Insular cortex stimulation alleviates neuropathic pain through changes in the expression of collapsin response mediator protein 2 involved in synaptic plasticity

In recent studies, brain stimulation has shown promising potential to alleviate chronic pain. Although studies have shown that stimulation of pain-related brain regions can induce pain-relieving effects, few studies have elucidated the mechanisms of brain stimulation in the insular cortex (IC). The present study was conducted to explore the changes in characteristic molecules involved in pain modulation mechanisms and to identify the changes in synaptic plasticity after IC stimulation (ICS). Following ICS, pain-relieving behaviors and changes in proteomics were explored. Neuronal activity in the IC after ICS was observed by optical imaging. Western blotting was used to validate the proteomics data and identify the changes in the expression of glutamatergic receptors associated with synaptic plasticity. Experimental results showed that ICS effectively relieved mechanical allodynia, and proteomics identified specific changes in collapsin response mediator protein 2 (CRMP2). Neuronal activity in the neuropathic rats was significantly decreased after ICS. Neuropathic rats showed increased expression levels of phosphorylated CRMP2, alpha amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR), and N-methyl-d-aspartate receptor (NMDAR) subunit 2B (NR2B), which were inhibited by ICS. These results indicate that ICS regulates the synaptic plasticity of ICS through pCRMP2, together with AMPAR and NR2B, to induce pain relief.

Alleviation of peripheral sensitization by quadriceps insertion of cog polydioxanone filaments in knee osteoarthritis rats

A recently established therapeutic strategy, involving the insertion of biodegradable cog polydioxanone filaments into the quadriceps muscles using the Muscle Enhancement and Support Therapy (MEST) device, has demonstrated significant efficacy in alleviating knee osteoarthritis (OA) pain. This study investigated changes in peripheral sensitization as the potential mechanism underlying MEST-induced pain relief in monoiodoacetate (MIA) induced OA rats. The results revealed that MEST treatment potently reduces MIA-induced sensitization of L3/L4 dorsal root ganglion (DRG) neurons, the primary nociceptor pathway for the knee joint. This reduction in DRG sensitization, as elucidated by voltage-sensitive dye imaging, is accompanied by a diminished overexpression of TRPA1 and NaV1.7, key nociceptor receptors involved in mechanical pain perception. Importantly, these observed alterations strongly correlate with a decrease in mechanically-evoked pain behaviors, providing compelling neurophysiological evidence that MEST treatment alleviates OA pain by suppressing peripheral sensitization.

Insular cortex stimulation alleviates neuropathic pain via ERK phosphorylation in neurons

AIMS

The clinical use of brain stimulation is attractive for patients who have side effects or tolerance. However, studies on insular cortex (IC) stimulation are lacking in neuropathic pain. The present study aimed to investigate the effects of IC stimulation (ICS) on neuropathic pain and to determine how ICS modulates pain.

METHODS

Changes in pain behaviors were observed following ICS with various parameters in neuropathic rats. Western blotting was performed to assess molecular changes in the expression levels of phosphorylated extracellular signal-regulated kinase (pERK), neurons, astrocytes, and microglia between experimental groups. Immunohistochemistry was performed to investigate the colocalization of pERK with different cell types.

RESULTS

The most effective pain-relieving effect was induced at 50 Hz-120 μA in single trial of ICS and it maintained 4 days longer after the termination of repetitive ICS. The expression levels of pERK, astrocytes, and microglia were increased in neuropathic rats. However, after ICS, the expression levels of pERK were decreased, and colocalization of pERK and neurons was reduced in layers 2-3 of the IC.

CONCLUSION

These results indicated that ICS attenuated neuropathic pain by the regulation of pERK in neurons located in layers 2-3 of the IC. This preclinical study may enhance the potential use of ICS and identify the therapeutic mechanisms of ICS in neuropathic pain.

Diffusion tensor imaging reveals sex differences in pain sensitivity of rats

Studies on differences in brain structure and function according to sex are reported to contribute to differences in behavior and cognition. However, few studies have investigated brain structures or used tractography to investigate gender differences in pain sensitivity. The identification of tracts involved in sex-based structural differences that show pain sensitivity has remained elusive to date. Here, we attempted to demonstrate the sex differences in pain sensitivity and to clarify its relationship with brain structural connectivity. In this study, pain behavior test and brain diffusion tensor imaging (DTI) were performed in male and female rats and tractography was performed on the whole brain using fiber tracking software. We selected eight brain regions related to pain and performed a tractography analysis of these regions. Fractional anisotropy (FA) measurements using automated tractography revealed sex differences in the anterior cingulate cortex (ACC)-, prefrontal cortex (PFC)-, and ventral posterior thalamus-related brain connections. In addition, the results of the correlation analysis of pain sensitivity and DTI tractography showed differences in mean, axial, and radial diffusivities, as well as FA. This study revealed the potential of DTI for exploring circuits involved in pain sensitivity. The behavioral and functional relevance's of measures derived from DTI tractography is demonstrated by their relationship with pain sensitivity.

