Anandamide (AEA) is an important modulator of nociception in the spinal dorsal horn, acting presynaptically through Cannabinoid (CB1) and Transient receptor potential vanilloid (TRPV1) receptors. The role of AEA (1 μM, 10 μM, and 30 μM) application on the modulation of nociceptive synaptic transmission under control and inflammatory conditions was studied by recording miniature excitatory postsynaptic currents (mEPSCs) from neurons in spinal cord slices. Inhibition of the CB1 receptors by PF514273, TRPV1 by SB366791, and the fatty acid amide hydrolase (FAAH) by URB597 was used. Under naïve conditions, the AEA application did not affect the mEPSCs frequency (1.43±0.12 Hz) when all the recorded neurons were considered. The mEPSC frequency increased (180.0±39.2%) only when AEA (30 μM) was applied with PF514273 and URB597. Analysis showed that one sub-population of neurons had synaptic input inhibited (39.1% of neurons), the second excited (43.5%), whereas 8.7% showed a mixed effect and 8.7% did not respond to the AEA. With inflammation, the AEA effect was highly inhibitory (72.7%), while the excitation was negligible (9.1%), and 18.2% were not modulated. After inflammation, more neurons (45.0%) responded even to low AEA by mEPSC frequency increase with PF514273/URB597 present. AEA-induced dual (excitatory/inhibitory) effects at the 1st nociceptive synapse should be considered when developing analgesics targeting the endocannabinoid system. These findings contrast the clear inhibitory effects of the AEA precursor 20:4-NAPE application described previously and suggest that modulation of endogenous AEA production may be more favorable for analgesic treatments.
- MeSH
- amidohydrolasy MeSH
- analgetika farmakologie MeSH
- benzamidy * MeSH
- endokanabinoidy * farmakologie MeSH
- karbamáty * MeSH
- kyseliny arachidonové * MeSH
- lidé MeSH
- nocicepce * MeSH
- polynenasycené alkamidy farmakologie MeSH
- zadní rohy míšní MeSH
- zánět farmakoterapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Transient receptor potential ion channel, vanilloid subfamily, type 1 (TRPV1) cation channel, and cannabinoid receptor 1 (CB1) are essential in the modulation of nociceptive signaling in the spinal cord dorsal horn that underlies different pathological pain states. TRPV1 and CB1 receptors share the endogenous agonist anandamide (AEA), produced from N-arachidonoylphosphatidylethanolamine (20:4-NAPE). We investigated the effect of the anandamide precursor 20:4-NAPE on synaptic activity in naive and inflammatory conditions. Patch-clamp recordings of miniature excitatory postsynaptic currents (mEPSCs) from superficial dorsal horn neurons in rat acute spinal cord slices were used. Peripheral inflammation was induced by subcutaneous injection of carrageenan. Under naive conditions, mEPSCs frequency (0.96 ± 0.11 Hz) was significantly decreased after 20 μM 20:4-NAPE application (55.3 ± 7.4%). This 20:4-NAPE-induced inhibition was blocked by anandamide-synthesizing enzyme N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD) inhibitor LEI-401. In addition, the inhibition was prevented by the CB1 receptor antagonist PF 514273 (0.2 μM) but not by the TRPV1 receptor antagonist SB 366791 (10 μM). Under inflammatory conditions, 20:4-NAPE (20 μM) also exhibited a significant inhibitory effect (74.5 ± 8.9%) on the mEPSCs frequency that was prevented by the TRPV1 receptor antagonist SB 366791 but not by PF 514273 application. Our results show that 20:4-NAPE application has a significant modulatory effect on spinal cord nociceptive signaling that is mediated by both TRPV1 and CB1 presynaptic receptors, whereas peripheral inflammation changes the underlying mechanism. The switch between TRPV1 and CB1 receptor activation by the AEA precursor 20:4-NAPE during inflammation may play an important role in nociceptive processing, hence the development of pathological pain.
