Morphine-induced Modulation of Nociceptive Spinal Dorsal Horn Neuronal Activities after Formalin-induced Inflammatory Pain

Park, Joo-Min,Li, Kang-Wu,Jung, Sung-Jin,Kim, Jun,Kim, Sang-Jeong The Korean Society of Pharmacology 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.2

In this study, we examined the morphine-induced modulation of the nociceptive spinal dorsal horn neuronal activities before and after formalin-induced inflammatory pain. Intradermal injection of formalin induced time-dependent changes in the spontaneous activity of nociceptive dorsal horn neurons. In naive cats before the injection of formalin, iontophoretically applied morphine attenuated the naturally and electrically evoked neuronal responses of dorsal horn neurons. However, neuronal responses after the formalin-induced inflammation were significantly increased by morphine. Bicuculline, $GABA_A$ antagonist, increased the naturally and electrically evoked neuronal responses of dorsal horn neurons. This increase in neuronal responses due to bicuculline after the formalin-induced inflammation was larger than that in the naive state, suggesting that basal $GABA_A$ tone increased after the formalin injection. Muscimol, $GABA_A$ agonist, reduced the neuronal responses before the treatment with formalin, but not after formalin treatment, again indicating an increase in the GABAergic basal tone after the formalin injection which saturated the neuronal responses to GABA agonist. Morphine-induced increase in the spinal nociceptive responses after formalin treatment was inhibited by co-application of muscimol. These data suggest that formalin-induced inflammation increases $GABA_A$ basal tone and the inhibition of this augmented $GABA_A$ basal tone by morphine results in a paradoxical morphineinduced increase in the spinal nociceptive neuronal responses after the formalin-induced inflammation.

Morphine-induced Modulation of Nociceptive Spinal Dorsal Horn Neuronal Activities after Formalin-induced Inflammatory Pain

Joo Min Park,Kang Wu Li,Sung Jun Jung,Jun Kim,Sang Jeong Kim 대한생리학회-대한약리학회 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.2

In this study, we examined the morphine-induced modulation of the nociceptive spinal dorsal horn neuronal activities before and after formalin-induced inflammatory pain. Intradermal injection of formalin induced time-dependent changes in the spontaneous activity of nociceptive dorsal horn neurons. In naïve cats before the injection of formalin, iontophoretically applied morphine attenuated the naturally and electrically evoked neuronal responses of dorsal horn neurons. However, neuronal responses after the formalin-induced inflammation were significantly increased by morphine. Bicuculline, GABA<SUB>A</SUB> antagonist, increased the naturally and electrically evoked neuronal responses of dorsal horn neurons. This increase in neuronal responses due to bicuculline after the formalin-induced inflammation was larger than that in the naïve state, suggesting that basal GABA<SUB>A</SUB> tone increased after the formalin injection. Muscimol, GABA<SUB>A</SUB> agonist, reduced the neuronal responses before the treatment with formalin, but not after formalin treatment, again indicating an increase in the GABAergic basal tone after the formalin injection which saturated the neuronal responses to GABA agonist. Morphine-induced increase in the spinal nociceptive responses after formalin treatment was inhibited by co-application of muscimol. These data suggest that formalin-induced inflammation increases GABA<SUB>A</SUB> basal tone and the inhibition of this augmented GABA<SUB>A</SUB> basal tone by morphine results in a paradoxical morphine- induced increase in the spinal nociceptive neuronal responses after the formalin-induced inflammation.