Modulation of Neuropathic Pain by Glial Regulation in the Insular Cortex of Rats

The insular cortex (IC) is known to process pain information. However, analgesic effects of glial inhibition in the IC have not yet been explored. The aim of this study was to investigate pain alleviation effects after neuroglia inhibition in the IC during the early or late phase of pain development. The effects of glial inhibitors in early or late phase inhibition in neuropathic pain were characterized in astrocytes and microglia expressions in the IC of an animal model of neuropathic pain. Changes in withdrawal responses during different stages of inhibition were compared, and morphological changes in glial cells with purinergic receptor expressions were analyzed. Inhibition of glial cells had an analgesic effect that persisted even after drug withdrawal. Both GFAP and CD11b/c expressions were decreased after injection of glial inhibitors. Morphological alterations of astrocytes and microglia were observed with expression changes of purinergic receptors. These findings indicate that inhibition of neuroglia activity in the IC alleviates chronic pain, and that purinergic receptors in glial cells are closely related to chronic pain development.

Inhibition of the Nav1.7 Channel in the Trigeminal Ganglion Relieves Pulpitis Inflammatory Pain

Pulpitis causes significant changes in the peripheral nervous system, which induce hyperalgesia. However, the relationship between neuronal activity and Nav1.7 expression following pulpal noxious pain has not yet been investigated in the trigeminal ganglion (TG). The aim of our study was to verify whether experimentally induced pulpitis activates the expression of Nav1.7 peripherally and the neuronal activities of the TGs can be affected by Nav1.7 channel inhibition. Acute pulpitis was induced through allyl isothiocyanate (AITC) application to the rat maxillary molar tooth pulp. Three days after AITC application, abnormal pain behaviors were recorded, and the rats were euthanized to allow for immunohistochemical, optical imaging, and western blot analyses of the Nav1.7 expression in the TG. A significant increase in AITC-induced pain-like behaviors and histological evidence of pulpitis were observed. In addition, histological and western blot data showed that Nav1.7 expressions in the TGs were significantly higher in the AITC group than in the naive and saline group rats. Optical imaging showed that the AITC group showed higher neuronal activity after electrical stimulation of the TGs. Additionally, treatment of ProTxII, selective Nav1.7 blocker, on to the TGs in the AITC group effectively suppressed the hyperpolarized activity after electrical stimulation. These findings indicate that the inhibition of the Nav1.7 channel could modulate nociceptive signal processing in the TG following pulp inflammation.

Possible Therapeutic Options for Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) describes an array of painful conditions that are characterized by continuing regional pain. CRPS comprises severe and inappropriate pain in cases of complete recovery after trauma. Research on the pharmacological treatment of CRPS, however, has not been well investigated. In this study, we compared the pain relief effects of different drugs (URB597, pyrrolidine dithiocarbamate, and hydralazine) in a rat model of chronic post-ischemic pain-induced CRPS. After drug injection, CRPS-induced mechanical allodynia was significantly recovered. After three repetitive drug injections, mechanical sensitivity generally improved as hyper-nociception subsided. Reduced Nav1.7 expression at dorsal root ganglions (DRGs) was observed in the drug treatment groups. Neural imaging analysis revealed decreased neural activity for each drug treatment, compared to vehicle. In addition, treatments significantly reduced IL-1β, IL-6, and TNFα expression in DRGs. These results indicated that drugs could reduce the expression of inflammatory factors and alleviate the symptoms of chronic post-ischemic pain-induced CRPS.

Combined treatment of Taraxaci Herba and R7050 alleviates the symptoms of herpes simplex virus-induced Behçet's disease in rats

Background

Behçet's disease (BD) is a chronic inflammatory systemic disease that affects multiple organs. The causes of BD are still unknown, but it is primarily characterized by autoimmune reaction in the blood vessels. Current research focuses on treatments that can reduce the non-typical inflammatory responses of BD. Nevertheless, studies on improving the inflammatory effect of BD using inflammation mechanisms are still insufficient. Therefore, we conducted the integrated treatments related to inflammation modulation and achieved alleviation of symptoms in BD mice.

Methods

To understand the complex etiology of BD and compare its management, the herpes simplex virus (HSV)-induced BD mouse model was used. In order to alleviate the inflammatory response in BD mice, Taraxaci Herba (TH, herbal medicine), R7050-a TNFα inhibitor, and a mixture of TH and R7050 were injected for 2 weeks repetitively. The SCORAD index was examined to evaluate the cutaneous inflammations. In addition, histological changes and inflammatory factors were analyzed.

Results

Repetitive injection of TH and/or R7050 reduced the symptoms of BD and significantly decreased IL-6, IL-1β, and TNFα in blood sera. Moreover, this treatment reduced the ulcers and the deterioration of skin.

Conclusions

The results of our study showed that the down-regulation of inflammatory factors is related to the control of immune responses in BD models, suggesting that a mixed drug treatment may be more effective in improving the condition of BD.

