Effect of autophagy on allodynia, hyperalgesia and astrocyte activation in a rat model of neuropathic pain

Mitigation of experimental ER stress and diabetes mellitus induced peripheral neuropathy by autophagy promoter, 6-BIO

Neuropathy occurs due to damage to the peripheral/central nervous system either due to injury, disease, or drug usage. Increased endoplasmic reticulum (ER) stress is observed in neuropathy. ER stress also leads to a block in autophagy amplifying neuropathic pain. 6-Bromoindirubin-3'-oxime (6-BIO) is an inhibitor of GSK-3β which suppresses mTOR activity thereby increasing autophagy. Tunicamycin (TM)-mediated ER stress and diabetic rat models were used to elucidate the role of ER stress and autophagy in mitigation of neuropathic pain by 6-BIO. Pain was assessed by behavioral studies in ER stressed/diabetic rats having neuropathy. Western blotting, RT-PCR, and fluorescence microscopy were used to assess the level of autophagy and ER stress after TM and 6-BIO treatment in SH-SY5Y neurons. Intraplantar injection of TM in rats led to peripheral neuropathy which was reduced upon 6-BIO injection. 6-BIO also reduced pain in animals exhibiting diabetic peripheral neuropathy. Modulation in the markers of autophagy (p-mTOR, LC-3, and SQSTM1/p62) shows that 6-BIO induces autophagolysosome formation post TM treatment. Concomitantly, 6-BIO reduces ER stress and c-Fos expression-a neuronal activity and pain marker. Alleviation of pain by the inhibition of ER stress and increased formation of autolysosomes by 6-BIO can be harnessed for treating peripheral neuropathy.

A comprehensive review of traditional Chinese medicine in treating neuropathic pain

Neuropathic pain (NP) is a common, intractable chronic pain caused by nerve dysfunction and primary lesion of the nervous system. The etiology and pathogenesis of NP have not yet been clarified, so there is a lack of precise and effective clinical treatments. In recent years, traditional Chinese medicine (TCM) has shown increasing advantages in alleviating NP. Our review aimed to define the therapeutic effect of TCM (including TCM prescriptions, TCM extracts and natural products from TCM) on NP and reveal the underlying mechanisms. Literature from 2018 to 2024 was collected from databases including Web of Science, PubMed, ScienceDirect, Google academic and CNKI databases. Herbal medicine, Traditional Chinese medicines (TCM), neuropathic pain, neuralgia and peripheral neuropathy were used as the search terms. The anti-NP activity of TCM is clarified to propose strategies for discovering active compounds against NP, and provide reference to screen anti-NP drugs from TCM. We concluded that TCM has the characteristics of multi-level, multi-component, multi-target and multi-pathway, which can alleviate NP through various pathways such as anti-inflammation, anti-oxidant, anti-apoptotic pathway, regulating autophagy, regulating intestinal flora, and influencing ion channels. Based on the experimental study and anti-NP mechanism of TCM, this paper can offer analytical evidence to support the effectiveness in treating NP. These references will be helpful to the research and development of innovative TCM with multiple levels and multiple targets. TCM can be an effective treatment for NP and can serve as a treasure house for new drug development.

Chronic Pruritus Alleviation in the Elderly Through Drug-Free Autophagy Activation by Magnetized Saline Water: A Case Series

Chronic pruritus is a common and distressing condition in the elderly population, frequently associated with various underlying systemic diseases and age-related skin changes. Conventional treatments, such as emollients and moisturizers, may not invariably provide adequate relief. Magnetized saline water has previously been shown to activate autophagy, a cellular process involved in maintaining skin barrier function, reducing inflammaging, and modulating neuropathic pain. This case series investigated the efficacy of a topical serum containing magnetized saline water in managing chronic pruritus with diverse etiologies in elderly patients. Five patients aged 69-80 years, presenting with chronic pruritus lasting two to six months, were instructed to apply the serum daily to the most affected areas for a minimum of 14 consecutive days. Pruritus severity was assessed using the 12-Item Pruritus Severity Scale (12-PSS) at baseline and post-intervention. The underlying causes of pruritus included end-stage renal disease, type 2 diabetes mellitus with peripheral neuropathy, advanced liver fibrosis, and xerosis cutis. All five patients reported a substantial improvement in pruritus severity following the application of the magnetized saline water serum, with post-intervention 12-PSS scores decreasing by 3-5 points. The serum was well-tolerated, and no adverse effects were reported. These findings suggest that topical formulations containing magnetized saline water may be a promising alternative or adjunctive therapy for managing chronic pruritus in the elderly population. However, clinical trials are needed to confirm these findings, elucidate the precise mechanisms of action, and establish optimal treatment protocols.

