Young Bae Kwon

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

&NA; 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 Freunds 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 Freunds 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 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 Freunds 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 Freunds 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.

Intrathecal injection of the ς1 receptor antagonist BD1047 blocks both mechanical allodynia and increases in spinal NR1 expression during the induction phase of rodent neuropathic pain

Background: Selective blockade of spinal &sfgr;1 receptors (Sig-1R) suppresses nociceptive behaviors in the mouse formalin test. The current study was designed to verify whether intrathecal Sig-1R antagonists can also suppress chronic neuropathic pain. Methods: Neuropathic pain was produced by chronic constriction injury (CCI) of the right sciatic nerve in rats. The Sig-1R antagonist BD1047 was administered intrathecally twice daily from postoperative days 0 to 5 (induction phase of neuropathic pain) or from days 15 to 20 (maintenance phase). Western blot and immunohistochemistry were performed to determine changes in Sig-1R expression and to examine the effect of BD1047 on N-methyl-d-aspartate receptor subunit 1 expression and phosphorylation in spinal cord dorsal horn from neuropathic rats. Results: BD1047 administered on postoperative days 0–5 significantly attenuated CCI-induced mechanical allodynia, but not thermal hyperalgesia, and this suppression was blocked by intrathecal administration of the Sig-1R agonist PRE084. In contrast, BD1047 treatment during the maintenance phase of neuropathic pain had no effect on mechanical allodynia. Sig-1R expression significantly increased in the ipsilateral spinal cord dorsal horn from days 1 to 3 after CCI. Importantly, BD1047 (30 nmol) administered intrathecally during the induction, but not the maintenance phase, blocked the CCI-induced increase in N-methyl-d-aspartate receptor subunit 1 expression and phosphorylation. Conclusions: These results demonstrate that spinal Sig-1Rs play a critical role in both the induction of mechanical allodynia and the activation of spinal N-methyl-d-aspartate receptors in CCI rats and suggest a potential therapeutic role for the use of Sig-1R antagonists in the clinical management of neuropathic pain.

The analgesic efficacy of bee venom acupuncture for knee osteoarthritis: a comparative study with needle acupuncture.

The aim of this investigation was to determine whether bee venom (BV) administered directly into an acupoint was a clinically effective and safe method for relieving the pain of patients with knee osteoarthritis (OA) as compared to traditional needle acupuncture. We evaluated the efficacy of BV acupuncture using both pain relief scores and computerized infrared thermography (IRT) following 4 weeks of BV acupuncture treatment. We observed that a significantly higher proportion of subjects receiving BV acupuncture reported substantial pain relief as compared with those receiving traditional needle acupuncture therapy. Furthermore, the IRT score was significantly improved and paralleled the level of pain relief.

Visceral antinociception produced by bee venom stimulation of the Zhongwan acupuncture point in mice: role of α2 adrenoceptors

The goal of the present study was to determine whether bee venom (BV) injection into the Zhongwan acupoint (CV12), compared to injection into a non-acupoint, produced antinociception in an acetic acid-induced visceral pain model. This was accomplished by injecting BV subcutaneously into the Zhongwan acupoint or into a non-acupoint 30 min before intraperitoneal injection of acetic acid in ICR mice. BV injection into the acupoint produced a dose dependent suppression of acetic acid-induced abdominal stretches and of acetic acid-induced Fos expression in the spinal cord and the nucleus tractus solitarii. In contrast BV injection into the non-acupoint only produced antinociception at the highest dose of BV tested. Naloxone pretreatment did not alter the antinociceptive effect of BV acupoint injection on the abdominal stretch reflex. On the other hand, pretreatment with the alpha 2-adrenoceptor antagonist, yohimbine completely blocked the antinociceptive effect of BV acupoint injection. These results imply that BV acupoint stimulation can produce visceral antinociception that is associated with activation of alpha 2-adrenoceptors, but not with naloxone-sensitive opioid receptors.

