Pulsed Radiofrequency Upregulates Serotonin Transporters and Alleviates Neuropathic Pain-Induced Depression in a Spared Nerve Injury Rat Model

Neuropathic pain (NP) is difficult to treat due to complex pathophysiological mechanisms. Pulsed radiofrequency (RRF) has been used widely with neuromodulation effect in refractory chronic pain treatment. A recent study found that PRF treatment may decrease chronic pain-related anxiety-depressant symptoms in patients, even though the mechanisms are unclear. Additionally, accumulated evidence has shown serotonin uptake is correlated with various neuropsychiatric diseases. Therefore, we investigated the effects and underlying mechanisms of PRF on depression-like behaviors, resulting from spared nerve injury (SNI)-induced NP. We examined the indexes of mechanical allodynia, cold allodynia, depression-like behavior, and blood cytokines by dynamic plantar aesthesiometry, acetone spray test, forced swimming test, and ProcartaPlex multiplex immunoassays in male Wistar rats, respectively. Serotonin transporters (SERTs) in rat brains were examined by using 4-[18F]-ADAM/PET imaging. We found that specific uptake ratios (SURs) of SERTs were significantly decreased in the brain regions of the thalamus and striatum in rats with SNI-induced NP and depression-like behaviors. Additionally, the decrease in SERT density was correlated with the development of a depression-like behavior indicated by the forced swimming test results and pronounced IL-6 cytokines. Moreover, we demonstrated that PRF application could modulate the descending serotoninergic pathway to relieve pain and depression behaviors.

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Environmental enrichment alleviates chronic pain in rats following a spared nerve injury to induce neuropathic pain. A preliminary study

Veterinary Medicine Research and Reports ◽

10.2147/vmrr.s181531 ◽

2018 ◽

Vol Volume 9 ◽

pp. 69-72 ◽

Cited By ~ 1

Author(s):

Madeleine Parent-Vachon ◽

Pascal Vachon

Keyword(s):

Chronic Pain ◽

Neuropathic Pain ◽

Nerve Injury ◽

Environmental Enrichment ◽

Spared Nerve Injury ◽

Preliminary Study

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Rostral Anterior Cingulate Cortex–Ventrolateral Periaqueductal Gray Circuit Underlies Electroacupuncture to Alleviate Hyperalgesia but Not Anxiety-Like Behaviors in Mice With Spared Nerve Injury

Frontiers in Neuroscience ◽

10.3389/fnins.2021.757628 ◽

2022 ◽

Vol 15 ◽

Author(s):

Xixiao Zhu ◽

Yingling Xu ◽

Zui Shen ◽

Haiyan Zhang ◽

Siqi Xiao ◽

...

Keyword(s):

Chronic Pain ◽

Neuropathic Pain ◽

Anterior Cingulate Cortex ◽

Nerve Injury ◽

Negative Emotions ◽

Periaqueductal Gray ◽

Anterior Cingulate ◽

Spared Nerve Injury ◽

Mice Model ◽

Rostral Anterior Cingulate Cortex

Neuropathic pain is a common cause of chronic pain and is often accompanied by negative emotions, making it complex and difficult to treat. However, the neural circuit mechanisms underlying these symptoms remain unclear. Herein, we present a novel pathway associated with comorbid chronic pain and anxiety. Using chemogenetic methods, we found that activation of glutamatergic projections from the rostral anterior cingulate cortex (rACCGlu) to the ventrolateral periaqueductal gray (vlPAG) induced both hyperalgesia and anxiety-like behaviors in sham mice. Inhibition of the rACCGlu-vlPAG pathway reduced anxiety-like behaviors and hyperalgesia in the spared nerve injury (SNI) mice model; moreover, electroacupuncture (EA) effectively alleviated these symptoms. Investigation of the related mechanisms revealed that the chemogenetic activation of the rACCGlu-vlPAG circuit effectively blocked the analgesic effect of EA in the SNI mice model but did not affect the chronic pain-induced negative emotions. This study revealed a novel pathway, the rACCGlu-vlPAG pathway, that mediates neuropathic pain and pain-induced anxiety.

