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Peng F, Qu ZW, Qiu CY, Liao M, Hu WP. Spinal vasopressin alleviates formalin-induced nociception by enhancing GABAA receptor function in mice. Neurosci Lett 2015; 593:61-5. [PMID: 25782631 DOI: 10.1016/j.neulet.2015.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/18/2022]
Abstract
Arginine vasopressin (AVP) plays a regulatory role in nociception. Intrathecal administration of AVP displays an antinociceptive effect. However, little is understood about the mechanism underlying spinal AVP analgesia. Here, we have found that spinal AVP dose dependently reduced the second, but not first, phase of formalin-induced spontaneous nociception in mice. The AVP analgesia was completely blocked by intrathecal injected SR 49059, a vasopressin-1A (V1A) receptor antagonist. However, spinal AVP failed to exert its antinociceptive effect on the second phase formalin-induced spontaneous nociception in V1A receptor knock-out (V1A-/-) mice. The AVP analgesia was also reversed by bicuculline, a GABAA receptor antagonist. Moreover, AVP potentiated GABA-activated currents in dorsal root ganglion neurons from wild-type littermates, but not from V1A-/- mice. Our results may reveal a novel spinal mechanism of AVP analgesia by enhancing the GABAA receptor function in the spinal cord through V1A receptors.
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Qiu F, Qiu CY, Cai H, Liu TT, Qu ZW, Yang Z, Li JD, Zhou QY, Hu WP. Oxytocin inhibits the activity of acid-sensing ion channels through the vasopressin, V1A receptor in primary sensory neurons. Br J Pharmacol 2015; 171:3065-76. [PMID: 24641084 DOI: 10.1111/bph.12635] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/01/2014] [Accepted: 02/04/2014] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE A growing number of studies have demonstrated that oxytocin (OT) plays an analgesic role in modulation of nociception and pain. Most work to date has focused on the central mechanisms of OT analgesia, but little is known about whether peripheral mechanisms are also involved. Acid-sensing ion channels (ASICs) are distributed in peripheral sensory neurons and participate in nociception. Here, we investigated the effects of OT on the activity of ASICs in dorsal root ganglion (DRG) neurons. EXPERIMENTAL APPROACH Electrophysiological experiments were performed on neurons from rat DRG. Nociceptive behaviour was induced by acetic acid in rats and mice lacking vasopressin, V1A receptors. KEY RESULTS OT inhibited the functional activity of native ASICs. Firstly, OT dose-dependently decreased the amplitude of ASIC currents in DRG neurons. Secondly, OT inhibition of ASIC currents was mimicked by arginine vasopressin (AVP) and completely blocked by the V1A receptor antagonist SR49059, but not by the OT receptor antagonist L-368899. Thirdly, OT altered acidosis-evoked membrane excitability of DRG neurons and significantly decreased the amplitude of the depolarization and number of action potentials induced by acid stimuli. Finally, peripherally administered OT or AVP inhibited nociceptive responses to intraplantar injection of acetic acid in rats. Both OT and AVP also induced an analgesic effect on acidosis-evoked pain in wild-type mice, but not in V1A receptor knockout mice. CONCLUSIONS AND IMPLICATIONS These results reveal a novel peripheral mechanism for the analgesic effect of OT involving the modulation of native ASICs in primary sensory neurons mediated by V1A receptors.
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Qiu F, Hu WP, Yang ZF. Enhancement of GABA-activated currents by arginine vasopressin in rat dorsal root ganglion neurons. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2014; 66:647-657. [PMID: 25516513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A growing number of studies have shown that arginine vasopressin (AVP) plays an analgesia role in the modulation of nociception. Previous studies have focused on the central mechanisms of AVP analgesia. The aim of the present study was to find out whether peripheral mechanisms are also involved. The effect of AVP on GABA-activated currents (IGABA) and GABAA receptor function in freshly isolated dorsal root ganglion (DRG) neurons of rats were studied using whole cell patch clamp technique. The result showed that, IGABA were potentiated by pre-treatment with AVP (1 × 10⁻¹⁰-1 × 10⁻⁵ mol/L) in a concentration-dependent manner. Meanwhile, the GABA concentration-response curve was shifted upwards, with an increase of (49.1 ± 4.0)% in the maximal current response but with no significant change in the EC50 values. These results indicate that the enhancing effect is non-competitive. In addition, the effects of AVP on IGABA might be voltage-independent. This potentiation of IGABA induced by AVP was almost completely blocked by the V1a receptor antagonist SR49059 (3 × 10⁻⁶ mol/L). Also it could be removed by intracellular dialysis of either GDP-β-S (5 × 10⁻⁴mol/L), a non-hydrolyzable GDP analog, or GF109203X (2 × 10⁻⁶ mol/L), a selective protein kinase C (PKC) inhibitor, with the re-patch clamp. These results suggest that AVP up-regulates the function of the GABAA receptor via G protein-coupled receptors and PKC-dependent signal pathways in rat DRG neurons, and this potentiation may underlie the analgesia induced by AVP.
