国产齐考诺肽对L5脊神经结扎后大鼠神经病理性疼痛的疗效

目的:观察国产齐考诺肽注射液对大鼠L5脊神经结扎后神经病理性疼痛(L5SNL)的镇痛作用.方法:取雄性SD大鼠共40只,随机分为5组(n=8),包括假手术组(SC组):0.9％NS20 μL、L5SNL模型组(L5SNL组):0.9％ NS20 μL;DZ1组:第一批次国产齐考诺肽100 ng;DZ2组:第二批次国产齐考诺肽100 ng;IZ组:进口齐考诺肽100 ng.采用测试50％机械刺激撤足阈值(50％PWT)和热刺激撤足潜伏值(TWD)的方法,观察大鼠治疗前后机械痛阈和热痛阈的变化,并计算药物的最大效应百分比(MPE),评价抗神经病理性疼痛的效果.结果:与L5SNL模型组相比,鞘内单次给予国产及进口齐考诺肽100 ng均可显著提高大鼠50％PWT和TWD(P＜0.01);与IZ组相比,国产齐考诺肽组的MPE和TWD均无统计学差异(P＞0.05).结论:国产齐考诺肽对L5脊神经结扎后大鼠神经病理性疼痛具有显著的疗效.     

Endogenous noradrenergic tone controls symptoms of allodynia in the spinal nerve ligation model of neuropathic pain

Endogenous inhibitory controls were studied in the spinal nerve ligation model of neuropathic pain. Atipamezole, a selective alpha2-adrenoceptor antagonist, produced both mechanical and cold allodynia in those rats which had not developed clear neuropathic symptoms. The same doses (50 microg i.t. or 1 mg/kg s.c.) did not increase the severity of symptoms in rats which had developed them. The opioid receptor antagonist naloxone (20 microg i.t. or 1 mg/kg s.c.) had no effect on the neuropathic symptoms. These results indicate that mechanical and cold allodynia are under endogenous noradrenergic rather than opioidergic control in this model of neuropathic pain.     

Effect of chronic administration of morphine on the expression of bovine adrenal medulla 22-like immunoreactivity in the spinal cord of rats

The aim of the present study was to investigate the effects of chronic administration of morphine on the expression of an endogenous opioid peptide in the spinal dorsal horn. Bovine adrenal medulla 22-like immunoreactivity (BAM22-IR) was found in the superficial layers of the spinal cord. Intrathecal (i.t.) administration of morphine (20 microg) for 6 days, but not 2 days, significantly reduced the expression of BAM22-IR whereas i.t. administration of saline for 2 and 6 days did not alter the expression of BAM22-IR. The present study suggests that reduction of BAM22-IR in the spinal cord is involved in the development of morphine tolerance.     

星形胶质细胞在坐骨神经分支选择性结扎神经病理性痛中的作用

目的 探讨星形胶质细胞在坐骨神经分支选择性结扎(spared nerve injury,SNI)神经病理性痛中的作用.方法 24只SD大鼠随机分为4组(6只/组):SNI组(建立SNI动物模型同时行鞘内置管术,术后13 d鞘内给予生理盐水);假手术组(处理方式同SNI组,但不损伤坐骨神经及其分支);L-α-aminoadipate(LAA)组(制作SNI动物模型同时行鞘内置管,术后13 d鞘内给予LAA);对照组(不给予任何处理因素).术前2 d及术后14 d检测机械痛和神经病理性痛阈值,术后14 d以Real-time PCR法检测脊髓背角GFAP mRNA变化.结果 术前2 d各组大鼠机械痛域及热痛阈无明显差异(P>0.05).术后14 d假手术组机械痛域、热痛阈及脊髓背角GFAP mRNA较对照组均无明显变化(P>0.05);与对照组相比,SNI组机械痛域及热痛阈明显降低(P<0.05),脊髓背角GFAP mRNA明显增高(P<0.05);与SNI组相比,LAA组机械痛域及热痛阈均明显增高(P<0.05),脊髓背角GFAP mRNA明显降低(P<0.05).结论 LAA特异性抑制脊髓背角星形胶质细胞活性可缓解SNI大鼠神经病理性痛,提示脊髓背角星形胶质细胞活化是SNI大鼠神经病理性的重要机制.     

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.     