Manganese-enhanced MRI depicts a reduction in brain responses to nociception upon mTOR inhibition in chronic pain rats

Neuropathic pain induced by a nerve injury can lead to chronic pain. Recent studies have reported hyperactive neural activities in the nociceptive-related area of the brain as a result of chronic pain. Although cerebral activities associated with hyperalgesia and allodynia in chronic pain models are difficult to represent with functional imaging techniques, advances in manganese (Mn)-enhanced magnetic resonance imaging (MEMRI) could facilitate the visualization of the activation of pain-specific neural responses in the cerebral cortex. In order to investigate the alleviation of pain nociception by mammalian target of rapamycin (mTOR) modulation, we observed cerebrocortical excitability changes and compared regional Mn²⁺ enhancement after mTOR inhibition. At day 7 after nerve injury, drugs were applied into the intracortical area, and drug (Vehicle, Torin1, and XL388) effects were compared within groups using MEMRI. Therein, signal intensities of the insular cortex (IC), primary somatosensory cortex of the hind limb region, motor cortex 1/2, and anterior cingulate cortex regions were significantly reduced after application of mTOR inhibitors (Torin1 and XL388). Furthermore, rostral-caudal analysis of the IC indicated that the rostral region of the IC was more strongly associated with pain perception than the caudal region. Our data suggest that MEMRI can depict pain-related signal changes in the brain and that mTOR inhibition is closely correlated with pain modulation in chronic pain rats.

Neuroprotective Effect of Antioxidants in the Brain

The brain is vulnerable to excessive oxidative insults because of its abundant lipid content, high energy requirements, and weak antioxidant capacity. Reactive oxygen species (ROS) increase susceptibility to neuronal damage and functional deficits, via oxidative changes in the brain in neurodegenerative diseases. Overabundance and abnormal levels of ROS and/or overload of metals are regulated by cellular defense mechanisms, intracellular signaling, and physiological functions of antioxidants in the brain. Single and/or complex antioxidant compounds targeting oxidative stress, redox metals, and neuronal cell death have been evaluated in multiple preclinical and clinical trials as a complementary therapeutic strategy for combating oxidative stress associated with neurodegenerative diseases. Herein, we present a general analysis and overview of various antioxidants and suggest potential courses of antioxidant treatments for the neuroprotection of the brain from oxidative injury. This review focuses on enzymatic and non-enzymatic antioxidant mechanisms in the brain and examines the relative advantages and methodological concerns when assessing antioxidant compounds for the treatment of neurodegenerative disorders.

Effects of mTOR inhibitors on neuropathic pain revealed by optical imaging of the insular cortex in rats

In the pain matrix, the insular cortex (IC) is mainly involved in discriminative sensory and motivative emotion. Abnormal signal transmission from injury site causes neuropathic pain, which generates enhanced synaptic plasticity. The mammalian target of rapamycin (mTOR) complex is the key regulator of protein synthesis; it is involved in the modulation of synaptic plasticity. To date, there has been no report on the changes in optical signals in the IC under neuropathic condition after treatment with mTOR inhibitors, such as Torin1 and XL388. Therefore, we aimed to determine the pain-relieving effect of mTOR inhibitors (Torin1 and XL388) and observe the changes in optical signals in the IC after treatment. Mechanical threshold was measured in adult male Sprague-Dawley rats after neuropathic surgery, and therapeutic effect of inhibitors was assessed on post-operative day 7 following the microinjection of Torin1 or XL388 into the IC. Optical signals were acquired to observe the neuronal activity of the IC in response to peripheral stimulation before and after treatment with mTOR inhibitors. Consequently, the inhibitors showed the most effective alleviation 4 h after microinjection into the IC. In optical imaging, peak amplitudes of optical signals and areas of activated regions were reduced after treatment with Torin1 and XL388. However, there were no significant optical signal changes in the IC before and after vehicle application. These findings suggested that Torin1 and XL388 are associated with the alleviation of neuronal activity that is excessively manifested in the IC, and is assumed to diminish synaptic plasticity.

Astroglial changes in the zona incerta in response to motor cortex stimulation in a rat model of chronic neuropathy

Although astrocytes are known to regulate synaptic transmission and affect new memory formation by influencing long-term potentiation and functional synaptic plasticity, their role in pain modulation is poorly understood. Motor cortex stimulation (MCS) has been used to reduce neuropathic pain through the incertothalamic pathway, including the primary motor cortex (M1) and the zona incerta (ZI). However, there has been no in-depth study of these modulatory effects and region-specific changes in neural plasticity. In this study, we investigated the effects of MCS-induced pain modulation as well as the relationship between the ZI neuroplasticity and MCS-induced pain alleviation in neuropathic pain (NP). MCS-induced threshold changes were evaluated after daily MCS. Then, the morphological changes of glial cells were compared by tissue staining. In order to quantify the neuroplasticity, MAP2, PSD95, and synapsin in the ZI and M1 were measured and analyzed with western blot. In behavioral test, repetitive MCS reduced NP in nerve-injured rats. We also observed recovered GFAP expression in the NP with MCS rats. In the NP with sham MCS rats, increased CD68 level was observed. In the NP with MCS group, increased mGluR1 expression was observed. Analysis of synaptogenesis-related molecules in the M1 and ZI revealed that synaptic changes occured in the M1, and increased astrocytes in the ZI were more closely associated with pain alleviation after MCS. Our findings suggest that MCS may modulate the astrocyte activities in the ZI and synaptic changes in the M1. Our results may provide new insight into the important and numerous roles of astrocytes in the formation and function.

