BACKGROUND: IL-6 is a typical injury-induced mediator. Together with its receptors, IL-6 contributes to both induction and maintenance of neuropathic pain deriving from changes in activity of primary sensory neurons in dorsal root ganglia (DRG). We used in situ hybridization to provide evidence of IL-6 and IL-6 receptors (IL-6R and gp130) synthesis in DRG along the neuraxis after unilateral chronic constriction injury (CCI) of the sciatic nerve as an experimental model of neuropathic pain. RESULTS: All rats operated upon to create unilateral CCI displayed mechanical allodynia and thermal hyperalgesia in ipsilateral hind paws. Contralateral hind paws and forepaws of both sides exhibited only temporal and nonsignificant changes of sensitivity. Very low levels of IL-6 and IL-6R mRNAs were detected in naïve DRG. IL-6 mRNA was bilaterally increased not only in DRG neurons but also in satellite glial cells (SGC) activated by unilateral CCI. In addition to IL-6 mRNA, substantial increase of IL-6R mRNA expression occurred in DRG neurons and SGC following CCI, while the level of gp130 mRNA remained similar to that of DRG from naïve rats. CONCLUSIONS: Here we evidence for the first time increased synthesis of IL-6 and IL-6R in remote cervical DRG nonassociated with the nerve injury. Our results suggest that unilateral CCI of the sciatic nerve induced not only bilateral elevation of IL-6 and IL-6R mRNAs in L4-L5 DRG but also their propagation along the neuraxis to remote cervical DRG as a general neuroinflammatory reaction of the nervous system to local nerve injury without correlation with signs of neuropathic pain. Possible functional involvement of IL-6 signaling is discussed.

• MeSH
• hybridizace in situ MeSH
• interleukin-6 genetika   MeSH
• krysa rodu Rattus MeSH
• messenger RNA metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• nemoci sedacího nervu genetika   MeSH
• neuralgie genetika   MeSH
• neuroglie metabolismus   MeSH
• potkani Wistar MeSH
• receptory interleukinu-6 genetika   MeSH
• spinální ganglia 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
• interleukin-6 MeSH
• messenger RNA MeSH
• receptory interleukinu-6 MeSH

Cannabinoid receptor type 2 (CB2R) plays a critical role in nociception. In contrast to cannabinoid receptor type 1 ligands, CB2R agonists do not produce undesirable central nervous system effects and thus promise to treat neuropathic pain that is often resistant to medical therapy. In the study presented here, we evaluated the bilateral distribution of the CB2R protein and messenger RNA (mRNA) in rat dorsal root ganglia (DRG) after unilateral peripheral nerve injury using immunohistochemistry, western blot, and in situ hybridization analysis. Unilateral chronic constriction injury (CCI) of the sciatic nerve induced neuropathic pain behavior and bilateral elevation of both CB2R protein and mRNA in lumbar L4-L5 as well as cervical C7-C8 DRG when compared with naive animals. CB2R protein and mRNA were increased not only in DRG neurons but also in satellite glial cells. The fact that changes appear bilaterally and (albeit at a lower level) even in the remote cervical DRG can be related to propagation of neuroinflammation alongside the neuraxis and to the neuroprotective effects of CB2R.

• Klíčová slova
• remote neuroinflammation, satellite glial cells, unilateral nerve injury,
• MeSH
• chování zvířat MeSH
• krysa rodu Rattus MeSH
• messenger RNA genetika   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• nervus ischiadicus zranění   MeSH
• neuralgie genetika   metabolismus   patologie   MeSH
• potkani Wistar MeSH
• receptor kanabinoidní CB2 genetika   metabolismus   MeSH
• regulace genové exprese * MeSH
• spinální ganglia metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• messenger RNA MeSH
• receptor kanabinoidní CB2 MeSH

BACKGROUND: Current research implicates interleukin (IL)-6 as a key component of the nervous-system response to injury with various effects. METHODS: We used unilateral chronic constriction injury (CCI) of rat sciatic nerve as a model for neuropathic pain. Immunofluorescence, ELISA, western blotting and in situ hybridization were used to investigate bilateral changes in IL-6 protein and mRNA in both lumbar (L4-L5) and cervical (C7-C8) dorsal root ganglia (DRG) following CCI. The operated (CCI) and sham-operated (sham) rats were assessed after 1, 3, 7, and 14 days. Withdrawal thresholds for mechanical hyperalgesia and latencies for thermal hyperalgesia were measured in both ipsilateral and contralateral hind and fore paws. RESULTS: The ipsilateral hind paws of all CCI rats displayed a decreased threshold of mechanical hyperalgesia and withdrawal latency of thermal hyperalgesia, while the contralateral hind and fore paws of both sides exhibited no significant changes in mechanical or thermal sensitivity. No significant behavioral changes were found in the hind and fore paws on either side of the sham rats, except for thermal hypersensitivity, which was present bilaterally at 3 days. Unilateral CCI of the sciatic nerve induced a bilateral increase in IL-6 immunostaining in the neuronal bodies and satellite glial cells (SGC) surrounding neurons of both lumbar and cervical DRG, compared with those of naive control rats. This bilateral increase in IL-6 protein levels was confirmed by ELISA and western blotting. More intense staining for IL-6 mRNA was detected in lumbar and cervical DRG from both sides of rats following CCI. The DRG removed from sham rats displayed a similar pattern of staining for IL-6 protein and mRNA as found in naive DRG, but there was a higher staining intensity in SGC. CONCLUSIONS: Bilateral elevation of IL-6 protein and mRNA is not limited to DRG homonymous to the injured nerve, but also extended to DRG that are heteronymous to the injured nerve. The results for IL-6 suggest that the neuroinflammatory reaction of DRG to nerve injury is propagated alongside the neuroaxis from the lumbar to the remote cervical segments. This is probably related to conditioning of cervical DRG neurons to injury.

