1
|
Kong D, Zhang Y, Gao P, Pan C, Deng H, Xu S, Tang D, Xiao J, Jiao Y, Yu W, Wen D. The locus coeruleus input to the rostral ventromedial medulla mediates stress-induced colorectal visceral pain. Acta Neuropathol Commun 2023; 11:65. [PMID: 37062831 PMCID: PMC10108465 DOI: 10.1186/s40478-023-01537-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 03/01/2023] [Indexed: 04/18/2023] Open
Abstract
Unlike physiological stress, which carries survival value, pathological stress is widespread in modern society and acts as a main risk factor for visceral pain. As the main stress-responsive nucleus in the brain, the locus coeruleus (LC) has been previously shown to drive pain alleviation through direct descending projections to the spinal cord, but whether and how the LC mediates pathological stress-induced visceral pain remains unclear. Here, we identified a direct circuit projection from LC noradrenergic neurons to the rostral ventromedial medulla (RVM), an integral relay of the central descending pain modulation system. Furthermore, the chemogenetic activation of the LC-RVM circuit was found to significantly induce colorectal visceral hyperalgesia and anxiety-related psychiatric disorders in naïve mice. In a dextran sulfate sodium (DSS)-induced visceral pain model, the mice also presented colorectal visceral hypersensitivity and anxiety-related psychiatric disorders, which were associated with increased activity of the LC-RVM circuit; LC-RVM circuit inhibition markedly alleviated these symptoms. Furthermore, the chronic restraint stress (CRS) model precipitates anxiety-related psychiatric disorders and induces colorectal visceral hyperalgesia, which is referred to as pathological stress-induced hyperalgesia, and inhibiting the LC-RVM circuit attenuates the severity of colorectal visceral pain. Overall, the present study clearly demonstrated that the LC-RVM circuit could be critical for the comorbidity of colorectal visceral pain and stress-related psychiatric disorders. Both visceral inflammation and psychological stress can activate LC noradrenergic neurons, which promote the severity of colorectal visceral hyperalgesia through this LC-RVM circuit.
Collapse
Affiliation(s)
- Dexu Kong
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Yunchun Zhang
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Po Gao
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Chao Pan
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Haoyue Deng
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Saihong Xu
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Dan Tang
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Jie Xiao
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China
| | - Yingfu Jiao
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China.
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China.
| | - Weifeng Yu
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China.
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China.
| | - Daxiang Wen
- Department of Anesthesiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200127, China.
- Key Laboratory of Anesthesiology (Shanghai Jiao Tong University), Ministry of Education, Shanghai, China.
| |
Collapse
|
2
|
Taylor BK, Westlund KN. The noradrenergic locus coeruleus as a chronic pain generator. J Neurosci Res 2016; 95:1336-1346. [PMID: 27685982 DOI: 10.1002/jnr.23956] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/25/2016] [Accepted: 09/07/2016] [Indexed: 12/17/2022]
Abstract
Central noradrenergic centers such as the locus coeruleus (LC) are traditionally viewed as pain inhibitory; however, complex interactions among brainstem pathways and their receptors modulate both inhibition and facilitation of pain. In addition to the well-described role of descending pontospinal pathways that inhibit spinal nociceptive transmission, an emerging body of research now indicates that noradrenergic neurons in the LC and their terminals in the dorsal reticular nucleus (DRt), medial prefrontal cortex (mPFC), spinal dorsal horn, and spinal trigeminal nucleus caudalis participate in the development and maintenance of allodynia and hyperalgesia after nerve injury. With time after injury, we argue that the balance of LC function shifts from pain inhibition to pain facilitation. Thus, the pain-inhibitory actions of antidepressant drugs achieved with elevated noradrenaline concentrations in the dorsal horn may be countered or even superseded by simultaneous activation of supraspinal facilitating systems dependent on α1 -adrenoreceptors in the DRt and mPFC as well as α2 -adrenoreceptors in the LC. Indeed, these opposing actions may account in part for the limited treatment efficacy of tricyclic antidepressants and noradrenaline reuptake inhibitors such as duloxetine for the treatment of chronic pain. We propose that the traditional view of the LC as a pain-inhibitory structure be modified to account for its capacity as a pain facilitator. Future studies are needed to determine the neurobiology of ascending and descending pathways and the pharmacology of receptors underlying LC-mediated pain inhibition and facilitation. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Bradley K Taylor