mTOR signaling intervention by Torin1 and XL388 in the insular cortex alleviates neuropathic pain

Signaling by mammalian target of rapamycin (mTOR), a kinase regulator of protein synthesis, has been implicated in the development of chronic pain. The mTOR comprises two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Although effective inhibitors of mTORC1 and C2 have been developed, studies on the effect of these inhibitors related to pain modulation are still lacking. This study was conducted to determine the inhibitory effects of Torin1 and XL388 in an animal model of neuropathic pain. Seven days after neuropathic surgery, Torin1 or XL388 were microinjected into the insular cortex (IC) of nerve-injured animals and behavioral changes were assessed. Administration of Torin1 or XL388 into the IC significantly increased mechanical thresholds and reduced mechanical allodynia. At the immunoblotting results, Torin1 and XL388 significantly reduced phosphorylation of mTOR, 4E-BP1, p70S6K, and PKCα, without affecting Akt. These results strongly suggest that Torin1 and XL388 may attenuate neuropathic pain via inhibition of mTORC1 and mTORC2 in the IC.

P3762The impact of type and burden of atrial fibrillation on stroke occurrence in patients with atrial fibrillation: from a prospective cohort of atrial fibrillation patients (CODE-AF Registry)

Background and purpose

Although several studies reported that stroke risk in patients with paroxysmal atrial fibrillation (AF) is similar to those with persistent or permanent AF, there is still controversy on the relationship of AF type and stroke occurrence. We investigated the effect of AF type on AF burden and stroke risk in patients with non-valvular AF.

Methods

Within the CODE-AF prospective, outpatient registry (COmparison study of Drugs for symptom control and complication prEvention of Atrial Fibrillation), we identified 8,883 patients ≥18 years of age with non-valvular AF and eligible follow-up visits. We compared AF burden and stroke risk among patients with 3 types of AF: paroxysmal (n=5,808) or persistent (n=2,806) or permanent (n=269).

Results

The median age of the overall population was 68.0 (interquartile range, 60.0–75.0); 36.0% were female. Patients with persistent and permanent AF were older and had higher CHA2DS2-VASc scores and anticoagulation rate than those with paroxysmal AF. Compared with permanent AF (5.2±16.4%), the arrhythmic burden of AF on 24hrs Holter monitoring was significantly lower in paroxysmal AF (2.1±7.2%, p<0.001) and persistent AF (2.0±7.5%, p<0.001). During median follow-up period of 1.38 years (interquartile range: 0.96–1.67), total 82 (0.92%) patients experienced ischemic stroke with incidence rates of 0.51, 1.04 and 1.69 events per 100 person-years for paroxysmal, persistent and permanent AF, respectively. Compared with paroxysmal AF, the risk of ischemic stroke was increased in persistent AF with clinical variable adjusted hazard ratio (aHR) of 1.94 (95% confidence intervals [CI], 1.23–3.07; P=0.005) and permanent AF with aHR of 2.64 (95% CI, 1.09–6.41; P=0.03).

AF type and HR of stroke occurrence Paroxysmal (n=5,808) Persistent (n=2,806) Permanent (n=269) Stoke events 39 37 6 Person years (PYs) 7673 3544 356 /100 PYs 0.51 1.04 1.69 HR (95% CI), p-value HR (95% CI), p-value HR (95% CI), p-value Unadjusted HR 1 (Reference) 2.05 (1.27–3.31), 0.003 3.32 (1.15–7.90), 0.02 Clinical variables adjusted HR 1 (Reference) 1.94 (1.23–3.07), 0.005 2.64 (1.09–6.41), 0.03 PYs: Person years; HR: Hazard ratio.

Conclusion

Persistent and permanent AF was associated with the increased risk of stroke than paroxysmal AF, after adjustment of clinical variables including age, sex, comorbidities and anticoagulation rate. These results suggest that AF type and burden might be related with the risk of ischemic stroke and should be considered in the stroke prevention of AF.

Manganese-enhanced magnetic resonance imaging of the spinal cord in rats with formalin-induced pain

Manganese-enhanced magnetic resonance imaging (MEMRI) is based on neuronal activity-dependent manganese uptake, and provides information about nervous system function. However, systematic studies of pain processing using MEMRI are rare, and few investigations of pain using MEMRI have been performed in the spinal cord. Herein, we investigated the pain dependence of manganese ions administered in the rat spinal cord. MnCl₂ was administered into the spinal cord via an intrathecal catheter before formalin injection into the right hind paw (50 μL of 5% formalin). The duration of flinching behavior was recorded and analyzed to measure formalin-induced pain. After the behavioral test, rats were sacrificed with an overdose of urethane (50 mg/kg), and spine samples were extracted and post-fixed in 4% paraformaldehyde solution. The samples were stored in 30% sucrose until molecular resonance (MR) scanning was performed. In axial Mn²⁺ enhancement images of the spinal cord, Mn²⁺ levels were found to be significantly elevated on the ipsilateral side of the spinal cord in formalin-injected rats. To confirm pain-dependent Mn enhancement in the spinal cord, c-Fos expression was analyzed, and was found to be increased in the formalin-injected rats. These results indicate that MEMRI is useful for functional analysis of the spinal cord under pain conditions. The gray matter appears to be the focus of intense paramagnetic signals. MEMRI may provide an effective technique for visualizing activity-dependent patterns in the spinal cord.

