Fos Expression In Spinal Cord Research Articles

A polymeric membrane dressing with antinociceptive properties: analysis with a rodent model of stab wound secondary hyperalgesia

The putative antinociceptive properties of a commercially available polymeric membrane dressing were tested by using a hind limb penetrating stab wound model in which secondary hyperalgesia could be evaluated from the hind paw. We examined the responses to mechanical and thermal stimuli applied to the hind paw remote to 2 small penetrating stab wounds of the calf. Application of the polymeric membrane dressing, but not gauze dressing, significantly reduced the development of both mechanical and thermal hyperalgesia induced by the penetrating stab wounds. In addition, animals with stab wounds showed a significant decrease in cage activity, and this decrease was prevented by application of the polymeric dressing. Analysis of spinal cord Fos expression demonstrated that the polymeric membrane, but not gauze, dressing significantly decreased stab wound–induced Fos expression in laminae I to VI of the ipsilateral L3-L5 cord segments. In addition, application of the polymeric membrane, but not gauze, dressing to the hind limb of naïve animals elicited Fos expression in laminae III and IV of the lumbar spinal cord. The data indicate that this model might be useful for evaluation of the mechanisms underlying deep tissue injury–induced secondary hyperalgesia, but they also demonstrate that the polymeric membrane dressing tested is capable of significantly reducing secondary hyperalgesia. Perspective Surgery and other types of penetrating wounds cause pain that is not always relieved by opioids and/or less potent analgesics. The present results suggest that the polymeric membrane dressing tested here may be used alone or in conjunction with analgesics to relieve pain caused by penetrating tissue injury.

Effects of tegaserod on Fos, substance P and calcitonin gene-related peptide expression induced by colon inflammation in lumbarsacral spinal cord.

To investigate the mechanisms of tegaserod, a partial 5-HT4 agonist, in reducing visceral sensitivity by observing Fos, substance P (SP) and calcitonin gene-related peptide (CGRP) expression in the lumbarsacral spinal cord induced by colonic inflammation in rats. Twenty-four male rats with colonic inflammation induced by intraluminal instillation of trinitrobenzenesulfonic acid (TNBS) were divided into 3 groups. Treatment group 1: intra-gastric administration of tegaserod, 2 mg/kg.d; Treatment group 2: intra-gastric administration of tegaserod, 1 mg/kg.d; intra-gastric administration of saline, 2.0 mL/d. After 7 d of intra-gastric administration, lumbarsacral spinal cord was removed and processed for Fos, SP and CGRP immunohistochemistry. In rats of the control group, the majority of Fos labeled neurons was localized in deeper laminae of the lumbarsacral spinal cord (L(5)-S(1)). SP and CGRP were primarily expressed in the superficial laminae of the spinal cord after TNBS injection. Intra-gastric administration of tegaserod (2 mg/kg.d) resulted in a significant decrease of Fos labeled neurons (22.0+/-7.7) and SP density (12.5+/-1.4) in the dorsal horn in the lumbarsacral spinal cord compared to those of the control group (62.2+/-18.9, 35.9+/-8.9, P<0.05). However, CGRP content in dorsal horn did not significantly reduce in rats of treatment group 1 (1.2+/-1.1) compared to that of the control group (2.8+/-2.4, P>0.05). Neither Fos expression nor SP or CGRP density in the dorsal horn significantly declined in rats of treatment group 2 compared to those of the control group (P>0.05). Tegaserod can significantly reduce Fos labeled neurons in the lumbarsacral spinal cord induced by colonic inflammation. Tegaserod may reduce visceral sensitivity by inhibiting SP expression in the dorsal horn of spinal cord.

