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Freezing revisited: coordinated autonomic and central optimization of threat coping. Nat Rev Neurosci 2022; 23:568-580. [PMID: 35760906 DOI: 10.1038/s41583-022-00608-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2022] [Indexed: 12/16/2022]
Abstract
Animals have sophisticated mechanisms for coping with danger. Freezing is a unique state that, upon threat detection, allows evidence to be gathered, response possibilities to be previsioned and preparations to be made for worst-case fight or flight. We propose that - rather than reflecting a passive fear state - the particular somatic and cognitive characteristics of freezing help to conceal overt responses, while optimizing sensory processing and action preparation. Critical for these functions are the neurotransmitters noradrenaline and acetylcholine, which modulate neural information processing and also control the sympathetic and parasympathetic branches of the autonomic nervous system. However, the interactions between autonomic systems and the brain during freezing, and the way in which they jointly coordinate responses, remain incompletely explored. We review the joint actions of these systems and offer a novel computational framework to describe their temporally harmonized integration. This reconceptualization of freezing has implications for its role in decision-making under threat and for psychopathology.
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Terpou BA, Harricharan S, McKinnon MC, Frewen P, Jetly R, Lanius RA. The effects of trauma on brain and body: A unifying role for the midbrain periaqueductal gray. J Neurosci Res 2019; 97:1110-1140. [PMID: 31254294 DOI: 10.1002/jnr.24447] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/09/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022]
Abstract
Post-traumatic stress disorder (PTSD), a diagnosis that may follow the experience of trauma, has multiple symptomatic phenotypes. Generally, individuals with PTSD display symptoms of hyperarousal and of hyperemotionality in the presence of fearful stimuli. A subset of individuals with PTSD; however, elicit dissociative symptomatology (i.e., depersonalization, derealization) in the wake of a perceived threat. This pattern of response characterizes the dissociative subtype of the disorder, which is often associated with emotional numbing and hypoarousal. Both symptomatic phenotypes exhibit attentional threat biases, where threat stimuli are processed preferentially leading to a hypervigilant state that is thought to promote defensive behaviors during threat processing. Accordingly, PTSD and its dissociative subtype are thought to differ in their proclivity to elicit active (i.e., fight, flight) versus passive (i.e., tonic immobility, emotional shutdown) defensive responses, which are characterized by the increased and the decreased expression of the sympathetic nervous system, respectively. Moreover, active and passive defenses are accompanied by primarily endocannabinoid- and opioid-mediated analgesics, respectively. Through critical review of the literature, we apply the defense cascade model to better understand the pathological presentation of defensive responses in PTSD with a focus on the functioning of lower-level midbrain and extended brainstem systems.
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Affiliation(s)
- Braeden A Terpou
- Department of Neuroscience, Western University, London, Ontario, Canada
| | | | - Margaret C McKinnon
- Mood Disorders Program, St. Joseph's Healthcare, Hamilton, Ontario, Canada.,Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.,Homewood Research Institute, Guelph, Ontario, Canada
| | - Paul Frewen
- Department of Psychology, Western University, London, Ontario, Canada
| | - Rakesh Jetly
- Canadian Forces, Health Services, Ottawa, Canada
| | - Ruth A Lanius
- Department of Neuroscience, Western University, London, Ontario, Canada.,Department of Psychiatry, Western University, London, Ontario, Canada
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Buhler AVK, Tachibana S, Zhang Y, Quock RM. nNOS immunoreactivity co-localizes with GABAergic and cholinergic neurons, and associates with β-endorphinergic and met-enkephalinergic opioidergic fibers in rostral ventromedial medulla and A5 of the mouse. Brain Res 2018; 1698:170-178. [PMID: 30081038 DOI: 10.1016/j.brainres.2018.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/24/2018] [Accepted: 08/02/2018] [Indexed: 11/26/2022]
Abstract
The present study examined the co-expression of neuronal nitric oxide synthase (nNOS) in the rostral ventromedial medulla (RVM) and A5 regions of the mouse brainstem within several neurochemical populations involved in nociceptive modulation. Double immunohistochemical methods showed that nNOS+ neurons do not co-localize with serotonergic neurons within any of these regions. Within the RVM, the nuclei raphe magnus and gigantocellularis contain a population of nNOS+/GAD67+ neurons, and within the paragigantocellularis lateralis, there is a smaller population of nNOS+/CHAT+ neurons. Further, nNOS+ neurons overlap the region of expression of β-endorphinergic and met-enkephalinergic fibers within the RVM. No co-labeling was found within the A5 for any of these populations. These findings suggest that pain-modulatory serotonergic neurons within the brainstem do not directly produce nitric oxide (NO). Rather, NO-producing neurons within the RVM belong to GABAergic and cholinergic cell populations, and are in a position to modulate or be modulated by local opioidergic neurons.