Repetitive motor cortex stimulation reinforces the pain modulation circuits of peripheral neuropathic pain

Recent evidence indicates that motor cortex stimulation (MCS) is a potentially effective treatment for chronic neuropathic pain. However, the neural mechanisms underlying the attenuated hyperalgesia after MCS are not completely understood. In this study, we investigated the neural mechanism of the effects of MCS using an animal model of neuropathic pain. After 10 daily sessions of MCS, repetitive MCS reduced mechanical allodynia and contributed to neuronal changes in the anterior cingulate cortex (ACC). Interestingly, inhibition of protein kinase M zeta (PKMζ), a regulator of synaptic plasticity, in the ACC blocked the effects of repetitive MCS. Histological and molecular studies showed a significantly increased level of glial fibrillary acidic protein (GFAP) expression in the ACC after peripheral neuropathy, and neither MCS treatment nor ZIP administration affected this increase. These results suggest that repetitive MCS can attenuate the mechanical allodynia in neuropathic pain, and that the activation of PKMζ in the ACC may play a role in the modulation of neuropathic pain via MCS.

Inhibition of Mammalian Target of Rapamycin (mTOR) Signaling in the Insular Cortex Alleviates Neuropathic Pain after Peripheral Nerve Injury

Injury of peripheral nerves can trigger neuropathic pain, producing allodynia and hyperalgesia via peripheral and central sensitization. Recent studies have focused on the role of the insular cortex (IC) in neuropathic pain. Because the IC is thought to store pain-related memories, translational regulation in this structure may reveal novel targets for controlling chronic pain. Signaling via mammalian target of rapamycin (mTOR), which is known to control mRNA translation and influence synaptic plasticity, has been studied at the spinal level in neuropathic pain, but its role in the IC under these conditions remains elusive. Therefore, this study was conducted to determine the role of mTOR signaling in neuropathic pain and to assess the potential therapeutic effects of rapamycin, an inhibitor of mTORC1, in the IC of rats with neuropathic pain. Mechanical allodynia was assessed in adult male Sprague-Dawley rats after neuropathic surgery and following microinjections of rapamycin into the IC on postoperative days (PODs) 3 and 7. Optical recording was conducted to observe the neural responses of the IC to peripheral stimulation. Rapamycin reduced mechanical allodynia and downregulated the expression of postsynaptic density protein 95 (PSD95), decreased neural excitability in the IC, thereby inhibiting neuropathic pain-induced synaptic plasticity. These findings suggest that mTOR signaling in the IC may be a critical molecular mechanism modulating neuropathic pain.

Spatiotemporal changes of optical signals in the somatosensory cortex of neuropathic rats after electroacupuncture stimulation

Background

Peripheral nerve injury causes physiological changes in primary afferent neurons. Neuropathic pain associated with peripheral nerve injuries may reflect changes in the excitability of the nervous system, including the spinothalamic tract. Current alternative medical research indicates that acupuncture stimulation has analgesic effects in various pain symptoms. However, activation changes in the somatosensory cortex of the brain by acupuncture stimulation remain poorly understood. The present study was conducted to monitor the changes in cortical excitability, using optical imaging with voltage-sensitive dye (VSD) in neuropathic rats after electroacupuncture (EA) stimulation.

Methods

Male Sprague–Dawley rats were divided into three groups: control (intact), sham injury, and neuropathic pain rats. Under pentobarbital anesthesia, rats were subjected to nerve injury with tight ligation and incision of the tibial and sural nerves in the left hind paw. For optical imaging, the rats were re-anesthetized with urethane, and followed by craniotomy. The exposed primary somatosensory cortex (S1) was stained with VSD for one hour. Optical signals were recorded from the S1 cortex, before and after EA stimulation on Zusanli (ST36) and Yinlingquan (SP9).

Results

After peripheral stimulation, control and sham injury rats did not show significant signal changes in the S1 cortex. However, inflamed and amplified neural activities were observed in the S1 cortex of nerve-injured rats. Furthermore, the optical signals and region of activation in the S1 cortex were reduced substantially after EA stimulation, and recovered in a time-dependent manner. The peak fluorescence intensity was significantly reduced until 90 min after EA stimulation (Pre-EA: 0.25 ± 0.04 and Post-EA 0 min: 0.01 ± 0.01), and maximum activated area was also significantly attenuated until 60 min after EA stimulation (Pre-EA: 37.2 ± 1.79 and Post-EA 0 min: 0.01 ± 0.10).