• MeSH
• ELISA MeSH
• funkční lateralita fyziologie   MeSH
• fyzikální stimulace MeSH
• hybridizace in situ MeSH
• hyperalgezie metabolismus   MeSH
• imunohistochemie MeSH
• interleukin-6 biosyntéza   genetika   MeSH
• krční obratle MeSH
• krysa rodu Rattus MeSH
• lumbosakrální krajina MeSH
• měření bolesti MeSH
• messenger RNA biosyntéza   genetika   MeSH
• nemoci sedacího nervu metabolismus   MeSH
• neuralgie metabolismus   MeSH
• počítačové zpracování obrazu MeSH
• potkani Wistar MeSH
• receptory interleukinu-6 biosyntéza   genetika   MeSH
• spinální ganglia metabolismus   MeSH
• stenóza MeSH
• úžinové syndromy metabolismus   MeSH
• vysoká teplota MeSH
• western blotting 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
• interleukin-6 MeSH
• messenger RNA MeSH
• receptory interleukinu-6 MeSH

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

Modulation of synaptic transmission in the spinal cord dorsal horn is thought to be involved in the development and maintenance of different pathological pain states. The proinflamatory cytokine, tumor necrosis factor alpha (TNFalpha), is an established pain modulator in both the peripheral and the central nervous system. Up-regulation of TNFalpha and its receptors (TNFR) in dorsal root ganglion (DRG) cells and in the spinal cord has been shown to play an important role in neuropathic and inflammatory pain conditions. Transient receptor potential vanilloid 1 (TRPV1) receptors are known as molecular integrators of nociceptive stimuli in the periphery, but their role on the spinal endings of nociceptive DRG neurons is unclear. The endogenous TRPV1 receptor agonist N-oleoyldopamine (OLDA) was shown previously to activate spinal TRPV1 receptors. In our experiments the possible influence of TNFalpha on presynaptic spinal cord TRPV1 receptor function was investigated. Using the patch-clamp technique, miniature excitatory postsynaptic currents (mEPSCs) were recorded in superficial dorsal horn neurons in acute slices after incubation with 60 nM TNFalpha. A population of dorsal horn neurons with capsaicin sensitive primary afferent input recorded after the TNFalpha pretreatment had a basal mEPSC frequency of 1.35 +/- 0.20 Hz (n = 13), which was significantly higher when compared to a similar population of neurons in control slices (0.76 +/- 0.08 Hz; n = 53; P < 0.01). In control slices application of a low concentration of OLDA (0.2 uM) did not evoke any change in mEPSC frequency. After incubation with TNFalpha, OLDA (0.2 uM) application to slices induced a significant increase in mEPSC frequency (155.5 +/- 17.5%; P < 0.001; n = 10). Our results indicate that TNFalpha may have a significant impact on nociceptive signaling at the spinal cord level that could be mediated by increased responsiveness of presynaptic TRPV1 receptors to endogenous agonists. This could be of major importance, especially during pathological conditions, when increased levels of TNFalpha and TNFR are present in the spinal cord.

• MeSH
• analýza rozptylu MeSH
• buňky zadních rohů míšních účinky léků   metabolismus   MeSH
• dopamin analogy a deriváty   farmakologie   MeSH
• excitační postsynaptické potenciály účinky léků   fyziologie   MeSH
• kationtové kanály TRPV metabolismus   MeSH
• krysa rodu Rattus MeSH
• metoda terčíkového zámku MeSH
• mícha účinky léků   metabolismus   MeSH
• miniaturní postsynaptické potenciály účinky léků   fyziologie   MeSH
• nervový přenos účinky léků   fyziologie   MeSH
• potkani Wistar 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
• dopamin MeSH
• kationtové kanály TRPV MeSH
• N-oleoyldopamine MeSH Prohlížeč
• TNF-alfa MeSH
• TRPV1 receptor MeSH Prohlížeč