Topical application of epidermal growth factor accelerates wound healing by myofibroblast proliferation and collagen synthesis in rat

Recombinant human epidermal growth factor (rhEGF) stimulates the proliferation and migration of epithelial cells in human cell culture systems and animal models of partial-thickness skin wounds. This study investigated the effect of a topical rhEGF ointment on the rate of wound healing and skin re-epithelialization in a rat full thickness wound model, and verified whether or not the rhEGF treatment affected both myofibroblast proliferation and collagen synthesis in the dermis. When rhEGF (10 µg/g ointment) was applied topically twice a day for 14 days, there was significantly enhanced wound closure from the 5th to the 12th day compared with the control (ointment base treatment) group. A histological examination at the postoperative 7th day revealed that the rhEGF treatment increased the number of proliferating nuclear antigen immunoreactive cells in the epidermis layer. In addition, the immunoreactive area of alpha-smooth muscle actin and the expression of prolyl 4-hydroxylase were significantly higher than those of the control group. Overall, a topical treatment of rhEGF ointment promotes wound healing by increasing the rate of epidermal proliferation and accelerating the level of wound contraction related to myofibroblast proliferation and collagen deposition.

Low-frequency electroacupuncture suppresses carrageenan-induced paw inflammation in mice via sympathetic post-ganglionic neurons, while high-frequency EA suppression is mediated by the sympathoadrenal medullary axis.

Although the frequency-dependent antinociceptive mechanisms of electroacupuncture (EA) have been well demonstrated, the anti-inflammatory mechanisms that underlie the suppressive effects induced by different frequencies of EA stimulation on peripheral inflammation are largely unknown. We have previously reported that EA stimulation can activate the sympathetic nervous system (SNS) and that this activation is responsible for the EA-induced suppression of zymosan-induced leukocyte migration. The present study was designed to evaluate the differential effect of low (1Hz, LF EA) versus high (120Hz, HF EA) frequency EA stimulation on SNS activation and ultimately on carrageenan-induced inflammation. Immediately after carrageenan injection, we applied either LF EA or HF EA bilaterally to the Zusanli (ST36) acupoints. To evaluate the anti-inflammatory effect of EA (EA-AI), paw volume and myeloperoxidase (MPO) activity, a marker of infiltrated leukocytes, were measured and the paw withdrawal latency to noxious heat stimulation was also assessed. Both LF EA and HF EA significantly suppressed the carrageenan-induced paw edema and MPO activity. Moreover, thermal hyperalgesia was strongly attenuated in both the LF EA and HF EA groups. Adrenalectomy significantly diminished HF EA-AI without affecting LF EA-AI. Pretreatment with the corticosterone receptor antagonist, RU-486 did not affect either LF EA- or HF EA-AI. On the other hand, administration of 6-hydroxydopamine (a neurotoxin for peripheral sympathetic nerve endings) selectively blocked LF EA-AI. Propranolol (a beta-adrenoceptor antagonist) completely abolished both LF EA- and HF EA-AI. The results of this study suggest that the suppressive effects of LF EA on carrageenan-induced paw inflammation are mediated by sympathetic post-ganglionic neurons, while the suppressive effects of HF EA are mediated by the sympatho-adrenal medullary axis.

Intrathecal clonidine suppresses phosphorylation of the N-methyl-D-aspartate receptor NR1 subunit in spinal dorsal horn neurons of rats with neuropathic pain.

BACKGROUND: Intrathecal (IT) administration of the &agr;-2 adrenoceptor agonist, clonidine, produces significant analgesic effects. Although several mechanisms underlying clonidine-induced analgesia have been proposed, the possible interaction with N-methyl-D-aspartate (NMDA) receptors as a major antinociceptive mechanism has not been addressed. We designed the present study to determine whether clonidine or other analgesics can affect spinal NMDA receptor activation in rats with chronic constriction injury (CCI)-induced neuropathy. METHODS: Rats underwent unilateral CCI, and received IT clonidine (1, 5, 20 &mgr;g/rat), [d-Ala2, NMe-Phe4, Gly-ol5]-enkephalin (DAMGO, &mgr; opioid receptor agonist, 1 &mgr;g/rat), gabapentin (anticonvulsant, 100 &mgr;g/rat) or vehicle 2 wks later. After drug injection, we measured the pain response to thermal or mechanical stimuli and used immunohistochemistry to evaluate spinal cord phosphorylated NMDA-receptor subunit 1 (pNR1) expression. RESULTS: Two weeks after CCI surgery, rats displayed significant mechanical allodynia and thermal hyperalgesia, and the spinal cord dorsal horn showed a significant increase in the number of pNR1 immunoreactive neurons. IT injection of clonidine (20 &mgr;g/rat), DAMGO and gabapentin potently reduced mechanical allodynia and thermal hyperalgesia. Importantly, IT clonidine, but not IT DAMGO or gabapentin, dose-dependently reduced CCI-induced pNR1 expression in all lamina of the spinal cord dorsal horn by 30 min after injection. In addition, IT injection of the &agr;-2 adrenoceptor antagonist, idazoxan (40 &mgr;g/rat) 10 min before clonidine injection completely reversed clonidine’s antihyperalgesic and antiallodynic effects, as well as clonidine’s suppressive effect on CCI-induced NR1 phosphorylation in the spinal cord dorsal horn. CONCLUSIONS: Our data indicate that IT clonidine’s antihyperalgesic/antiallodynic effect on neuropathic pain is associated with a significant reduction in spinal NMDA receptor phosphorylation and suggests a potentially novel mechanism of clonidine’s action.