Opioid 수용체 효능제의 뇌실 내 주입이 고양이 척수후각세포의 활성에 미치는 영향

문태상(Tae Sang Moon),오우택(Uhtaek Oh) 대한약학회 1999 약학회지 Vol.43 No.4

Intracerebroventricular (ICV) infusion of morphine (MOR) produces strong analgesia in man and animals. The analgesic effect is thought to be mediated by the centrifugal inhibitory control. But neural mechanisms of the analgesic effect of ICV morphine are not well understood. In the present study, we found that ICV MOR had dual actions on the activity of dorsal horn neurons: it produced both inhibition and excitation of dorsal horn neurons. Since MOR exerts its action via three different types of opioid receptors, we further sought to investigate if there are differential effects of opioid receptor agonists on dorsal horn neurons of the spinal cord in the cat. ICV VOR inhibited, excited and did not affect the heat responsers of dorsal horn neurons. ICV DAMGO and DADLE, mu-and delta-opioid agonist, respectively, exhibited the excitation of dorsal horn neurons. In contrast, U-50488, a k-opioid agonist, exhibited both the inhibition and excitation of dorsal horn neurons. These results suggest that opioid receptors have different actions on activity of dorsal horn neuron and that the inhibitory action of k-opioid agonist may subserve the analgesia often produced by ICV MOR.

적출 백서 연수후각 신경세포에 미치는 아미노산 신경전달물질과 GABA성 약물의 영향

김재연(Jae Youn Kim),이상한(Sang Han Lee) 대한구강악안면외과학회 1993 대한구강악안면외과학회지 Vol.19 No.3

This study was performed to elucidate the effects of glutamate, aspartate, substance P and GABAergics on the intracellular membrane potential and membrane input resistance of isolated medullary dorsal horn, and the interrelations between EAA, substance P and GABA in medullary dorsal horn. Transectional slices of caudal part of trigeminal sensory nucleus were prepared from rats about 5 weeks old, then transferred and fixed in the recording chamber where it was preincubated and continuously perfused with airated modified Krebs-Ringer solution. Intracellular recordings were carried out with glass microelectrode to record the changes of membrane potential and membrane resistance induced by perfusion of glutamate, aspartate, substance P, GABA, baclofen and/or bicuculline. Results obtained as follows : 1. Glutamate and aspartate respectively depolarized medullary dorsal horn neurons and decreased membrane input resistance in a dose-dependent manner. Effect of glutamate and aspartate applied simultaneously on medullary dorsal horn neuron was not different from that of glutamate or aspartate, respectively. Substance P also depolarized medullary dorsal horn neurons. 2. Medullary dorsal horn neurons responding to glutamate also responded to aspartate and substance P. 3. GABA and baclofen showed little effects on menbrane potential and input resistance. 4. Bicuculline evoked a depolarization of neurons of medullary dorsal horn.

랫드 척수후각 단일세포 분리 및 특성에 관한 연구

한성규,류판동,Han, Seong-Kyu,Ryu, Pan-Dong 대한약리학회 1996 대한약리학잡지 Vol.32 No.2

The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region. In this study, single neurons of the spinal dorsal horn were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by patch clamp technique. Transverse slice ($(300{\mu}m$) of lumbar spinal cords from young rats$(7{\sim}14\;days)$ were sequentially treated with two pretenses(pronase 0.75 mg/ml and thermolysin 0.75 mg/ml), then single neurons were mechanically dissociated. These neurons showed near-intact morphology such as multipolar, ellipsoidal and bipolar, and pyramidal cells and we recorded the typical whole cell currents of $K^+$, $Ca^{2+}$ and ligand-operated channels from these neurons. Glutamate $(30{\mu}M)$ and N-methyl-D-aspartate(NMDA, $30{\mu}M)$ induced inward currents of $117{\pm}12.4$ pA(n=5) and $49{\pm}6.9$ pA(n=3), respectively. Glycine $(1{\mu}M)$ potentiated glutamate-induced currents $4{\sim}5$ times and NMDA-induced currents $8{\sim}10$ times. In addition, glycine $(30{\mu}M)$ induced Inward current ($31{\pm}6.1$ nA, n=2), which was rapidly desensitized after the peak to a new steady-state level. However, the inward currents induced by ${\gamma}-amino$ butyric acid(GABA, $1{\mu}M$) decreased continuously after the peak($226{\pm}41.6$ pA, n=3) under the similar experimental condition. The ionic currents and pharmacological responses of isolated neurons in this work were similar to those observed in vivo or in vitro spinal cord slice, indicating that acutely isolated neurons could be effectively used for further pharmacological studies.

