The orbital content was removed en bloc. The lateral rectus muscle was detached from its insertion and reflected. After the removal of the orbital fat, the ciliary ganglion was visualized. Then, the morphology, roots and location of the ganglion were assessed. The location of the ciliary ganglion varied from 17 to 83.7% (mean = 51.4%, median = 53%, SD 14.8%) of the distance between the point of the optic nerve emerging from the eyeball and the common tendinous ring (counting from the front). In most cases (55%) it was found between 50.1 and 75% of the distance between the back of the eye and the common tendinous ring, while in 37.5% of cases it was found between 25 and 50% of this distance. The parasympathetic root of the ciliary ganglion was variable. Its origin was from the nerve to the inferior oblique muscle in most of cases. In four cases (10%), the parasympathetic root of the ciliary ganglion was duplicated. The ciliary ganglion occupies a variable position with regards to the optic nerve. The parasympathetic root of the ganglion may be unusually short or doubled.

Important regulatory function of transient receptor potential ankyrin 1 receptors in age-related learning and memory alterations of mice

Expression of the transient receptor potential ankyrin 1 (TRPA1) receptor has been demonstrated not only in the dorsal root and trigeminal ganglia but also in different brain regions (e.g., hippocampus, hypothalamus, and cortex). However, data concerning their role in neurodegenerative and age-related diseases of the CNS is still indistinct. The aim of our study was to investigate the potential role of TRPA1 in a mouse model of senile dementia. For the investigation of changes during aging, we used male young (3–4-month-old) and old (18-month-old) wild-type (TRPA1+/+;WT) and TRPA1 receptor gene-deleted (TRPA1−/−) mice. Novel object recognition (NOR) test as well as Y maze (YM), radial arm maze (RAM), and Morris water maze (MWM) tests were used to assess the decline of memory and learning skills. In the behavioral studies, significant memory loss was detected in aged TRPA1+/+ mice with the NOR and RAM, but there was no difference measured by YM and MWM tests regarding the age and gene. TRPA1−/− showed significantly reduced memory loss, which could be seen as higher discrimination index in the NOR and less exploration time in the RAM. Furthermore, young TRPA1−/− animals showed significantly less reference memory error in the RAM and notably higher mobility in NOR, RAM, and YM compared with the age-matched WTs. Our present work has provided the first evidence that TRPA1 receptors mediate deteriorating effects in the old age memory decline. Understanding the underlying mechanisms could open new perspectives in the pharmacotherapy of dementia.

Autophagy is essential for oligodendrocyte differentiation, survival, and proper myelination.

Deficient myelination, the spiral wrapping of highly specialized membrane around axons, causes severe neurological disorders. Maturation of oligodendrocyte progenitor cells (OPC) to myelinating oligodendrocytes (OL), the sole providers of central nervous system (CNS) myelin, is tightly regulated and involves extensive morphological changes. Here, we present evidence that autophagy, the targeted isolation of cytoplasm and organelles by the double-membrane autophagosome for lysosomal degradation, is essential for OPC/OL differentiation, survival, and proper myelin development. A marked increase in autophagic activity coincides with OL differentiation, with OL processes having the greatest increase in autophagic flux. Multiple lines of evidence indicate that autophagosomes form in developing myelin sheathes before trafficking from myelin to the OL soma. Mice with conditional OPC/OL-specific deletion of the essential autophagy gene Atg5 beginning on postnatal Day 5 develop a rapid tremor and die around postnatal Day 12. Further analysis revealed apoptotic death of OPCs, reduced differentiation, and reduced myelination. Surviving Atg5-/- OLs failed to produce proper myelin structure. In vitro, pharmacological inhibition of autophagy in OPC/dorsal root ganglion (DRG) co-cultures blocked myelination, producing OLs surrounded by many short processes. Conversely, autophagy stimulation enhanced myelination. These results implicate autophagy as a key regulator of OPC survival, maturation, and proper myelination. Autophagy may provide an attractive target to promote both OL survival and subsequent myelin repair after injury.