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Affiliation(s)
- Amber V K Buhler
- School of Pharmacy, Pacific University Oregon, 222 SE 8th Ave, Hillsboro, OR 97123, United States.
| | - Sean Tachibana
- School of Pharmacy, Pacific University Oregon, 222 SE 8th Ave, Hillsboro, OR 97123, United States
| | - Yangmiao Zhang
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, United States
| | - Raymond M Quock
- Department of Psychology, Washington State University, Pullman, WA 99164, United States
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Gawel K, Gibula-Bruzda E, Dziedzic M, Jenda-Wojtanowska M, Marszalek-Grabska M, Silberring J, Kotlinska JH. Cholinergic activation affects the acute and chronic antinociceptive effects of morphine. Physiol Behav 2016; 169:22-32. [PMID: 27865771 DOI: 10.1016/j.physbeh.2016.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 11/05/2016] [Accepted: 11/05/2016] [Indexed: 12/24/2022]
Abstract
Current studies indicate that the cholinergic and opioid systems interact to modulate pain. In the present work, we investigated the influence of the cholinesterase inhibitors, donepezil (0.5; 1 or 3mg/kg, i.p.) and rivastigmine (0.03; 0.5 or 1mg/kg, i.p.), on the acute antinociceptive effects of morphine (5mg/kg, i.p.) in the hot plate test in mice. Herein, both inhibitors were found to enhance and prolong the analgesic effects of morphine without affecting latencies themselves. In an extension of this work, we determined which cholinergic receptors subtype mediates the enhancement of analgesic effects of morphine, following inhibition of cholinesterases. In this part of the study, scopolamine (0.5mg/kg, i.p.), a muscarinic cholinergic receptors antagonist, but not mecamylamine (3mg/kg, i.p.), a nicotinic cholinergic receptors antagonist, reversed the enhancing effects of donepezil (3mg/kg, i.p.) and rivastigmine (1mg/kg, i.p.) on the morphine antinociception. Moreover, both cholinesterase inhibitors attenuated the development of tolerance to the antinociceptive effects of morphine. In contrast, acute administration of donepezil (3mg/kg, i.p.) or rivastigmine (1mg/kg, i.p.) on the day of expression of tolerance, had no effect on the already developed morphine tolerance. What is more, in both set of experiments, rivastigmine was slightly more potent than donepezil due to the broader inhibitory spectrum of this drug on acetylcholine degradation. Thus, our results suggest that the cholinesterase inhibitors, donepezil and rivastigmine, may be administered with morphine in order to enhance the latter's analgesic effects for the treatment of acute and chronic pain.
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Affiliation(s)
- Kinga Gawel
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4a, 20-093 Lublin, Poland; Department of Experimental and Clinical Pharmacology, Medical University, Jaczewskiego 8b, 20-090 Lublin, Poland
| | - Ewa Gibula-Bruzda
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4a, 20-093 Lublin, Poland
| | - Marcin Dziedzic
- Department of Laboratory Diagnostic, Medical University, Chodzki 1, 20-093 Lublin, Poland
| | | | - Marta Marszalek-Grabska
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4a, 20-093 Lublin, Poland
| | - Jerzy Silberring
- Department of Biochemistry and Neurobiology, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - Jolanta H Kotlinska
- Department of Pharmacology and Pharmacodynamics, Medical University, Chodzki 4a, 20-093 Lublin, Poland.