Leukemia inhibitory factor induces neurotrophic effects and TrkA/PI3K/Akt activation in dorsal root ganglion neurons

( Dai Hyun Kim ),( Se Jeong Lee ),( Sung Jin Park ),( Min Seok Ham ),( Ji Hyuck Hong ),( Soo Hong Seo ),( Hyo Hyun Ahn ),( Young Chul Kye ),( Hyeon Soo Kim ),( Im Joo Rhyu ) 대한피부과학회 2020 대한피부과학회 학술발표대회집 Vol.72 No.1

Background: Myokines could be associated with peripheral inflammation. The impaired skin barrier function triggers abnormal muscle contraction leading to an increased neurosensory response and neurogenic inflammation. Objectives: The aim of this study was to verify that the specific myokine, leukemia inhibitory factor (LIF), could have meaningful roles on aggravation of pruritus in chronic inflammatory skin disorders. Methods: An in vitro coculture model between dorsal root ganglion (DRG) neurons and keratinocytes was adopted for assessment of possible trophic effect. The activation of serial signaling pathways in DRG neurons by LIF and/or nerve growth factor (NGF) were examined. Results: LIF treatment to DRG neurons showed significant neurite outgrowth comparable with NGF. LIF also meaningfully affected axonal growth in coculture models. The LIF induced neurotrophic effects were effectively diminished by TrkA inhibitor, K252a. LIF application resulted in time- and dose-dependent tropomyosin receptor kinase A (TrkA) and Akt phosphorylation in DRG neurons. In addition, TrkA and Akt phosphorylation by LIF in DRG neurons were effectively prohibited with TrkA inhibitor, K252a respectively. Lastly, Akt phosphorylation induced by LIF was also meaningfully restrained by phosphoinositide 3-kinase (PI3K) inhibitor, LY-294002. Conclusion: LIF could cause increased neurite outgrowth and activation of TrkA/PI3K/Akt phosphorylation in DRG neurons.

The Protective Effects of IGF-1 on Different Subpopulations of DRG Neurons with Neurotoxicity Induced by gp120 and Dideoxycytidine In Vitro

( Lin Lu ),( Hai Xia Dong ),( Gui Xiang Liu ),( Bin Yuan ),( Yizhao Li ),( Hua Xiang Liu ) 한국응용약물학회 2014 Biomolecules & Therapeutics(구 응용약물학회지) Vol.22 No.6

Peripheral neuropathy induced by human immunodeficiency virus (HIV) infection and antiretroviral therapy is not only difficult to distinguish in clinical practice, but also difficult to relieve the pain symptoms by analgesics because of the severity of the disease at the later stage. Hence, to explore the mechanisms of HIV-related neuropathy and find new therapeutic options are particularly important for relieving neuropathic pain symptoms of the patients. In the present study, primary cultured embryonic rat dorsal root ganglion (DRG) neurons were used to determine the neurotoxic effects of HIV-gp120 protein and/or antiretroviral drug dideoxycytidine (ddC) and the therapeutic actions of insulin-like growth factor-1 (IGF-1) on gp120- or ddC-induced neurotoxicity. DRG neurons were exposed to gp120 (500 pmol/L), ddC (50 μmol/L), gp120 (500 pmol/L) plus ddC (50 μmol/L), gp120 (500 pmol/L) plus IGF-1 (20 nmol/L), ddC (50 μmol/L) plus IGF-1 (20 nmol/L), gp120 (500 pmol/L) plus ddC (50 μmol/L) plus IGF-1 (20 nmol/L), respectively, for 72 hours. The results showed that gp120 and/or ddC caused neurotoxicity of primary cultured DRG neurons. Interestingly, the severity of neurotoxicity induced by gp120 and ddC was different in different subpopulation of DRG neurons. gp120 mainly affected large diameter DRG neurons (>25 μm), whereas ddC mainly affected small diameter DRG neurons (≤25 μm). IGF-1 could reverse the neurotoxicity induced by gp120 and/or ddC on small, but not large, DRG neurons. These data provide new insights in elucidating the pathogenesis of HIV infection- or antiretroviral therapy-related peripheral neuropathy and facilitating the development of novel treatment strategies.