- Publikační typ
- časopisecké články MeSH
The development of painful paclitaxel-induced peripheral neuropathy (PIPN) represents a major dose-limiting side effect of paclitaxel chemotherapy. Here we report a promising effect of duvelisib (Copiktra), a novel FDA-approved PI3Kδ/γ isoform-specific inhibitor, in preventing paclitaxel-induced pain-like behavior and pronociceptive signaling in DRGs and spinal cord dorsal horn (SCDH) in rat and mouse model of PIPN. Duvelisib blocked the development of mechanical hyperalgesia in both males and females. Moreover, duvelisib prevented paclitaxel-induced sensitization of TRPV1 receptors, and increased PI3K/Akt signaling in small-diameter DRG neurons and an increase of CD68+ cells within DRGs. Specific optogenetic stimulation of inhibitory neurons combined with patch-clamp recording revealed that duvelisib inhibited paclitaxel-induced weakening of inhibitory, mainly glycinergic control on SCDH excitatory neurons. Enhanced excitatory and reduced inhibitory neurotransmission in the SCDH following PIPN was also alleviated by duvelisib application. In summary, duvelisib showed a promising ability to prevent neuropathic pain in PIPN. The potential use of our findings in human medicine may be augmented by the fact that duvelisib is an FDA-approved drug with known side effects.SIGNIFICANCE STATEMENT We show that duvelisib, a novel FDA-approved PI3Kδ/γ isoform-specific inhibitor, prevents the development of paclitaxel-induced pain-like behavior in males and females and prevents pronociceptive signaling in DRGs and spinal cord dorsal horn in rat and mouse model of paclitaxel-induced peripheral neuropathy.
- MeSH
- bolest MeSH
- fosfatidylinositol-3-kinasy MeSH
- fytogenní protinádorové látky * farmakologie MeSH
- hyperalgezie chemicky indukované farmakoterapie prevence a kontrola MeSH
- isochinoliny MeSH
- krysa rodu rattus MeSH
- myši MeSH
- nemoci periferního nervového systému MeSH
- neuralgie * chemicky indukované farmakoterapie prevence a kontrola MeSH
- paclitaxel škodlivé účinky MeSH
- puriny MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Opioid analgesics remain widely used for pain treatment despite the related serious side effects. Some of those, such as opioid tolerance and opioid-induced hyperalgesia may be at least partially due to modulation of opioid receptors (OR) function at nociceptive synapses in the spinal cord dorsal horn. It was suggested that increased release of different chemokines under pathological conditions may play a role in this process. The goal of this study was to investigate the crosstalk between the μOR, transient receptor potential vanilloid 1 (TRPV1) receptor and C-C motif ligand 2 (CCL2) chemokine and the involvement of spinal microglia in the modulation of opioid analgesia. METHODS: Patch-clamp recordings of miniature excitatory postsynaptic currents (mEPSCs) and dorsal root evoked currents (eEPSC) in spinal cord slices superficial dorsal horn neurons were used to evaluate the effect of μOR agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO), CCL2, TRPV1 antagonist SB366791 and minocycline. Paw withdrawal test to thermal stimuli was combined with intrathecal (i.t.) delivery of CCL2 and DAMGO to investigate the modulation in vivo. RESULTS: Application of DAMGO induced a rapid decrease of mEPSC frequency and eEPSC amplitude, followed by a delayed increase of the eESPC amplitude, which was prevented by SB366791. Chemokine CCL2 treatment significantly diminished all the DAMGO-induced changes. Minocycline treatment prevented the CCL2 effects on the DAMGO-induced eEPSC depression, while mEPSC changes were unaffected. In behavioral experiments, i.t. injection of CCL2 completely blocked DAMGO-induced thermal hypoalgesia and intraperitoneal pre-treatment with minocycline prevented the CCL2 effect. CONCLUSIONS: Our results indicate that opioid-induced inhibition of the excitatory synaptic transmission could be severely attenuated by increased CCL2 levels most likely through a microglia activation-dependent mechanism. Delayed potentiation of neurotransmission after μOR activation is dependent on TRPV1 receptors activation. Targeting CCL2 and its receptors and TRPV1 receptors in combination with opioid therapy could significantly improve the analgesic properties of opioids, especially during pathological states.
