川芎嗪对大鼠坐骨神经慢性压迫性损伤L4/L5段背根神经节P2X3受体表达的影响

目的 探讨川芎嗪抑制P2X₃受体介导慢性神经病理痛的作用途径。方法 制备大鼠坐骨神经慢性压迫性损伤(CCI)神经病理痛模型，于d 2起ip川芎嗪100 mg·kg^-1，每天1次，共14 d。免疫组织化学法观察CCI大鼠L₄/L₅段背根神经节P2X₃受体的表达，全细胞膜片钳技术测定新鲜分离的L₄/L₅段背根神经节三磷酸腺苷（ATP）和α,β-亚甲基三磷酸腺苷（α,β-meATP）激活的电流。结果 与正常对照组比较，正常大鼠ip川芎嗪14 d，L₄/L₅段背根神经节P2X₃受体表达、ATP激活电流和α,β-meATP激活电流无明显变化，假手术组亦无明显变化。与假手术组比较，CCI模型组大鼠L₄/L₅段背根神经节P2X₃受体的表达、ATP和α,β-meATP激活电流明显增强。CCI大鼠ip川芎嗪14 d，L₄/L₅段背根神经节P2X₃受体表达、ATP和α,β-meATP激活电流较CCI模型组明显降低。结论 川芎嗪可抑制CCI大鼠L₄/L₅段背根神经节P2X₃受体的表达，从而对P2X₃受体介导的神经病理痛产生抑制作用。     

Inhibition of SNL-induced upregulation of CGRP and NPY in the spinal cord and dorsal root ganglia by the 5-HT(2A) receptor antagonist ketanserin in rats

Our previous study has demonstrated that topical and systemic administration of the 5-HT_2A receptor antagonist ketanserin attenuates neuropathic pain. To explore the mechanisms involved, we examined whether ketanserin reversed the plasticity changes associated with calcitonin gene-related peptides (CGRP) and neuropeptide Y (NPY) which may reflect distinct mechanisms: involvement and compensatory protection. Behavioral responses to thermal and tactile stimuli after spinal nerve ligation (SNL) at L5 demonstrated neuropathic pain and its attenuation in the vehicle- and ketanserin-treated groups, respectively. SNL surgery induced an increase in CGRP and NPY immunoreactivity (IR) in laminae I-II of the spinal cord. L5 SNL produced an expression of NPY-IR in large, medium and small diameter neurons in dorsal root ganglion (DRG) only at L5, but not adjacent L4 and L6. Daily injection of ketanserin (0.3 mg/kg, s.c.) for two weeks suppressed the increase in CGRP-IR and NPY-IR in the spinal cord or DRG. The present study demonstrated that: (1) the expression of CGRP was enhanced in the spinal dorsal horn and NPY was expressed in the DRG containing injured neurons, but not in the adjacent DRG containing intact neurons, following L5 SNL; (2) the maladaptive changes in CGRP and NPY expression in the spinal cord and DRG mediated the bioactivity of 5-HT/5-HT_2A receptors in neuropathic pain and (3) the blockade of 5-HT_2A receptors by ketanserin reversed the evoked upregulation of both CGRP and NPY in the spinal cord and DRG contributing to the inhibition of neuropathic pain.     

川芎嗪对P2X_3受体介导的神经病理痛的作用研究

目的探讨川芎嗪(tetramethylpyrazine,TMP)对P2X3受体介导的神经病理痛的作用。方法建立大鼠坐骨神经慢性压迫性损伤(CCI)神经病理痛模型,应用vonFrey细丝法和热辐射法测定机械缩足反射阈值(mechanical withdrawal threshold,MWT)和热缩足反射潜伏期(thermal withdrawal latency,TWL),观察川芎嗪对CCI大鼠MWT和TWL的影响。结合免疫组织化学方法观察大鼠L4/L5段脊髓P2X3受体的表达变化。结果术后14d,Ⅴ组(CCI模型组)和Ⅰ组(生理盐水对照组)、Ⅱ组(TMP对照组)、Ⅲ组(假手术组)、Ⅳ组(CCI模型+TMP治疗组)相比较大鼠后爪的机械和热痛敏阈值明显降低(P<0.05),大鼠脊髓P2X3受体表达明显升高(P<0.05);Ⅰ、Ⅱ、Ⅲ、Ⅳ组之间相比大鼠后爪的机械和热痛敏阈值差异没有显著性(P>0.05),大鼠脊髓P2X3受体表达差异没有显著性(P>0.05);Ⅳ组脊髓P2X3受体的表达较Ⅴ组低(P<0.05)。结论川芎嗪对P2X3受体介导的神经病理痛有抑制作用。     