Involvement of NMDA Receptor and L-type Calcium Channel in the Excitatory Action of Morphine

Koo, Bon-Seop,Shin, Hong-Kee,Kang, Suk-Han,Jun, Jong-Hun The Korean Society of Pharmacology 2002 The Korean Journal of Physiology & Pharmacology Vol.6 No.5

We studied the excitatory action of morphine on the responses of dorsal horn neuron to iontophoretic application of excitatory amino acid and C-fiber stimulation by using the in vivo electrophysiological technique in the rat. In 137 of the 232 wide dynamic range (WDR) neurons tested, iontophoretic application of morphine enhanced the WDR neuron responses to N-methyl-D-aspartate (NMDA), kainate, and graded electrical stimulation of C-fibers. Morphine did not have any excitatory effects on the responses of low threshold cells. Morphine-induced excitatory effect at low ejection current was naloxone-reversible and reversed to an inhibitory action at high ejection current. NMDA receptor, calcium channel and intracellular $Ca^{2+}$ antagonists strongly antagonized the morphine-induced excitatory effect. These results suggest that changes in intracellular ionic concentration, especially $Ca^{2+},$ play an important role in the induction of excitatory effect of morphine in the rat dorsal horn neurons.

Activation of the cGMP/Protein Kinase G Pathway by Nitric Oxide Can Decrease TRPV1 Activity in Cultured Rat Dorsal Root Ganglion Neurons

Jin, Yun-Ju,Kim, Jun,Kwak, Ji-Yeon The Korean Society of Pharmacology 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.3

Recent studies have demonstrated that nitric oxide (NO) activates transient receptor potential vanilloid subtype 1 (TRPV1) via S-nitrosylation of the channel protein. NO also modulates various cellular functions via activation of the soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway and the direct modification of proteins. Thus, in the present study, we investigated whether NO could indirectly modulate the activity of TRPV1 via a cGMP/PKG-dependent pathway in cultured rat dorsal root ganglion (DRG) neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), decreased capsaicin-evoked currents ($I_{cap}$). NO scavengers, hemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), prevented the inhibitory effect of SNP on $I_{cap}$. Membrane-permeable cGMP analogs, 8-bromoguanosine 3', 5'-cyclic monophosphate (8bromo-cGMP) and 8-(4chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP), and the guanylyl cyclase stimulator YC-1 mimicked the effect of SNP on $I_{cap}$. The PKG inhibitor KT5823 prevented the inhibition of $I_{cap}$ by SNP. These results suggest that NO can downregulate the function of TRPV1 through activation of the cGMP/PKG pathway in peripheral sensory neurons.

Activation of the cGMP/Protein Kinase G Pathway by Nitric Oxide Can Decrease TRPV1 Activity in Cultured Rat Dorsal Root Ganglion Neurons

Yunju Jin,김전,곽지연 대한약리학회 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.3

Recent studies have demonstrated that nitric oxide (NO) activates transient receptor potential vanilloid subtype 1 (TRPV1) via S-nitrosylation of the channel protein. NO also modulates various cellular functions via activation of the soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway and the direct modification of proteins. Thus, in the present study, we investigated whether NO could indirectly modulate the activity of TRPV1 via a cGMP/PKG-dependent pathway in cultured rat dorsal root ganglion (DRG) neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), decreased capsaicin-evoked currents (Icap). NO scavengers, hemoglobin and 2-(4-carboxyphenyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), prevented the inhibitory effect of SNP on Icap. Membrane-permeable cGMP analogs, 8-bromoguanosine 3’, 5’-cyclic monophosphate (8bromo-cGMP) and 8-(4chlorophenylthio)-guanosine 3’,5’-cyclic monophosphate (8-pCPT-cGMP), and the guanylyl cyclase stimulator YC-1 mimicked the effect of SNP on Icap. The PKG inhibitor KT5823 prevented the inhibition of Icap by SNP. These results suggest that NO can downregulate the function of TRPV1 through activation of the cGMP/PKG pathway in peripheral sensory neurons.