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Experimental anxiety-depressive state in rats caused by neonatal exposure to the inhibitor of dipeptidyl peptidase IV, diprotin A: effects of imipramine

ZHurnal «Patologicheskaia fiziologiia i eksperimental`naia terapiia» ◽

10.25557/igpp.2017.4.8517 ◽

2017 ◽

pp. 4-12

Author(s):

Н.Н. Хлебникова ◽

Н.А. Крупина

Keyword(s):

Forced Swimming Test ◽

Dipeptidyl Peptidase ◽

Dipeptidyl Peptidase Iv ◽

Forced Swimming ◽

Face Validity ◽

Neonatal Exposure ◽

Depressive State ◽

Serum Corticosterone ◽

Old Rats ◽

Swimming Test

В наших предыдущих исследованиях было показано, что ингибитор пролинспецифической пептидазы дипептидилпептидазы-IV (ДП-IV, EC 3.4.14.5) трипептид дипротин А, введенный крысам в 5-18 постнатальные дни, приводит к развитию у крыс подросткового возраста и взрослых животных эмоционально-мотивационных расстройств. Такие расстройства можно рассматривать как модель смешанного тревожно-депрессивного состояния. Однако специальных исследований по валидности данной модели проведено не было. Цель настоящей работы состояла в проверке влияния трициклического антидепрессанта имипрамина (ИМИ) на депрессивноподобное поведение крыс и уровень кортикостерона в сыворотке крови животных на модели смешанного тревожно-депрессивного состояния. Методика. У крыс в возрасте одного и двух мес. определяли уровень тревожности в автоматизированном тесте «Приподнятый крестообразный лабиринт» и оценивали депрессивноподобное поведение в тесте принудительного плавания. ИМИ вводили взрослым животным в течение 10 дней (20 мг/кг/день, интрагастрально). Уровень кортикостерона в сыворотке крови определяли методом твердофазного иммуноферментного анализа. Результаты. Неонатальное действие дипротина А приводило к повышению тревожности у крыс в возрасте 1 мес. Депрессивноподобное поведение обнаружено у животных в возрасте одного и двух мес. ИМИ нормализовал поведение животных в тесте принудительного плавания и снижал уровень кортикостерона в сыворотке крови крыс. Кроме того, ИМИ снижал вес крыс. Заключение. Результаты исследования свидетельствуют в пользу адекватности модели смешанного тревожно-депрессивного расстройства, возникающего у крыс вследствие действия ингибитора ДП-IV дипротина А на второй-третьей неделях постнатального развития, клиническому прообразу заболевания по критериям «внешней схожести», прогностической и конструкционной валидности. Previously, we have shown that the inhibitor of proline-specific peptidase, dipeptidyl peptidase-IV (DP-IV, EC 3.4.14.5), tripeptide diproptin A administered on postnatal days 5-18 induced emotional and motivational disorders in adolescent and adult rats. These disorders can be considered a model of a mixed anxiety-depression-like disorder. However, validation studies of this model are not available. The aim of this work was to test the effect of the tricyclic antidepressant, imipramine (IMI), on depressive-like behavior in rats and the level of serum corticosterone using the model of mixed anxiety-depressive state. Methods. The level of anxiety was assessed by the automated Elevated Plus Maze test and the depressive-like behavior was evaluated by the forced swimming test in one- and two-month old rats. IMI was administered to adult animals for ten days (20 mg/kg a day, intragastrically). Serum corticosterone concentrations were measured using ELISA. Results. The neonatal exposure to diprotin A increased anxiety in one-month old rats. The depressive-like behavior was observed in animals aged one and two months. IMI normalized behavior of animals in the forced swimming test and reduced serum levels of corticosterone. Also, IMI reduced body weight of rats. Conclusion. The results of the study evidenced adequacy of the model of mixed anxiety-depressive state induced by the DP-IV inhibitor, diprotin A, on the second and third postnatal weeks to the clinical prototype of disease according to criteria of face validity, predictive and construct validity.