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Liu TT, Qu ZW, Qiu CY, Qiu F, Ren C, Gan X, Peng F, Hu WP. Inhibition of acid-sensing ion channels by levo-tetrahydropalmatine in rat dorsal root ganglion neurons. J Neurosci Res 2014; 93:333-9. [DOI: 10.1002/jnr.23484] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/16/2014] [Accepted: 08/20/2014] [Indexed: 12/19/2022]
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Qu ZW, Liu TT, Qiu CY, Li JD, Hu WP. Inhibition of acid-sensing ion channels by chlorogenic acid in rat dorsal root ganglion neurons. Neurosci Lett 2014; 567:35-9. [PMID: 24680850 DOI: 10.1016/j.neulet.2014.03.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 03/15/2014] [Accepted: 03/17/2014] [Indexed: 12/22/2022]
Abstract
Chlorogenic acid (CGA) is one of the most abundant polyphenol compounds in the human diet. Recently, it is demonstrated to have potent antinociceptive effect. However, little is understood about the mechanism underlying CGA analgesia. Here, we have found that CGA can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. First, CGA decreased the peak amplitude of proton-gated currents mediated by ASICs in a concentration-dependent manner. Second, CGA shifted the proton concentration-response curve downward, with a decrease of 41.76 ± 8.65% in the maximum current response to protons but with no significant change in the pH0.5 value. Third, CGA altered acidosis-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral administered CGA attenuated nociceptive response to intraplantar injection of acetic acid in rats. ASICs are distributed in peripheral sensory neurons and participate in nociception. Our findings CGA inhibition of native ASICs indicated that CGA may exert analgesic action by modulating ASICs in the primary afferent neurons, which revealed a novel cellular and molecular mechanism underlying CGA analgesia.
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Qiu F, Liu TT, Qu ZW, Qiu CY, Yang Z, Hu WP. Gastrodin inhibits the activity of acid-sensing ion channels in rat primary sensory neurons. Eur J Pharmacol 2014; 731:50-7. [PMID: 24642360 DOI: 10.1016/j.ejphar.2014.02.044] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 01/23/2014] [Accepted: 02/23/2014] [Indexed: 01/24/2023]
Abstract
Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are believed to mediate pain caused by extracellular acidification. Gastrodin is a main bioactive constituent of the traditional herbal Gastrodia elata Blume, which has been widely used in Oriental countries for centuries. As an analgesic, gastrodin has been used clinically to treat pain such as migraine and headache. However, the mechanisms underlying analgesic action of gastrodin are still poorly understood. Here, we have found that gastrodin inhibited the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Gastrodin dose-dependently inhibited proton-gated currents mediated by ASICs. Gastrodin shifted the proton concentration-response curve downwards, with a decrease of 36.92 ± 6.23% in the maximum current response but with no significant change in the pH0.5 value. Moreover, gastrodin altered acid-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral applied gastrodin relieved pain evoked by intraplantar injection of acetic acid in rats. Our results indicate that gastrodin can inhibit the activity of ASICs in the primary sensory neurons, which provided a novel mechanism underlying analgesic action of gastrodin.
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Cai Q, Qiu CY, Qiu F, Liu TT, Qu ZW, Liu YM, Hu WP. Morphine inhibits acid-sensing ion channel currents in rat dorsal root ganglion neurons. Brain Res 2014; 1554:12-20. [PMID: 24491633 DOI: 10.1016/j.brainres.2014.01.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 01/18/2014] [Accepted: 01/24/2014] [Indexed: 02/08/2023]
Abstract
Extracellular acidosis is a common feature in pain-generating pathological conditions. Acid-sensing ion channels (ASICs), pH sensors, are distributed in peripheral sensory neurons and participate in nociception. Morphine exerts potent analgesic effects through the activation of opioid receptors for various pain conditions. A cross-talk between ASICs and opioid receptors in peripheral sensory neurons has not been shown so far. Here, we have found that morphine inhibits the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Morphine dose-dependently inhibited proton-gated currents mediated by ASICs in the presence of the TRPV1 inhibitor capsazepine. Morphine shifted the proton concentration-response curve downwards, with a decrease of 51.4±3.8% in the maximum current response but with no significant change in the pH0.5 value. Another μ-opioid receptor agonist DAMGO induced a similar decrease in ASIC currents compared with morphine. The morphine inhibition of ASIC currents was blocked by naloxone, a specific opioid receptor antagonist. Pretreatment of forskolin, an adenylyl cyclase activator, or the addition of cAMP reversed the inhibitory effect of morphine. Moreover, morphine altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, peripheral applied morphine relieved pain evoked by intraplantar of acetic acid in rats. Our results indicate that morphine can inhibit the activity of ASICs via μ-opioid receptor and cAMP dependent signal pathway. These observations demonstrate a cross-talk between ASICs and opioid receptors in peripheral sensory neurons, which was a novel analgesic mechanism of morphine.
