Three decades ago, the first endocannabinoid, anandamide (AEA), was identified, and its analgesic effect was recognized in humans and preclinical models. However, clinical trial failures pointed out the complexity of the AEA-induced analgesia. The first synapses in the superficial laminae of the spinal cord dorsal horn represent an important modulatory site in nociceptive transmission and subsequent pain perception. The glutamatergic synaptic transmission at these synapses is strongly modulated by two primary AEA-activated receptors, cannabinoid receptor 1 (CB1) and transient receptor potential vanilloid 1 (TRPV1), both highly expressed on the presynaptic side formed by the endings of primary nociceptive neurons. Activation of these receptors can have predominantly inhibitory (CB1) and excitatory (TRPV1) effects that are further modulated under pathological conditions. In addition, dual AEA-mediated signaling and action may occur in primary sensory neurons and dorsal horn synapses. AEA application causes balanced inhibition and excitation of primary afferent synaptic input on superficial dorsal horn neurons in normal conditions, whereas peripheral inflammation promotes AEA-mediated inhibition. This review focuses mainly on the modulation of synaptic transmission at the spinal cord level and signaling in primary nociceptive neurons by AEA via CB1 and TRPV1 receptors. Furthermore, the spinal analgesic effect in preclinical studies and clinical aspects of AEA-mediated analgesia are considered.

• MeSH
• endokanabinoidy * metabolismus   MeSH
• kationtové kanály TRPV metabolismus   MeSH
• kyseliny arachidonové * metabolismus   farmakologie   MeSH
• lidé MeSH
• mícha * metabolismus   účinky léků   MeSH
• nervový přenos * fyziologie   účinky léků   MeSH
• nocicepce fyziologie   účinky léků   MeSH
• nociceptory metabolismus   účinky léků   fyziologie   MeSH
• polynenasycené alkamidy * metabolismus   MeSH
• receptor kanabinoidní CB1 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• anandamide MeSH Prohlížeč
• endokanabinoidy * MeSH
• kationtové kanály TRPV MeSH
• kyseliny arachidonové * MeSH
• polynenasycené alkamidy * MeSH
• receptor kanabinoidní CB1 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.

• Klíčová slova
• 20:4-NAPE, CB1, NAPE-PLD, TRPV1, anandamide, inflammation, spinal cord,
• Publikační typ
• časopisecké články 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.

• Klíčová slova
• CCL2, Hyperalgesia, MOR, Microglia, Spinal cord, Synaptic transmission, TRPV1,
• 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
• Názvy látek
• anilidy MeSH
• chemokin CCL2 MeSH
• cinnamáty MeSH
• enkefalin, Ala(2)-MePhe(4)-Gly(5)- MeSH
• N-(3-methoxyphenyl)-4-chlorocinnamanilide MeSH Prohlížeč
• opioidní analgetika 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.

• Klíčová slova
• OLDA, TRPV1, allodynia, bradykinin, hyperalgesia, spinal cord,
• MeSH
• bradykinin MeSH
• dopamin analogy a deriváty   MeSH
• hyperalgezie metabolismus   MeSH
• kationtové kanály TRPV agonisté   metabolismus   MeSH
• krysa rodu Rattus MeSH
• mícha metabolismus   MeSH
• potkani Wistar MeSH
• spinální injekce MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bradykinin MeSH
• dopamin MeSH
• kationtové kanály TRPV MeSH
• N-oleoyldopamine MeSH Prohlížeč
• TRPV1 protein, mouse MeSH Prohlížeč

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.

• Klíčová slova
• PAR2, TRPV1, inflammatory pain, nociception, peripheral inflammation, spinal cord, superficial dorsal horn, synaptic transmission, thermal hyperalgesia,
• 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
• Názvy látek
• anilidy MeSH
• cinnamáty MeSH
• karagenan MeSH
• kationtové kanály TRPV MeSH
• N-(3-methoxyphenyl)-4-chlorocinnamanilide MeSH Prohlížeč
• receptor PAR-2 MeSH
• staurosporin MeSH
• Trpv1 protein, rat MeSH Prohlížeč

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
• Názvy látek
• fosfatidylethanolaminy MeSH
• karagenan MeSH

UNLABELLED: 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.