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Alterations in the rostral ventromedial medulla after the selective ablation of μ-opioid receptor expressing neurons. Pain 2016; 157:166-173. [PMID: 26335909 DOI: 10.1097/j.pain.0000000000000344] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The rostral ventromedial medulla (RVM) exerts both inhibitory and excitatory controls over nociceptive neurons in the spinal cord and medullary dorsal horn. Selective ablation of mu-opioid receptor (MOR)-expressing neurons in the RVM using saporin conjugated to the MOR agonist dermorphin-saporin (derm-sap) attenuates stress and injury-induced behavioral hypersensitivity, yet the effect of RVM derm-sap on the functional integrity of the descending inhibitory system and the properties of RVM neurons remain unknown. Three classes of RVM neurons (on-cells, off-cells, and neutral cells) have been described with distinct responses to noxious stimuli and MOR agonists. Using single unit recording in lightly anesthetized rats, RVM neurons were characterized after microinjections of derm-sap or saporin. Derm-sap treatment resulted in a reduction in on-cells and off-cells when compared to saporin controls (P < 0.05). The number of neutral cells remained unchanged. After derm-sap treatment, RVM microinjections of the glutamate receptor agonist homocysteic acid increased tail-flick latencies, whereas the MOR agonist DAMGO had no effect. Furthermore, electrical stimulation of the periaqueductal gray produced analgesia in both derm-sap and saporin controls with similar thresholds. Microinjection of kynurenic acid, a glutamate receptor antagonist, into the RVM disrupted periaqueductal gray stimulation-produced analgesia in both saporin-treated and derm-sap-treated rats. These results indicate that MOR-expressing neurons in the RVM are not required for analgesia produced by either direct or indirect activation of neurons in the RVM.
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Abstract
Evolution has endowed all humans with a continuum of innate, hard-wired, automatically activated defense behaviors, termed the defense cascade. Arousal is the first step in activating the defense cascade; flight or fight is an active defense response for dealing with threat; freezing is a flight-or-fight response put on hold; tonic immobility and collapsed immobility are responses of last resort to inescapable threat, when active defense responses have failed; and quiescent immobility is a state of quiescence that promotes rest and healing. Each of these defense reactions has a distinctive neural pattern mediated by a common neural pathway: activation and inhibition of particular functional components in the amygdala, hypothalamus, periaqueductal gray, and sympathetic and vagal nuclei. Unlike animals, which generally are able to restore their standard mode of functioning once the danger is past, humans often are not, and they may find themselves locked into the same, recurring pattern of response tied in with the original danger or trauma. Understanding the signature patterns of these innate responses--the particular components that combine to yield the given pattern of defense-is important for developing treatment interventions. Effective interventions aim to activate or deactivate one or more components of the signature neural pattern, thereby producing a shift in the neural pattern and, with it, in mind-body state. The process of shifting the neural pattern is the necessary first step in unlocking the patient's trauma response, in breaking the cycle of suffering, and in helping the patient to adapt to, and overcome, past trauma.