Different Roles of Beclin1 in the Interaction Between Glia and Neurons after Exposure to Morphine and the HIV- Trans-Activator of Transcription (Tat) Protein

Previously we showed that Beclin1 has a regulatory role in the secretion of inflammatory molecules in glia after exposure to morphine and Tat (an HIV protein). Here we show increased secretion of neuronal growth factors and increased neuronal survival in Beclin1-deficient glia. However, without glia co-culture, neurons deficient in Beclin1 showed greater death and enhanced dendritic beading when compared to wild-type neurons, suggesting that glial-secreted growth factors compensate for the damage reduced autophagy causes neurons. To assess if our ex vivo results correlated with in vivo studies, we used a wild-type (Becn1+/+) and Beclin1-deficient (Becn1+/+) mouse model and intracranially infused the mice with Tat and subcutaneously administered morphine pellets. After morphine implantation, significantly impaired locomotor activities were detected in both Becn1+/+ and Becn1+/- mice, irrespective of Tat infusion. After induction of pain, morphine-induced antinociception was detected. Interestingly, co-exposure to morphine and Tat increased sensitivity to pain in Becn1+/+ mice, but not in similarly treated Becn1+/- mice. Brain homogenates from Becn1+/+ mice exposed to Tat, alone and in combination with morphine, showed increased secretion of pro-inflammatory cytokines and reduced expression of growth factors when compared to similarly treated Becn1+/- mice. Likewise, increased neuronal loss was detected when both Tat and morphine were administered to Becn1+/+ mice, but not in similarly treated Becn1+/- mice. Overall, our findings show that there is a Beclin1-driven interaction between Tat and morphine in glia and neurons. Moreover, reduced glial-Beclin1 may provide a layer of protection to neurons under stressful conditions, such as when exposed to morphine and Tat.

Electroacupuncture attenuates spared nerve injury-induced neuropathic pain possibly by promoting the progression of AMPK/mTOR-mediated autophagy in spinal microglia

Background

Neuropathic pain (NP) is a syndrome that arises from central or peripheral nerve injury, which manifests primarily as hyperalgesia, spontaneous pain, and allodynia. The recent trend has exhibited a shift towards the development of therapies for managing NP. Activation of autophagy is involved in the function of the glial cells, which may be implicated further to attenuate pain.

Methods

In this study, the analgesic effects of electroacupuncture (EA) were evaluated among NP rats developed using spared nerve injury (SNI). Acupuncture treatment or EA was carried out after 7 days of SNI at two acupoints, i.e., the Zusanli (ST36) and Huantiao (GB30).

Results

The application of EA was found to attenuate mechanical hyperalgesia. The marker protein for microglial cells (CD11b) alone, without either the astrocyte marker or neuronal marker, was co-expressed with the autophagy indicator p62, as illustrated with immunofluorescence staining. Western blotting demonstrated that the expression levels of p62, Beclin-1, and LC3-II/LC3-I were elevated in the spinal cords of rats in the SNI group compared to the control levels. EA treatment resulted in reduced expression of p62, while the expressions of Beclin-1 and LC3-II/LC3-I were increased. The electron microscopy results indicated that EA could induce autophagy progression in the microglia of the spinal dorsal horn in SNI rats. Furthermore, we explored the causal relationship between EA-induced inhibition of NP and increased autophagic levels in microglia using the AMPK inhibitor compound C, and found that the mechanism of EA-induced analgesia may contribute to the promotion of AMPK/mTOR-mediated autophagy in spinal microglia.