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Liu YQ, Qiu F, Qiu CY, Cai Q, Zou P, Wu H, Hu WP. Cannabinoids inhibit acid-sensing ion channel currents in rat dorsal root ganglion neurons. PLoS One 2012; 7:e45531. [PMID: 23029075 PMCID: PMC3446897 DOI: 10.1371/journal.pone.0045531] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/21/2012] [Indexed: 12/26/2022] Open
Abstract
Local acidosis has been found in various pain-generating conditions such as inflammation and tissue injury. Cannabinoids exert a powerful inhibitory control over pain initiation via peripheral cognate receptors. However, the peripheral molecular targets responsible for the antinociceptive effects of cannabinoids are still poorly understood. Here, we have found that WIN55,212-2, a cannabinoid receptor agonist, inhibits the activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. WIN55,212-2 dose-dependently inhibited proton-gated currents mediated by ASICs. WIN55,212-2 shifted the proton concentration–response curve downwards, with an decrease of 48.6±3.7% in the maximum current response but with no significant change in the EC50 value. The inhibition of proton-gated current induced by WIN55,212-2 was almost completely blocked by the selective CB1 receptor antagonist AM 281, but not by the CB2 receptor antagonist AM630. Pretreatment of forskolin, an AC activator, and the addition of cAMP also reversed the inhibition of WIN55,212-2. Moreover, WIN55,212-2 altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, WIN55,212-2 attenuated nociceptive responses to injection of acetic acid in rats. These results suggest that WIN55,212-2 inhibits the activity of ASICs via CB1 receptor and cAMP dependent pathway in rat primary sensory neurons. Thus, cannabinoids can exert their analgesic action by interaction with ASICs in the primary afferent neurons, which was novel analgesic mechanism of cannabinoids.
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Zhou W, Li JD, Hu WP, Cheng MY, Zhou QY. Prokineticin 2 is involved in the thermoregulation and energy expenditure. ACTA ACUST UNITED AC 2012; 179:84-90. [PMID: 22960406 DOI: 10.1016/j.regpep.2012.08.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 06/28/2012] [Accepted: 08/27/2012] [Indexed: 01/26/2023]
Abstract
Animals have developed adaptive strategies to survive tough situations such as food shortage. However, the underlying molecular mechanism is not fully understood. Here, we provided evidence that the regulatory peptide prokineticin 2 (PK2) played an important role in such an adaptation. The PK2 expression was rapidly induced in the hypothalamic paraventricular nucleus (PVN) after fasting, which can be mimicked by 2-deoxy-D-glucose (2-DG) injection. The fasting-induced arousal was absent in the PK2-deficient (PK2(-/-)) mice. Furthermore, PK2(-/-) mice showed less energy expenditure and body weight loss than wild-type (WT) controls upon fasting. As a result, PK2(-/-) mice entered torpor after fasting. Supply of limited food (equal to 5% of body weight) daily during fasting rescued the body weight loss and hypothermal phenotype in WT mice, but not in PK2(-/-) mice. Our study thus demonstrated PK2 as a regulator in the thermoregulation and energy expenditure.
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Qiu CY, Liu YQ, Qiu F, Wu J, Zhou QY, Hu WP. Prokineticin 2 potentiates acid-sensing ion channel activity in rat dorsal root ganglion neurons. J Neuroinflammation 2012; 9:108. [PMID: 22642848 PMCID: PMC3413530 DOI: 10.1186/1742-2094-9-108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 05/29/2012] [Indexed: 12/16/2022] Open
Abstract
Background Prokineticin 2 (PK2) is a secreted protein and causes potent hyperalgesia in vivo, and is therefore considered to be a new pronociceptive mediator. However, the molecular targets responsible for the pronociceptive effects of PK2 are still poorly understood. Here, we have found that PK2 potentiates the activity of acid-sensing ion channels in the primary sensory neurons. Methods In the present study, experiments were performed on neurons freshly isolated from rat dorsal root ganglion by using whole-cell patch clamp and voltage-clamp recording techniques. Results PK2 dose-dependently enhanced proton-gated currents with an EC50 of 0.22 ± 0.06 nM. PK2 shifted the proton concentration-response curve upwards, with a 1.81 ± 0.11 fold increase of the maximal current response. PK2 enhancing effect on proton-gated currents was completely blocked by PK2 receptor antagonist. The potentiation was also abolished by intracellular dialysis of GF109203X, a protein kinase C inhibitor, or FSC-231, a protein interacting with C-kinase 1 inhibitor. Moreover, PK2 enhanced the acid-evoked membrane excitability of rat dorsal root ganglion neurons and caused a significant increase in the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, PK2 exacerbated nociceptive responses to the injection of acetic acid in rats. Conclusion These results suggest that PK2 increases the activity of acid-sensing ion channels via the PK2 receptor and protein kinase C-dependent signal pathways in rat primary sensory neurons. Our findings support that PK2 is a proalgesic factor and its signaling likely contributes to acidosis-evoked pain by sensitizing acid-sensing ion channels.