Peripheral kinin B(1) and B(2) receptor-operated mechanisms are implicated in neuropathic nociception induced by spinal nerve ligation in rats

The kinin system can contribute distinctly to the sensory changes associated with different models of nerve injury-induced neuropathic pain. This study examines the roles of kinin B(1) and B(2) receptor-operated mechanisms in alterations in nociceptive responses of rats submitted to unilateral L5/L6 spinal nerve ligation (SNL) injury. Behavioural responses to ipsilateral hind paw stimulation with acetone (evaporation-evoked cooling), radiant heat (Hargreaves method) or von Frey hairs revealed that SNL rats developed long-lasting cold allodynia (from Days 3 to 40 post-surgery, peak on Day 6), heat hyperalgesia (stable peak from Days 9 to 36) and tactile allodynia (stable peak from Days 3 to 51). SNL rats manifested nocifensive responses to intraplantar injections on Day 12 of the selective B(1) receptor agonist des-Arg(9)-bradykinin (DABK) and augmented responses to the selective B(2) receptor agonist bradykinin (BK; each at 0.01-1nmol/paw). Systemic treatment of SNL rats with des-Arg(9)-Leu(8)-BK or HOE 140 (peptidic B(1) and B(2) receptor antagonists, respectively; 0.1-1mumol/kg, i.p.) selectively blocked responses triggered by DABK and BK (1nmol/paw) and alleviated partially and transiently established cold allodynia, heat hyperalgesia and (to a lesser extent) tactile allodynia. Western blot analysis revealed enhanced expression of kinin B(1) and B(2) receptor protein in ipsilateral L4-L6 spinal nerve and hind paw skin samples collected on Day 12 after SNL surgery. These results indicate that peripheral pronociceptive kinin B(1) and B(2) receptor-operated mechanisms contribute significantly to the maintenance of hind paw cold and mechanical allodynia and heat hyperalgesia induced by L5/L6 SNL in rats.     

Antinociceptive effect of ambroxol in rats with neuropathic spinal cord injury pain

Symptoms of neuropathic spinal cord injury (SCI) pain include evoked cutaneous hypersensitivity and spontaneous pain, which can be present below the level of the injury. Adverse side-effects obtained with currently available analgesics complicate effective pain management in SCI patients. Voltage-gated Na⁺ channels expressed in primary afferent nociceptors have been identified to mediate persistent hyperexcitability in dorsal root ganglia (DRG) neurons, which in part underlies the symptoms of nerve injury-induced pain. Ambroxol has previously demonstrated antinociceptive effects in rat chronic pain models and has also shown to potently block Na⁺ channel current in DRG neurons. Ambroxol was tested in rats that underwent a mid-thoracic spinal cord compression injury. Injured rats demonstrated robust hind paw (below-level) heat and mechanical hypersensitivity. Orally administered ambroxol significantly attenuated below-level hypersensitivity at doses that did not affect performance on the rotarod test. Intrathecal injection of ambroxol did not ameliorate below-level hypersensitivity. The current data suggest that ambroxol could be effective for clinical neuropathic SCI pain. Furthermore, the data suggest that peripherally expressed Na⁺ channels could lend themselves as targets for the development of pharmacotherapies for SCI pain.     

Depression of C fibre-evoked spinal field potentials by the spinal delta opioid receptor is enhanced in the spinal nerve ligation model of neuropathic pain: involvement of the mu-subtype