Intrathecal Administration of Sigma-1 Receptor Agonists Facilitates Nociception : Involvement of a Protein Kinase C-dependent Pathway

Sigma sites, originally proposed as opioid receptor subtypes, are currently thought to represent unique receptors with a specific pattern of drug selectivity, a well‐established anatomical distribution and broad range of functional roles including potential involvement in nociceptive mechanisms. We have recently demonstrated that intrathecal (i.t.) treatment with a sigma‐1 receptor antagonist reduced formalin‐induced pain behavior. In the present study, we investigated the potential role of spinal sigma‐1 receptor agonists in peripherally initiated nociception and attempted to elucidate intracellular signaling mechanisms associated with spinal cord sigma‐1 receptor activation in mice. The i.t. injection of the sigma‐1 receptor agonists PRE‐084 (PRE) or carbetapentane (CAR) significantly decreased tail‐flick latency (TFL) and increased the frequency of paw withdrawal responses to mechanical stimulation (von Frey filament, 0.6 g) as well as the amount of Fos expression in the spinal cord dorsal horn induced by noxious paw‐pinch stimulation. These PRE‐ or CAR‐induced facilitatory effects on nociception were significantly blocked by i.t. pretreatment with the sigma‐1 receptor antagonist, BD‐1047, the phospholipase C (PLC) inhibitor, U‐73,122, the Ca2+‐ATPase inhibitor, thapsigargin, and the protein kinase C (PKC) inhibitor, chelerythrine. Western blot analysis further revealed that i.t. PRE or CAR injection significantly increased pan‐PKC as well as the PKCα, ϵ, and ζ isoforms in the dorsal horn. Collectively, these findings demonstrate that calcium‐dependent second messenger cascades including PKC are involved in the facilitation of nociception associated with spinal sigma‐1 receptor activation.

Depletion of capsaicin sensitive afferents prevents lamina-dependent increases in spinal N-methyl-d-aspartate receptor subunit 1 expression and phosphorylation associated with thermal hyperalgesia in neuropathic rats

Phosphorylation of the N‐methyl‐d‐aspartate (NMDA) receptor NR1 subunit (pNR1) in the spinal cord is associated with increased neuronal responsiveness, which underlies the process of central sensitization. Because of the importance of NR1 in central sensitization, the first goal of this study was to examine both time‐ and lamina‐dependent changes in spinal NR1 and pNR1 expression in a chronic constriction injury (CCI) model of neuropathic pain. Increased excitability of capsaicin sensitive primary afferents (CSPAs), which express TRPV1 receptors, also contributes to central sensitization. Thus, we next examined whether the depletion of CSPAs with resiniferatoxin (RTX) modified the change of spinal NR1 and pNR1 expression induced by CCI. Experimental rats were euthanized at 1, 3, 7, 14, and 28 days post‐CCI surgery and spinal cords processed for NR1 or pNR1 immunostaining. The number of NR1 or pNR1‐immunoreactive neurons was significantly increased in all lamina (I–VI) of the ipsilateral L4/L5 dorsal horn from 1 or 7 days post‐CCI, respectively. Pretreatment with RTX (0.3mg/kg, s.c. in the scruff of the neck or intraplantar) 2 days prior to CCI completely prevented induction of thermal hyperalgesia, but not mechanical allodynia in neuropathic rats. Interestingly, RTX treatment significantly attenuated the CCI‐induced upregulation of NR1 and pNR1 in spinal laminae I–II and V–VI, but not laminae III–IV as compared with that of vehicle‐treated CCI rats. These findings demonstrate that the increased expression of NR1 and pNR1 in spinal laminae I–II and V–VI is dependent on activation of CSPAs, which ultimately contribute to the development of thermal hyperalgesia in neuropathic rats.