- Short report
- Open Access
Pain-related anxiety-like behavior requires CRF1 receptors in the amygdala
© Ji et al; licensee BioMed Central Ltd. 2007
- Received: 10 May 2007
- Accepted: 05 June 2007
- Published: 05 June 2007
Corticotropin-releasing factor receptor CRF1 has been implicated in the neurobiological mechanisms of anxiety and depression. The amygdala plays an important role in affective states and disorders such as anxiety and depression. The amygdala is also emerging as a neural substrate of pain affect. However, the involvement of the amygdala in the interaction of pain and anxiety remains to be determined. This study tested the hypothesis that CRF1 receptors in the amygdala are critically involved in pain-related anxiety. Anxiety-like behavior was determined in adult male rats using the elevated plus maze (EPM) test. The open-arm preference (ratio of open arm entries to the total number of entries) was measured. Nocifensive behavior was assessed by measuring hindlimb withdrawal thresholds for noxious mechanical stimulation of the knee. Measurements were made in normal rats and in rats with arthritis induced in one knee by intraarticular injections of kaolin/carrageenan. A selective CRF1 receptor antagonist (NBI27914) or vehicle was administered systemically (i.p.) or into the central nucleus of the amygdala (CeA, by microdialysis). The arthritis group showed a decreased preference for the open arms in the EPM and decreased hindlimb withdrawal thresholds. Systemic or intraamygdalar (into the CeA) administration of NBI27914, but not vehicle, inhibited anxiety-like behavior and nocifensive pain responses, nearly reversing the arthritis pain-related changes. This study shows for the first time that CRF1 receptors in the amygdala contribute critically to pain-related anxiety-like behavior and nocifensive responses in a model of arthritic pain. The results are a direct demonstration that the clinically well-documented relationship between pain and anxiety involves the amygdala.
- Elevated Plus Maze
- CRF1 Receptor
- Elevated Plus Maze Test
- Arthritis Group
- CRF1 Receptor Antagonist
Pain, including arthritis pain, has a negative affective component and is closely related to anxiety and depression [1–3]. The neural pathways and mechanisms involved in pain-related anxiety remain to be determined, but the amygdala is known to play a key role in emotional-affective behavior and anxiety disorders [4–6]. Importantly, the amygdala is emerging as an important element of the brain network involved in the emotional-affective component of pain [7–11]. The amygdala is also believed to be a key substrate of the reciprocal relationship between pain and affective states and disorders such as anxiety [3, 10, 12, 13].
Our previous studies demonstrated central sensitization [14–19] and synaptic plasticity [14, 20–23] in the central nucleus of the amygdala (CeA) in the kaolin/carrageenan-induced arthritis pain model. The CeA integrates affect-related information from the fear-anxiety circuitry in the lateral-basolateral amygdala with purely nociceptive inputs from the spino-parabrachio-amygdaloid pain pathway [7, 9, 10]. Pain-related synaptic plasticity in the CeA has also been confirmed in a model of chronic neuropathic pain . It has become clear now that reversal of pain-related plasticity by pharmacologic deactivation of the CeA decreases nocifensive and affective pain responses in animal models of arthritic pain [14, 25], visceral pain  and neuropathic pain  and in the prolonged phase of the formalin test .
The present study focused on the role of corticotropin-releasing factor receptor 1 (CRF1) in the CeA in pain-related anxiety. The CeA is a major site of extrahypothalamic expression of CRF and a key element of the extrahypothalamic circuits through which CRF contributes to anxiety-like behavior and affective disorders [28–32]. CRF1 receptors have emerged as drug targets for depression and anxiety disorders in preclinical studies [29–31, 33–36]. A CRF1 receptor antagonist has been used successfully in humans to reduce depression and anxiety scores [37, 38]. Finally, the presence of CRF-containing neurons in the parabrachial area  links the CRF system in the amygdala to the spino-parabrachio-amygdaloid pain pathway and implicates CRF in the transmission of nociceptive information to the amygdala.