Conclusion

Our results indicate that EA stimulation has inhibitory effects on excitatory neuronal signaling in the S1 cortex, caused by noxious stimulation in neuropathic pain. These findings suggest that EA stimulation warrants further study as a potential adjuvant modulation of neuropathic pain.

In vivo voltage-sensitive dye imaging of the insular cortex in nerve-injured rats

The insular cortex (IC) is a pain-related brain region that receives various types of sensory input and processes the emotional aspects of pain. The present study was conducted to investigate spatiotemporal patterns related to neuroplastic changes in the IC after nerve injury using voltage-sensitive dye imaging. The tibial and sural nerves of rats were injured under pentobarbital anesthesia. To observe optical signals in the IC, rats were re-anesthetized with urethane 7days after injury, and a craniectomy was performed to allow for optical imaging. Optical signals of the IC were elicited by peripheral electrical stimulation. Neuropathic rats showed a significantly higher optical intensity following 5.0mA electrical stimulation compared to sham-injured rats. A larger area of activation was observed by 1.25 and 2.5mA electrical stimulation compared to sham-injured rats. The activated areas tended to be larger, and the peak amplitudes of optical signals increased with increasing stimulation intensity in both groups. These results suggest that the elevated responsiveness of the IC to peripheral stimulation is related to neuropathic pain, and that neuroplastic changes are likely to be involved in the IC after nerve injury.

In situ patch-clamp recordings from Merkel cells in rat whisker hair follicles, an experimental protocol for studying tactile transduction in tactile-end organs

Mammals use tactile end-organs to perform sensory tasks such as environmental exploration, social interaction, and tactile discrimination. However, cellular and molecular mechanisms underlying tactile transduction in tactile end-organs remain poorly understood. The patch-clamp recording technique may be the most valuable approach for detecting and studying tactile transduction in tactile end-organs, but it is technically challenging because tactile transduction elements in an end-organ are normally inaccessible by patch-clamp recording electrodes. Here we describe an in situ patch-clamp recording protocol for the study of tactile transduction in Merkel cells of rat whisker hair follicles, one of the most sensitive tactile end-organs in mammals. This technique offers an opportunity to explore the identities and properties of ion channels that are involved in tactile transduction in whisker hair follicles, and it may also lend a useful tool for researchers to study other tactile end-organs. The experimental protocol describes procedures for 1) tissue dissection and whisker hair follicle preparation, 2) device setup and steps for performing patch-clamp recordings from Merkel cells in a whisker hair follicle, 3) methods of delivering mechanical stimuli, and 4) intra-follicle microinjection for receptor knockdown in whisker hair follicles. The main procedures in this protocol, from tissue preparation to whole-cell patch-clamp recordings, can be completed in a few hours.

Behavioral, metabolic and functional brain changes in a rat model of chronic neuropathic pain: a longitudinal MRI study

Peripheral neuropathy often manifests clinically with symptoms of mechanical and cold allodynia. However, the neuroplastic changes associated with peripheral neuropathic pain and the onset and progression of allodynic symptoms remain unclear. Here, we used a chronic neuropathic pain model (spared nerve injury; SNI) to examine functional and metabolic brain changes associated with the development and maintenance of mechanical and cold hypersensitivity, the latter which we assessed both behaviorally and during a novel acetone application paradigm using functional MRI (fMRI). Female Sprague-Dawley rats underwent SNI (n=7) or sham (n=5) surgery to the left hindpaw. Rats were anesthetized and scanned using a 7 T MRI scanner 1 week prior to (pre-injury) and 4 (early/subchronic) and 20 weeks (late/chronic) post-injury. Functional scans were acquired during acetone application to the left hindpaw. (1)H magnetic resonance spectroscopy was also performed to assess SNI-induced metabolic changes in the anterior cingulate cortex (ACC) pre- and 4 weeks post-injury. Mechanical and cold sensitivity, as well as anxiety-like behaviors, were assessed 2 weeks pre-injury, and 2, 5, 9, 14, and 19 weeks post-injury. Stimulus-evoked brain responses (acetone application to the left hindpaw) were analyzed across the pre- and post-injury time points. In response to acetone application during fMRI, SNI rats showed widespread and functionally diverse changes within pain-related brain regions including somatosensory and cingulate cortices and subcortically within the thalamus and the periaqueductal gray. These functional brain changes temporally coincided with early and sustained increases in both mechanical and cold sensitivity. SNI rats also showed increased glutamate within the ACC that correlated with behavioral measures of cold hypersensitivity. Together, our findings suggest that extensive functional reorganization within pain-related brain regions may underlie the development and chronification of allodynic-like behaviors.