Fos expression in rat spinal cord induced by peripheral injection of BmK I, an α-like scorpion neurotoxin

In this paper, the central neuronal activities elicited by BmK I, a specific voltage-gated Na + channel modulator, were examined by monitoring the c-Fos expression pattern of rat spinal cord. c-Fos protein in laminae I–II, V–VI, and VII–X could be detected at 0.5 h, increased steadily at 1 h, reached a peak at 2 h, and then decreased rapidly from 4 to 24 h after Bmk I was subcutaneously injected into the rat hind paw. However, c-Fos expression in laminae III–IV was activated to a peak at 0.5 h and then declined gradually from 0.5 to 24 h. Furthermore, c-Fos expression could be induced by BmK I in a dose-dependent manner. In addition, the increase of c-Fos expression in laminae I–II, V–VI, and VII–X induced by BmK I, and not in laminae III–IV, could be partially inhibited by systemic morphine in a dose-dependent manner. The results suggested that peripheral administration of BmK I could evoke a profound change of spinal neuronal activities manifested as specific patterns of c-Fos expression, which may be partially attributed to the selective modulation of BmK I on voltage-gated Na + channels located in peripheral nociceptors.

Taking the sting out of summer: A look at bee allergy and its treatment☆

We recently demonstrated that bee venom (BV) injection into the Zusanli acupoint produced a significantly more potent anti-inflammatory and antinociceptive effect than injection into a non-acupoint in a Freund's adjuvant induced rheumatoid arthritis (RA) model. However, the precise BV constituents responsible for these antinociceptive and/or anti-inflammatory effects are not fully understood. In order to investigate the possible role of the soluble fraction of BV in producing the anti-arthritic actions of BV acupuncture, whole BV was extracted into two fractions according to solubility (a water soluble fraction, BVA and an ethylacetate soluble fraction, BVE) and the BVA fraction was further tested.Subcutaneous BVA injection (0.9 mg/kg/day) into the Zusanli acupoint was found to dramatically inhibit paw edema and radiological change (i.e. new bone proliferation and soft tissue swelling) caused by Freund's adjuvant injection. BVA treatment also reduced the increase in serum interleukin-6 caused by RA induction to levels observed in non-arthritic animals. In addition, BVA therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). Finally, BVA treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. In contrast, BVE treatment (0.05 mg/kg/day) failed to show any anti-inflammatory or antinociceptive effects on RA.The results of the present study demonstrate that BVA is the effective fraction of whole BV responsible for the antinociception and anti-inflammatory effects of BV acupuncture treatment. Thus it is recommended that this fraction of BV be used for long-term treatment of RA-induced pain and inflammation. However, further study is necessary to clarify which constituents of the BVA fraction are directly responsible for these anti-arthritis effects.

Acupoint stimulation using bee venom attenuates formalin-induced pain behavior and spinal cord fos expression in rats.

In two previous reports, we have demonstrated that injection of bee venom (BV) into an acupoint produces a significant antinociceptive and anti-inflammatory effect in both a mouse model of visceral nociception and a rat model of chronic arthritis. The present study was designed to evaluate the potential antinociceptive effect of BV pretreatment on formalin-induced pain behavior and it associated spinal cord Fos expression in rats. Adult Sprague-Dawley rats were injected with BV directly into the Zusanli (ST36) acupoint or into an arbitrary non-acupoint located on the back. BV pretreatment into the Zusanli acupoint significantly decreased paw-licking time in the late phase of the formalin test. In contrast, BV injected into a non-acupoint in the back region did not suppress the paw-licking time. In addition, BV pretreatment into the Zusanli acupoint markedly inhibited spinal cord Fos expression induced by formalin injection. These findings indicate that BV pretreatment into the Zusanli acupoint has an antinociceptive effect on formalin-induced pain behavior.