Cytokine activin C ameliorates chronic neuropathic pain in peripheral nerve injury rodents by modulating the TRPV1 channel

Background and PurposeThe cytokine activin C is mainly expressed in small‐diameter dorsal root ganglion (DRG) neurons and suppresses inflammatory pain. However, the effects of activin C in neuropathic pain remain elusive.Experimental ApproachMale rats and wild‐type and TRPV1 knockout mice with peripheral nerve injury ‐ sciatic nerve axotomy and spinal nerve ligation in rats; chronic constriction injury (CCI) in mice – provided models of chronic neuropathic pain. Ipsilateral lumbar (L)4–5 DRGs were assayed for activin C expression. Chronic neuropathic pain animals were treated with intrathecal or locally pre‐administered activin C or the vehicle. Nociceptive behaviours and pain‐related markers in L4–5 DRGs and spinal cord were evaluated. TRPV1 channel modulation by activin C was measured.Key ResultsFollowing peripheral nerve injury, expression of activin βC subunit mRNA and activin C protein was markedly up‐regulated in L4–5 DRGs of animals with axotomy, SNL or CCI. [Correction added on 26 November 2020, after first online publication: The preceding sentence has been corrected in this current version.] Intrathecal activin C dose‐dependently inhibited neuropathic pain in spinal nerve ligated rats. Local pre‐administration of activin C decreased neuropathic pain, macrophage infiltration into ipsilateral L4–5 DRGs and microglial reaction in L4–5 spinal cords of mice with CCI. In rat DRG neurons, activin C enhanced capsaicin‐induced TRPV1 currents. Pre‐treatment with activin C reduced capsaicin‐evoked acute hyperalgesia and normalized capsaicin‐evoked persistent hypothermia in mice. Finally, the analgesic effect of activin C was abolished in TRPV1 knockout mice with CCI.Conclusion and ImplicationsActivin C inhibits neuropathic pain by modulating TRPV1 channels, revealing potential analgesic applications in chronic neuropathic pain therapy.     

Increase in hemokinin-1 mRNA in the spinal cord during the early phase of a neuropathic pain state

Background and purpose:

Substance P (SP), a representative member of the tachykinin family, is involved in nociception under physiological and pathological conditions. Recently, hemokinin-1 (HK-1) was identified as a new member of this family. Although HK-1 acts on NK₁ tachykinin receptors that are thought to be innate for SP, the roles of HK-1 in neuropathic pain are still unknown.

Experimental approach:

Using rats that had been subjected to chronic constrictive injury (CCI) of the sciatic nerve as a neuropathic pain model, we examined the changes in expression of SP- and HK-1-encoding genes (TAC1 and TAC4, respectively) in the L4/L5 spinal cord and L4/L5 dorsal root ganglia (DRGs) in association with changes in pain-related behaviours in this neuropathic pain state.

Key results:

The TAC4 mRNA level was increased on the ipsilateral side of the dorsal spinal cord, but not in DRGs, at day 3 after CCI. In contrast, the TAC1 mRNA level was significantly increased in the DRGs at day 3 after CCI without any changes in the dorsal spinal cord. Analysis of a cultured microglial cell line revealed the presence of TAC4 mRNA in microglial cells. Minocycline, an inhibitor of microglial activation, blocked the increased expression of TAC4 mRNA after CCI and inhibited the associated pain-related behaviours and microglial activation in the spinal cord.

Conclusions and implications:

The present results suggest that HK-1 expression is increased at least partly in activated microglial cells after nerve injury and is clearly involved in the early phase of neuropathic pain.     