The behavioral and pharmacological studies reported here tested the hypothesis that CRF1 receptors in the amygdala (CeA) are critically involved in pain-related anxiety-like behavior. Adult male Sprague-Dawley rats (250–350 g) were used. All experimental procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Texas Medical Branch (UTMB) and conform to the guidelines of the International Association for the Study of Pain (IASP) and of the National Institutes of Health (NIH).
Next we determined the effects of a selective CRF1 receptor antagonist (5-chloro-4-(N-(cyclopropyl)methyl-N-propylamino)-2-methyl-6-(2,4,6-trichlorophenyl) amino-pyridine, NBI 27914 ; purchased from Tocris Bioscience, Ellisville, MO). NBI27014 was administered either systemically (intraperitoneally, i.p.) or locally into the amygdala (CeA) by microdialysis in rats with arthritis (Fig. 1B). For drug application by microdialysis a guide cannula was implanted stereotaxically on the dorsal margin of the CeA as previously described in detail using the following coordinates [14, 25]: 1.8–2.0 mm caudal to bregma, 4.0 mm lateral to midline, depth 7.0 mm. On the day of the experiment a microdialysis probe (CMA/Microdialysis 11; membrane diameter: 250 μm, membrane length: 2 mm) was inserted into the CeA through the guide cannula so that the probe protruded by 2 mm. The probe was connected to a Harvard infusion pump and perfused with ACSF (2 μl/min) for at least 1 h to establish equilibrium in the tissue.
Anxiety-like behavior was measured in 5 groups of rats to determine the role of CRF1 receptors: arthritic rats without any additional intervention; arthritic rats that received systemic administration of vehicle (saline); arthritic rats with systemic administration of NBI27014 (5 mg/kg, i.p.); arthritic rats with vehicle (ACSF) administration into the CeA; and arthritic rats with intra-CeA administration of NBI27014 (100 μM; concentration in microdialysis probe which is 100-fold that predicted to be needed based on data from our previous studies ). The open-arm preferences of arthritic rats without any interventions (n = 6) and of arthritis rats with systemic saline (n = 5) or intra-amygdala ACSF (n = 5) were not significantly different (P > 0.05, Newman-Keuls Multiple Comparison Test; GraphPad Prism software 3.0; Fig. 1B). Systemic application of NBI27914 30 min before the EPM test in increased the open-arm preference significantly (n = 5; P < 0.05, compared to saline group; Newman-Keuls Multiple Comparison Test). Administration of NBI27914 into the CeA for 30 min also increased the open-arm preference significantly (n = 5; P < 0.05, compared to ACSF control group; Newman-Keuls Multiple Comparison Test). The effects of systemic and intra-CeA administration of NBI27914 were not significantly different (P > 0.05; Newman-Keuls Multiple Comparison Test), suggesting that CRF1 receptors in the amygdala (CeA) account for the anxiolytic effect of CRF1 receptor antagonists.
In summary, this study showed that systemic or intra-amygdalar administration of a CRF1 receptor antagonist decreased anxiety-like behavior and nocifensive reflex responses in a model of arthritis pain, suggesting a key role of CRF1 receptors in the amygdala (CeA) in the modulation of pain-related anxiety. The novelty of this study is that it directly links the amygdala, through CRF1 receptors in the CeA, to pain-related anxiety, which is clinically well-documented but mechanistically not well understood.