- Department of Physiology, School of Medicine, University of Kentucky Medical Center, Lexington, Kentucky
| | - Karin N Westlund
- Department of Physiology, School of Medicine, University of Kentucky Medical Center, Lexington, Kentucky
| |
Collapse
|
3
|
Kaushal R, Taylor BK, Jamal AB, Zhang L, Ma F, Donahue R, Westlund KN. GABA-A receptor activity in the noradrenergic locus coeruleus drives trigeminal neuropathic pain in the rat; contribution of NAα1 receptors in the medial prefrontal cortex. Neuroscience 2016; 334:148-159. [PMID: 27520081 DOI: 10.1016/j.neuroscience.2016.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 07/20/2016] [Accepted: 08/03/2016] [Indexed: 12/24/2022]
Abstract
Trigeminal neuropathic pain is described as constant excruciating facial pain. The study goal was to investigate the role of nucleus locus coeruleus (LC) in a model of chronic orofacial neuropathic pain (CCI-ION). The study examines LC's relationship to both the medullary dorsal horn receiving trigeminal nerve sensory innervation and the medial prefrontal cortex (mPFC). LC is a major source of CNS noradrenaline (NA) and a primary nucleus involved in pain modulation. Although descending inhibition of acute pain by LC is well established, contribution of the LC to facilitation of chronic neuropathic pain is also reported. In the present study, a rat orofacial pain model of trigeminal neuropathy was induced by chronic constrictive injury of the infraorbital nerve (CCI-ION). Orofacial neuropathic pain was indicated by development of whisker pad mechanical hypersensitivity. Hypersensitivity was alleviated by selective elimination of NA neurons, including LC (A6 cell group), with the neurotoxin anti-dopamine-β-hydroxylase saporin (anti-DβH-saporin) microinjected either intracerebroventricularly (i.c.v.) or into trigeminal spinal nucleus caudalis (spVc). The GABAA receptor antagonist, bicuculline, administered directly into LC (week 8) inhibited hypersensitivity. This indicates a valence shift in which increased GABAA signaling ongoing in LC after trigeminal nerve injury paradoxically produces excitatory facilitation of the chronic pain state. Microinjection of NAα1 receptor antagonist, benoxathian, into mPFC attenuated whisker pad hypersensitivity, while NAα2 receptor antagonist, idazoxan, was ineffective. Thus, GABAA-mediated activation of NA neurons during CCI-ION can facilitate hypersensitivity through NAα1 receptors in the mPFC. These data indicate LC is a chronic pain generator.
Collapse
Affiliation(s)
- R Kaushal
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - B K Taylor
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - A B Jamal
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - L Zhang
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - F Ma
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - R Donahue
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States
| | - K N Westlund
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298, United States.
| |
Collapse
|
4
|
The effects of picric acid (2,4,6-trinitrophenol) and a bite-deterrent chemical (denatonium benzoate) on autotomy in rats after peripheral nerve lesion. Lab Anim (NY) 2016; 44:141-5. [PMID: 25793680 DOI: 10.1038/laban.711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 08/20/2014] [Indexed: 11/08/2022]
Abstract
Denervation of the hind limb is a technique used to study peripheral nerve regeneration. Autotomy or autophagia is an undesirable response to denervation in such studies. Application of a commercially available lotion used to deter nail biting in humans reduced autotomy in rats after denervation but did not completely prevent it. In this study, this authors evaluated the application of picric acid to prevent autotomy in rats in peripheral nerve experiments. They carried out sciatic nerve transection in 41 adult female Wistar rats and then applied either bite-deterrent lotion (n = 26) or saturated picric acid solution (n = 15) topically to the affected hind limb immediately after surgery and every day for 1 month. Autotomy scores were lower for rats treated with picric acid than for rats treated with bite-deterrent lotion 1 week and 2 weeks after surgery but were not different between the two groups 4 weeks after surgery. The authors conclude that application of picric acid could be used as an alternative strategy to prevent autotomy in peripheral nerve studies.