Actions of a series of PPADS analogs at P2X1 and P2X3 receptors

Seven PPADS ( P yridoxal‐5′‐ P hosphate 6‐ A zophenyl 2′,4′‐ D i S ulfonate) analogs were investigated at Group 1 P2X receptors expressed in Xenopus oocytes. All seven analogs potently inhibited P2X₁ (IC₅₀ range, 5–32 nM) and P2X₃ (IC₅₀ range, 22–345 nM), the two Group I P2X receptor subtypes. Analogs showed greater inhibitory activity where the pyridoxal moiety of PPADS contained a 5′‐phosphonate group, rather than a 5′‐phosphate group. Analogs also showed greater potency where disulfonate groups were removed from, or substituted at, the azophenyl moiety. The most active analog was MRS 2257 (pyridoxal‐5′‐phosphonate 6‐azophenyl 3′,5′‐bismethylenephosphonate) at P2X₁ (IC₅₀, 5 nM) and P2X₃ (IC₅₀, 22 nM) receptors, being 14‐fold and 10‐fold more potent than PPADS itself. MRS 2257 produced a nonsurmountable inhibition when tested against a range of ATP concentrations, although blockade was reversed by about 85% after 20 minutes of washout. TNP‐ATP and Ip₅I were equipotent with MRS 2257 at P2X₁ receptors, whereas TNP‐ATP was 64‐fold more potent than MRS 2257 at P2X₃ receptors. In conclusion, the PPADS template can be altered at the pyridoxal and phenyl moieties to produce P2X₁ and P2X₃ receptor antagonists showing higher potency and greater degree of reversibility than the parent compound at these Group I P2X receptors. Drug Dev. Res. 53:281–291, 2001. © 2001 Wiley‐Liss, Inc.     

神经病理性疼痛大鼠背根神经节TRPM8表达变化的研究

目的: 观察慢性神经病理性疼痛大鼠背根神经节TRPM8表达的变化.方法: 健康成年雄性SD大鼠72只,体质量250~280 g,随机分为慢性坐骨神经束缚性损伤(CCI)组和假手术组(n = 36), CCI或假手术前1 d,术后1、4、7、10、14 d每组各随机取6只大鼠,测定冷痛阈值、热痛阈值和机械痛阈值后立即处死大鼠,取L5背根神经节行免疫组织化学染色,观察瞬时受体电位melastatin 8(TRPM8)在慢性神经病理性疼痛下的表达变化.结果: CCI组于术后4 d术侧冷痛阈值、机械痛阈值和热痛阈值开始下降,至术后14 d仍处于较低水平,冷痛阈值和热痛阈值于术后10 d降至最低,机械痛阈值术后14 d降至最低(P ＜ 0.05或P ＜ 0.01);CCI组术侧L5背根神经节TRPM8的表达于术后4 d开始增加,术后10 d达到高峰,至术后14 d仍维持在高水平(P ＜ 0.05或P ＜ 0.01).结论: 背根神经节TRPM8受体表达的上调参与神经病理性疼痛的发生和维持.     

Down-regulation of GFRalpha-1 expression by antisense oligodeoxynucleotide aggravates thermal hyperalgesia in a rat model of neuropathic pain

Glial cell line-derived neurotrophic factor (GDNF) has been hypothesized to play an important role in the modulation of nociceptive signals especially during neuropathic pain. The present study examined the expression of GDNF and GFRalpha-1 (the high-affinity receptor of GDNF) in dorsal root ganglions (DRG) in a rat model of neuropathic pain induced by chronic constriction injury (CCI) to the sciatic nerve. In order to address the role of GDNF and GFRalpha-1 in neuropathic pain, antisense oligodeoxynucleotide (ODN) specifically against GFRalpha-1 was intrathecally administered to result in down-regulation of GFRalpha-1 expression. The results showed that both the protein and mRNA levels of GDNF and GFRalpha-1 were significantly increased after CCI, while the thermal hyperalgesia of neuropathic pain rats could be significantly aggravated by antisense ODN treatment, but not by normal saline (NS) or mismatch ODN treatment. The present study demonstrated that endogenous GDNF and GFRalpha-1 might play an anti-hyperalgesic role in neuropathic pain of rats. In addition, we found a down-regulation of somatostatin (SOM) in DRG and spinal dorsal horn after expression of GFRalpha-1 was knocked down, which suggested the possible relationship between the anti-hyperalgesic effect of GDNF and GFRalpha-1 on neuropathic pain and endogenous SOM.     