The protective effects of aripiprazole on vincristine - induced peripheral neuropathy in a rat model

Clinical use of vincristine (VCR), an effective chemotherapeutic agent, has been limited due to its peripheral neuropathy toxicity. Aripiprazole, which is an antipsychotic agent is a partial agonist the dopaminergic D2 receptor (D2R) and the serotonin 5-HT1A and 5-HT7 receptors Several studies have shown that aripiprazole exerts neuroprotective and immunomodulatory properties. This study aimed to investigate the effects of aripiprazole on brain injury in a rat model. Male Wistar rats were intraperitoneally injected with VCR and normal saline four times per week for 2 weeks. In the treatment group, aripiprazole (3 mg/kg) was administered intraperitoneally 30 min prior to VCR injection every day. Mortality rate, weight variations and histopathological changes were monitored. Hot plate, tail flick, von fery and motor nerve conduction velocity (MNCV) tests were used to evaluate sensory and motor neuropathy. Levels of nNOS and iNOS were assessed by enzyme-linked immunosorbent assay (ELISA). Moreover, the protein levels of caspase-3, p65 nuclear factor kappa B (NF-<kappa>B) and phospho-p65 NF-<kappa>B in the dorsal ganglion root were examined by Western blot analysis. Co-administration of aripiprazole with VCR significantly reversed alterations in the hot plate, tail flick threshold, von frey and sciatic MNCV induced by VCR and also prevented mixed sensory-motor neuropathy, as indicated by better general conditions, behavioral and electrophysiological results. In addition, aripiprazole improved the body weight loss caused by VCR. The levels of iNOS and nNOS were significantly diminished in the treatment group. These findings were confirmed by western blot and histopathological analysis. In conclusion, this study demonstrated that aripiprazole significantly attenuated VCR-induced neuropathy and could be considered as a neuroprotective agent to prevent the VCR-induced neuropathy.

The protective effects of sumatriptan on vincristine - induced peripheral neuropathy in a rat model

Clinical use of vincristine (VCR), an effective chemotherapeutic agent, has been limited due to its peripheral neuropathy toxicity. Sumatriptan, which is an anti-migraine agent is a specific agonist for 5-hydroxytryptamine 1B, 1D (5HT1B, 1D) receptors. Several studies have shown that sumatriptan exerts anti-inflammatory and immunomodulatory properties. This study aimed to investigate the effects of sumatriptan on VCR-induced peripheral neuropathy in a rat model. Male Wistar rats were intraperitoneally injected with VCR and normal saline four times per week for 2 weeks. In the treatment group, sumatriptan (1 mg/kg) was administered intraperitoneally 30 min prior to VCR injection every day. Mortality rate, weight variations and histopathological changes were monitored. Hot plate, tail flick and motor nerve conduction velocity (MNCV) tests were used to evaluate sensory and motor neuropathy. Levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and caspase-3 in the dorsal ganglion root were assessed by quantitative reverse transcription-PCR (qRT-PCR). Moreover, the protein levels of p65 nuclear factor kappa B (NF-<kappa > B) and phospho-p65 NF-<kappa > B were examined by Western blot analysis. Co-administration of sumatriptan with VCR significantly reversed alterations in the hot plate, tail flick threshold and sciatic MNCV induced by VCR and also prevented mixed sensory-motor neuropathy, as indicated by better general conditions, behavioral and electrophysiological results. In addition, sumatriptan improved the body weight loss caused by VCR. The mRNA levels of TNF-α, IL-1β and caspase-3 were significantly diminished in the treatment group. These findings were confirmed by histopathological analysis. In conclusion, this study demonstrated that sumatriptan significantly attenuated VCR-induced neuropathy and could be considered as a neuroprotective agent to prevent the VCR-induced neuropathy.