Motor cortex stimulation activates the incertothalamic pathway in an animal model of spinal cord injury

We have shown previously that electrical stimulation of the motor cortex reduces spontaneous painlike behaviors in animals with spinal cord injury (SCI). Because SCI pain behaviors are associated with abnormal inhibition in the inhibitory nucleus zona incerta (ZI) and because inactivation of the ZI blocks motor cortex stimulation (MCS) effects, we hypothesized that the antinociceptive effects of MCS are due to enhanced inhibitory inputs from ZI to the posterior thalamus (Po)-an area heavily implicated in nociceptive processing. To test this hypothesis, we used a rodent model of SCI pain and performed in vivo extracellular electrophysiological recordings in single well-isolated neurons in anesthetized rats. We recorded spontaneous activity in ZI and Po from 48 rats before, during, and after MCS (50 μA, 50 Hz; 300-ms pulses). We found that MCS enhanced spontaneous activity in 35% of ZI neurons and suppressed spontaneous activity in 58% of Po neurons. The majority of MCS-enhanced ZI neurons (81%) were located in the ventrorateral subdivision of ZI-the area containing Po-projecting ZI neurons. In addition, we found that inactivation of ZI using muscimol (GABAA receptor agonist) blocked the effects of MCS in 73% of Po neurons. Although we cannot eliminate the possibility that muscimol spread to areas adjacent to ZI, these findings support our hypothesis and suggest that MCS produces antinociception by activating the incertothalamic pathway.

PERSPECTIVE

This article describes a novel brain circuit that can be manipulated, in rats, to produce antinociception. These results have the potential to significantly impact the standard of care currently in place for the treatment of patients with intractable pain.

Assessment of chronic trigeminal neuropathic pain by the orofacial operant test in rats

Classical behavioral tests in animal models of trigeminal neuropathic pain measure reflexive responses that are not necessarily measures of pain. To overcome the problem, we created a chronic constrictive nerve injury (CCI) rat model of pain by ligation of the infraorbital nerve (ION), and applied the orofacial operant test to assess behavioral responses to mechanical and cold stimulation in these rats. Animals were trained to voluntarily contact their facial region to a mechanical or a cold stimulation module in order to access sweetened milk as a positive reward. ION-CCI rats displayed aversive behaviors to innocuous mechanical stimuli, as indicated by a significant decrease in both contact time and the numbers of long contact events in comparison with sham group. For cold stimulation, ION-CCI rats displayed aversive behaviors to both innocuous (17 °C) and noxious cold temperatures (12 °C and 5 °C), as indicated by a significant decrease in both contact time and the numbers of long contact events at the cooling temperatures. The decreases of the contact time and numbers in ION-CCI rats were partially abolished by morphine. Our orofacial operant test demonstrates mechanical allodynia, cold allodynia, and hyperalgesia in rats with chronic trigeminal nerve injury. The neuropathic pain in ION-CCI rats was partially alleviated by morphine. Thus, orofacial operant test provides a desirable behavioral assessment method for preclinical studies of chronic trigeminal neuropathic pain.

Green tea consumption, abdominal obesity as related factors of lacunar infarction in Korean women

OBJECTIVES

Our purpose was to evaluate interaction of green tea consumption and abdominal obesity as related factors for lacunar infarction in Korean women.

DESIGN

A hospital-based, incident case-control study.

SETTINGS

The Prevention and Managements of Stroke in Women study.

PARTICIPANTS

Cases (n=233) of first incident lacunar infarction were enrolled and matched by age to stroke-free hospital controls (n=204).

MEASUREMENTS

The data were collected through face-to-face interviews by well trained research assistants to assess demographic, medical, lifestyle, marital status, religions status, green tea consumptions, family history of stroke, smoking status, alcohol consumption, meat and vegetable intake frequency, and past history of hypertension. Biochemical analysis, fasting blood specimens for lipid, glucose, and cholesterol level were acquired.

RESULTS

Compared with the non green tea consumer and obese women group, only the green tea consumption and non obese women group had a protective effect of lacunar infarction when adjusted for age, and age plus diet factors (OR, 0.23; 95% CI, 0.09, 0.59; OR, 0.21; 95% CI, 0.08, 0.56 respectively), but lost their significance after adjustment for age, diet factors, vascular risk factors and full model included atherogenic index factors (OR, 0.32; 95% CI, 0.09 to 1.01; OR, 0.49; 95% CI, 0.12, 1.89 respectively).

CONCLUSIONS

The interaction of green tea consumption and non obesity have reduced risk of lacunar infarction, but not after adjustment for age, diet factors, vascular risk factors and atherogenic index. Also individually green tea consumption and abdominal obesity have failed to find an independent relationship with lacunar infarction after adjustment by all risk factors. Green tea consumption and green tea consumption with non obese group seemed to have a protective effect for lacunar infarction. In the results of our study, these results still remain controversial, and then we need further and larger study to get at the root of real causal effect of both relationships.