A peripherally acting,selective T-type calcium channel blocker,ABT-639, effectively reduces nociceptive and neuropathic pain in rats

Activation of T-type Ca²⁺ channels contributes to nociceptive signaling by facilitating action potential bursting and modulation of membrane potentials during periods of neuronal hyperexcitability. The role of T-type Ca²⁺ channels in chronic pain is supported by gene knockdown studies showing that decreased Ca_v3.2 channel expression results in the loss of low voltage-activated (LVA) currents in dorsal root ganglion (DRG) neurons and attenuation of neuropathic pain in the chronic constriction injury (CCI) model. ABT-639 is a novel, peripherally acting, selective T-type Ca²⁺ channel blocker. ABT-639 blocks recombinant human T-type (Ca_v3.2) Ca²⁺ channels in a voltage-dependent fashion (IC₅₀ = 2 μM) and attenuates LVA currents in rat DRG neurons (IC₅₀ = 8 μM). ABT-639 was significantly less active at other Ca²⁺ channels (e.g. Ca_v1.2 and Ca_v2.2) (IC₅₀ > 30 μM). ABT-639 has high oral bioavailability (%F = 73), low protein binding (88.9%) and a low brain:plasma ratio (0.05:1) in rodents. Following oral administration ABT-639 produced dose-dependent antinociception in a rat model of knee joint pain (ED₅₀ = 2 mg/kg, p.o.). ABT-639 (10–100 mg/kg, p.o.) also increased tactile allodynia thresholds in multiple models of neuropathic pain (e.g. spinal nerve ligation, CCI, and vincristine-induced, and capsaicin secondary hypersensitivity). ABT-639 did not attenuate hyperalgesia in inflammatory pain models induced by complete Freund's adjuvant or carrageenan. At higher doses (e.g. 100 - 300 mg/kg) ABT-639 did not significantly alter hemodynamic or psychomotor function. The antinociceptive profile of ABT-639 provides novel insights into the role of peripheral T-type (Ca_v3.2) channels in chronic pain states.     

Guggulipid of Commiphora mukul,with antiallodynic and antihyperalgesic activities in both sciatic nerve and spinal nerve ligation models of neuropathic pain

Abstract

Context: Guggulipid is a neutral fraction of ethyl acetate extract of gum resin of the tree Commiphora mukul Engl. (Burseraceae) and used in Ayurvedic medicine for treatment of neurological disorders.

Objectives: The present study was undertaken to assess the antiallodynic and antihyperalgesic activities of guggulipid in rats.

Materials and methods: The screening study included the CCI and L5–L6 SNL models of neuropathic pain. Guggulipid (100 and 50?mg/kg) or saline was administered intraperitoneally in a blinded, randomized manner from postoperative day (POD) 7 to 13. Paw withdrawal duration (PWD) to spontaneous pain, chemical allodynia and mechanical hyperalgesia and paw withdrawal latency (PWL) to mechanical allodynia and thermal hyperalgesia were tested before surgery, before and after guggulipid or saline administration (from POD7 to 13) and after the withdrawal of treatment (from POD14 to 20).

Results: The activity profiles of the different doses of guggulipid were found to vary with time. In CCI rats, guggulipid (100 and 50?mg/kg) significantly (p?<?0.05) reduced the spontaneous pain, mechanical allodynia and mechanical and thermal hyperalgesia responses and the LD₅₀ of guggulipid was 1600?mg/kg. In SNL rats, both doses of guggulipid were found to be ineffective in reversing the spontaneous pain but showing antiallodynic and antihyperalgesic activity.

Discussion and conclusion: The results demonstrated that guggulipid produce antinociception in the peripheral nerve injury (CCI and SNL) models of neuropathic pain. The underlying mechanisms are expected to be modulating microglial activation occurring due to peripheral nerve injury.     