Collapse
|
5
|
Song Z, Ansah O, Meyerson B, Pertovaara A, Linderoth B. Exploration of supraspinal mechanisms in effects of spinal cord stimulation: Role of the locus coeruleus. Neuroscience 2013; 253:426-34. [DOI: 10.1016/j.neuroscience.2013.09.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/29/2013] [Accepted: 09/03/2013] [Indexed: 01/29/2023]
|
6
|
Role of different brain areas in peripheral nerve injury-induced neuropathic pain. Brain Res 2011; 1381:187-201. [DOI: 10.1016/j.brainres.2011.01.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 12/16/2010] [Accepted: 01/03/2011] [Indexed: 02/07/2023]
|
7
|
Lin JY, Peng B, Yang ZW, Min S. Number of synapses increased in the rat spinal dorsal horn after sciatic nerve transection: a stereological study. Brain Res Bull 2011; 84:430-3. [PMID: 21272619 DOI: 10.1016/j.brainresbull.2011.01.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 01/07/2011] [Accepted: 01/14/2011] [Indexed: 10/18/2022]
Abstract
We recently found that the number of synapses in the spinal dorsal horn, as estimated by stereological techniques, increased by 86% after chronic constriction injury of sciatic nerve in rats. In this study, we aimed to reveal whether transection of sciatic nerve was also associated with a plasticity change in the number of synapses. 18 adult SD rats were randomly divided into 3 groups undergoing (i) unilateral sham operation, (ii) unilateral sciatic nerve transection, and (iii) unilateral sciatic nerve transection with postoperative medication (parecoxib) for 3 days, respectively. 28 days postoperation, the L4-6 segment of the spinal cord was removed; paraffin-embedded sections were prepared and stained with Nissl's method and synaptophysin immunohistochemistry. The optical disector (a contemporary stereological technique) was used to estimate the numbers of neurons and synapses in the spinal dorsal horn. Compared to the non-operated side, the axotomy induced a 74.3% increase in the number of synapses per unit length of spinal cord or a 67.4% increase in the ratio between the numbers of synapses and neurons in the middle tissue block from the L4-6 segment on the operated side but not in either the rostral or caudal tissue block. Parecoxib had no effect on the parameters. In conclusion, peripheral nerve injury, model for neuropathic pain, is associated with a synaptic plasticity (numerical increase) in the spinal dorsal horn.
Collapse
Affiliation(s)
- Jing-Yan Lin
- Department of Anesthesiology, The First Affiliated Hospital, Chongqing Medical University, 1 Youyi Road, Yuan Jia Gang, Chongqing, China
| | | | | | | |
Collapse
|
8
|
Viisanen H, Pertovaara A. Antinociception by motor cortex stimulation in the neuropathic rat: does the locus coeruleus play a role? Exp Brain Res 2009; 201:283-96. [PMID: 19826796 DOI: 10.1007/s00221-009-2038-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 09/24/2009] [Indexed: 11/29/2022]
Abstract
We studied whether stimulation of the primary motor cortex (M1) attenuates pain-related spinal withdrawal responses of neuropathic and healthy control rats, and whether the descending antinociceptive effect is relayed through the noradrenergic locus coeruleus (LC). The assessments of the noxious heat-evoked limb withdrawals reflecting spinal nociception and recordings of single LC units were performed in spinal nerve-ligated neuropathic and sham-operated control rats under light pentobarbital anesthesia. Electric stimulation of M1 produced equally strong spinal antinociception in neuropathic and control rats. Following microinjection into M1, a group I metabotropic glutamate receptor agonist (DHPG; 10 nmol) and a high (25 nmol) but not low (2.5 nmol) dose of glutamate slightly increased on-going discharge rates of LC neurons in neuropathic but not in control animals. Influence of electric stimulation of M1 on LC neurons was studied only in the neuropathic group, in which discharge rates of LC neurons were increased by electric M1 stimulation. Lidocaine block of the LC or block of descending noradrenergic influence by intrathecal administration of a alpha(2)-adrenoceptor antagonist failed to produce a significant attenuation of the spinal antinociceptive effect induced by electric M1 stimulation in the neuropathic or the sham group. The results indicate that stimulation of the rat M1 induces spinal antinociception in neuropathic as well as control conditions. While M1 stimulation may activate the LC, particularly in the neuropathic group, the contribution of coeruleospinal noradrenergic pathways may not be critical for the spinal antinociceptive effect induced by M1 stimulation.