- MeSH
- anilidy farmakologie MeSH
- chemokin CCL2 farmakologie MeSH
- cinnamáty farmakologie MeSH
- enkefalin, Ala(2)-MePhe(4)-Gly(5)- farmakologie MeSH
- excitační postsynaptické potenciály účinky léků MeSH
- krysa rodu rattus MeSH
- mícha účinky léků MeSH
- miniaturní postsynaptické potenciály účinky léků MeSH
- nervový přenos účinky léků MeSH
- neurony účinky léků MeSH
- nocicepce účinky léků MeSH
- opioidní analgetika farmakologie MeSH
- potkani Wistar MeSH
- zadní rohy míšní účinky léků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Transient receptor potential vanilloid 1 (TRPV1) channels contribute to the development of several chronic pain states and represent a possible therapeutic target in many painful disease treatment. Proinflammatory mediator bradykinin (BK) sensitizes TRPV1, whereas noxious peripheral stimulation increases BK level in the spinal cord. Here, we investigated the involvement of spinal TRPV1 in thermal and mechanical hypersensitivity, evoked by intrathecal (i.t.) administration of BK and an endogenous agonist of TRPV1, N-oleoyldopamine (OLDA), using behavioral tests and i.t. catheter implantation, and administration of BK-induced transient thermal and mechanical hyperalgesia and mechanical allodynia. All these hypersensitive states were enhanced by co-administration of a low dose of OLDA (0.42 µg i.t.), which was ineffective only under the control conditions. Intrathecal pretreatment with TRPV1 selective antagonist SB366791 prevented hypersensitivity induced by i.t. co-administration of BK and OLDA. Our results demonstrate that both thermal and mechanical hypersensitivity evoked by co-administration of BK and OLDA is mediated by the activation of spinal TRPV1 channels.
The mechanisms of inflammatory pain need to be identified in order to find new superior treatments. Protease-activated receptors 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) are highly co-expressed in dorsal root ganglion neurons and implicated in pain development. Here, we examined the role of spinal PAR2 in hyperalgesia and the modulation of synaptic transmission in carrageenan-induced peripheral inflammation, using intrathecal (i.t.) treatment in the behavioral experiments and recordings of spontaneous, miniature and dorsal root stimulation-evoked excitatory postsynaptic currents (sEPSCs, mEPSCs and eEPSCs) in spinal cord slices. Intrathecal PAR2-activating peptide (AP) administration aggravated the carrageenan-induced thermal hyperalgesia, and this was prevented by a TRPV1 antagonist (SB 366791) and staurosporine i.t. pretreatment. Additionally, the frequency of the mEPSC and sEPSC and the amplitude of the eEPSC recorded from the superficial dorsal horn neurons were enhanced after acute PAR2 AP application, while prevented with SB 366791 or staurosporine pretreatment. PAR2 antagonist application reduced the thermal hyperalgesia and decreased the frequency of mEPSC and sEPSC and the amplitude of eEPSC. Our findings highlight the contribution of spinal PAR2 activation to carrageenan-induced hyperalgesia and the importance of dorsal horn PAR2 and TRPV1 receptor interactions in the modulation of nociceptive synaptic transmission.
- MeSH
- anilidy farmakologie MeSH
- buňky zadních rohů míšních účinky léků metabolismus fyziologie MeSH
- cinnamáty farmakologie MeSH
- excitační postsynaptické potenciály MeSH
- hyperalgezie etiologie metabolismus patofyziologie MeSH
- karagenan farmakologie toxicita MeSH
- kationtové kanály TRPV antagonisté a inhibitory metabolismus MeSH
- krysa rodu rattus MeSH
- miniaturní postsynaptické potenciály MeSH
- nocicepce MeSH
- potkani Wistar MeSH
- receptor PAR-2 metabolismus MeSH
- staurosporin farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Paclitaxel-induced peripheral neuropathy (PIPN) is often associated with neuropathic pain and neuroinflammation in the central and peripheral nervous system. Antihypertensive drug losartan, an angiotensin II receptor type 1 (AT1R) blocker, was shown to have anti-inflammatory and neuroprotective effects in disease models, predominantly via activation of peroxisome proliferator-activated receptor gamma (PPARγ). Here, the effect of systemic losartan treatment (100 mg/kg/d) on mechanical allodynia and neuroinflammation was evaluated in rat PIPN model. The expression of pro-inflammatory markers protein and mRNA levels in dorsal root ganglia (DRGs) and spinal cord dorsal horn (SCDH) were measured with Western blot, ELISA and qPCR 10 and 21 days after PIPN induction. Losartan treatment attenuated mechanical allodynia significantly. Paclitaxel induced overexpression of C-C motif chemokine ligand 2 (CCL2), tumour necrosis alpha (TNFα) and interleukin-6 (IL-6) in DRGs, where the presence of macrophages was demonstrated. Neuroinflammatory changes in DRGs were accompanied with glial activation and pro-nociceptive modulators production in SCDH. Losartan significantly attenuated paclitaxel-induced neuroinflammatory changes and induced expression of pro-resolving markers (Arginase 1 and IL-10) indicating a possible shift in macrophage polarization. Considering the safety profile of losartan, acting also as partial PPARγ agonist, it may be considered as a novel treatment strategy for PIPN patients.