Spinal nociceptin inhibits AMPA-induced nociceptive behavior and Fos expression in rat spinal cord

The effects of intrathecal nociceptin (NOCI) on the nociceptive behavior (biting, scratching and licking; BSL) and the spinal Fos expression induced by intrathecal administration of N-methyl- d-aspartate (NMDA, 4 μg/rat) or α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA, 2 μg/rat) were studied. Coadministration of NOCI (3 and 10 nmol/rat) with NMDA did not modify the NMDA-induced BSL or Fos expression. In contrast, NOCI (0.1–3 nmol/rat) dose-dependently inhibited the BSL behavior induced by AMPA. Furthermore, coadministration of NOCI (3 and 10 nmol/rat) significantly reduced the AMPA-induced expression of Fos protein in the superficial layers of the spinal dorsal horn. In order to test whether classical or opioid receptor-like type 1 (ORL1) receptors are involved in the inhibitions by NOCI of AMPA-evoked BSL, the corresponding antagonists were assayed. The administration of the nonselective opioid receptor antagonist, naloxone (10 mg/kg i.p.), did not modify the NOCI-induced inhibition of AMPA-evoked BSL. However, the selective ORL1 receptor antagonist, [N-Phe 1]nociceptin-(1–13)-NH 2 (90 nmol/rat i.t.), completely prevented the NOCI-mediated inhibition of the nociceptive responses evoked by AMPA. In conclusion, NOCI, acting at ORL1 receptors can, at least in part, induce spinal analgesia by blocking the nociceptive responses produced through the stimulation of AMPA receptors.

NMDA receptor antagonists attenuate noxious and nonnoxious colorectal distention-induced Fos expression in the spinal cord and the visceromotor reflex

In the present three-part study, the effects of intrathecally administered N-methyl- D-aspartate (NMDA) receptor antagonists on responses to noxious and innocuous colorectal distention (CRD) were examined. In the first part, a passive-avoidance paradigm was used to confirm that 80 mm Hg CRD is a noxious stimulus since it produced avoidance behavior. Acquisition of this behavior was blocked by the NMDA receptor antagonist D(−)-2-amino-5-phosphonopetanoic acid (APV, 60 nmol, intrathecal). In contrast, 20 mm Hg CRD is an innocuous stimulus since there was no difference in the behavior of these animals compared to nondistended controls. In the second part, the effects of the NMDA receptor antagonist dizocilpine maleate (MK-801, 0–100 nmol, intrathecal) on CRD-induced Fos expression in the lumbosacral spinal cord were examined. Noxious and innocuous CRD induced 98±4 and 50±2 Fos labeled cells per section per side of the spinal cord, respectively. MK-801 dose-dependently attenuated noxious CRD-induced Fos. Compared to saline, the peak attenuation was 55%. Innocuous CRD-induced Fos was attenuated by 36% following 100 nmol MK-801. In the third part, the effects of APV (0–240 nmol, intrathecal) on the visceromotor reflex were examined. APV dose-dependently attenuated the visceromotor reflex to graded intensities of CRD that went from the innocuous into the noxious range. In separate animals that only received innocuous stimulation, APV dose-dependently attenuated the visceromotor reflex. The magnitude of attenuation was similar for both stimulus paradigms. These data expand upon our previous dorsal horn neuronal recordings which showed that spinal NMDA receptors partially mediate the processing of both noxious and innocuous colorectal stimuli. They further underscore a difference from somatic tissue in the role of NMDA receptors in processing acute or transient visceral stimuli in the absence of tissue injury.

Attenuation of nerve growth factor-induced visceral hyperalgesia via cannabinoid CB 1 and CB 2-like receptors

Cannabinoids have previously been shown to possess analgesic properties in a model of visceral hyperalgesia in which the neurotrophin, nerve growth factor (NGF), plays a pivotal role. The purpose of this study was to investigate the antihyperalgesic effects of two cannabinoids in NGF-evoked visceral hyperalgesia in order to test the hypothesis that endocannabinoids may modulate the NGF-driven elements of inflammatory hyperalgesia. Intra-vesical installation of NGF replicates many features of visceral hyperalgesia, including a bladder hyper-reflexia and increased expression of the immediate early gene c fos in the spinal cord. We investigated the action of anandamide and palmitoylethanolamide (PEA) on these parameters. Both anandamide (at a dose of 25 mg/kg) and PEA (at a dose of 2.5 mg/kg) attenuated the bladder hyper-reflexia induced by intra-vesical NGF. The use of cannabinoid CB 1 receptor (SR141617A) and CB 2 receptor (SR144528) antagonists suggested that the effect of anandamide was mediated by both CB 1 and CB 2 cannabinoid receptors whilst the action of PEA was via CB 2 (or CB 2-like) receptors only. Furthermore, anandamide (25 mg/kg) and PEA (2.5 mg/kg) reduced intra-vesical NGF-evoked spinal cord Fos expression at the appropriate level (L6) by 35 and 43%, respectively. However, neither CB 1 nor CB 2 receptor antagonists altered the action of anandamide. PEA-induced reduction in Fos expression was abrogated by SR144528. These data add to the growing evidence of a therapeutic potential for cannabinoids, and support the hypothesis that the endogenous cannabinoid system modulates the NGF-mediated components of inflammatory processes.