Collapse
Affiliation(s)
- Hanna Viisanen
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, POB 63, University of Helsinki, 00014, Helsinki, Finland
| | | |
Collapse
|
9
|
Brightwell JJ, Taylor BK. Noradrenergic neurons in the locus coeruleus contribute to neuropathic pain. Neuroscience 2009; 160:174-85. [PMID: 19223010 DOI: 10.1016/j.neuroscience.2009.02.023] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 01/20/2009] [Accepted: 02/04/2009] [Indexed: 12/17/2022]
Abstract
Current theories of neuropathic hypersensitivity include an imbalance of supraspinal inhibition and facilitation. Our overall hypothesis is that the locus coeruleus (LC), classically interpreted as a source of pain inhibition, may paradoxically result in facilitation after tibial and common peroneal nerve transection (spared sural nerve injury--SNI). We first tested the hypothesis that non-noxious tactile hind paw stimulation of the spared sural innervation territory increases neuronal activity in the LC in male rats. We observed a bilateral increase in the stimulus-evoked expression of transcription factors Fos and phosphorylated CREB (pCREB) in LC after SNI but not sham surgery; these markers of neuronal activity correlated with the intensity of tactile allodynia. We next tested the hypothesis that noradrenergic neurons contribute to the development of neuropathic pain. To selectively destroy these neurons, we delivered antidopamine-beta-hydroxylase saporin (anti-DbetaH-saporin) into the i.c.v. space 2 weeks before SNI. We found that anti-DbetaH-saporin, but not an IgG-saporin control, reduced behavioral signs of tactile allodynia, mechanical hyperalgesia, and cold allodynia from 3 to 28 days. after SNI. Our final experiment tested the hypothesis that the LC contributes to the maintenance of neuropathic pain. We performed SNI, waited 2 weeks for maximal allodynia and hyperalgesia to develop, and then administered the local anesthetic lidocaine (4%) directly into the LC parenchyma. Lidocaine reduced all behavioral signs of neuropathic pain in a reversible manner, suggesting that the LC contributes to pain facilitation. We conclude that, in addition to its well-known inhibition of acute and inflammatory pain, the LC facilitates the development and maintenance of neuropathic pain in the SNI model. Further studies are needed to determine the facilitatory pathways emanating from the LC.
Collapse
Affiliation(s)
- J J Brightwell
- Department of Pharmacology, School of Medicine, Tulane University, New Orleans, LA 70112, USA
| | | |
Collapse
|
10
|
Pertovaara A. Noradrenergic pain modulation. Prog Neurobiol 2006; 80:53-83. [PMID: 17030082 DOI: 10.1016/j.pneurobio.2006.08.001] [Citation(s) in RCA: 395] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 08/25/2006] [Accepted: 08/30/2006] [Indexed: 11/18/2022]
Abstract
Norepinephrine is involved in intrinsic control of pain. Main sources of norepinephrine are sympathetic nerves peripherally and noradrenergic brainstem nuclei A1-A7 centrally. Peripheral norepinephrine has little influence on pain in healthy tissues, whereas in injured tissues it has variable effects, including aggravation of pain. Its peripheral pronociceptive effect has been associated with injury-induced expression of novel noradrenergic receptors, sprouting of sympathetic nerve fibers, and pronociceptive changes in the ionic channel properties of primary afferent nociceptors, while an interaction with the immune system may contribute in part to peripheral antinociception induced by norepinephrine. In the spinal cord, norepinephrine released from descending pathways suppresses pain by inhibitory action on alpha-2A-adrenoceptors on central terminals of primary afferent nociceptors (presynaptic inhibition), by direct alpha-2-adrenergic action on pain-relay neurons (postsynaptic inhibition), and by alpha-1-adrenoceptor-mediated activation of inhibitory interneurons. Additionally, alpha-2C-adrenoceptors on axon terminals of excitatory interneurons of the spinal dorsal horn possibly contribute to spinal control of pain. At supraspinal levels, the pain modulatory effect by norepinephrine and noradrenergic receptors has varied depending on many factors such as the supraspinal site, the type of the adrenoceptor, the duration of the pain and pathophysiological condition. While in baseline conditions the noradrenergic system may have little effect, sustained pain induces noradrenergic feedback inhibition of pain. Noradrenergic systems may also contribute to top-down control of pain, such as induced by a change in the behavioral state. Following injury or inflammation, the central as well as peripheral noradrenergic system is subject to various plastic changes that influence its antinociceptive efficacy.