Spinal anandamide produces analgesia in neuropathic rats: possible CB(1)- and TRPV1-mediated mechanisms

The endocannabinoid anandamide (AEA) activates also transient receptor potential vanilloid-1 (TRPV1) channels. However, no data exist on the potential role of spinal TRPV1 activation by AEA in neuropathic pain. We tested the effect of: 1) AEA (5–100 μg), alone or in the presence of an inhibitor of its hydrolysis, and 2) elevated levels of endogenous AEA (following inhibition of AEA hydrolysis), in CCI rats, and the involvement of TRPV1 or cannabinoid CB₁ receptors in the observed effects. Levels of AEA in the spinal cord of CCI rats were measured following all treatments. AEA (50 μg) displayed anti-allodynic and anti-hyperalgesic effects which were abolished by previous antagonism of TRPV1, but not CB₁, receptors. Depending on the administered dose, the selective inhibitor of AEA enzymatic hydrolysis, URB597 (10–100 μg), reduced thermal and tactile nociception via CB₁ or CB₁/TRPV1 receptors. The anti-nociceptive effects of co-administered per se ineffective doses of AEA (5 μg) and URB597 (5 μg) was abolished by antagonism of CB₁, but not TRPV1, receptors. Spinal AEA levels were increased after CCI, slightly increased further by URB597, 10 μg i.t., and strongly elevated by URB597, 100 μg. Injection of AEA (50 μg) into the lumbar spinal cord led to its dramatic elevation in this tissue, whereas, when a lower dose was used (5 μg) AEA endogenous levels were elevated only in the presence of URB597 (5 μg). We suggest that spinal AEA reduces neuropathic pain via CB₁ or TRPV1, depending on its local concentration.     

Pre-emptive intrathecal quinidine alleviates spinal nerve ligation-induced peripheral neuropathic pain

Objectives Quinidine, a class I anti‐arrhythmic agent, is a sodium channel blocker that is more potent than lidocaine and mexiletine. This study tested pre‐emptive intrathecal quinidine to attenuate neuropathic pain induced by lumbar spinal nerve ligation (SNL). Methods Ninety‐six adult male Sprague–Dawley rats were grouped equally (n = 24 per group) as follows: group S (sham), removal of transverse process only; group L, SNL; group Q₃₅, SNL pretreated with intrathecal quinidine 35 mm (50 µl); group Q₇₀, SNL pretreated with intrathecal quinidine 70 mm (50 µl). Neuropathic pain was measured by thermal hyperalgesia and mechanical allodynia. Other measurements included dys‐regulation of sodium channel Nav_1.3 in dorsal root ganglion (DRG) and spinal microglia activation in spinal dorsal horn. Key findings Spinal nerve ligation induced abnormal mechanical allodynia and thermal hyperalgesia, up‐regulated Nav_1.3 in DRG, and activated microglia in spinal cord. Group Q₇₀ showed attenuated thermal hyperalgesia (P < 0.001) and mechanical allodynia (P < 0.05) on postoperative day 5 (POD₅) but not on POD₇, reversed up‐regulated expression of Nav_1.3 on POD₃ and POD₇ in DRG and significantly attenuated microglia activation on POD₇ (P = 0.032) in spinal cord. Conclusions Pretreatment with intrathecal quinidine 70 mm before SNL attenuates nerve ligation‐induced neuropathic pain. The duration of the effect is 5 days.     

Activation of NK₁ receptors in the locus coeruleus induces analgesia through noradrenergic-mediated descending inhibition in a rat model of neuropathic pain

BACKGROUND AND PURPOSE

The locus coeruleus (LC) is a major source of noradrenergic projections to the dorsal spinal cord, and thereby plays an important role in the modulation of nociceptive information. The LC receives inputs from substance P (SP)-containing fibres from other regions, and expresses the NK₁ tachykinin receptor, a functional receptor for SP. In the present study, we investigated the roles of SP in the LC in neuropathic pain.