The depression rate of C fibre-evoked spinal field potentials by spinally applied morphine is increased in two states of spinal hyperexcitation, namely the spinal ligation model (SNL) of neuropathic pain and long-term potentiation (LTP) of C fibre-evoked spinal field potentials. This present work sought to determine opioid receptor subtypes involved in such increase in the SNL model.We recorded spinal field potentials during spinal superfusion with increasing, cumulative concentrations of selective subtype-specific agonists in rats subjected to SNL, as well as in non-ligated animals. The μ opioid receptor (MOR) agonist DAMGO significantly depressed field potentials evoked by C (100 nM) or Aδ fibres (1 μM) both in neuropathic and non-ligated rats, whereas the κ receptor opioid (KOR) agonist ±U-50488 was ineffective. The δ opioid receptor (DOR) (D-Ala²)-Deltorphin II was more effective in reducing C fibre-evoked spinal field potentials in rats subjected to SNL (100 nM) than in non-ligated rats (100 μM). Subclinical MOR activation (10 nM DAMGO) produced a leftward shift in (D-Ala²)-Deltorphin II dose-response curve in non-ligated rats (IC₅₀ 16.59 ± 0.99 μM vs 120.3 ± 1.0 μM in the absence of DAMGO), and isobolar analysis revealed synergistic interaction (interaction index 0.25). MOR blockade (100 μM CTOP) disinhibited C fibre-evoked potentials in neuropathic, but not in basal animals, and partially impeded DOR depression in both groups. DOR blockade (1 mM naltrindole) was ineffective in either group.We show that DOR-mediated depression of spinal responses to peripheral unmyelinated fibre-input is increased in the SNL model, an increase that is contributed to by positive interaction with the spinal MOR.     

氯胺酮对神经病理性疼痛大鼠行为学及坐骨神经的影响

目的 探讨氯胺酮对神经病理性疼痛(NP)大鼠行为学和坐骨神经的影响.方法 24只SD大鼠随机均分为假手术组(S组)、坐骨神经慢性压迫性损伤(CCI)模型组(NP组)和CCI模型+氯胺酮处理组(NPK组).S组大鼠仅分离坐骨神经;NP组和NPK组建立CCI模型.S组和NP组分别于术后7～14 d每天腹腔注射生理盐水10 ...     

Gelsemine alleviates both neuropathic pain and sleep disturbance in partial sciatic nerve ligation mice

Aim:

Gelsemine, an alkaloid from the Chinese herb Gelsemium elegans (Gardn & Champ) Benth., is effective in mitigating chronic pain in rats. In the present study we investigated whether the alkaloid improved sleep disturbance, the most common comorbid symptoms of chronic pain, in a mouse model of neuropathic pain.

Methods:

Mice were subjected to partial sciatic nerve ligation (PSNL). After the mice were injected with gelsemine or pregabalin (the positive control) intraperitoneally, mechanical allodynia and thermal hyperalgesia were assessed, and electroencephalogram (EEG)/electromyogram (EMG) recording was performed. Motor performance of the mice was assessed using rota-rod test. c-Fos expression in the brain was analyzed with immunohistochemical staining.

Results:

In PSNL mice, gelsemine (2 and 4 mg/kg) increased the mechanical threshold for 4 h and prolonged the thermal latencies for 3 h. Furthermore, gelsemine (4 mg/kg, administered at 6:30 AM) increased non-rapid eye movement (non-REM, NREM) sleep, decreased wakefulness, but did not affect REM sleep during the first 3 h in PSNL mice. Sleep architecture analysis showed that gelsemine decreased the mean duration of wakefulness and increased the total number of episodes of NREM sleep during the first 3 h after the dosing. Gelsemine (4 mg/kg) did not impair motor coordination in PSNL mice. Immunohistochemical study showed that PSNL increased c-Fos expression in the neurons of the anterior cingulate cortex, and gelsemine (4 mg/kg) decreased c-Fos expression by 58%. Gelsemine (4 mg/kg, administered at either 6:30 AM or 8:30 PM) did not produce hypnotic effect in normal mice. Pregabalin produced similar antinociceptive and hypnotic effects, but impaired motor coordination in PSNL mice.

Conclusion:

Gelsemine is an effective agent for treatment of both neuropathic pain and sleep disturbance in PSNL mice; anterior cingulate cortex might play a role in the hypnotic effects of gelsemine.     

The effects of co-administration of pregabalin and vitamin E on neuropathic pain induced by partial sciatic nerve ligation in male rats

Objective

This study was performed to evaluate the effect of pregabalin co-administration with vitamin E in Partial Sciatic Nerve Ligation (PSNL)-induced neuropathic pain in rats.

Methods

Male Wistar rats were randomly allocated as control, sham, and PSNL groups (n = 8). PSNL was induced by tight ligation of the sciatic nerve with a copper wire. On day 14th, the PSNL and sham operated rats received either pregabalin (1, 3, and 30 mg/kg), vitamin E (100 and 200 mg/kg), or their combination intraperitoneally. An antinociceptive effect was evaluated as latency times and Maximum possible Effect Percent (%MPE) using tail-flick test. Locomotor activity was evaluated by open-field test before PSNL surgery and then twice at the 14th days (before and after drug injection). Ligated nerves were removed on the 28th days after surgery for histological examinations.