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Sokolov AY, Lyubashina OA, Amelin AV, Panteleev SS. The role of noradrenalin in the pathogenesis of primary headaches. NEUROCHEM J+ 2013. [DOI: 10.1134/s1819712413040090] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Jeong Y, Moes JR, Wagner M, Holden JE. The posterior hypothalamus exerts opposing effects on nociception via the A7 catecholamine cell group in rats. Neuroscience 2012; 227:144-53. [PMID: 23036619 DOI: 10.1016/j.neuroscience.2012.09.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 09/19/2012] [Accepted: 09/22/2012] [Indexed: 01/16/2023]
Abstract
Stimulation of the posterior hypothalamic area (PH) produces antinociception in rats and humans, but the precise mechanisms are unknown. The PH forms anatomical connections with the parabrachial area, which contains the pontine A7 catecholamine cell group, a group of spinally projecting noradrenergic neurons known to produce antinociception in the dorsal horn. The aim of the present study was to determine whether PH-induced antinociception is mediated in part through connections with the A7 cell group in female Sprague-Dawley rats, as measured by the tail flick and foot withdrawal latency. Stimulation of the PH with the cholinergic agonist carbachol (125 nmol) produced antinociception that was blocked by pretreatment with atropine sulfate. Intrathecal injection of the α(2)-adrenoceptor antagonist yohimbine reversed PH-induced antinociception, but the α(1)-adrenoceptor antagonist WB4101 facilitated antinociception. Intrathecal injection of normal saline had no effect. In a separate experiment, cobalt chloride, which reversibly arrests synaptic activity, was microinjected into the A7 cell group and blocked PH-induced antinociception. These findings provide evidence that the PH modulates nociception in part through connections with the A7 catecholamine cell group through opposing effects. Antinociception occurs from actions at α(2)-adrenoceptors in the dorsal horn, while concurrent hyperalgesia occurs from actions of norepinephrine at α(1)-adrenoceptors. This hyperalgesic response likely attenuates antinociception from PH stimulation.
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Affiliation(s)
- Y Jeong
- College of Nursing Science, Kyung Hee University, 26 Kyunghee-daero, Dongdaemun-gu, Seoul 130-701, Korea.
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Saadé NE, Al Amin HA, Barchini J, Tchachaghian S, Shamaa F, Jabbur SJ, Atweh SF. Brainstem injection of lidocaine releases the descending pain-inhibitory mechanisms in a rat model of mononeuropathy. Exp Neurol 2012; 237:180-90. [DOI: 10.1016/j.expneurol.2012.06.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/11/2012] [Accepted: 06/20/2012] [Indexed: 10/28/2022]
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10
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Rostral ventromedial medulla modulates nociception and tonic immobility behavior through connections with the A7 catecholaminergic region. Behav Brain Res 2012; 233:422-7. [DOI: 10.1016/j.bbr.2012.05.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 05/08/2012] [Accepted: 05/12/2012] [Indexed: 12/13/2022]
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11
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Adrenergic mechanisms of the Kölliker-Fuse/A7 area on the control of water and sodium intake. Neuroscience 2009; 164:370-9. [DOI: 10.1016/j.neuroscience.2009.08.048] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 08/21/2009] [Accepted: 08/22/2009] [Indexed: 11/20/2022]
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12
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Gear RW, Levine JD. Rostral ventral medulla cholinergic mechanism in pain-induced analgesia. Neurosci Lett 2009; 464:170-2. [PMID: 19699268 DOI: 10.1016/j.neulet.2009.08.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 10/20/2022]
Abstract
The ascending nociceptive control (ANC), a novel spinostriatal pain modulation pathway, mediates a form of pain-induced analgesia referred to as noxious stimulus-induced antinociception (NSIA). ANC includes specific spinal cord mechanisms as well as circuitry in nucleus accumbens, a major component of the ventral striatum. Here, using the trigeminal jaw-opening reflex (JOR) in the rat as a nociceptive assay, we show that microinjection of the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine into the rostral ventral medulla (RVM) blocks NSIA, implicating RVM as a potentially important link between ANC and the PAG-RVM-spinal descending pain modulation system. A circuit connecting nucleus accumbens to the RVM is proposed as a novel striato-RVM pathway.
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Affiliation(s)
- Robert W Gear
- Department of Oral and Maxillofacial Surgery, University of California, San Francisco, California 94143-0440, United States.