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Li JD, Hu WP, Zhou QY. The circadian output signals from the suprachiasmatic nuclei. PROGRESS IN BRAIN RESEARCH 2012; 199:119-127. [DOI: 10.1016/b978-0-444-59427-3.00028-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Ren P, Zhang H, Qiu F, Liu YQ, Gu H, O'Dowd DK, Zhou QY, Hu WP. Prokineticin 2 regulates the electrical activity of rat suprachiasmatic nuclei neurons. PLoS One 2011; 6:e20263. [PMID: 21687716 PMCID: PMC3110640 DOI: 10.1371/journal.pone.0020263] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 04/21/2011] [Indexed: 12/11/2022] Open
Abstract
Neuropeptide signaling plays roles in coordinating cellular activities and maintaining robust oscillations within the mammalian suprachiasmatic nucleus (SCN). Prokineticin2 (PK2) is a signaling molecule from the SCN and involves in the generation of circadian locomotor activity. Prokineticin receptor 2 (PKR2), a receptor for PK2, has been shown to be expressed in the SCN. However, very little is known about the cellular action of PK2 within the SCN. In the present study, we investigated the effect of PK2 on spontaneous firing and miniature inhibitory postsynaptic currents (mIPSCs) using whole cell patch-clamp recording in the SCN slices. PK2 dose-dependently increased spontaneous firing rates in most neurons from the dorsal SCN. PK2 acted postsynaptically to reduce γ-aminobutyric acid (GABA)-ergic function within the SCN, and PK2 reduced the amplitude but not frequency of mIPSCs. Furthermore, PK2 also suppressed exogenous GABA-induced currents. And the inhibitory effect of PK2 required PKC activation in the postsynaptic cells. Our data suggest that PK2 could alter cellular activities within the SCN and may influence behavioral and physiological rhythms.
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Hu WP, Li JD, Colwell CS, Zhou QY. Decreased REM sleep and altered circadian sleep regulation in mice lacking vasoactive intestinal polypeptide. Sleep 2011; 34:49-56. [PMID: 21203371 DOI: 10.1093/sleep/34.1.49] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVES Vasoactive intestinal polypeptide (VIP) has been implicated in sleep regulation as a promoter of rapid eye movement (REM) sleep. Previous work has shown that the amount of time spent in REM sleep is increased by intracerebroventricular administration of VIP, and reduced by treatment with VIP antagonists or antibodies against VIP. A variety of evidence suggests that VIP is critical for normal expression of circadian rhythmicity of diverse physiological and behavioral parameters. In the present study, we investigated the role of this peptide in sleep regulation using VIP-deficient (VIP-/-) mice. METHODS EEG/EMG sleep-wake patterns were recorded in VIP-/- mice and their wild-type littermate controls under normal light-dark (LD), constant darkness (DD) and sleep deprivation conditions. RESULTS VIP-/- mice exhibited reduced REM sleep time over the 24-h cycle while total daily amounts of NREM sleep and wakefulness were not altered significantly. The reduced REM sleep time in VIP-/- mice occurred entirely during the day due to a reduction in the duration, but not the frequency, of REM sleep bouts. In response to sleep deprivation, compensatory rebounds in NREM sleep and REM sleep were also attenuated in VIP-/- mice. Finally, the loss of VIP altered the temporal distribution of sleep in that the VIP -/- mice exhibited smaller amplitude rhythms in total sleep, NREM sleep, and REM sleep under both LD and DD. CONCLUSIONS These results indicate that VIP regulates the duration of REM sleep, sleep homeostatic mechanisms as well as the temporal patterning of sleep.