Results

The time course of latency times and %MPE showed significant decrease in PSNL but not in sham and control groups. Pregabalin (3 and 30 mg/kg) and vitamin E (100 and 200 mg/kg) caused significant increases in latency time in PSNL (but not sham) group compared to control group. Vitamin E 200 mg/kg increased significantly %MPE in PSNL group compared to sham group. In addition, the %MPE following combination treatment of pregabalin (30 mg/kg) and vitamin E (100 mg/kg) was significantly higher than both vitamin E and control group. Also combination of pregabalin with 100 mg/kg of vitamin E reversed Wallerian degeneration of sciatic nerve and the inflammatory responses to almost similar to sham group. Pregabalin and vitamin E did not affect locomotor activity.

Conclusion

Our results showed antinociceptive effects of both vitamin E and pregabalin alone or in combination in PSNL rats and also neuroprotective properties without affecting locomotor activity.

     

Cannabinoid receptor-mediated antinociception with acetaminophen drug combinations in rats with neuropathic spinal cord injury pain

Pre-clinical evidence demonstrates that neuropathic spinal cord injury (SCI) pain is maintained by a number of neurobiological mechanisms, suggesting that treatments directed at several pain-related targets may be more advantageous compared to a treatment focused on a single target. The current study evaluated the efficacy of the non-opiate analgesic acetaminophen, which has several putative analgesic mechanisms, combined with analgesic drugs used to treat neuropathic pain in a rat model of below-level neuropathic SCI pain. Following an acute compression of the mid-thoracic spinal cord, rats exhibited robust hind paw hypersensitivity to innocuous mechanical stimulation. Fifty percent antinociceptive doses of gabapentin, morphine, tramadol or memantine were combined with an ineffective dose of acetaminophen; acetaminophen alone was not antinociceptive. The combination of acetaminophen with either tramadol or memantine resulted in an additive antinociceptive effect. Acetaminophen combined with either morphine or gabapentin, however, resulted in supra-additive (synergistic) efficacy. One of the analgesic mechanisms of acetaminophen is inhibiting the uptake of endocannabinoids from the extracellular space. Pre-treatment with AM251, a cannabinoid-1 receptor (CB1) antagonist, significantly diminished the antinociceptive effect of the acetaminophen + gabapentin combination. Pre-treatment with AM630, a cannabinoid-2 receptor (CB2) antagonist, did not have an effect on this combination. By contrast, both AM251 and AM630 reduced the efficacy of the acetaminophen + morphine combination. None of the active drugs alone were affected by either CB receptor antagonist. The results imply that modulation of the endocannabinoid system in addition to other mechanisms mediate the synergistic antinociceptive effects of acetaminophen combinations. Despite the presence of a cannabinoid mechanism, synergism was not present in all acetaminophen combinations. The combination of currently available drugs may be an appropriate option in ameliorating neuropathic SCI pain if single drug therapy is ineffective.     

Tetranitromethane modification of the muscarinic receptors in bovine adrenal medulla

Muscarinic receptor binding was examined in bovine adrenal medullary microsomes following exposure to tetranitromethane (TNM) that modifies tyrosine and cysteine residues in proteins. The TNM (10-100 microM) treatment of adrenal medullary microsomes caused a concentration-dependent and irreversible reduction in the maximum number of binding sites (Bmax) for l-(3H)quinuclidinyl benzilate (QNB), with a slight increase in the equilibrium dissociation constant (KD). Typically, about a 36% decrease and a 1.3-fold increase in the corresponding values were obtained at 50 microM of TNM. The alteration in the Bmax was partially prevented by atropine but not carbamylcholine, and it was not reversed by subsequent treatment with dithiothreitol, a disulfide reducing agent. The change in the KD was unaffected by these agents. The TNM (50 microM) treatment also caused a slight decrease in the affinity of atropine and pirenzepine (for both the high and low affinity sites), and it caused a slight decrease in the affinity of carbamylcholine at the high affinity site, with a large loss of the low affinity site. Thus, the results indicate that TNM causes a loss of muscarinic binding sites and a decrease in the binding affinity of muscarinic receptors in bovine adrenal medulla, probably through modifications of functional groups such as tyrosine residues.     