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Role of the immune system in neuropathic pain

Scandinavian Journal of Pain ◽

10.1515/sjpain-2019-0138 ◽

2019 ◽

Vol 20 (1) ◽

pp. 33-37 ◽

Cited By ~ 16

Author(s):

Marzia Malcangio

Keyword(s):

Spinal Cord ◽

Chronic Pain ◽

Nervous System ◽

Neuropathic Pain ◽

Immune System ◽

Peripheral Nerve ◽

Dorsal Horn ◽

Nerve Injury ◽

Immune Cells ◽

Peripheral Nerve Injury

AbstractBackgroundAcute pain is a warning mechanism that exists to prevent tissue damage, however pain can outlast its protective purpose and persist beyond injury, becoming chronic. Chronic Pain is maladaptive and needs addressing as available medicines are only partially effective and cause severe side effects. There are profound differences between acute and chronic pain. Dramatic changes occur in both peripheral and central pathways resulting in the pain system being sensitised, thereby leading to exaggerated responses to noxious stimuli (hyperalgesia) and responses to non-noxious stimuli (allodynia).Critical role for immune system cells in chronic painPreclinical models of neuropathic pain provide evidence for a critical mechanistic role for immune cells in the chronicity of pain. Importantly, human imaging studies are consistent with preclinical findings, with glial activation evident in the brain of patients experiencing chronic pain. Indeed, immune cells are no longer considered to be passive bystanders in the nervous system; a consensus is emerging that, through their communication with neurons, they can both propagate and maintain disease states, including neuropathic pain. The focus of this review is on the plastic changes that occur under neuropathic pain conditions at the site of nerve injury, the dorsal root ganglia (DRG) and the dorsal horn of the spinal cord. At these sites both endothelial damage and increased neuronal activity result in recruitment of monocytes/macrophages (peripherally) and activation of microglia (centrally), which release mediators that lead to sensitisation of neurons thereby enabling positive feedback that sustains chronic pain.Immune system reactions to peripheral nerve injuriesAt the site of peripheral nerve injury following chemotherapy treatment for cancer for example, the occurrence of endothelial activation results in recruitment of CX3C chemokine receptor 1 (CX3CR1)-expressing monocytes/macrophages, which sensitise nociceptive neurons through the release of reactive oxygen species (ROS) that activate transient receptor potential ankyrin 1 (TRPA1) channels to evoke a pain response. In the DRG, neuro-immune cross talk following peripheral nerve injury is accomplished through the release of extracellular vesicles by neurons, which are engulfed by nearby macrophages. These vesicles deliver several determinants including microRNAs (miRs), with the potential to afford long-term alterations in macrophages that impact pain mechanisms. On one hand the delivery of neuron-derived miR-21 to macrophages for example, polarises these cells towards a pro-inflammatory/pro-nociceptive phenotype; on the other hand, silencing miR-21 expression in sensory neurons prevents both development of neuropathic allodynia and recruitment of macrophages in the DRG.Immune system mechanisms in the central nervous systemIn the dorsal horn of the spinal cord, growing evidence over the last two decades has delineated signalling pathways that mediate neuron-microglia communication such as P2X4/BDNF/GABAA, P2X7/Cathepsin S/Fractalkine/CX3CR1, and CSF-1/CSF-1R/DAP12 pathway-dependent mechanisms.Conclusions and implicationsDefinition of the modalities by which neuron and immune cells communicate at different locations of the pain pathway under neuropathic pain states constitutes innovative biology that takes the pain field in a different direction and provides opportunities for novel approaches for the treatment of chronic pain.

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