Serum response factor mediates nociceptor inflammatory pain plasticity.

Chronic metabotropic glutamate receptor activation in nociceptive afferents may upregulate A-Kinase Anchoring Protein 150 (AKAP150) expression and/or function. To quantify transcriptional changes in AKAP150 expression and/or function after long-term mGluR5 agonist exposure, and identify transcriptional elements responsible. Dorsal root ganglia (DRG) were dissected from Sprague-Dawley rats and cultured for biochemical analysis of AKAP150 expression after prolonged mGluR5 agonist exposure. Serum response factor (SRF) expression was knocked down through siRNA in cultures to demonstrate significance to AKAP150 upregulation. Serum response factor was also knocked down in vivo through intrathecal injections of specifically targeted oligonucleotides to demonstrate significance to hyperalgesic priming behavior in persistent mechanical hypersensitivity. Serum response factor and AKAP150 are coexpressed in TRPV1(+) DRG neurons in intact DRG. Prolonged mGluR5 agonist exposure increases SRF-dependent transcription and AKAP150 expression in a manner sensitive to protein kinase C inhibition and SRF knock down. Serum response factor in vivo knock down reduces mechanical hyperalgesic priming. Serum response factor transcription plays an important role in transcriptional upregulation of AKAP and hyperalgesic priming behavior, and may contribute to the increased role of AKAP150 in the transition from acute to chronic pain.

Sex differences in primary muscle afferent sensitization following ischemia and reperfusion injury

BackgroundChronic pain conditions are more prevalent in women, but most preclinical studies into mechanisms of pain generation are performed using male animals. Furthermore, whereas group III and IV nociceptive muscle afferents provoke central sensitization more effectively than their cutaneous counterparts, less is known about this critical population of muscle nociceptors. Here, we compare the physiology of individual muscle afferents in uninjured males and females. We then characterize the molecular, physiological, and behavioral effects of transient ischemia and reperfusion injury (I/R), a model we have extensively studied in males and in females.MethodsResponse properties and phenotypes to mechanical, thermal, and chemical stimulation were compared using an ex vivo muscle/nerve/dorsal root ganglia (DRG)/spinal cord recording preparation. Analyses of injury-related changes were also performed by assaying evoked and spontaneous pain-related behaviors, as well as mRNA expression of the affected muscle and DRGs. The appropriate analyses of variance and post hoc tests (with false discovery rate corrections when needed) were performed for each measure.ResultsFemales have more mechanically sensitive muscle afferents and show greater mechanical and thermal responsiveness than what is found in males. With I/R, both sexes show fewer cells responsive to an innocuous metabolite solution (ATP, lactic acid, and protons), and lower mechanical thresholds in individual afferents; however, females also possess altered thermal responsiveness, which may be related to sex-dependent changes in gene expression within the affected DRGs. Regardless, both sexes show similar increases in I/R-induced pain-like behaviors.ConclusionsHere, we illustrate a unique phenomenon wherein discrete, sex-dependent mechanisms of primary muscle afferent sensitization after ischemic injury to the periphery may underlie similar behavioral changes between the sexes. Furthermore, although the group III and IV muscle afferents are fully developed functionally, the differential mechanisms of sensitization manifest prior to sexual maturity. Hence, this study illustrates the pressing need for further exploration of sex differences in afferent function throughout the lifespan for use in developing appropriately targeted pain therapies.