- MeSH
- biologické markery MeSH
- ELISA MeSH
- fytogenní protinádorové látky škodlivé účinky MeSH
- krysa rodu rattus MeSH
- losartan farmakologie MeSH
- makrofágy účinky léků metabolismus MeSH
- management bolesti MeSH
- modely nemocí na zvířatech MeSH
- neuralgie diagnóza farmakoterapie etiologie metabolismus MeSH
- paclitaxel škodlivé účinky MeSH
- spinální ganglia účinky léků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Paclitaxel chemotherapy treatment often leads to neuropathic pain resistant to available analgesic treatments. Recently spinal Toll-like receptor 4 (TLR4) and the transient receptor potential cation channel subfamily V member 1 (TRPV1) were identified to be involved in the pro-nociceptive effect of paclitaxel. The aim of this study was to investigate the role of phosphatidylinositol 3-kinase (PI3K) and serine/threonine kinases in this process, with the use of their antagonists (wortmannin, LY-294002, and staurosporine). The single paclitaxel administration (8 mg/kg i.p.) in mice induced robust mechanical allodynia measured as a reduced threshold to von Frey filament stimulation and generated reduced tachyphylaxis of capsaicin-evoked responses, recorded as changes in mEPSC frequency in patch-clamp recordings of dorsal horn neurons activity in vitro, for up to eight days. Paclitaxel application also induced increased Akt kinase phosphorylation in rat DRG neurons. All these paclitaxel-induced changes were prevented by the wortmannin in vivo pretreatment. Acute co-application of wortmannin or LY-294002 with paclitaxel in spinal cord slices also attenuated the paclitaxel effect on capsaicin-evoked responses. Staurosporine was effective in the acute in vitro experiments and on the first day after the paclitaxel treatment in vivo, but in contrast to wortmannin, it did not have a significant impact later. Our data suggest that the inhibition of PI3K signaling may help alleviate pathological pain syndromes in the paclitaxel-induced neuropathy.
- MeSH
- buňky zadních rohů míšních účinky léků metabolismus MeSH
- excitační postsynaptické potenciály účinky léků MeSH
- fosfatidylinositol-3-kinasy metabolismus MeSH
- hyperalgezie chemicky indukované farmakoterapie metabolismus MeSH
- inhibitory proteinkinas farmakologie MeSH
- kapsaicin farmakologie MeSH
- kationtové kanály TRP MeSH
- kationtové kanály TRPV metabolismus MeSH
- krysa rodu rattus MeSH
- lipopolysacharidy farmakologie MeSH
- mícha účinky léků metabolismus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- neuralgie chemicky indukované farmakoterapie metabolismus MeSH
- onkogenní protein v-akt metabolismus MeSH
- paclitaxel toxicita MeSH
- peptidové fragmenty imunologie metabolismus MeSH
- potkani Wistar MeSH
- protein-serin-threoninkinasy antagonisté a inhibitory metabolismus MeSH
- proteinkinasa C imunologie metabolismus MeSH
- signální transdukce účinky léků MeSH
- toll-like receptor 4 metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Controlling pain in burn-injured patients poses a major clinical challenge. Recent findings suggest that reducing the activity of the voltage-gated sodium channel Nav1.7 in primary sensory neurons could provide improved pain control in burn-injured patients. Here, we report that partial thickness scalding-type burn injury on the rat paw upregulates Nav1.7 expression in primary sensory neurons 3 h following injury. The injury also induces upregulation in phosphorylated cyclic adenosine monophosphate response element-binding protein (p-CREB), a marker for nociceptive activation in primary sensory neurons. The upregulation in p-CREB occurs mainly in Nav1.7-immunopositive neurons and exhibits a peak at 5 min and, following a decline at 30 min, a gradual increase from 1 h post-injury. The Nav1.7 blocker protoxin II (ProTxII) or morphine injected intraperitoneally 15 min before or after the injury significantly reduces burn injury-induced spinal upregulation in phosphorylated serine 10 in histone H3 and phosphorylated extracellular signal-regulated kinase 1/2, which are both markers for spinal nociceptive processing. Further, ProTxII significantly reduces the frequency of spontaneous excitatory post-synaptic currents in spinal dorsal horn neurons following burn injury. Together, these findings indicate that using Nav1.7 blockers should be considered to control pain in burn injury. KEY MESSAGES: • Burn injury upregulates Nav1.7 expression in primary sensory neurons. • Burn injury results in increased activity of Nav1.7-expressing primary sensory neurons. • Inhibiting Nav1.7 by protoxin II reduces spinal nociceptive processing. • Nav1.7 represents a potential target to reduce pain in burn injury.