Although the amygdala is known to play a key role in anxiety-like behavior through mechanisms that appear to involve CRF [28–32, 44], its contribution to pain-related anxiety remains to be determined. Recent biochemical [45–47] and behavioral [48–51] studies point to the amygdala as an important site for the pain-modulatory effects of CRF. Increased expression of CRF1 receptor mRNA was detected in the amygdala in a model of somato-visceral pain induced by intra-peritoneal acetic acid . CRF mRNA increased in the CeA in models of colitis pain  and chronic neuropathic pain . Intracerebroventricular or intra-CeA administration of a broad-spectrum CRF receptor antagonist (alpha-hCRF9-41) had antinociceptive effects on hyperalgesic behavior associated with opiate withdrawal . Systemic administration of a CRF1 receptor antagonist nearly reversed colon hypersensitivity (visceromotor response) induced by stereotaxic delivery of corticosterone to the CeA . On the other hand, intra-CeA administration of a non-selective CRF receptor antagonist (alpha-hCRF9-41) produced hyperalgesic behavior (decreased mechanical and thermal withdrawal thresholds) and attenuated the antinociceptive effects of CRF administered into the CeA in normal animals . The reason for these conflicting findings is unclear at this time. Our recent electrophysiological data show that administration of a CRF1 receptor antagonist (NBI27914) into the CeA clearly inhibits the sensitization of CeA neurons in the arthritis pain model. Taken together with the present study, these findings suggest that CRF1 receptors critically contribute to pain-related sensitization that results in increased pain responses and anxiety-like behavior.
This work was supported by NIH grants NS38261 and NS11255.
- Gallagher RM, Verma S: Mood and anxiety disorders in chronic pain. Progress in Pain Res and Management 2004, 27: 139–178.Google Scholar
- Grachev ID, Fredickson BE, Apkarian AV: Dissociating anxiety from pain: mapping the neuronal marker N-acetyl aspartate to perception distinguishes closely interrelated characteristics of chronic pain. Mol Psychiatry 2001, 6: 256–258. 10.1038/sj.mp.4000834PubMedView ArticleGoogle Scholar
- Rhudy JL, Meagher MW: Negative affect: effects on an evaluative measure of human pain. Pain 2003, 104: 617–626. 10.1016/S0304-3959(03)00119-2PubMedView ArticleGoogle Scholar
- Maren S: Synaptic Mechanisms of Associative Memory in the Amygdala. Neuron 2005, 47: 783–786. 10.1016/j.neuron.2005.08.009PubMedView ArticleGoogle Scholar
- Kalin NH, Shelton SE, Davidson RJ: The Role of the Central Nucleus of the Amygdala in Mediating Fear and Anxiety in the Primate. J Neurosci 2004, 24: 5506–5515. 10.1523/JNEUROSCI.0292-04.2004PubMedView ArticleGoogle Scholar
- Phelps EA, Ledoux JE: Contributions of the Amygdala to Emotion Processing: From Animal Models to Human Behavior. Neuron 2005, 48: 175–187. 10.1016/j.neuron.2005.09.025PubMedView ArticleGoogle Scholar
- Neugebauer V, Li W, Bird GC, Han JS: The amygdala and persistent pain. The Neuroscientist 2004, 10: 221–234. 10.1177/1073858403261077PubMedView ArticleGoogle Scholar
- Baliki MN, Chialvo DR, Geha PY, Levy RM, Harden RN, Parrish TB, Apkarian AV: Chronic Pain and the Emotional Brain: Specific Brain Activity Associated with Spontaneous Fluctuations of Intensity of Chronic Back Pain. J Neurosci 2006, 26: 12165–12173. 10.1523/JNEUROSCI.3576-06.2006PubMed CentralPubMedView ArticleGoogle Scholar