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Xiong YC, Li XM, Wang XJ, Liu YQ, Qiu F, Wu D, Gan YB, Wang BH, Hu WP. Prokineticin 2 suppresses GABA-activated current in rat primary sensory neurons. Neuropharmacology 2010; 59:589-94. [PMID: 20800074 DOI: 10.1016/j.neuropharm.2010.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2010] [Revised: 08/16/2010] [Accepted: 08/16/2010] [Indexed: 10/19/2022]
Abstract
Prokineticin 2 (PK2) is a newly identified regulatory protein, which is involved in a wide range of physiological processes including pain perception in mammals. However, the precise role of PK2 in nociception is yet not fully understood. Here, we investigate the effects of PK2 on GABA(A) receptor function in rat trigeminal ganglion neurons using whole-cell patch clamp technique. PK2 reversibly depressed inward currents produced by GABA(A) receptor activation (I(GABA)) with an IC₅₀ of 0.26 ± 0.02 nM. PK2 appeared to decrease the efficacy of GABA to GABA(A) receptor but not the affinity. The maximum response of the GABA dose-response curve decreased to 71.2 ± 7.0% of control after pretreatment with PK2, while the threshold value and EC₅₀ of curve did not alter significantly. The effects of PK2 on I(GABA) were voltage independent. The PK2-induced inhibition of I(GABA) was removed by intracellular dialysis of either GDP-β-S (a non-hydrolyzable GDP analog), EGTA (a Ca²+ chelator) or GF109203X (a selective protein kinase C inhibitor), but not by H89 (a protein kinase A inhibitor). These results suggest that PK2 down-regulates the function of the GABA(A) receptor via G-protein and protein kinase C dependent signal pathways in primary sensory neurons and this depression might underlie the hyperalgesia induced by PK2.
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Li ZW, Zhang J, Ouyang CH, Li CY, Zhao FB, Liu YW, Ai YX, Hu WP. Potentiation by WIN 55,212-2 of GABA-activated currents in rat trigeminal ganglion neurones. Br J Pharmacol 2010; 158:1904-10. [PMID: 19917064 DOI: 10.1111/j.1476-5381.2009.00482.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND AND PURPOSE Although both natural and synthetic cannabinoid compounds have been shown to exert an antinociceptive effect on acute and persistent pain, the anatomical locus of the target of cannabinoid-induced analgesia has not been fully elucidated. Here, we investigated the effects of the cannabinoid agonist WIN 55,212-2 on GABA-activated currents (I(GABA)) in rat primary sensory neurones. EXPERIMENTAL APPROACH In the present study, experiments were performed on neurones freshly isolated from rat trigeminal ganglion (TG) by using whole-cell patch clamp and repatch techniques. KEY RESULTS GABA-evoked inward currents were potentiated by pretreatment with WIN 55,212-2 in a concentration-dependent manner (10(-10)-10(-8) M). WIN 55,212-2 shifted the GABA concentration-response curve upwards, with an increase of 30.3 +/- 3.7% in the maximal current response but with no significant change in the EC(50) (agonist concentration producing a half-maximal response) value. WIN 55,212-2 potentiated the responses to GABA in a manner independent of holding potential and in the absence of any change in the reversal potential of the current. This potentiation of I(GABA) induced by WIN 55,212-2 was almost completely blocked by AM 251 (3 x 10(-8) M), a CB(1) receptor antagonist, and, using the repatch technique, was found to be abolished after intracellular dialysis with the protein kinase A (PKA) activator cAMP or the PKA inhibitor H89. CONCLUSIONS AND IMPLICATIONS The potentiation by WIN 55,212-2 of I(GABA) in primary sensory neurones may help to elucidate the mechanism underlying the modulation of analgesia by cannabinoids in the spinal dorsal horn.
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Hu WP, Ma SY, Wu JL, Li ZW. 5-Hydroxytryptamine directly inhibits neuronal nicotinic acetylcholine receptors in rat trigeminal ganglion neurons. Eur J Pharmacol 2007; 574:120-6. [PMID: 17698057 DOI: 10.1016/j.ejphar.2007.07.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2007] [Revised: 07/16/2007] [Accepted: 07/23/2007] [Indexed: 11/26/2022]
Abstract
In the present study, whole-cell patch clamp recording technique was used to investigate the action of 5-hydroxytryptamine (5-HT) on the function of native neuronal nicotinic acetylcholine receptors expressed in the rat trigeminal ganglion neurons. Inward currents (I(nic)) caused by externally-applied nicotine were observed in majority of the examined neurons, which were mediated by alpha-bungarotoxin-insensitive nicotinic acetylcholine receptors. We found that 5-HT could reversibly inhibit I(nic) in a concentration-dependent manner, and the inhibition did not involve 5-HT receptors. Other serotonergic agents, such as 2-methyl-5-HT, alpha-methyl-5-HT, sumatriptan and ICS-205,930, also had similar inhibitory effects on I(nic). 5-HT inhibited nicotinic acetylcholine receptors in a non-competitive manner, as 5-HT decreased the maximal current response to nicotine but had no effect on the threshold and EC(50). The inhibition of I(nic) by 5-HT was voltage-dependent and became stronger at hyperpolarized potentials. These results indicated that 5-HT directly inhibited nicotinic acetylcholine receptors in the trigeminal ganglion neurons. As a local modulator of the nicotinic acetylcholine receptor, 5-HT might play a role in the modulation of sensory information.