• Klíčová slova
• Pain, Primary sensory neuron, Spinal cord, p-ERK1/2, p-S10H3,
• 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 element responzivní pro cyklický AMP metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• analgetika MeSH
• blokátory sodíkových kanálů řízených napětím MeSH
• napěťově řízený sodíkový kanál, typ 9 MeSH
• pavoučí jedy MeSH
• peptidy MeSH
• protein vázající element responzivní pro cyklický AMP MeSH
• protoxin II, Thrixopelma pruriens MeSH Prohlížeč

Protease-activated receptors 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) receptors in the peripheral nerve endings are implicated in the development of increased sensitivity to mechanical and thermal stimuli, especially during inflammatory states. Both PAR2 and TRPV1 receptors are co-expressed in nociceptive dorsal root ganglion (DRG) neurons on their peripheral endings and also on presynaptic endings in the spinal cord dorsal horn. However, the modulation of nociceptive synaptic transmission in the superficial dorsal horn after activation of PAR2 and their functional coupling with TRPV1 is not clear. To investigate the role of spinal PAR2 activation on nociceptive modulation, intrathecal drug application was used in behavioural experiments and patch-clamp recordings of spontaneous, miniature and dorsal root stimulation-evoked excitatory postsynaptic currents (sEPSCs, mEPSCs, eEPSCs) were performed on superficial dorsal horn neurons in acute rat spinal cord slices. Intrathecal application of PAR2 activating peptide SLIGKV-NH2 induced thermal hyperalgesia, which was prevented by pretreatment with TRPV1 antagonist SB 366791 and was reduced by protein kinases inhibitor staurosporine. Patch-clamp experiments revealed robust decrease of mEPSC frequency (62.8 ± 4.9%), increase of sEPSC frequency (127.0 ± 5.9%) and eEPSC amplitude (126.9 ± 12.0%) in dorsal horn neurons after acute SLIGKV-NH2 application. All these EPSC changes, induced by PAR2 activation, were prevented by SB 366791 and staurosporine pretreatment. Our results demonstrate an important role of spinal PAR2 receptors in modulation of nociceptive transmission in the spinal cord dorsal horn at least partially mediated by activation of presynaptic TRPV1 receptors. The functional coupling between the PAR2 and TRPV1 receptors on the central branches of DRG neurons may be important especially during different pathological states when it may enhance pain perception.

• MeSH
• alergie metabolismus   patologie   MeSH
• anilidy farmakologie   MeSH
• buňky zadních rohů míšních účinky léků   fyziologie   MeSH
• chování zvířat účinky léků   MeSH
• cinnamáty farmakologie   MeSH
• excitační postsynaptické potenciály účinky léků   MeSH
• hyperalgezie etiologie   prevence a kontrola   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• kationtové kanály TRPV antagonisté a inhibitory   metabolismus   MeSH
• krysa rodu Rattus MeSH
• metoda terčíkového zámku MeSH
• mícha metabolismus   MeSH
• nervový přenos fyziologie   MeSH
• oligopeptidy farmakologie   MeSH
• potkani Wistar MeSH
• receptor PAR-2 agonisté   metabolismus   MeSH
• staurosporin farmakologie   MeSH
• techniky in vitro MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• anilidy MeSH
• cinnamáty MeSH
• inhibitory proteinkinas MeSH
• kationtové kanály TRPV MeSH
• N-(3-methoxyphenyl)-4-chlorocinnamanilide MeSH Prohlížeč
• oligopeptidy MeSH
• receptor PAR-2 MeSH
• seryl-leucyl-isoleucyl-glycyl-lysyl-valinamide MeSH Prohlížeč
• staurosporin MeSH
• TRPV1 receptor MeSH Prohlížeč

BACKGROUND: Acute postoperative pain is one of the frequent reasons for pain treatment. However, the exact mechanisms of its development are still not completely clear. Transient receptor potential vanilloid 1 (TRPV1) receptors are involved in nociceptive signaling in various hypersensitive states. Here we have investigated the contribution of TRPV1 receptors expressed on cutaneous peripheral nociceptive fibers and in the spinal cord on the development and maintenance of hypersensitivity to thermal and mechanical stimuli following surgical incision. A rat plantar incision model was used to test paw withdrawal responses to thermal and mechanical stimuli. The effect of the TRPV1 receptor antagonist SB366791 was investigated 1) by intrathecal injection 15 min before incision and 2) intradermal injection before (30 min) and immediately after the surgery. Vehicle-injected rats and naïve animals treated identically were used as controls. RESULTS: Plantar incision induced mechanical allodynia and hyperalgesia and thermal hyperalgesia. A single intrathecal administration of SB366791 significantly reduced postincisional thermal hyperalgesia and also attenuated mechanical allodynia, while mechanical hyperalgesia remained unaffected. Local intradermal SB366791 treatment reduced thermal hyperalgesia and mechanical allodynia without affecting mechanical hyperalgesia. CONCLUSIONS: Our experiments suggest that both peripheral and spinal cord TRPV1 receptors are involved in increased cutaneous sensitivity following surgical incision. The analgesic effect of the TRPV1 receptor antagonist was especially evident in the reduction of thermal hyperalgesia. The activation of TRPV1 receptors represents an important mechanism in the development of postoperative hypersensitivity.