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13
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DeSantana JM, Da Silva LFS, De Resende MA, Sluka KA. Transcutaneous electrical nerve stimulation at both high and low frequencies activates ventrolateral periaqueductal grey to decrease mechanical hyperalgesia in arthritic rats. Neuroscience 2009; 163:1233-41. [PMID: 19576962 DOI: 10.1016/j.neuroscience.2009.06.056] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 06/24/2009] [Accepted: 06/27/2009] [Indexed: 10/20/2022]
Abstract
Transcutaneous electric nerve stimulation (TENS) is widely used for the treatment of pain. TENS produces an opioid-mediated antinociception that utilizes the rostroventromedial medulla (RVM). Similarly, antinociception evoked from the periaqueductal grey (PAG) is opioid-mediated and includes a relay in the RVM. Therefore, we investigated whether the ventrolateral or dorsolateral PAG mediates antinociception produced by TENS in rats. Paw and knee joint mechanical withdrawal thresholds were assessed before and after knee joint inflammation (3% kaolin/carrageenan), and after TENS stimulation (active or sham). Cobalt chloride (CoCl(2); 5 mM) or vehicle was microinjected into the ventrolateral periaqueductal grey (vlPAG) or dorsolateral periaqueductal grey (dlPAG) prior to treatment with TENS. Either high (100 Hz) or low (4 Hz) frequency TENS was then applied to the inflamed knee for 20 min. Active TENS significantly increased withdrawal thresholds of the paw and knee joint in the group microinjected with vehicle when compared to thresholds prior to TENS (P<0.001) or to sham TENS (P<0.001). The increases in withdrawal thresholds normally observed after TENS were prevented by microinjection of CoCl(2) into the vlPAG, but not the dlPAG prior to TENS and were significantly lower than controls treated with TENS (P<0.001). In a separate group of animals, microinjection of CoCl(2) into the vlPAG temporarily reversed the decreased mechanical withdrawal threshold suggesting a role for the vlPAG in the facilitation of joint pain. No significant difference was observed for dlPAG. We hypothesize that the effects of TENS are mediated through the vlPAG that sends projections through the RVM to the spinal cord to produce an opioid-mediated analgesia.
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Affiliation(s)
- J M DeSantana
- Department of Physical Therapy, Federal University of Sergipe, Cidade Universitária Professor José Aloísio de Campos. Av. Marechal Rondon s/n, Jardim Rosa Else, São Cristóvão/Sergipe, Brazil.
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Holden JE, Pizzi JA, Jeong Y. An NK1 receptor antagonist microinjected into the periaqueductal gray blocks lateral hypothalamic-induced antinociception in rats. Neurosci Lett 2009; 453:115-9. [PMID: 19356605 PMCID: PMC3463133 DOI: 10.1016/j.neulet.2009.01.083] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 01/23/2009] [Accepted: 01/31/2009] [Indexed: 12/22/2022]
Abstract
Substantial data are accumulating that implicate the lateral hypothalamus (LH) as part of the descending pain modulatory system. The LH modifies nociception in the spinal cord dorsal horn partly through connections with the periaqueductal gray (PAG), an area known to play a central role in brainstem modulation of nociception. Early work demonstrated a putative substance P connection between the LH and the PAG, but the connection is not fully defined. To determine whether LH-induced antinociception mediated by the PAG is neurokinin1 (NK1) receptor-dependent, we conducted behavioral experiments in which the cholinergic agonist carbachol (125 nmol) was microinjected into the LH of lightly anesthetized female Sprague-Dawley rats (250-350 g) and antinociception was obtained on the tail flick or foot withdrawal tests. Cobalt chloride (100 nM), which reversibly blocks synaptic activation, blocked LH-induced antinociception. In another set of experiments, the specific NK1 receptor antagonist L-703,606 (5 microg) was microinjected in the PAG following LH stimulation with carbachol abolished LH-induced antinociception as well. Microinjection of cobalt chloride or L-703,606 in the absence of LH stimulation had no effect. These behavioral experiments coupled with earlier work provide converging evidence to support the hypothesis that antinociception produced by activating neurons in the LH is mediated in part by the subsequent activation of neurons in the PAG by NK1 receptors.