The water-soluble fraction of bee venom produces antinociceptive and anti-inflammatory effects on rheumatoid arthritis in rats

We recently demonstrated that bee venom (BV) injection into the Zusanli acupoint produced a significantly more potent anti-inflammatory and antinociceptive effect than injection into a non-acupoint in a Freund's adjuvant induced rheumatoid arthritis (RA) model. However, the precise BV constituents responsible for these antinociceptive and/or anti-inflammatory effects are not fully understood. In order to investigate the possible role of the soluble fraction of BV in producing the anti-arthritic actions of BV acupuncture, whole BV was extracted into two fractions according to solubility (a water soluble fraction, BVA and an ethylacetate soluble fraction, BVE) and the BVA fraction was further tested. Subcutaneous BVA injection (0.9 mg/kg/day) into the Zusanli acupoint was found to dramatically inhibit paw edema and radiological change (i.e. new bone proliferation and soft tissue swelling) caused by Freund's adjuvant injection. BVA treatment also reduced the increase in serum interleukin-6 caused by RA induction to levels observed in non-arthritic animals. In addition, BVA therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). Finally, BVA treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. In contrast, BVE treatment (0.05 mg/kg/day) failed to show any anti-inflammatory or antinociceptive effects on RA. The results of the present study demonstrate that BVA is the effective fraction of whole BV responsible for the antinociception and anti-inflammatory effects of BV acupuncture treatment. Thus it is recommended that this fraction of BV be used for long-term treatment of RA-induced pain and inflammation. However, further study is necessary to clarify which constituents of the BVA fraction are directly responsible for these anti-arthritis effects.

Peripheral Amitriptyline Suppresses Formalin-Induced Fos Expression in the Rat Spinal Cord

We examined the effects of systemically, spinally, and peripherally administered amitriptyline on formalininduced Fos immunoreactivity in the lumbar spinal cord. Formalin (2.5%), injected subcutaneously into the rat hindpaw, increased Fos immunoreactivity in laminae I–II, III–IV, and V–VI of the dorsal L5 spinal cord. Amitriptyline, administered both systemically and spinally before formalin, increased flinching and concurrently decreased biting/licking behaviors, but neither route of administration produced any statistically significant change in Fos immunoreactivity. Amitriptyline coadministered with the formalin reduced both flinching and biting/licking behaviors, and significantly reduced Fos immunoreactivity, particularly in laminae I–II. These immunohistochemical changes reflect the net behavioral effects observed after the different routes of drug administration. The profile of amitriptyline action after peripheral administration may be of clinical importance because of the potential use of antidepressants as topical analgesics.

Peripheral amitriptyline suppresses formalin-induced Fos expression in the rat spinal cord.