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Hu WP, Li JD, Zhang C, Boehmer L, Siegel JM, Zhou QY. Altered circadian and homeostatic sleep regulation in prokineticin 2-deficient mice. Sleep 2007; 30:247-56. [PMID: 17425220 PMCID: PMC2673012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
STUDY OBJECTIVES Sleep is regulated by circadian and homeostatic processes. Recent studies with mutant mice have indicated that circadian-related genes regulate sleep amount, as well as the timing of sleep. Thus a direct link between circadian and homeostatic regulation of sleep may exist, at least at the molecular level. Prokineticin 2 (PK2), which oscillates daily with high amplitude in the suprachiasmatic nuclei (SCN), has been postulated to be an SCN output molecule. In particular, mice lacking the PK2 gene (PK2-/-) have been shown to display significantly reduced rhythmicity for a variety of circadian physiological and behavioral parameters. We investigated the role of PK2 in sleep regulation. DESIGN EEG/EMG sleep-wake patterns were recorded in PK2-/- mice and their wild-type littermate controls under baseline and challenged conditions. MEASUREMENTS AND RESULTS PK2-/- mice exhibited reduced total sleep time under entrained light-dark and constant darkness conditions. The reduced sleep time in PK2-/- mice occurred predominantly during the light period and was entirely due to a decrease in non-rapid eye movement (NREM) sleep time. However, PK2-/- mice showed increased rapid eye movement (REM) sleep time in both light and dark periods. After sleep deprivation, compensatory rebound in NREM sleep, REM sleep, and EEG delta power was attenuated in PK2-/- mice. In addition, PK2-/- mice had an impaired response to sleep disturbance caused by cage change in the light phase. CONCLUSIONS These results indicate that PK2 plays roles in both circadian and homeostatic regulation of sleep. PK2 may also be involved in maintaining the awake state in the presence of behavioral challenges.
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Li JD, Hu WP, Boehmer L, Cheng MY, Lee AG, Jilek A, Siegel JM, Zhou QY. Attenuated circadian rhythms in mice lacking the prokineticin 2 gene. J Neurosci 2006; 26:11615-23. [PMID: 17093083 PMCID: PMC2713041 DOI: 10.1523/jneurosci.3679-06.2006] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circadian clocks drive daily rhythms in virtually all organisms. In mammals, the suprachiasmatic nucleus (SCN) is recognized as the master clock that synchronizes central and peripheral oscillators to evoke circadian rhythms of diverse physiology and behavior. How the timing information is transmitted from the SCN clock to generate overt circadian rhythms is essentially unknown. Prokineticin 2 (PK2), a clock-controlled gene that encodes a secreted protein, has been indicated as a candidate SCN clock output signal that regulates circadian locomotor rhythm. Here we report the generation and analysis of PK2-null mice. The reduction of locomotor rhythms in PK2-null mice was apparent in both hybrid and inbred genetic backgrounds. PK2-null mice also displayed significantly reduced rhythmicity for a variety of other physiological and behavioral parameters, including sleep-wake cycle, body temperature, circulating glucocorticoid and glucose levels, as well as the expression of peripheral clock genes. In addition, PK2-null mice showed accelerated acquisition of food anticipatory activity during a daytime food restriction. We conclude that PK2, acting as a SCN output factor, is important for the maintenance of robust circadian rhythms.
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Hu WP, Zhang C, Li JD, Luo ZD, Amadesi S, Bunnett N, Zhou QY. Impaired pain sensation in mice lacking prokineticin 2. Mol Pain 2006; 2:35. [PMID: 17107623 PMCID: PMC1660571 DOI: 10.1186/1744-8069-2-35] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 11/15/2006] [Indexed: 01/08/2023] Open
Abstract
Prokineticins (PKs), consisting of PK1 and PK2, are a pair of newly identified regulatory peptides. Two closely related G-protein coupled receptors, PKR1 and PKR2, mediate the signaling of PKs. PKs/PKRs participate in the regulation of diverse biological processes, ranging from development to adult physiology. A number of studies have indicated the involvement of PKs/PKRs in nociception. Here we show that PK2 is a sensitizer for nociception. Intraplantar injection of recombinant PK2 resulted in a strong and localized hyperalgesia with reduced thresholds to nociceptive stimuli. PK2 mobilizes calcium in dissociated dorsal root ganglion (DRG) neurons. Mice lacking the PK2 gene displayed strong reduction in nociception induced by thermal and chemical stimuli, including capsaicin. However, PK2 mutant mice showed no difference in inflammatory response to capsaicin. As the majority of PK2-responsive DRG neurons also expressed transient receptor potential vanilloid (TRPV1) and exhibited sensitivity to capsaicin, TRPV1 is likely a significant downstream molecule of PK2 signaling. Taken together, these results reveal that PK2 sensitize nociception without affecting inflammation.