- Gauriau C, Bernard JF: Pain pathways and parabrachial circuits in the rat. Exp Physiol 2002, 87: 251–258. 10.1113/eph8702357PubMedView ArticleGoogle Scholar
- Neugebauer V: Subcortical processing of nociceptive information: basal ganglia and amygdala. In Handbook of Clinical Neurology. Volume 81. Edited by: Cervero F and Jensen TS. Amsterdam, Elsevier; 2006:141–158.Google Scholar
- Pedersen LH, Scheel-Kruger J, Blackburn-Munro G: Amygdala GABA-A receptor involvement in mediating sensory-discriminative and affective-motivational pain responses in a rat model of peripheral nerve injury. Pain 2007, 127: 17–26. 10.1016/j.pain.2006.06.036PubMedView ArticleGoogle Scholar
- Heinricher MM, McGaraughty S: Pain-modulating neurons and behavioral state. In Handbook of Behavioral State Control. Edited by: Lydic R and Baghdoyan HA. New York, CRC Press; 1999:487–503.Google Scholar
- Fields H: State-dependent opioid control of pain. Nat Rev Neurosci 2004, 5: 565–575. 10.1038/nrn1431PubMedView ArticleGoogle Scholar
- Han JS, Li W, Neugebauer V: Critical role of calcitonin gene-related peptide 1 receptors in the amygdala in synaptic plasticity and pain behavior. J Neurosci 2005, 25: 10717–10728. 10.1523/JNEUROSCI.4112-05.2005PubMedView ArticleGoogle Scholar
- Ji G, Neugebauer V: Differential effects of CRF1 and CRF2 receptor antagonists on pain-related sensitization of neurons in the central nucleus of the amygdala. J Neurophysiol 2007.Google Scholar
- Li W, Neugebauer V: Differential roles of mGluR1 and mGluR5 in brief and prolonged nociceptive processing in central amygdala neurons. J Neurophysiol 2004, 91: 13–24. 10.1152/jn.00485.2003PubMedView ArticleGoogle Scholar
- Li W, Neugebauer V: Block of NMDA and non-NMDA receptor activation results in reduced background and evoked activity of central amygdala neurons in a model of arthritic pain. Pain 2004, 110: 112–122. 10.1016/j.pain.2004.03.015PubMedView ArticleGoogle Scholar
- Li W, Neugebauer V: Differential changes of group II and group III mGluR function in central amygdala neurons in a model of arthritic pain. J Neurophysiol 2006, 96: 1803–1815. 10.1152/jn.00495.2006PubMedView ArticleGoogle Scholar
- Neugebauer V, Li W: Differential sensitization of amygdala neurons to afferent inputs in a model of arthritic pain. J Neurophysiol 2003, 89: 716–727. 10.1152/jn.00799.2002PubMedView ArticleGoogle Scholar
- Neugebauer V, Li W, Bird GC, Bhave G, Gereau RW: Synaptic plasticity in the amygdala in a model of arthritic pain: differential roles of metabotropic glutamate receptors 1 and 5. J Neurosci 2003, 23: 52–63.PubMedGoogle Scholar
- Bird GC, Lash LL, Han JS, Zou X, Willis WD, Neugebauer V: Protein kinase A-dependent enhanced NMDA receptor function in pain-related synaptic plasticity in rat amygdala neurones. J Physiol 2005, 564: 907–921. 10.1113/jphysiol.2005.084780PubMed CentralPubMedView ArticleGoogle Scholar
- Han JS, Bird GC, Neugebauer V: Enhanced group III mGluR-mediated inhibition of pain-related synaptic plasticity in the amygdala. Neuropharmacology 2004, 46: 918–926. 10.1016/j.neuropharm.2004.01.006PubMedView ArticleGoogle Scholar
- Han JS, Fu Y, Bird GC, Neugebauer V: Enhanced group II mGluR-mediated inhibition of pain-related synaptic plasticity in the amygdala. Mol Pain 2006, 2: 18. 10.1186/1744-8069-2-18PubMed CentralPubMedView ArticleGoogle Scholar