We examined the effects of systemically, spinally, and peripherally administered amitriptyline on formalin-induced Fos immunoreactivity in the lumbar spinal cord. Formalin (2.5%), injected subcutaneously into the rat hindpaw, increased Fos immunoreactivity in laminae I-II, III-IV, and V-VI of the dorsal L5 spinal cord. Amitriptyline, administered both systemically and spinally before formalin, increased flinching and concurrently decreased biting/licking behaviors, but neither route of administration produced any statistically significant change in Fos immunoreactivity. Amitriptyline coadministered with the formalin reduced both flinching and biting/licking behaviors, and significantly reduced Fos immunoreactivity, particularly in laminae I-II. These immunohistochemical changes reflect the net behavioral effects observed after the different routes of drug administration. The profile of amitriptyline action after peripheral administration may be of clinical importance because of the potential use of antidepressants as topical analgesics. In the formalin test, amitriptyline produces different effects on pain behaviors after systemic, spinal administration and peripheral administration. Fos protein, an indicator of neuronal activity after noxious stimulation, is upregulated after formalin injection. We examined the effects of amitriptyline on such expression and observed a reduction in expression with peripheral administration.

Colonic inflammation induces fos expression in the thoracolumbar spinal cord increasing activity in the spinoparabrachial pathway

The descending colon and rectum are innervated by primary afferent fibers projecting to the lumbosacral and thoracolumbar spinal cord segments. Previous work from this laboratory has suggested that afferent input and sensory processing in the lumbosacral spinal cord is necessary and sufficient to mediate reflex responses to transient colorectal stimulation while processing in both the lumbosacral and thoracolumbar spinal cord segments contribute to visceral hyperalgesia. In the rat, repetitive noxious colorectal distention (CRD) induces >200 Fos labeled cells per section in the lumbosacral segments, but few in the thoracolumbar segments, further suggesting that transient colonic nociceptive input is transduced primarily in the lumbosacral spinal cord. The laminar distribution of this CRD-induced Fos suggests some of these neurons project to the parabrachial nucleus (PBn), an important relay for visceroceptive input from the spinal cord to higher order centers for nociceptive processing. In this study, two hypotheses were tested: first, inflammation of the colon prior to CRD would induce Fos expression in neurons in the thoracolumbar spinal cord segments and increase the number of neurons in the lumbosacral spinal cord segments that express Fos in response to noxious CRD; and second, the inflammation-induced increase in Fos expression in the spinal cord would be partially manifest as an increase in the number of spinoparabrachial projection neurons that respond to CRD. The retrograde tracer Fluorogold (FG) was injected unilaterally into the PBn of male Sprague–Dawley rats. Ten to 14 days later the rat's colon was either distended or inflamed and distended. Sections from the T13-L2 and L6-S2 spinal cord segments were double labeled using antibodies directed against FG and Fos protein. The results show that: (1) colonic inflammation plus distention induced Fos expression in the thoracolumbar spinal cord and increased Fos expression in the lumbosacral spinal cord compared to distention alone. In the lumbosacral cord, the increase in Fos expression was localized primarily to the superficial dorsal horn (SDH). In the thoracolumbar spinal segments, Fos was induced primarily in the SDH and the area around the central canal. (2) Injection of FG into the PBn produced dense retrograde labeling in the SDH, the lateral deeper gray matter and the area around the central canal at the lumbosacral and thoracolumbar levels. (3) In the lumbosacral spinal cord, 30–40% of the FG labeled cells double labeled for Fos. Colonic inflammation plus CRD did not significantly increase the percentage of spinoparabrachial neurons that were labeled for Fos compared to distention alone. (4) In the thoracolumbar spinal cord less than 10% of the FG labeled neurons were double labeled for Fos following CRD, but 25% of the FG labeled neurons in the SDH were double labeled following colonic inflammation. These data support the hypothesis that colonic inflammation activates viscerosensory processing in the thoracolumbar spinal cord and further suggests that this information is relayed to the PBn. The increase in information reaching the PBn over these parallel pathways may contribute to the affective-motivational component of the pain experience.