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Zhang J, Hu WP, Zhou KC, Luo JL, Fan YZ, Ru LQ, Li ZW. [Interaction of 5-HT2 and 5-HT3 receptor subtype in 5-HT-induced nociceptive responses in peripheral primary sensory nerve ending]. ZHONGGUO YING YONG SHENG LI XUE ZA ZHI = ZHONGGUO YINGYONG SHENGLIXUE ZAZHI = CHINESE JOURNAL OF APPLIED PHYSIOLOGY 2006; 22:40-44. [PMID: 21186576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
AIM To study the correlation between 5-HT-induced pain response and the contribution by individual 5-HTR subtypes including 5-HT1R, 5-HT2R and 5-HT3R at the level of peripheral primary afferent. METHODS The experiments were done on acutely isolated trigeminal ganglion (TG) neurons using whole-cell patch clamp technique and the nociceptive effect was observed on behavior experiments by intraplantar injection of test drugs. RESULTS The majority of cells examined responded to 5-HT in a manner of concentration dependence (10(-6) - 10(-3) mol/) (61.4%, 54/88) and with a fast activating and rapid desensitizing inward current (I(5-HT)), which was thought to be mediated by the activation of 5-HT3R, since it could be blocked by 5-HT3R antagonist ICS 205930 and mimicked by 5-HT3R agonist 2-methyl-5-HT. It was found that I(5-HT) was potentiated by 5-HT2R agonist alpha-methyl-5-HT markedly, while 5-HT1R agonist R-(+)-UH 301 did not. In behavioral experiment performed on conscious rats, intraplantar injection of 5-HT(10(-5), 10(-4) and 10(-3) mol/L) induced an increment of cumulative lifting time first 20 min in a manner of concentration dependence. By dissociating 5-HTR subtypes using their corresponding antagonists (ICS and CYP) the potency order of hindpaw lifting time was identified as follows: 5-HT > 5-HT + ICS > 5-HT + CYP. CONCLUSION The results suggest that in 5-HT-induced nociceptive response at the primary sensory level 5-HT3R may play a role of initiation, but 5-HT2R mediates maintaining and modulatory effect in the processes of nociceptive information convey.
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Hu WP, Hsu HY, Chiou A, Tseng KY, Lin HY, Chang GL, Chen SJ. Immunodetection of pentamer and modified C-reactive protein using surface plasmon resonance biosensing. Biosens Bioelectron 2006; 21:1631-7. [PMID: 16343891 DOI: 10.1016/j.bios.2005.11.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Revised: 11/01/2005] [Accepted: 11/02/2005] [Indexed: 11/23/2022]
Abstract
In clinical practices, the examination of pentamer C-reactive protein (pCRP) is commonly used as a prognostic indicator of the risk of a patient developing cardiovascular disease (CVD). Structural modification of pCRP produces a modified CRP (mCRP) which exhibits different biological activities in the body. In recent years, mCRP has come to be regarded as a more powerful inducer than pCRP, and hence mCRP measurement has emerged as an important indicator for assessing the risk of developing CVD. The surface plasmon resonance (SPR) biosensing technique can be employed to increase the detection accuracy and real-time response when sensing pCRP or mCRP. In this study, three monoclonal antibodies (Mabs), C8, 8D8, and 9C9, are immobilized on a protein G layer for subsequent CRP detection. The experimental results reveal that the Mab C8 reacts with both pCRP and mCRP, the Mab 8D8 with pCRP, and the Mab 9C9 with mCRP. No false signals caused by non-specific binding are observed. When detecting pCRP using Mab C8, the SPR bioassay provides sufficient sensitivity to evaluate whether or not a patient is at risk of developing CVD. SPR biosensing provides a viable and accurate approach for the real-time evaluation of pCRP and mCRP levels, and is therefore of considerable benefit in clinical examinations of CPR.
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Tan EK, Shen H, Tan JMM, Lim KL, Fook-Chong S, Hu WP, Paterson MC, Chandran VR, Yew K, Tan C, Yuen Y, Pavanni R, Wong MC, Puvan K, Zhao Y. Differential expression of splice variant and wild-type parkin in sporadic Parkinson's disease. Neurogenetics 2005; 6:179-84. [PMID: 16086186 DOI: 10.1007/s10048-005-0001-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Accepted: 06/01/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Altered splicing of parkin under cellular stress could lead to changes in gene expression and altered protein activity. The causative role of parkin in sporadic Parkinson's disease (PD) is unknown. OBJECTIVES We described a parkin splice variant (SV) in the substantia nigra and leukocytes of sporadic PD patients. Using a case control methodology, we investigated the exon 4 SV (E4SV) and wild-type parkin expression in the leukocytes of sporadic PD patients and healthy individuals. METHODS/RESULTS We identified a parkin E4SV in the substantia nigra and leukocytes of sporadic PD patients and controls by reverse transcriptase-polymerase chain reaction (PCR). The exon 4 (122 bp) deletion resulted in a reading frame shift over the junction of exons 3-5 and a stop codon (tga) 17 bp downstream from exon 3. The translated truncated protein was associated with a total loss of the two-RING finger functional domain. Utilizing TaqMan real-time PCR with probes located across the junction of exons 3-4 or 3-5, we demonstrated an over-expression of E4SV/wild-type parkin ratio in the leukocytes of sporadic PD patients compared to age-, gender-, and race-matched controls (p<0.0005). A multivariate regression analysis demonstrated that the ratio of E4SV/wild-type parkin expression increased with age in PD patients, but this was not observed in the controls (p<0.0005). CONCLUSION The relative expression of E4SV/wild type parkin was increased in sporadic PD compared to healthy controls. Based on our observations, further functional studies to determine the pathophysiologic role of E4SV in sporadic PD patients will be of importance.