Conclusions

Our work showed that the analgesic impact of EA is partly related to AMPK/mTOR pathway activation and autophagy induction in microglial cells, providing a potential therapeutic target for NP.

Electroacupuncture alleviates neuropathic pain caused by spared nerve injury by promoting AMPK/mTOR-mediated autophagy in dorsal root ganglion macrophage

Background

Dorsal root ganglia (DRG) plays an important role in mediating the peripheral sensation transduction through the primary afferent neurons in pain research. Neuropathic pain (NP) is a syndrome of hyperalgesia, spontaneous pain and allodynia caused by central or peripheral nerve injury. Recent trends of study are turning towards the development of therapies for the management of NP. Activation of autophagy in glial cells in the spinal cord has been reported to be associated with attenuation of NP, but the autophagic process in DRG is rarely studied.

Methods

The analgesic effect of electroacupuncture (EA) was evaluated in NP-induced rats developed using spared nerve injury (SNI). Acupuncture or EA was performed after 7 days of SNI at Zusanli (ST36) and Huantiao (GB30) acupoints. Then, the activation status of autophagy process in DRGs of rats treated with SNI and EA were investigated, and the possible mechanism of the analgesic effect of EA were explored.

Results

Application of EA has been found to reduce mechanical hyperalgesia. Autophagy indicator p62 was colocalized with the marker proteins for macrophages (CD11b), but not with NeuN (marker protein for neurons) or GFAP (marker protein for satellite glial cells), as shown by immunofluorescence. Western blots results indicate that the expression levels of p62, Beclin-1 and LC3-II in the L4-L6 DRG of rats in the SNI group were increased, compared with that in the control group. EA treatment resulted in decreased expression of p62 and increased expression of Beclin-1 and LC3-II/LC3-I. Furthermore, we explored the causal relationship between EA-induced suppression of NP and increased levels of autophagy in DRG using electron microscopy and the AMPK (AMP-activated protein kinase) inhibitor compound C.

Conclusions

SNI achieved a significant upregulation of autophagy levels in DRG macrophages. Furthermore, EA attenuated NP, which may contribute to the promotion of AMPK/mTOR (mammalian target of rapamycin)-mediated autophagy in DRG macrophages. Therefore, this strategy provides a new target for therapeutic intervention of NP.

scRNA-seq generates a molecular map of emerging cell subtypes after sciatic nerve injury in rats

Patients with peripheral nerve injury, viral infection or metabolic disorder often suffer neuropathic pain due to inadequate pharmacological options for relief. Developing novel therapies has been challenged by incomplete mechanistic understanding of the cellular microenvironment in sensory nerve that trigger the emergence and persistence of pain. In this study, we report a high resolution transcriptomics map of the cellular heterogeneity of naïve and injured rat sensory nerve covering more than 110,000 individual cells. Annotation reveals distinguishing molecular features of multiple major cell types totaling 45 different subtypes in naïve nerve and an additional 23 subtypes emerging after injury. Ligand-receptor analysis revealed a myriad of potential targets for pharmacological intervention. This work forms a comprehensive resource and unprecedented window into the cellular milieu underlying neuropathic pain and demonstrates that nerve injury is a dynamic process orchestrated by multiple cell types in both the endoneurial and epineurial nerve compartments.

Interplay between exosomes and autophagy machinery in pain management: State of the art

Despite recent progress regarding inexpensive medical approaches, many individuals suffer from moderate to severe pain globally. The discovery and advent of exosomes, as biological nano-sized vesicles, has revolutionized current knowledge about underlying mechanisms associated with several pathological conditions. Indeed, these particles are touted as biological bio-shuttles with the potential to carry specific signaling biomolecules to cells in proximity and remote sites, maintaining cell-to-cell communication in a paracrine manner. A piece of evidence points to an intricate relationship between exosome biogenesis and autophagy signaling pathways at different molecular levels. A close collaboration of autophagic response with exosome release can affect the body's hemostasis and physiology of different cell types. This review is a preliminary attempt to highlight the possible interface of autophagy flux and exosome biogenesis on pain management with a special focus on neuropathic pain. It is thought that this review article will help us to understand the interplay of autophagic response and exosome biogenesis in the management of pain under pathological conditions. The application of therapies targeting autophagy pathway and exosome abscission can be an alternative strategy in the regulation of pain.