C-fos Antisense Oligodeoxynucleotide Decreases Subcutaneous Bee Venom Injection-Induced Nociceptive Behavior and Fos Expression in the Rat

Oligodeoxynucleotide complementary to c-fos mRNA was applied to characterize its effect on the spinal cord Fos expression and relevant nociceptive behaviors challenged by subcutaneous injection of bee venom to the rat hind paw. Nociceptive behavioral responses (spontaneous pain and hyperalgesia) following bee venom (0.2 mg/50 µl) injection were assessed in adult male Sprague-Dawley rats receiving intrathecal administra- tion of c-fos antisense oligodeoxynucleotide (ASO, 50 µg/ 10 µl), sense oligodeoxynucleotide (SO, 50 µg/10 µl) and saline (10 µl) 4 h prior to bee venom injection. The lumbar spinal cord expression of Fos protein 2 h after bee venom injection in the ASO-, SO- and saline-treated animals was observed by immunohistochemistry. The results showed that pretreatment of c-fos ASO markedly reduced the flinching response and primary thermal hyperalgesia, but without significant effects on mechanical hyperalgesia and secondary thermal hyperalgesia. At the same time, ASO treatment also significantly decreased the expression of Fos protein within the lumbar region of the spinal cord ipsilateral to the injection. The results provide further evidence that Fos protein contributes to the activation of the spinal dorsal horn neurons and the generation and/or maintenance of spontaneous pain and primary thermal hyperalgesia induced by subcutaneous injection of bee venom.

Local pentoxifylline administration decreases the formalin induced Fos expression in rat spinal cord

AbstractPro‐inflammatory cytokines play a key role in the inflammatory response and contributing to producing local hyperalgesia. It is known that pentoxifylline inhibits inflammatory cytokine production. Therefore, the aim of this study was to find out, using a behavioural test and neuronal Fos expression, if this drug had some antinociceptive effect decreasing nociresponsive neuron activation in the spinal cord after nociceptive inflammation (injection of formalin in the hind paw). Our data showed that formalin induced a great number of Fos‐positive neurons in the dorsal horn of the lumbar spinal cord mainly in the ipsilateral I and II laminae. The local pre‐treatment with pentoxifylline before the formalin injection, decreased the nociceptive response in the formalin test and the number of Fos positive neurons in the spinal cord. This finding suggests that pentoxifylline is involved in decreasing the activation of nociceptive neurons in the spinal cord playing a role in local anti‐nociception.

Heme oxygenase inhibitors reduce formalin-induced Fos expression in mouse spinal cord tissue

Recent work from our laboratory and others supports a role for heme oxygenase in nociception and pain of several etiologies including inflammatory, incisional and neuropathic. Since it has been observed that heme oxygenase inhibitors reduce formalin-induced pain behaviors in mice and rats, we attempted to determine if this analgesic effect was reflected in a reduction in formalin-induced spinal cord Fos expression, an index of neuronal activation. To perform these studies, it was necessary to first examine the cytoarchitecture of the mouse lumbar spinal cord so that histological sections from known segmental levels could be chosen, and Fos-positive nuclei could be assigned to established dorsal horn laminae. After documenting the segmental and laminar distribution of Fos-positive nuclei following a 5% formalin injection, we went on to determine that the heme oxygenase inhibitor tin-protoporphyrin or morphine reduced this Fos expression as analyzed using confocal fluorescence microscopy. It was also observed that mice lacking expression of heme oxygenase type 2, an isozyme of heme oxygenase found in high abundance in the spinal cord, had lowered Fos expression after the formalin injection. Additional confocal microscopy studies demonstrated widespread expression of heme oxygenase type 2 in spinal cord neuron cell bodies. Double-labeling experiments showed that a high percentage of Fos-positive nuclei identified after administration of formalin were located within heme oxygenase type 2-positive cell profiles. Our studies support the hypothesis that heme oxygenase type 2 plays a role in formalin-induced nociception. Furthermore, from these results we suggest that the heme oxygenase type 2 located in spinal cord dorsal horn neurons participates in this nociceptive pathway.