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Hu WP, Guan BC, Ru LQ, Chen JG, Li ZW. Corrigendum to “Potentiation of 5-HT3 receptor function by the activation of coexistent 5-HT2 receptors in trigeminal ganglion neurons of rats” [Neuropharmacology 47 (2004) 833–840]. Neuropharmacology 2005. [DOI: 10.1016/j.neuropharm.2004.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hu WP, Guan BC, Ru LQ, Chen JG, Li ZW. Potentiation of 5-HT3 receptor function by the activation of coexistent 5-HT2 receptors in trigeminal ganglion neurons of rats. Neuropharmacology 2005; 47:833-40. [PMID: 15527817 DOI: 10.1016/j.neuropharm.2004.06.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Accepted: 06/18/2004] [Indexed: 10/26/2022]
Abstract
5-HT receptor subtypes are widely expressed in primary sensory neurons, yet so far little is known about the interaction among them. This study aimed to investigate whether the activation of 5-HT2 and 5-HT1 receptors could modulate 5-HT3 receptor mediated current in rat trigeminal ganglion (TG) neurons using whole-cell patch clamp technique. The majority of TG neurons examined responded to 5-HT (10(-7)-10(-3) M) with a fast activating and rapid desensitizing inward current (77.2%, 71/92). This 5-HT activated current (I(5-HT)) was blocked by ICS 205-930 and mimicked by 2-methyl-5-HT, indicating that it was mediated by 5-HT3 receptor. With alpha-methyl-5-HT applied prior to 5-HT application, I(5-HT) was potentiated in a concentration-dependent manner, with the maximal modulatory effect at 10(-9) M of alpha-methyl-5-HT. The concentration-response curve for I(5-HT) pretreated with alpha-methyl-5-HT shifts upwards compared with that for I(5-HT) without alpha-methyl-5-HT pretreatment, the maximal I(5-HT) value having increased by (60.3 +/- 5.7)% of its control while the EC50 values of the two curves being very close, i.e. (2.0 +/- 0.3) x 10(-5) M vs (1.7 +/- 0.2) x 10(-5) M, respectively. The alpha-methyl-5-HT potentiation of I(5-HT) was removed by intracellular dialysis of either GDP-beta-S, a non-hydrolyzable GDP analog, or GF109203X, a selective PKC inhibitor, almost completely. Preapplication of R-(+)-UH-301, a selective agonist of 5-HT(1A) receptor, had no modulatory effect on I(5-HT). These results suggest that in the membrane of TG neurons, the activation of 5-HT2 receptors can exert an enhancing effect on the function of coexistent 5-HT3 receptors while that of 5-HT(1A) receptors cannot.
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Hu WP, Li ZW, Ru LQ, Fan YZ. Opposite modulatory effects of substance P on GABA-and 5-HT-activated currents in the same sensory neurons. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2004; 56:703-7. [PMID: 15614418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The modulation by substance P of gamma-aminobutyric acid (GABA)- and 5-hydroxytryptamine (5-HT)-activated currents (I(GABA) and I(5-HT)) was studied by using patch-clamp technique in rat trigeminal ganglion (TG) neurons. The majority of neurons examined responded to GABA and 5-HT with inward currents in the same cells (63.8%, 30/47). In 22 out of 30 neurons sensitive to both GABA and 5-HT, pretreatment with substance P (SP, 0.01 micromol/L) suppressed I(GABA) by (35.7 +/-6.1)% and enhanced I(5-HT) by (65.2 +/- 8.7)%. GR 82334, a potent and specific antagonist of NK1 tachykinin receptor, reversibly blocked the modulatory effects of SP. The SP modulation on I(GABA) and I(5-HT) was also abolished by intracellular dialysis of GDP-beta-S, a non-hydrolyzable GDP analog, or GF 109203X, a selective protein kinase C inhibitor. These results suggest that SP exerts opposite modulatory actions on GABA(A) receptor and 5-HT3 receptor activity of the same primary sensory neuron via the same intracellular signal transduction pathway.
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