EXPERIMENTAL APPROACH

Chronic constriction injury (CCI) of the left sciatic nerve was performed in rats to induce neuropathic pain. After development of neuropathic pain, SP was injected into the LC and the nocifensive behaviours were assessed. The involvement of noradrenergic descending inhibition in SP-induced analgesia was examined by i.t. administration of yohimbine, an α₂-adrenoceptor antagonist. NK₁ receptor expression in the LC was examined by immunohistochemistry.

KEY RESULTS

In CCI rats, mechanical allodynia was alleviated by SP injection into the LC. These effects were abolished by prior injection of WIN 51708, an NK₁ receptor antagonist, into the LC or i.t. treatment with yohimbine. NK₁ receptor-like immunoreactivity was observed in noradrenergic neurons throughout the LC in intact rats, and remained unchanged after CCI.

CONCLUSION AND IMPLICATIONS

SP in the LC exerted analgesic effects on neuropathic pain through NK₁ receptor activation and resulted in facilitation of spinal noradrenergic transmission. Accordingly, manipulation of the SP/NK₁ receptor signalling pathway in the LC may be a promising strategy for effective treatment of neuropathic pain.     

Subunit specificity of polyclonal antisera to the carboxy terminal regions of P2X receptors,P2X1 through P2X7

Polyclonal antisera generated to peptides corresponding to the carboxy termini of the seven cloned rat P2X receptors were compared using membranes from CHO‐K1 or 1321N1 cells expressing recombinant rat or human P2X receptors (rat P2X₃, P2X₄, and P2X₅ and human P2X₁, P2X₂, P2X₆, and P2X₇). Preimmune sera failed to recognize any bands in immunoblots against the membrane fractions. Antiserum to the P2X₁ receptor recognized a band of approximately 58 kDa while those to the rP2X₂ and the rP2X₃ receptors recognized doublets of approximately 60 and 64 kDa. The antiserum to the rP2X₄ receptor recognized a similarly sized doublet as well as a higher molecular weight species at the expected size for a receptor dimer. Antiserum to the rP2X₅ receptor revealed a single band at 64 kDa while antiserum to rP2X₆ and rP2X₇ gave single bands at 50 kDa and 95 kDa, respectively. In all cases, immunoreactivity was eliminated by preincubation of the antisera with the cognate peptide and there was no cross‐reactivity of antisera with heterologous receptors. These antisera are useful reagents for the analysis of the P2X receptor subtypes in native tissues as well as for measuring receptor expression levels in transfected cell lines. Drug Dev. Res. 47:189–195, 1999. © 1999 Wiley‐Liss, Inc.     

Pentoxifylline decreases allodynia and hyperalgesia in a rat model of neuropathic pain

BACKGROUND AND THE PURPOSE OF THE STUDY: Pentoxifylline (PTX) is a non-specific cytokite pain in several animal models and humans. However, long-term therapeutic effects of PTX on neuropathic pain in a rat model of chronic constriction injury (CCI) are not completely clear. This study was conducted to examine the effect of long-term administration of PTX on neuropathic pain in rats. METHODS : Neuropathic pain was induced by sciatic nerve ligation using of CCI model in rats. Rats were randomly assigned into sham, CCI-saline treated, and CCI-PTX treated (30 or 60 mg/kg ip) groups. PTX or saline administered at 30 min before CCI and daily for 14 days post-CCI. At the days of 3, 7, 11 and 14 following CCI, by using standard methods effects of thermal hyperalgesia, thermal and mechanical allodynia in all groups were examined using the standard methods. RESULTS : The CCI-saline treated group showed a significant increase in mechanical and thermal allodynia, and thermal hyperalgesia as compared with the sham group in the tested days. Administration of the higher dose of PTX (60 mg/kg/day), but not the lower dose (30 mg/kg/day) significantly reduced mechanical and thermal allodynia, as compared with the CCI-saline treated group on days of 3, 7, 11 and 14 (all P values<0.001). Also, both doses of PTX significantly reduced thermal hyperalgesia as compared with the CCI-saline treated group on these days (all P values<0.001). CONCLUSION : Results of this study show that chronic administration of PTX reduces the neuropathic pain in a rat model of CCI. Thus, this drug may have a therapeutic application in the treatment and management of neuropathic pain in humans.     