Diagnostic Value and Prognostic Evaluation of Autophagy-Related Protein Expression Level in Sepsis Complicated with Acute Respiratory Distress Syndrome

Objective. To explore the diagnostic value and prognostic evaluation of the autophagy-related protein expression level among patients with sepsis comorbid with acute respiratory distress syndrome. Methods. A total of 182 sepsis patients were admitted to Naval Medical Center from March 2016 to April 2020 and divided into the acute respiratory distress syndrome and non-ARDS groups. Immunoblotting was employed to identify the expression of autophagy-associated protein from participants’ peripheral blood mononuclear cells. Multivariate linear regression analysis was used to examine the association between mortality and the protein expression in sepsis complicated with acute respiratory distress syndrome. Results. Among the 182 patients with sepsis included in this study, 82 patients had acute respiratory distress syndrome and 100 patients did not have acute respiratory distress syndrome. We observed that microtubule-related protein 1A/1B LC3II, Beclin-1, RAB7, and LAMP2 protein expression was significantly decreased in septic patients with ARDS, and p62 was significantly increased. Further receiver operating characteristic curve analysis showed that autophagy-related proteins had a high recognition ability in sepsis complicated with acute respiratory distress syndrome. LAMP2 protein was the best among them, and its specificity was up to 91.46%. In this study, 38 of the 82 patients with sepsis complicated with acute respiratory distress syndrome died, with a mortality rate of 46.34%. We found that the autophagy level was further inhibited in the patients with death, LC3II, Beclin-1, and RAB7. However, the lysosomal-associated membrane protein 2 levels in the survival patients were remarkably higher than that in the dead patients. In addition, the p62 level was lower in survival patients as well. Our results indicated age and SOFA score were the independent risk factors for mortality in septic patients with acute respiratory distress syndrome. Conclusion. The autophagy level is significantly inhibited in septic patients with acute respiratory distress syndrome, and autophagy-associated proteins LC3II, Beclin-1, RAB7, LAMP2, and p62 have good value for the diagnosis and prognosis evaluation of sepsis comorbid with acute respiratory distress syndrome.

The Role of Autophagy and Apoptosis in Neuropathic Pain Formation

Neuropathic pain indicates pain caused by damage to the somatosensory system and is difficult to manage and treat. A new treatment strategy urgently needs to be developed. Both autophagy and apoptosis are critical adaptive mechanisms when neurons encounter stress or damage. Recent studies have shown that, after nerve damage, both autophagic and apoptotic activities in the injured nerve, dorsal root ganglia, and spinal dorsal horn change over time. Many studies have shown that upregulated autophagic activities may help myelin clearance, promote nerve regeneration, and attenuate pain behavior. On the other hand, there is no direct evidence that the inhibition of apoptotic activities in the injured neurons can attenuate pain behavior. Most studies have only shown that agents can simultaneously attenuate pain behavior and inhibit apoptotic activities in the injured dorsal root ganglia. Autophagy and apoptosis can crosstalk with each other through various proteins and proinflammatory cytokine expressions. Proinflammatory cytokines can promote both autophagic/apoptotic activities and neuropathic pain formation, whereas autophagy can inhibit proinflammatory cytokine activities and further attenuate pain behaviors. Thus, agents that can enhance autophagic activities but suppress apoptotic activities on the injured nerve and dorsal root ganglia can treat neuropathic pain. Here, we summarized the evolving changes in apoptotic and autophagic activities in the injured nerve, dorsal root ganglia, spinal cord, and brain after nerve damage. This review may help in further understanding the treatment strategy for neuropathic pain during nerve injury by modulating apoptotic/autophagic activities and proinflammatory cytokines in the nervous system.