Bee venom injection into an acupuncture point reduces arthritis associated edema and nociceptive responses

Bee venom (BV) has traditionally been used in Oriental medicine to relieve pain and to treat inflammatory diseases such as rheumatoid arthritis (RA). While several investigators have evaluated the anti-inflammatory effect of BV treatment, the anti-nociceptive effect of BV treatment on inflammatory pain has not been examined. Previous studies in experimental animals suggest that the therapeutic effect of BV on arthritis is dependent on the site of administration. Because of this potential site specificity, the present study was designed to evaluate the anti-nociceptive effect of BV injections into a specific acupoint (Zusanli) compared to a non-acupoint in an animal model of chronic arthritis. Subcutaneous BV treatment (1 mg/kg per day) was found to dramatically inhibit paw edema caused by Freund's adjuvant injection. Furthermore, BV therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. the nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). These anti-nociceptive/anti-inflammatory effects of BV were observed from 12 days through 21 days post-BV treatment. In addition, BV treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. Finally, injection of BV into the Zusanli acupoint resulted in a significantly greater analgesic effect on arthritic pain as compared to BV injection in to a more distant non-acupoint. The present study demonstrates that BV injection into the Zusanli acupoint has both anti-inflammatory and anti-nociceptive effects on Freund's adjuvant-induced arthritis in rats. These findings raise the possibility that BV acupuncture may be a promising alternative medicine therapy for the long-term treatment of rheumatoid arthritis.

The antinociceptive and anti-inflammatory effect of water-soluble fraction of bee venom on rheumatoid arthritis in rats

We recently demonstrated that bee venom (BV) injection into acupoint (i.e. Zusanli) produced more potent anti-inflammatory and antinociciptive effect in Freunds adjuvant induced rheumatoid arthritis (RA) model as compared with that of non-acupoint injection(i.e back). However, the precise components underlying BV-induced antinociceptive and/or anti-inflammatory effects have not been fully understood. Therefore, we further investigated the anti-arthritic effect of BV after extracting the whole BV according to solubility (water soluble: BVA, ethylacetate soluble: BVE). Subcutaneous BVA treatment (0.9 mg/kg/day) into Zusanli acupoint was found to dramatically inhibit paw edema and radiological change (i.e. new bone proliferation and soft tissue swelling) caused by Freunds adjuvant injection. In addition, the increase of serum interleukin-6 by RA induction was normalized by the BVA treatment as similar with that of non-arthritic animals. On the other hand, BVA therapy significantly reduced arthritis induced nociceptive behaviors (i.e., nociceptive score for mechanical hyperalgesia and thermal hyperalgesia). Furthermore, BVA treatment significantly suppressed adjuvant induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. However, BVE treatment (0.05 mg/kg/day) has not any anti-inflammatory and anti-nociceptive effect on RA. Based on the present results, we demonstrated that BVA might be a effective fraction in whole BV for long-term treatment of RA-induced pain and inflammation. However, it is clear necessary that further fraction study about BVA was required for elucidating an effective component of BVA.

Effects of baclofen on colon inflammation-induced Fos, CGRP and SP expression in spinal cord and brainstem

The present study demonstrates sites of expression for Fos protein in the brainstem and lumbosacral spinal cord of rats subjected to mustard oil irritation of the colon. The protective effect of baclofen, a selective GABA B receptor agonist, on the induced Fos protein increases was determined. Mustard oil injected into the lumen of the colon produces an acute site-specific inflammation. Immunocytochemical localization of Fos protein in neuronal nuclei was evident after 1 h, was greatest at 2 h and was still evident but declining at 8 h. In the spinal cord the majority of Fos labeled neurons were localized in the superficial laminae of lumbar (L6) cord with more found in the sacral (S1) cord. Some labeled neurons were also found in the deeper spinal laminae, intermediolateral nucleus and around lamina X. Brainstem sites expressing Fos included the nucleus of the solitary tract in the medulla, parabrachial, locus coeruleus, pontine and caudal dorsal raphe nuclei and periaqueductal gray. Weak Fos protein labeling existed in a few cells in vehicle control animals. Systemic administration of the GABA B receptor agonist, baclofen (10 mg/kg, i.p.), significantly reduced Fos expression in the spinal cord after mustard oil treatment but significantly increased the relative number of nuclei labeled in the nucleus of the solitary tract. Baclofen also significantly decreases dorsal horn CGRP immunoreactivity relative to the increased levels seen after inflammation of the colon. The SP content increases observed after inflammation of the colon were not altered by baclofen. These data suggest that: (1) neurons in regions important for nociceptive transmission, descending inhibitory control and autonomic control are activated by noxious stimulation of the colon, and (2) baclofen specifically reduces Fos expression in the superficial dorsal horn of the spinal cord induced by nociceptive afferent input.