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Affiliation(s)
- Janean E Holden
- Division of Acute, Critical and Long-Term Care Programs, School of Nursing, The University of Michigan, Ann Arbor, MI 48109-5482, USA.
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Holden JE, Pizzi JA. Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla. Brain Res 2008; 1214:40-9. [PMID: 18457815 PMCID: PMC2483309 DOI: 10.1016/j.brainres.2008.03.051] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 11/17/2022]
Abstract
Stimulation of the lateral hypothalamus (LH) produces antinociception modified by intrathecal serotonergic receptor antagonists. Spinally-projecting serotonergic neurons in the LH have not been identified, suggesting that the LH innervates brainstem serotonergic neurons in the rostral ventromedial medulla (RVM), known to modify nociception in the spinal cord dorsal horn. To determine whether substance P (SP) plays a role in LH-induced antinociception mediated by the RVM, we conducted an anatomical experiment using retrograde tract tracing combined with double label immunocytochemistry and found that neuron profiles immunoreactive for SP in the LH project to the RVM. To further identify a functional connection between SP neurons in the LH and the RVM, the cholinergic agonist carbachol (125 nmol) was microinjected into the LH of female Sprague-Dawley rats (250-350 g) and antinociception was obtained on the tail flick or foot withdrawal tests. Cobalt chloride (100 nM) was then microinjected in the RVM to block synaptic activation of spinally-projecting RVM neurons. Within 5 min of the cobalt chloride injection, the antinociceptive effect of carbachol stimulation was blocked. In another set of experiments, the specific NK1 receptor antagonist L-703,606 (5 microg) was microinjected in the RVM following LH stimulation with carbachol and abolished LH-induced antinociception as well. Microinjection of cobalt chloride or L-703,606 in the absence of LH stimulation had no effect. These anatomical and behavioral experiments provide converging evidence to support the hypothesis that antinociception produced by activating neurons in the LH is mediated in part by the subsequent activation of spinally-projecting neurons in the RVM.
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Affiliation(s)
- Janean E Holden
- Department of Medical-Surgical Nursing, College of Nursing, University of Illinois at Chicago, 845 South Damen Avenue, Chicago, IL 60612-7350, USA.
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Pinto-Ribeiro F, Ansah OB, Almeida A, Pertovaara A. Influence of arthritis on descending modulation of nociception from the paraventricular nucleus of the hypothalamus. Brain Res 2008; 1197:63-75. [DOI: 10.1016/j.brainres.2007.12.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 12/12/2007] [Accepted: 12/12/2007] [Indexed: 01/22/2023]
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17
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Buhler AV, Proudfit HK, Gebhart GF. Neurotensin-produced antinociception in the rostral ventromedial medulla is partially mediated by spinal cord norepinephrine. Pain 2007; 135:280-290. [PMID: 17664042 PMCID: PMC2423280 DOI: 10.1016/j.pain.2007.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Revised: 06/08/2007] [Accepted: 06/11/2007] [Indexed: 02/07/2023]
Abstract
Microinjection of neurotensin (NT) into the rostral ventromedial medulla (RVM) produces dose-dependent antinociception. Here we show that antinociception produced by intra-RVM microinjection of neurotensin (NT) or the selective NT receptor subtype 1 (NTR1) agonist PD149163 can be partially blocked by intrathecal (i.t.) yohimbine, an alpha2-adrenoceptor antagonist and by methysergide, a serotonin receptor antagonist. Antinociception produced by the NTR2 agonist beta-lactotensin (beta-LT) is blocked by intrathecal (i.t.) yohimbine, but not by methysergide i.t. It is not known which noradrenergic cell group is involved in this newly identified noradrenergic component of NTR-mediated antinociception. These experiments provide the first evidence that selective activation of NTR2 in the RVM produces antinociception. These results also provide evidence that activation of NTR1 in the RVM produces antinociception through spinal release of norepinephrine (NE) and serotonin, and that activation of NTR2 in the RVM produces antinociception mediated by spinal release of NE.