- MeSH
- analgetika terapeutické užití MeSH
- blokátory sodíkových kanálů řízených napětím terapeutické užití MeSH
- bolest farmakoterapie MeSH
- mícha cytologie fyziologie MeSH
- myši inbrední C57BL MeSH
- myši knockoutované MeSH
- napěťově řízený sodíkový kanál, typ 9 fyziologie MeSH
- nervové receptory fyziologie MeSH
- pavoučí jedy terapeutické užití MeSH
- peptidy terapeutické užití MeSH
- popálení farmakoterapie MeSH
- potkani Sprague-Dawley MeSH
- potkani Wistar MeSH
- protein vázající cAMP responzivní element metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND AND PURPOSE: Endocannabinoids play an important role in modulating spinal nociceptive signalling, crucial for the development of pain. The cannabinoid CB1 receptor and the TRPV1 cation channel are both activated by the endocannabinoid anandamide, a product of biosynthesis from the endogenous lipid precursor N-arachidonoylphosphatidylethanolamine (20:4-NAPE). Here, we report CB1 receptor- and TRPV1-mediated effects of 20:4-NAPE on spinal synaptic transmission in control and inflammatory conditions. EXPERIMENTAL APPROACH: Spontaneous (sEPSCs) and dorsal root stimulation-evoked (eEPSCs) excitatory postsynaptic currents from superficial dorsal horn neurons in rat spinal cord slices were assessed. Peripheral inflammation was induced by carrageenan. Anandamide concentration was assessed by mass spectrometry. KEY RESULTS: Application of 20:4-NAPE increased anandamide concentration in vitro. 20:4-NAPE (20 μM) decreased sEPSCs frequency and eEPSCs amplitude in control and inflammatory conditions. The inhibitory effect of 20:4-NAPE was sensitive to CB1 receptor antagonist PF514273 (0.2 μM) in both conditions, but to the TRPV1 antagonist SB366791 (10 μM) only after inflammation. After inflammation, 20:4-NAPE increased sEPSCs frequency in the presence of PF514273 and this increase was blocked by SB366791. CONCLUSIONS AND IMPLICATIONS: While 20:4-NAPE treatment inhibited the excitatory synaptic transmission in both naive and inflammatory conditions, peripheral inflammation altered the underlying mechanisms. Our data indicate that 20:4-NAPE application induced mainly CB1 receptor-mediated inhibitory effects in naive animals while TRPV1-mediated mechanisms were also involved after inflammation. Increasing anandamide levels for analgesic purposes by applying substrate for its local synthesis may be more effective than systemic anandamide application or inhibition of its degradation. LINKED ARTICLES: This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
- MeSH
- buňky zadních rohů míšních účinky léků metabolismus MeSH
- fosfatidylethanolaminy chemická syntéza chemie farmakologie MeSH
- hmotnostní spektrometrie MeSH
- karagenan MeSH
- krysa rodu rattus MeSH
- mícha účinky léků metabolismus MeSH
- nervový přenos účinky léků MeSH
- potkani Wistar MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zánět chemicky indukované metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