Collapse
Affiliation(s)
- Antti Pertovaara
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, PO Box 63, University of Helsinki, FIN-00014 Helsinki, Finland.
| |
Collapse
|
11
|
Al-Adawi S, Burke DT, Mastronardi SE. Seizure heralding functional recovery in a patient with apallic syndrome: A case report with retrospective-prospective observation. Epilepsy Behav 2006; 8:776-80. [PMID: 16647300 DOI: 10.1016/j.yebeh.2006.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 02/28/2006] [Accepted: 03/01/2006] [Indexed: 11/22/2022]
Abstract
BACKGROUND It has been suggested that there exists a close relationship between seizure discharges and functional recovery from brain injury, and that paroxysmal bombardment in late seizures may herald functional recovery or may "kick-start" recovery. CASE REPORT We report the case of a 52-year-old patient who, following a subarachnoid hemorrhage and multiple surgeries, experienced discernible apallic syndrome of long duration. His hospitalization is well documented. The patient underwent protracted, intense rehabilitation, but he remained in this prolonged state of loss of consciousness and behavioral passivity until he experienced a series of periodic seizures. Widespread improvement in his cognitive and functional abilities coincided closely with the seizure activity. The literature on this topic is reviewed. CONCLUSION This case confirms the close relationship between seizure discharges and functional recovery reported in preclinical literature.
Collapse
Affiliation(s)
- Samir Al-Adawi
- Department of Behavioral Medicine, College of Medicine and Health Science, Sultan Qaboos University, Muscat, Oman.
| | | | | |
Collapse
|
12
|
Greenfield SA, Collins TFT. A neuroscientific approach to consciousness. PROGRESS IN BRAIN RESEARCH 2005; 150:11-23. [PMID: 16186012 DOI: 10.1016/s0079-6123(05)50002-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
For a neuroscientist, consciousness currently defies any formal operational definition. However, the phenomenon is distinct from self-consciousness: after all, one can "let oneself go," when experiencing extreme emotion, but still be accessing a sentiment, subjective, conscious state. This raw, basic subjective state does not appear to be an exclusive property of the human brain. There is no obvious qualitative transformation in either the anatomy or the physiology of the central nervous system of human or non-human animals, no phylogenetic Rubicon in the animal kingdom. Similarly, there is no clear ontogenetic line that is crossed as the brain grows in the womb, no single event or change in brain physiology, and certainly not at birth, when consciousness might be generated in an all-or-none fashion. A more plausible, and scientific, view of consciousness might be therefore that it is not a different property of the brain, some magic bullet, but that it is a consequence of a quantitative increase in the complexity of the human brain: consciousness will grow as brains grow. Hence, consciousness is most likely to be a continuously variable property of the brain, in both phylogenetic and ontogenetic terms. Here, we describe how modern techniques may be utilized to determine the physiological basis of consciousness.
Collapse
Affiliation(s)
- Susan A Greenfield
- Department of Pharmacology, Mansfield Road, University of Oxford, Oxford, OX1 3QT, UK.
| | | |
Collapse
|
13
|
Hanna PA, Kumar S, Walters AS. Restless Legs Symptoms in a Patient With Above Knee Amputations: A Case of Phantom Restless Legs. Clin Neuropharmacol 2004; 27:87-9. [PMID: 15252270 DOI: 10.1097/00002826-200403000-00008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We describe a 78-year-old gentleman who, following bilateral above-knee amputations, developed symptoms of restless legs syndrome in the absent portions of his lower extremities. These symptoms improved with dopamine agonist therapy. In addition, he later developed parkinsonism with prominent rest tremor on metoclopramide. This suggests that this individual had a dopamine-deficient state which predisposed him to both restless legs syndrome and drug-induced or drug-exacerbated parkinsonism. We propose expanding the spectrum of phantom limb phenomena to include phantom restless legs.