Shear mechanical force induces an increase of intracellular Ca2+ in cultured Merkel cells prepared from rat vibrissal hair follicles

Merkel cells have been proposed to play a role in mechanical transduction of light touch in mammals. In the present study, Merkel cells were prepared from upper segments of rat vibrissal hair follicles and maintained in culture. Reponses of these cells to shear mechanical forces were examined by Ca(2+) imaging technique. Shear forces of ≥ 0.8 dyn/cm(2) that were delivered to the cells by the application of normal bath solution significantly increased intracellular Ca(2+) levels ([Ca(2+)](i)) in some of these cells, and up to 30% cells responded to 1.6 dyn/cm(2) shear force applied for 20 s. Gd(3+) (100 μM), a compound widely used to inhibit mechanically activated channels, abolished shear force-induced increases of [Ca(2+)](i) in these cells. Reduction of extracellular Ca(2+) concentration from 2 mM to 0.2 mM also abolished shear force-induced increases of [Ca(2+)](i) in these cells. In addition to shear force, we found that many shear force-responding cells also responded to hypotonic solution. However, the response to hypotonic solution was not abolished by Gd(3+) (100 μM). We also found that all shear force-responding cells responded to ATP (100 μM) with large increases of [Ca(2+)](i). The responses to ATP remained in the presence of Gd(3+). Taken together, our results suggest that Merkel cells in culture are sensitive to shear force stress, osmotic, and chemical stimuli and that shear force-induced increases of [Ca(2+)](i) may be mediated by the activation of mechanically activated channels.

Tertiary treatment of biologically treated piggery wastewater using vibratory shear-enhanced RO membrane

This study presents a good example for the tertiary treatment of biologically treated piggery wastewater using vibratory shear enhanced RO membrane (VSEP RO). Through a simple process combination, utilizing Bioceramic SBR(BCS) and VSEP RO, at Gimhae plant livestock wastewater is treated excellently to meet the strict effluent standards. Application of RO membrane directly to the biologically treated effluent has been successful without any pretreatment to reduce high suspended solids. The combination of VESP UF followed by RO filtration processes produced a higher recovery rate in the 3-week pilot test.

Nonlinear ellipsometric method for measuring second-order cascaded phase shift

An ellipsometric method for measuring second-order cascaded phase shift is experimentally demonstrated in a KNbO(3) single crystal. We analyze the polarization state composed of the two orthogonal polarizations of the transmitted fundamental wave, one of which experiences intensity-dependent depletion and phase shift while the other does not. This method does not require a well-defined beam profile or interferometric stability.

Cascaded phase shift and intensity modulation in aperiodic quasi-phase-matched gratings

I propose a method for enhancing the cascaded phase shift of the fundamental wave associated with second-harmonic generation in aperiodic quasi-phase matched (QPM) gratings. The position and length of one of the domains were varied to maximize the cascaded phase shift. A maximum enhancement of 84% in the cascaded phase shift relative to a perfectly periodic QPM grating was obtained at a moderate fundamental input intensity without initial seeding of the second-harmonic wave. All-optical intensity modulation is also proposed with another optimized aperiodic QPM grating.

[Determination of aucubin in Plantago asiatica L., P. major L. and P. depressa Willd. by HPLC]

A HPLC method for the determination of aucubin in P. asiatica, P. major and P. depressa was established. The mobile phase is MeOH-H2O (17:83). Good in producibility and high in rate of recovery, this method provides an effective way for the study of Plantago.

Calcium regulation of antigen expression on normal and malignant human squamous cells in vitro

In vitro, normal keratinocytes exhibit undifferentiated morphologic features and proliferate for multiple passages in low-calcium medium (less than or equal to 0.3 mmol/L) whereas, in high-calcium medium (greater than or equal to 1.0 mmol/L), these cells assume differentiation characteristics, begin to stratify, and eventually cease proliferating. In contrast, malignant keratinocytes grow well in high-calcium medium. Expression of pemphigus vulgaris antigen, a squamous cell marker, is altered on cultured normal keratinocytes by calcium. In this study we compared the effects of calcium levels on expression of cell surface antigens by UM-SCC-38, a human squamous carcinoma cell line, and normal keratinocytes cultured from newborn foreskin. Pemphigus, pemphigoid, beta 2-microglobulin antigens, as well as the epidermal growth factor receptor and the A9 germinal epithelial cell basement membrane squamous carcinoma antigen were examined. Pemphigus antigen was strongly expressed on normal and malignant cells in high-calcium but not low-calcium medium. Calcium concentration did not affect the expression of any of the other antigens tested. Thus, although calcium induces differentiation and eventual loss of proliferative capacity in normal but not malignant keratinocytes in vitro, we were unable to demonstrate differences in pemphigus vulgaris antigen expression that might be linked to the growth inhibitory effects induced by high calcium levels in nontransformed epithelial cells in culture.

Effects of mammalian insulin on metabolism, growth, and morphology of a wall-less strain of Neurospora crassa

Addition of mammalian insulin to a nutritionally rich, chemically defined culture medium affects Neurospora crassa "slime" (wall-less) cells, as indicated by enhancement of growth, extension of viability at the stationary phase of growth, alteration of morphology, and stimulation of glucose oxidation. Bovine, porcine, and recombinant human insulin had similar effects on growth and morphology, while proinsulin, reduced insulin, and several other proteins were inactive. Insulin added in the presence of excess antiinsulin antibody was without activity. Intact cells possessed high affinity insulin-binding sites, represented by a curvilinear Scatchard plot, suggesting that effects are mediated through insulin receptors on the cell surface. These findings establish a role for insulin or insulin-like molecules in regulating growth and metabolism in this fungal cell and demonstrate a close similarity to insulin effects on certain mammalian cells.