Lipopolysaccharide from Rhodobacter sphaeroides (TLR4 antagonist) attenuates hypersensitivity and modulates nociceptive factors

Context: Accumulating evidence has demonstrated that Toll-like receptors (TLRs), especially TLR4 localized on microglia/macrophages, may play a significant role in nociception.Objective: We examine the role of TLR4 in a neuropathic pain model. Using behavioural/biochemical methods, we examined the influence of TLR4 antagonist on levels of hypersensitivity and nociceptive factors whose contribution to neuropathy development has been confirmed.Materials and methods: Behavioural (von Frey’s/cold plate) tests were performed with Wistar male rats after intrathecal administration of a TLR4 antagonist (LPS-RS ULTRAPURE (LPS-RSU), 20 μG: lipopolysaccharide from Rhodobacter sphaeroides, InvivoGen, San Diego, CA) 16 H and 1 h before chronic constriction injury (cci) to the sciatic nerve and then daily for 7 d. three groups were used: an intact group and two cci-exposed groups that received vehicle or LPS-RSU. tissue [spinal cord/dorsal root ganglia (DRG)] for western blot analysis was collected on day 7.Results: The pharmacological blockade of TLR4 diminished mechanical (from ca. 40% to 16% that in the INTACT group) and thermal (from ca. 51% to 32% that in the INTACT group) hypersensitivity despite the enhanced activation of IBA-1-positive cells in DRG. Moreover, LPS-RSU changed the ratio between IL-18/IL-18BP and MMP-9/TIMP-1 in favour of the increase of antinociceptive factors IL-18BP (25%-spinal; 96%-DRG) and TIMP-1 (15%-spinal; 50%-DRG) and additionally led to an increased IL-6 (40%-spinal; 161%-DRG), which is known to have analgesic properties in neuropathy.Conclusions: Our results provide evidence that LPS-RSU influences pain through the expression of TLR4. TLR4 blockade has analgesic properties and restores the balance between nociceptive factors, which indicates its engagement in neuropathy development.

Lentiviral Transduction of Rat Schwann Cells and Dorsal Root Ganglia Neurons for In Vitro Myelination Studies.

Lentiviral transduction is a gene delivery method that provides numerous advantages over direct transfection and traditional retroviral or adenoviral delivery methods. It facilitates for the transduction of primary cells inherently difficult to transfect, delivers constructs of interest to nondividing as well as dividing cells, and permits the long-term expression of sizable DNA inserts (e.g., <7kb). The study of peripheral nerve myelination at the molecular level has long benefited from the Schwann cells/dorsal root ganglia (DRG) neurons myelinating co-culture system. As this culture system takes about a month to develop and perform experiments with, lentiviral-delivered constructs can be used to manipulate gene expression in Schwann cells and DRG neurons, primary cells that are otherwise resilient to direct transfection. Here we present our protocol for lentiviral production and purification and subsequent infection of large numbers of Schwann cells and/or DRG neurons for the molecular study of peripheral nerve myelination in vitro.

MiR-106a Associated with Diabetic Peripheral Neuropathy Through the Regulation of 12/15-LOX-meidiated Oxidative/Nitrative Stress.

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes with a complex pathogenesis. Study has reported that oxidative stress and nitrative stress are all involved in the DPN. However, the mechanism between them is still unclear. In the present study, we investigated whether miR-106a regulated 12/15-Lipoxygenase (12/15-LOX) of oxidative/nitrative stress (OS/NS) in DPN. Dorsal root ganglion (DRG) was isolated from 10 healthy mice and 10 DPN mice. DPN mouse model was established by the injection of streptozotocin (STZ), and high glucose was used for inducing the in vitro model of DPN. In DPN mice, the levels of fasting blood-glucose (FBG) level, Methane Dicarboxylic Aldehyde (MDA) and the Inducible Nitric Oxide Synthase (iNOS) were increased, while the levels of motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNCV) and superoxide dismutase (SOD) were decreased. MiR-106a level in DRG cells of DPN was decreased. The 12/15-LOX expression and cell apoptosis were increased. DRG cells subjected to high glucose resulted in the same effects as above. MiR-106a was observed to target 12/15-LOX and regulated its expression. MiR-106a overexpression reversed the effect that was induced by high glucose, however, overexpression of 12/15-LOX reversed the effect that was induced by miR-106a overexpression. MiR-106 may be associated with 12/15-LOX mediated OS/NS in DPN and may be considered as a potential therapeutic target.