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Affiliation(s)
- A V Buhler
- School of Pharmacy, Pacific University, 222 SE 8th Avenue, Ste 451, Hillsboro, OR 97123, United States Department of Pharmacology, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States Center for Pain Research, University of Pittsburgh School of Medicine, PA, United States
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Walker SM, Fitzgerald M. Characterization of spinal alpha-adrenergic modulation of nociceptive transmission and hyperalgesia throughout postnatal development in rats. Br J Pharmacol 2007; 151:1334-42. [PMID: 17533423 PMCID: PMC2189833 DOI: 10.1038/sj.bjp.0707290] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The selective alpha(2)-adrenergic agonist dexmedetomidine is used clinically for analgesia and sedation, but effects in early life are not well characterized. Investigation of age-related effects of dexmedetomidine is important for evaluating responses to exogenously administered analgesics and provides insight into postnatal function of noradrenergic pathways. EXPERIMENTAL APPROACH We examined effects of epidural dexmedetomidine in anaesthetized rat pups (3, 10 and 21 postnatal days) using a quantitative model of nociception and C-fibre induced hyperalgesia. Electromyographic recordings of withdrawal responses to hindpaw mechanical stimuli measured effects of dexmedetomidine upon the baseline reflex and the response to mustard oil application on the hindpaw (primary hyperalgesia) or hindlimb (secondary hyperalgesia). In addition, we compared epidural with systemic administration, examined effects of spinal transection and evaluated heart rate changes following dexmedetomidine. KEY RESULTS Epidural dexmedetomidine dose-dependently prevented mustard oil-induced hyperalgesia at all ages but dose requirements were lower in the youngest pups. Higher doses also suppressed the baseline nociceptive reflex when given epidurally, but had no effect when given systemically. Analgesic efficacy was the same for primary and secondary hyperalgesia, and was not diminished by spinal cord transection. CONCLUSIONS AND IMPLICATIONS Our laboratory studies predict that spinally mediated alpha(2)-agonist analgesia would be effective throughout postnatal development, dose requirements would be lower in early life and selective anti-hyperalgesic effects could be achieved with epidural administration at doses lower than associated with antinociceptive or cardiovascular effects. Clinical trials of alpha(2) agonists in neonates and infants should consider developmentally regulated changes.
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Affiliation(s)
- S M Walker
- Portex Anaesthesia Unit, UCL Institute of Child Health, University College London, London, UK.
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Zanella S, Viemari JC, Hilaire G. Muscarinic receptors and alpha2-adrenoceptors interact to modulate the respiratory rhythm in mouse neonates. Respir Physiol Neurobiol 2006; 157:215-25. [PMID: 17267295 DOI: 10.1016/j.resp.2006.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 12/01/2006] [Accepted: 12/01/2006] [Indexed: 11/27/2022]
Abstract
The respiratory rhythm generator (RRG) is modulated by several endogenous substances, including acetylcholine (ACh) and noradrenaline (NA) that interact in several modulatory processes. To know whether ACh and NA interacted to modulate the RRG activity, we used medullary "en bloc" and slice preparations from neonatal mice where the RRG has been shown to receive a facilitatory modulation from A1/C1 neurons, via a continuous release of endogenous NA and activation of alpha2 adrenoceptors. Applying ACh at 25 microM activated the RRG but ACh had no effects at 50 microM. Applying the ACh receptor agonists nicotine and muscarine facilitated and depressed the RRG, respectively. After yohimbine pre-treatment that blocked the alpha2 facilitation, the nicotinic facilitation was not altered, the muscarinic depression was reversed and ACh 50 microM significantly facilitated the RRG. After L-tyrosine pre-treatment that potentiated the alpha2 facilitation, the muscarinic depression was enhanced. Thus, ACh regulates the RRG activity via nicotinic and muscarinic receptors, the muscarinic receptors interacting with alpha2 adrenoceptors.