Abnormal Insulin-like Growth Factor 1 Signaling Regulates Neuropathic Pain by Mediating the Mechanistic Target of Rapamycin-Related Autophagy and Neuroinflammation in Mice

Neuropathic pain is a chronic condition with little specific treatment. Insulin-like growth factor 1 (IGF1), interacting with its receptor, IGF1R, serves a vital role in neuronal and brain functions such as autophagy and neuroinflammation. Yet, the function of spinal IGF1/IGF1R in neuropathic pain is unclear. Here, we examined whether and how spinal IGF1 signaling affects pain-like behaviors in mice with chronic constriction injury (CCI) of the sciatic nerve. To corroborate the role of IGF1, we injected intrathecally IGF1R inhibitor (nvp-aew541) or anti-IGF1 neutralizing antibodies. We found that IGF1 (derived from astrocytes) in the lumbar cord increased along with the neuropathic pain induced by CCI. IGF1R was predominantly expressed on neurons. IGF1R antagonism or IGF1 neutralization attenuated pain behaviors induced by CCI, relieved mTOR-related suppression of autophagy, and mitigated neuroinflammation in the spinal cord. These findings reveal that the abnormal IGF1/IGF1R signaling contributes to neuropathic pain by exacerbating autophagy dysfunction and neuroinflammation.

Hydrogen alleviates cell damage and acute lung injury in sepsis via PINK1/Parkin-mediated mitophagy

BACKGROUND

Multiple organ failure (MOF) is the main cause of early death in septic shock. Lungs are among the organs that are affected in MOF, resulting in acute lung injury. Inflammation is an important factor that causes immune cell dysfunction in the pathogenesis of sepsis. Autophagy is involved in the process of inflammation and also occurs in response to cell and tissue injury in several diseases. We previously demonstrated that hydrogen alleviated the inflammation-induced cell injury and organ damage in septic mice.

AIM

The focus of the present study was to elucidate whether mitophagy mediates the inflammatory response or oxidative injury in sepsis in vitro and in vivo. Furthermore, we evaluated the role of mitophagy in the protective effects of hydrogen against cell injury or organ dysfunction in sepsis.

METHOD

RAW 264.7 macrophages induced by lipopolysaccharide (LPS) were used as an in vitro model for inflammation, and cecal ligation and puncture (CLP)-induced acute lung injury mice were used as an in vivo model for sepsis. The key protein associated with mitophagy, PTEN-induced putative kinase 1 (PINK1), was knocked down by PINK1 shRNA transfection in RAW 264.7 macrophages or mice.

RESULTS

Hydrogen ameliorated cell injury and enhanced mitophagy in macrophages stimulated by LPS. PINK1 was required for the mitigation of the cell impairment in LPS-stimulated macrophages by hydrogen treatment. PINK1 knockdown abrogated the beneficial effects of hydrogen on mitophagy in LPS-stimulated macrophages. Hydrogen inhibited acute lung injury in CLP mice via activation of PINK1-mediated mitophagy.

CONCLUSION

These results suggest that PINK1-mediated mitophagy plays a key role in the protective effects of hydrogen against cell injury in LPS-induced inflammation and CLP-induced acute lung injury.

Intracerebroventricular injection of propranolol blocked analgesic and neuroprotective effects of resveratrol following L5 spinal nerve ligation in rat

OBJECTIVES

Resveratrol as a natural polyphenolic agent can alleviate neuropathic pain symptoms. The mechanism of analgesic activity of resveratrol is far from clear. The current study examine whether analgesic activity of resveratrol is mediated by its neuroprotective and anti-oxidant activity in the neuropathic pain. We further examine whether analgesic activity of resveratrol is mediated by β-adrenoceptors in the brain.