• MeSH
• anilidy farmakologie   terapeutické užití   MeSH
• časové faktory MeSH
• cinnamáty farmakologie   terapeutické užití   MeSH
• fyzikální stimulace škodlivé účinky   MeSH
• hmat MeSH
• hyperalgezie farmakoterapie   etiologie   MeSH
• kationtové kanály TRPV antagonisté a inhibitory   metabolismus   MeSH
• krysa rodu Rattus MeSH
• měření bolesti účinky léků   MeSH
• mícha účinky léků   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• pooperační bolest komplikace   farmakoterapie   MeSH
• potkani Wistar MeSH
• práh bolesti účinky léků   MeSH
• reakční čas účinky léků   MeSH
• vysoká teplota MeSH
• způsoby aplikace léků MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anilidy MeSH
• cinnamáty MeSH
• kationtové kanály TRPV MeSH
• N-(3-methoxyphenyl)-4-chlorocinnamanilide MeSH Prohlížeč
• Trpv1 protein, rat MeSH Prohlížeč

BACKGROUND: The cytokine tumor necrosis factor α (TNFα) is an established pain modulator in both the peripheral and central nervous systems. Modulation of nociceptive synaptic transmission in the spinal cord dorsal horn (DH) is thought to be involved in the development and maintenance of several pathological pain states. Increased levels of TNFα and its receptors (TNFR) in dorsal root ganglion (DRG) cells and in the spinal cord DH have been shown to play an essential role in neuropathic pain processing. In the present experiments the effect of TNFα incubation on modulation of primary afferent synaptic activity was investigated in a model of peripheral neuropathy. METHODS: Spontaneous and miniature excitatory postsynaptic currents (sEPSC and mEPSCs) were recorded in superficial DH neurons in acute spinal cord slices prepared from animals 5 days after sciatic nerve transection and in controls. RESULTS: In slices after axotomy the sEPSC frequency was 2.8 ± 0.8 Hz, while neurons recorded from slices after TNFα incubation had significantly higher sEPSC frequency (7.9 ± 2.2 Hz). The effect of TNFα treatment was smaller in the slices from the control animals, where sEPSC frequency was 1.2 ± 0.2 Hz in slices without and 2.0 ± 0.5 Hz with TNFα incubation. Tetrodotoxin (TTX) application in slices from axotomized animals and after TNFα incubation decreased the mEPSC frequency to only 37.4 ± 6.9% of the sEPSC frequency. This decrease was significantly higher than in the slices without the TNFα treatment (64.4 ± 6.4%). TTX application in the control slices reduced the sEPSC frequency to about 80% in both TNFα untreated and treated slices. Application of low concentration TRPV1 receptors endogenous agonist N-oleoyldopamine (OLDA, 0.2 μM) in slices after axotomy induced a significant increase in mEPSC frequency (175.9 ± 17.3%), similar to the group with TNFα pretreatment (158.1 ± 19.5%). CONCLUSIONS: Our results indicate that TNFα may enhance spontaneous transmitter release from primary afferent fibres in the spinal cord DH by modulation of TTX-sensitive sodium channels following sciatic nerve transection. This nerve injury also leads to enhanced sensitivity of presynaptic TRPV1 receptors to endogenous agonist. Modulation of presynaptic receptor activity on primary sensory terminals by TNFα may play an important role in neuropathic pain development.

• MeSH
• excitační postsynaptické potenciály MeSH
• krysa rodu Rattus MeSH
• metoda terčíkového zámku MeSH
• mícha patologie   fyziologie   ultrastruktura   MeSH
• nemoci periferního nervového systému chemicky indukované   patologie   patofyziologie   MeSH
• nervový přenos fyziologie   MeSH
• neurony aferentní cytologie   účinky léků   fyziologie   MeSH
• nocicepce účinky léků   fyziologie   MeSH
• potkani Wistar MeSH
• sodíkové kanály metabolismus   MeSH
• spinální ganglia cytologie   fyziologie   MeSH
• synapse fyziologie   MeSH
• TNF-alfa farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• sodíkové kanály MeSH
• TNF-alfa MeSH