- Ikeda R, Takahashi Y, Inoue K, Kato F: NMDA receptor-independent synaptic plasticity in the central amygdala in the rat model of neuropathic pain. Pain 2007, 127: 161–172. 10.1016/j.pain.2006.09.003PubMedView ArticleGoogle Scholar
- Han JS, Neugebauer V: mGluR1 and mGluR5 antagonists in the amygdala inhibit different components of audible and ultrasonic vocalizations in a model of arthritic pain. Pain 2005, 113: 211–222. 10.1016/j.pain.2004.10.022PubMedView ArticleGoogle Scholar
- Tanimoto S, Nakagawa T, Yamauchi Y, Minami M, Satoh M: Differential contributions of the basolateral and central nuclei of the amygdala in the negative affective component of chemical somatic and visceral pains in rats. Eur J Neurosci 2003, 18: 2343–2350. 10.1046/j.1460-9568.2003.02952.xPubMedView ArticleGoogle Scholar
- Carrasquillo Y, Gereau RW: Activation of the extracellular signal-regulated kinase in the amygdala modulates pain perception. J Neurosci 2007, 27: 1543–1551. 10.1523/JNEUROSCI.3536-06.2007PubMedView ArticleGoogle Scholar
- Gray TS: Amygdaloid CRF pathways. Role in autonomic, neuroendocrine, and behavioral responses to stress. Ann N Y Acad Sci 1993, 697: 53–60. 10.1111/j.1749-6632.1993.tb49922.xPubMedView ArticleGoogle Scholar
- Bale TL, Vale WW: CRF and CRF receptors: role in stress responsivity and other behaviors. Annu Rev Pharmacol Toxicol 2004, 44: 525–557. 10.1146/annurev.pharmtox.44.101802.121410PubMedView ArticleGoogle Scholar
- Reul JM, Holsboer F: Corticotropin-releasing factor receptors 1 and 2 in anxiety and depression. Curr Opin Pharmacol 2002, 2: 23–33. 10.1016/S1471-4892(01)00117-5PubMedView ArticleGoogle Scholar
- Steckler T, Holsboer F: Corticotropin-releasing hormone receptor subtypes and emotion. Biological Psychiatry 1999, 46: 1480–1508. 10.1016/S0006-3223(99)00170-5PubMedView ArticleGoogle Scholar
- Asan E, Yilmazer-Hanke DM, Eliava M, Hantsch M, Lesch KP, Schmitt A: The Corticotropin-Releasing Factor (CRF)-system and monoaminergic afferents in the central amygdala: Investigations in different mouse strains and comparison with the rat. Neuroscience 2005, 131: 953–967.PubMedView ArticleGoogle Scholar
- Charney DS: Neuroanatomical circuits modulating fear and anxiety behaviors. Acta Psychiatr Scand Suppl 2003, 38–50. 10.1034/j.1600-0447.108.s417.3.xGoogle Scholar
- Takahashi LK: Role of CRF(1) and CRF(2) receptors in fear and anxiety. Neurosci Biobehav Rev 2001, 25: 627–636. 10.1016/S0149-7634(01)00046-XPubMedView ArticleGoogle Scholar
- Chalmers DT, Lovenberg TW, Grigoriadis DE, Behan DP, De Souza EB: Corticotrophin-releasing factor receptors: from molecular biology to drug design. Trends in Pharmacological Sciences 1996, 17: 166–172. 10.1016/0165-6147(96)81594-XPubMedView ArticleGoogle Scholar
- Dautzenberg FM, Hauger RL: The CRF peptide family and their receptors: yet more partners discovered. Trends Pharmacol Sci 2002, 23: 71–77. 10.1016/S0165-6147(02)01946-6PubMedView ArticleGoogle Scholar
- Kunzel HE, Ising M, Zobel AW, Nickel T, Ackl N, Sonntag A, Holsboer F, Uhr M: Treatment with a CRH-1-receptor antagonist (R121919) does not affect weight or plasma leptin concentration in patients with major depression. J Psychiatr Res 2005, 39: 173–177. 10.1016/j.jpsychires.2004.06.006PubMedView ArticleGoogle Scholar
- Zobel AW, Nickel T, Kunzel HE, Ackl N, Sonntag A, Ising M, Holsboer F: Effects of the high-affinity corticotropin-releasing hormone receptor 1 antagonist R121919 in major depression: the first 20 patients treated. J Psychiatr Res 2000, 34: 171–181. 10.1016/S0022-3956(00)00016-9PubMedView ArticleGoogle Scholar