Collapse
Affiliation(s)
- Philip A Hanna
- New Jersey Neuroscience Institute, JFK Medical Center, Edison, NJ, USA.
| | | | | |
Collapse
|
14
|
Jasmin L, Tien D, Janni G, Ohara PT. Is noradrenaline a significant factor in the analgesic effect of antidepressants? Pain 2003; 106:3-8. [PMID: 14581104 DOI: 10.1016/j.pain.2003.08.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Luc Jasmin
- Department of Neurological Surgery, University of California San Francisco, Box 0112, 505 Parnassus Avenue, San Francisco, CA 94143, USA.
| | | | | | | |
Collapse
|
15
|
Han F, Zhang YF, Li YQ. Fos expression in tyrosine hydroxylase-containing neurons in rat brainstem after visceral noxious stimulation: an immunohistochemical study. World J Gastroenterol 2003; 9:1045-50. [PMID: 12717853 PMCID: PMC4611369 DOI: 10.3748/wjg.v9.i5.1045] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To prove that neurons in the different structures of the brainstem that express tyrosine hydroxylase (TH) are involved in the transmission and modulation of visceral or somatic nociceptive information in rat.
METHODS: Immunohistochemical double-staining method was used to co-localize TH and Fos expression in neurons of the rat brainstem in visceral or subcutaneous noxious stimulation models.
RESULTS: Neurons co-expressing TH/Fos were observed in lateral reticular nucleus (LRT), rostroventrolateral reticular nucleus (RVL), solitary tract nucleus (SOL), locus coeruleus (LC), A5, A7 neuronal groups and ventrolateral subdivision of the periaqueductal gray (vlPAG) in both models. But the proportion and number of the double-labeled neurons responding to the two noxious stimuli were significantly different in the LRT, RVL and LC nuclei. The proportion and number of the TH/Fos double-labeled neurons in the visceral pain model were smaller than that in the subcutaneous pain model. However, in the case of SOL, they were similar in the two models.
CONCLUSION: Differences of Fos expression in TH immunoreactive neurons in animals after visceral and somatic noxious stimulation indicate that the mechanisms of the transmission and modulation of visceral nociceptive information in the brainstem may be different from that of somatic nociceptive information.
Collapse
Affiliation(s)
- Feng Han
- Department of Anatomy and K. K. Leung Brain Research Centre, the Fourth Military Medical University, Xi'an 710032, Shanxi Province, China
| | | | | |
Collapse
|
16
|
Zarei M, Stephenson JD. Effects of DSP4 and dizolcipine on connectivity of solid E19 cortical grafts to ablated SmI region of adult rats; an in vivo electrophysiological study. Brain Res 2002; 947:182-90. [PMID: 12176159 DOI: 10.1016/s0006-8993(02)02921-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The functional connectivity of an embryonic graft implanted into the lesioned somatosensory cortex and the effect of DSP4 (a selective noradrenergic neurotoxin to noradrenergic terminals) and dizolcipine (a non-competitive NMDA receptor antagonist), was studied electrophysiologically. The forepaw representational area of the rat primary somatosensory cortex was lesioned unilaterally and, 3-4 weeks later, tissue from the same region of E19 rat embryos was implanted into the cavity. At 7-9 months later, the rats were anaesthetized and single unit activity was recorded from the grafts in response to contralateral forepaw, ipsilateral hindpaw and contralateral hindpaw stimulation and compared with that obtained in control rats, in rats pretreated with dizolcipine immediately after lesioning and in rats given DSP4 24 h before transplantation. Neurones within the graft were integrated into the host brain and developed a pattern of representation similar to that of intact rats, but with a reduced proportion of neurones exhibiting short-latency response to contralateral forepaw stimulation and an increased proportion responding to stimulation of more than one paw. Pretreatment with dizolcipine did not increase short-latency responses to stimulation of contralateral forepaw stimulation however pretreatment with DSP4 reduced such responses and increased proportion of inhibitory responses. It was concluded that the noradrenergic system plays an important role in establishing host-graft connectivity. The importance of further pharmacological studies on host-graft connectivity and the relation of such connections to neural plasticity were discussed.
Collapse
Affiliation(s)
- Mojtaba Zarei
- Institute of Psychiatry, King's College London, Department of Neuroscience, De Crespigny Park, London SE5 8AF, UK.
| | | |
Collapse
|