Species and agonist dependent zinc modulation of endogenous and recombinant ATP-gated P2X7 receptors

Zinc (Zn²⁺) and copper (Cu²⁺) are key signalling molecules in the immune system and regulate the activity of many ion channels. Both Zn²⁺ and Cu²⁺ potently inhibit rat P2X₇ receptors via a binding site identified by mutagenesis. Here we show that extracellular Cu²⁺ also potently inhibits mouse P2X₇ receptors. By contrast, the receptor expression system and agonist strongly influence the action of extracellular Zn²⁺ at mouse P2X₇ receptors. Consistent with previous reports, Zn²⁺ inhibits recombinant rat P2X₇ receptors. However, recombinant mouse P2X₇ receptors are potentiated by Zn²⁺ when activated by ATP⁴⁻ but inhibited when stimulated with the ATP analogue BzATP⁴⁻. Endogenous murine macrophage P2X₇ receptors are not modulated by Zn²⁺ when stimulated by ATP⁴⁻ however Zn²⁺ inhibits BzATP⁴⁻ mediated responses. In summary, these findings provide a fundamental insight into the differential actions of Zn²⁺ and Cu²⁺ between different P2X₇ receptor species.     

高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角NOS 表达的影响

目的：观察高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角 NOS 表达的影响。方法成年雄性 SD大鼠32只,随机分成4组,每组8只,包括：假手术组（S 组）、坐骨神经结扎组（CCI 组）、HBO 预处理组（pre－HBO 组）和 HBO 后处理组（post－HBO 组）。所有大鼠 CCI 术前1 d 测量机械痛阈值基线（MWT）。 CCI 术后第1、2、3、7、14、21和第28天观察疼痛反应行为,测量 MWT。 CCI 术后第28天,对脊髓背角中 nNOS、 eNOS 及 iNOS 阳性神经元进行计数。结果CCI 术前4组 MWT 值无明显差异（ P ＞0．05）。每个时间点,与 S 组比较,pre－HBO、post－HBO 和 CCI 组MWT 值明显降低（ P ＜0．05）,且 CCI 组下降幅度最大。每个时间点,与 CCI 组比较,pre－HBO 组和 post－HBO 组 MWT值明显高于 CCI 组（ P ＜0．05）。与 S 组比较,CCI 后第28天 CCI 组、pre－HBO 组和 post－HBO 组大鼠脊髓 nNOS 和iNOS 阳性神经元数量明显增多（ P ＜0．05）。 CCI 组大鼠脊髓 nNOS 和 iNOS 阳性神经元数量明显高于 pre－HBO 组和post－HBO 组（ P ＜0．05）。4组大鼠脊髓 eNOS 阳性神经元数量未见明显差异（ P ＞0．05）。结论高压氧对神经痛的发生有预防和治疗作用,可能通过降低 NOS 的表达缓解疼痛。     

Characterization of protoberberine analogs employed as novel human P2X7 receptor antagonists

The P2X₇ receptor (P2X₇R), a member of the ATP-gated ion channel family, is regarded as a promising target for therapy of immune-related diseases including rheumatoid arthritis and chronic pain. A group of novel protoberberine analogs (compounds 3-5), discovered by screening of chemical libraries, was here investigated with respect to their function as P2X₇R antagonists. Compounds 3-5 non-competitively inhibited BzATP-induced ethidium ion influx into hP2X₇-expressing HEK293 cells, with IC₅₀ values of 100-300 nM. This antagonistic action on the channel further confirmed that both BzATP-induced inward currents and Ca²⁺ influx were strongly inhibited by compounds 3-5 in patch-clamp and Ca²⁺ influx assays. The antagonists also effectively suppressed downstream signaling of P2X₇ receptors including IL-1β release and phosphorylation of ERK1/2 and p38 proteins in hP2X₇-expressing HEK293 cells or in differentiated human monocytes (THP-1 cells). Moreover, IL-2 secretion from CD3/CD28-stimulated Jurkat T cell was also dramatically inhibited by the antagonist. These results imply that novel protoberberine analogs may modulate P2X₇ receptor-mediated immune responses by allosteric inhibition of the receptor.