Antihyperalgesic effects of a novel muscarinic agonist (LASSBio‐873) in spinal nerve ligation in rats

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Copper-induced alteration of muscarinic binding in bovine adrenal medulla

In microsomes of bovine adrenal medulla, there were two affinity binding sites for carbamylcholine with a high and a low affinity. Copper (1-10 microM) largely enhanced the affinity of carbamylcholine at the low affinity binding site, with a slight increase in the affinity at the high affinity binding site. On the other hand, copper slightly decreased the binding affinity of pirenzepine and atropine. Thus, low concentrations of copper modulate the muscarinic receptors in the adrenal medulla by selectively increasing agonist affinity.     

不同材料制备大鼠神经病理性疼痛CCI模型的比较

目的比较肠线、丝线、PE套管3种材料制备的CCI模型的造模效果。方法用肠线、丝线4道轻结扎大鼠坐骨神经干,或用PE90套管造成大鼠坐骨神经干慢性压迫性损伤,测定伤足底热痛阈和机械痛阈评定模型的效果。结果3种材料造模后d9和d15测定热痛阈和机械痛阈,比造模前均下降,其中肠线CCI模型对热痛阈的影响强于丝线或PE管CCI模型(d9,P<0·05;d15,P<0·01)。3种材料制备的CCI模型间机械痛阈差异无显著性。结论3种材料均可造成满意的CCI模型,但肠线造模的效果优于丝线和PE管。     

Binding sites for 125I-neuropeptide Y (NPY) on membranes from bovine adrenal medulla

Bovine adrenal medulla membranes were examined for the presence of specific 125I-neuropeptide Y (125I-NPY) binding sites using rapid centrifugation to measure the amount of bound ligand. Specific binding was determined from the difference between 125I-NPY bound in the presence and absence of 10(-7) M unlabeled NPY. The binding was saturable and reached equilibrium within 5 min at 0 degrees C. Analysis of specific 125I-NPY binding using the LIGAND computer program indicated a best fit for a two site model with a Kd of 0.26 nM and a Bmax of 12 fmol/mg protein for the high affinity site and a Kd of 170 nM and a Bmax of 6 pmol/mg protein for the low affinity site. The rate of dissociation (k-1) was 0.071/min with a t1/2 of 9 min. Displacement curves for avian or human pancreatic polypeptide revealed that these peptides displaced 125I-NPY from both sites with IC50 values greater than 10 nM.     

Presence of sigma and phencyclidine (PCP)-like receptors in membrane preparations of bovine adrenal medulla

Receptor binding studies with [3H]-(+)SKF-10047 were carried out to characterize the putative sigma (sigma) and phencyclidine (PCP) receptors in membrane preparations of bovine adrenal medulla. Specific binding of the radiolabelled compound was observed after incubation with the membrane preparation at 37 degrees, the equilibrium being reached at 20 min and the maximal binding being observed with 0.6 mg/ml protein. Saturation binding studies were performed at equilibrium (30 min at 37 degrees with 0.5 mg/ml of membrane protein) in the presence of haloperidol (1 microM) or 1-[1-(2-thienyl) cyclohexyl] piperidine (TCP; 0.2 microM) to block sigma or PCP receptors, respectively. The binding of [3H]-(+)SKF-10047 was characterized by two distinct components. A high affinity binding site (haloperidol sensitive) had an apparent KD of 8.3 nM and a Bmax of 67 pmol/g protein. A lower affinity binding site (TCP sensitive) had an apparent KD of 32.7 nM and a Bmax of 83 pmol/g protein. The drug specificity of the high affinity binding site resembled that of the putative sigma receptor, being potently inhibited by haloperidol and pentazocine. The binding pharmacology of the low affinity site resembled that of the phencyclidine receptor, being potently displaced by TCP and PCP. The binding of [3H]-(+)SKF-10047 to both receptors showed marked stereoselectivity for the dextrorotatory (+) isomer of SKF-10047 and was insensitive to the receptor specific opioid ligands DAGO (mu), DSLET (delta) and U-69593 (kappa). These data indicate that bovine adrenal medulla contains sigma and PCP-like receptors.