METHODS

Neuropathic pain induced by L₅ spinal nerve ligation (SNL). Male Wistar rats assigned into sham, SNL, SNL + resveratrol (40 μg/5 μL), and SNL + resveratrol + propranolol (a non-selective β-adrenoceptor antagonist, 30 μg/5 μL) groups. Drugs injected intracerebroventricular (ICV) at day SNL surgery and daily for 6 days following SNL. Thermal allodynia and anxiety examined on days of -1, 2, 4, and 6 following SNL. Electrophysiological study performed on day 6 following SNL for evaluation of resveratrol effects on sciatic nerve conduction velocity (NCV). The activity of catalase (Cat) and superoxide dismutase (SOD) enzymes in the brain assessed on days 6 following SNL.

RESULTS

Resveratrol significantly decreased thermal allodynia (and not anxiety) in all experimental days. Additionally, resveratrol significantly increased NCV, and also normalized the disrupted Cat and SOD activities following neuropathic pain. Furthermore, propranolol significantly blocked the analgesic and neuroprotective effects of resveratrol.

CONCLUSIONS

It is suggested that the analgesic effects of resveratrol is mediated by its neuroprotective and antioxidant activities in the neuropathic rats. Furthermore, propranolol blocked the analgesic and neuroprotective effects of resveratrol.

The E50K optineurin mutation impacts autophagy-mediated degradation of TDP-43 and leads to RGC apoptosis in vivo and in vitro

The glaucoma-associated E50K mutation in optineurin (OPTN) is known to affect autophagy and cause the apoptosis of retinal ganglion cells (RGCs), but the pathogenic mechanism remains unclear. In this study, we investigated whether the OPTN (E50K) mutation caused TDP-43 aggregation by disrupting autophagy in vivo and in vitro. OPTN (E50K) mutant mice were generated and analysed for genotype and phenotype. Adeno-associated virus type 2 vectors containing either GFP only, GFP-tagged wild-type OPTN or GFP-tagged E50K-mutated OPTN were used to transfect R28 cells. Loss of RGCs decreased retinal thickness and visual impairment were observed in OPTN (E50K) mice compared with WT mice. Moreover, overexpression of E50K OPTN induced R28 cell apoptosis. Increased p62/SQSTM1 and LC3-II levels indicated that autophagic flux was inhibited and contributed to TDP-43 aggregation in vivo and in vitro. We found that rapamycin effectively reduced the aggregation of TDP-43 in OPTN (E50K) mice and decreased the protein levels of p62/SQSTM1 and the autophagic marker LC3-II. Moreover, rapamycin increased the RGC number and visual function of E50K mice. In addition, we also observed increased cytoplasmic TDP-43 in the spinal cord and motor dysfunction in 24-month-old OPTN (E50K) mice, indicating that TDP-43 accumulation may be the common pathological mechanism of glaucoma and amyotrophic lateral sclerosis (ALS). In conclusion, the disruption of autophagy by OPTN (E50K) affected the degradation of TDP-43 and may play an important role in OPTN (E50K)-mediated glaucomatous retinal neurodegeneration.

Inhibition of Different Pain Pathways Attenuates Oxidative Stress in Glial Cells: A Mechanistic View on Neuroprotective Effects of Different Types of Analgesics

Neuropathic pain results from trauma or diseases affecting the central nervous system (CNS) and triggers a cascade of events in different CNS parts that eventually lead to oxidative injury. This study was aimed to investigate the protective effects of some selected analgesics in neuropathic pain-induced oxidative damage in the isolated glial cells of the rat brain. In this experiment, rats were randomly divided into 5 main groups. Rats in group 1 received no medication, whereas rats in groups 2 to 5 received ASA (aspirin), celecoxib, morphine, and etanercept daily, respectively. Each main group divides into 3 subgroups: normal, sham, and neuropathic pain model rats. The glial cells of the rat brain were isolated at different time points. Our results demonstrate that neuropathic pain induces ROS generation as the major cause of mitochondrial membrane potential collapse (%∆Ψm) and lysosomal membrane rupture, which result in oxidative damage of the glial cells. In addition, ASA and celecoxib had protective effects on the neuropathic pain-induced oxidative stress markers, including ROS production, mitochondrial membrane potential collapse, and lysosomal membrane leakiness at different time points. Furthermore, the oxidative damage markers were significantly decreased by morphine and etanercept in all investigated days. Since arachidonic acid metabolites and TNF-α are produced during neuropathic pain and inflammation, it can be concluded that the inhibition of the substances production or inhibition of the ligands binding with their receptors would help to decrease the destructive effects of neuropathic pain in the glial cells of rat brain.