Bee venom pretreatment has both an antinociceptive and anti-inflammatory effect on carrageenan-induced inflammation.

Although the injection of bee venom (BV) has been reported to evoke tonic pain and hyperalgesia, there is conflicting evidence in the literature indicating that BV can also exert an anti-inflammatory and antinociceptive effects on inflammation. In this regard, BV has been traditionally used in Oriental medicine to relieve pain and to treat chronic inflammatory diseases such as rheumatoid arthritis. The present study was designed to test the hypothesis that BV induces acute nociception under normal conditions, but that it can serve as a potent anti-inflammatory and antinociceptive agent in a localized inflammatory state. The experiments were designed to evaluate the effect of BV pretreatment on carrageenan (CR)-induced acute paw edema and thermal hyperalgesia. In addition, spinal cord Fos expression induced by peripheral inflammation was quantitatively analyzed. In normal animals subcutaneous BV injection into the hindlimb was found to slightly increase Fos expression in the spinal cord without producing detectable nociceptive behaviors or hyperalgesia. In contrast pretreatment with BV (0.8 mg/kg) 30 min prior to CR injection suppressed both the paw edema and thermal hyperalgesia evoked by CR. In addition, there was a positive correlation between the percent change in paw volume and the expression of Fos positive neurons in the spinal cord. These results indicate that BV pretreatment has both antinociceptive and anti-inflammatory effects in CR-induced inflammatory pain. These data also suggest that BV administration may be useful in the treatment of the pain and edema associated with chronic inflammatory diseases.

The NMDA receptor antagonist MK-801 attenuates c-Fos expression in the lumbosacral spinal cord following repetitive noxious and non-noxious colorectal distention

The effects of pretreatment with an NMDA receptor antagonist, MK-801, on c-Fos (Fos) expression in the lumbosacral spinal cord following repetitive, noxious (80 mmHg) or non-noxious (20 mmHg) colorectal distention (CRD) was examined immunocytochemically in awake and urethane anesthetized rats. In awake rats, noxious CRD induced Fos expression in the lumbosacral spinal cord. Pretreatment with MK-801 (0.1–1.0 mg/kg, i.p.) produced no change or an increase in noxious CRD induced-Fos expression and caused aversive side effects. In order to examine greater doses of MK-801, further experiments were performed in rats anesthetized with urethane. Both noxious and non-noxious CRD induced Fos in the lumbosacral spinal cord. Pretreatment with MK-801 (0.5, 1.0, 5.0 mg/kg, i.p.) dose-dependently attenuated noxious CRD-induced Fos by 20–40%. Five mg/kg MK-801 attenuated non-noxious CRD-induced Fos by 20%. Lesser doses did not significantly attenuate Fos expression. The laminar distribution of Fos following MK-801 pretreatment revealed a tendency towards the deeper laminae showing the greatest attenuation at the highest dose of MK-801. Protein plasma extravasation in the colon measured with Evan's blue dye showed no difference between rats without balloons, rats with balloons that were not distended and non-noxious CRD. There was significantly more extravasation following noxious CRD. Pretreatment with systemic MK-801 had no effect on plasma extravasation produced by noxious CRD. These data suggest that the induction of Fos in the lumbosacral spinal cord by noxious and non-noxious CRD is partially NMDA receptor mediated. However, NMDA receptor activation contributes significantly more to noxious than non-noxious CRD-induced Fos. Inflammation of the colon following noxious CRD likely contributes to sensitization of colonic afferents which may contribute to the increased NMDA receptor-mediated Fos following the noxious stimulus.