- Merchenthaler I, Vigh S, Petrusz P, Schally AV: Immunocytochemical localization of corticotropin-releasing factor (CRF) in the rat brain. Am J Anat 1982, 165: 385–396. 10.1002/aja.1001650404PubMedView ArticleGoogle Scholar
- Olivier B, Miczek KA: Fear and anxiety: mechanisms, models, and molecules. In Psychopharmacology of animal behavior disorders. Edited by: Dodman N and Shuster I. Malden, MA, Blackwell Sciences; 1998:105–121.Google Scholar
- Han JS, Bird GC, Li W, Neugebauer V: Computerized analysis of audible and ultrasonic vocalizations of rats as a standardized measure of pain-related behavior. Neurosci Meth 2005, 141: 261–269. 10.1016/j.jneumeth.2004.07.005View ArticleGoogle Scholar
- Neugebauer V, Han JS, Adwanikar H, Fu Y, Ji G: Techniques for assessing knee joint pain in arthritis. Mol Pain 2007, 3: 8. 10.1186/1744-8069-3-8PubMed CentralPubMedView ArticleGoogle Scholar
- Chen C, Dagnino R Jr., De Souza EB, Grigoriadis DE, Huang CQ, Kim KI, Liu Z, Moran T, Webb TR, Whitten JP, Xie YF, McCarthy JR: Design and synthesis of a series of non-peptide high-affinity human corticotropin-releasing factor1 receptor antagonists. J Med Chem 1996, 39: 4358–4360. 10.1021/jm960149ePubMedView ArticleGoogle Scholar
- Rainnie DG, Bergeron R, Sajdyk TJ, Patil M, Gehlert DR, Shekhar A: Corticotrophin releasing factor-induced synaptic plasticity in the amygdala translates stress into emotional disorders. J Neurosci 2004, 24: 3471–3479. 10.1523/JNEUROSCI.5740-03.2004PubMedView ArticleGoogle Scholar
- Greenwood-Van Meerveld B, Johnson AC, Schulkin J, Myers DA: Long-term expression of corticotropin-releasing factor (CRF) in the paraventricular nucleus of the hypothalamus in response to an acute colonic inflammation. Brain Research 2006, 1071: 91–96. 10.1016/j.brainres.2005.11.071PubMedView ArticleGoogle Scholar
- Sinniger V, Porcher C, Mouchet P, Juhem A, Bonaz B: c-fos and CRF receptor gene transcription in the brain of acetic acid-induced somato-visceral pain in rats. Pain 2004, 110: 738–750. 10.1016/j.pain.2004.05.014PubMedView ArticleGoogle Scholar
- Ulrich-Lai YM, Xie W, Meij JTA, Dolgas CM, Yu L, Herman JP: Limbic and HPA axis function in an animal model of chronic neuropathic pain. Physiology & Behavior 2006, 88: 67–76. 10.1016/j.physbeh.2006.03.012View ArticleGoogle Scholar
- Cui XY, Lundeberg T, Yu LC: Role of corticotropin-releasing factor and its receptor in nociceptive modulation in the central nucleus of amygdala in rats. Brain Research 2004, 995: 23–28. 10.1016/j.brainres.2003.09.050PubMedView ArticleGoogle Scholar
- Myers DA, Gibson M, Schulkin J, Greenwood Van-Meerveld B: Corticosterone implants to the amygdala and type 1 CRH receptor regulation: effects on behavior and colonic sensitivity. Behav Brain Res 2005, 161: 39–44. 10.1016/j.bbr.2005.03.001PubMedView ArticleGoogle Scholar
- McNally GP, Akil H: Role of corticotropin-releasing hormone in the amygdala and bed nucleus of the stria terminalis in the behavioral, pain modulatory, and endocrine consequences of opiate withdrawal. Neuroscience 2002, 112: 605–617. 10.1016/S0306-4522(02)00105-7PubMedView ArticleGoogle Scholar
- Lariviere WR, Melzack R: The role of corticotropin-releasing factor in pain and analgesia. Pain 2000, 84: 1–12. 10.1016/S0304-3959(99)00193-1PubMedView ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.