[Escin alleviates chemotherapy-induced peripheral neuropathic pain by inducing autophagy in the spinal cord of rats]

OBJECTIVE

To investigate the effect of escin in relieving chemotherapy-induced peripheral neuropathic pain in rats and explore and the underlying mechanism.

METHODS

Eighteen SD rats were randomly divided into 3 groups (n=6), including an escin preconditioning group (treated with 4 mg/kg escin on days 1-7 and then with 2 mg/kg taxol on days 8, 10, 12, and 14), an escin postconditioning group (treated with 2 mg/kg taxol on days 1, 3, 5, and 7 and then with 4 mg/mg escin on days 8-14) and control group (treated with 2 mg/kg taxol on days 1, 3, 5, and 7 and then with saline on days 8-14). Mechanical allodynia and thermal hyperalgesia of the mice were tested on days 4, 7, 10 and 14, and the expression levels of LC3II and p62 in the spinal cord of the rats were detected using Western blotting.

RESULTS

The rats in both the escin preconditioning group and escin postconditioning group showed obviously increased thresholds of mechanical allodynia and thermal hyperalgesia as compared with those in the control group (P < 0.01). Western blotting showed that the expression level of LC3II was significantly increased while p62 expression was lowered in escin preconditioning group as compared with those in the control group (P < 0.05). The escin postconditioning group also showed significantly higher LC3II expression and lower p62 expression levels than the control group (P < 0.05).

CONCLUSIONS

Escin can alleviate chemotherapy-induced peripheral neuropathic pain in rats possibly by upregulating the expressions of autophagy-related proteins in the spinal cord.

Calcium Dynamics in Astrocytes During Cell Injury

The changes in intracellular calcium concentration ([Ca²⁺]) following laser-induced cell injury in nearby cells were studied in primary mouse astrocytes selectively expressing the Ca²⁺ sensitive GFAP-Cre Salsa6f fluorescent tandem protein, in an Ast1 astrocyte cell line, and in primary mouse astrocytes loaded with Fluo4. Astrocytes in these three systems exhibit distinct changes in [Ca²⁺] following induced death of nearby cells. Changes in [Ca²⁺] appear to result from release of Ca²⁺ from intracellular organelles, as opposed to influx from the external medium. Salsa6f expressing astrocytes displayed dynamic Ca²⁺ changes throughout the phagocytic response, including lamellae protrusion, cytosolic signaling during vesicle formation, vesicle maturation, and vesicle tract formation. Our results demonstrate local changes in [Ca²⁺] are involved in the process of phagocytosis in astrocytes responding to cell corpses and/or debris.

Rab27a Contributes to the Processing of Inflammatory Pain in Mice

Tissue injury and inflammation may result in chronic pain, a severe debilitating disease that is associated with great impairment of quality of life. An increasing body of evidence indicates that members of the Rab family of small GTPases contribute to pain processing; however, their specific functions remain poorly understood. Here, we found using immunofluorescence staining and in situ hybridization that the small GTPase Rab27a is highly expressed in sensory neurons and in the superficial dorsal horn of the spinal cord of mice. Rab27a mutant mice, which carry a single-nucleotide missense mutation of Rab27a leading to the expression of a nonfunctional protein, show reduced mechanical hyperalgesia and spontaneous pain behavior in inflammatory pain models, while their responses to acute noxious mechanical and thermal stimuli is not affected. Our study uncovers a previously unrecognized function of Rab27a in the processing of persistent inflammatory pain in mice.