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Affiliation(s)
- Sébastien Zanella
- Formation de Recherche en Fermeture, FRE CNRS 2722, 280 Boulevard Sainte Marguerite, 13009 Marseille, France
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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.
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Affiliation(s)
- Antti Pertovaara
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, PO Box 63, University of Helsinki, FIN-00014 Helsinki, Finland.
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Park SJ, Zhang S, Chiang CY, Hu JW, Dostrovsky JO, Sessle BJ. Central sensitization induced in thalamic nociceptive neurons by tooth pulp stimulation is dependent on the functional integrity of trigeminal brainstem subnucleus caudalis but not subnucleus oralis. Brain Res 2006; 1112:134-45. [PMID: 16930568 DOI: 10.1016/j.brainres.2006.06.115] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 06/23/2006] [Accepted: 06/25/2006] [Indexed: 11/21/2022]
Abstract
We have previously demonstrated that application of the inflammatory irritant mustard oil (MO) to the rat molar tooth pulp induces central sensitization in nociceptive neurons within the contralateral ventroposterior medial (VPM) nucleus and posterior nuclear group (PO) of the thalamus as well as brainstem subnucleus caudalis (Vc) and subnucleus oralis (Vo). Since Vc and Vo are important relays of pulp afferent input to thalamus, the aim of this study was to test if local application of the synaptic blocker CoCl2 to Vc or Vo influences the pulp-induced thalamic central sensitization. The activity of 32 nociceptive-specific (NS) neurons within the rat VPM and immediately adjacent PO was recorded. Spontaneous activity, mechanoreceptive field (RF), mechanical activation threshold and evoked responses to graded mechanical stimuli were assessed before and after MO application to the pulp. MO application evoked immediate but short-lasting neuronal discharges in 21 of the 32 NS neurons tested, as well as central sensitization reflected in significant and long-lasting (> 60 min) RF expansion, decrease in activation threshold, and increase in graded pinch-evoked responses in all 32 NS neurons. CoCl2 applied to the ipsilateral Vc significantly attenuated these pulp-induced changes for 20 min or more. In contrast, CoCl2 applied to the ipsilateral Vo did not reverse this MO-induced central sensitization. Isotonic saline applied to Vc or Vo was also ineffective. These findings indicate that central sensitization induced in nociceptive neurons within VPM and PO by noxious stimulation of the tooth pulp is dependent upon the functional integrity of Vc but not Vo.
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Affiliation(s)
- Soo Joung Park
- Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON, Canada M5G 1G6
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da Silva LFS, Menescal-de-Oliveira L. Cholinergic modulation of tonic immobility and nociception in the NRM of guinea pig. Physiol Behav 2006; 87:821-7. [PMID: 16545845 DOI: 10.1016/j.physbeh.2006.01.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 01/23/2006] [Accepted: 01/25/2006] [Indexed: 01/08/2023]
Abstract
Tonic immobility (TI) is an inborn defensive behavior characterized by a temporary state of profound and reversible motor inhibition elicited by some forms of physical restraint. It is known that endogenous antinociceptive systems are activated during the emission of defensive behaviors including TI. The nucleus raphe magnus (NRM) is related to the modulation of nociceptive and behavioral responses. In the present study, we investigated the role of the cholinergic system of the NRM in the modulation of TI and nociception in guinea pigs. Microinjection of the cholinergic agonist carbachol (0.5 microg/0.2 microl) into the NRM promoted a reduction in the duration of TI episodes and nociception, the latter measured by the vocalization test in guinea pigs. The effect of microinjection of carbachol on TI reduction and antinociception was blocked by the previous microinjection of the cholinergic antagonist atropine (0.5 microg/0.2 microl and 1 microg/0.2 microl, respectively), demonstrating the participation of muscarinic receptors in the modulation of these responses. Microinjection of atropine per se did not interfere with the duration of TI episodes. In summary, the present results demonstrate that cholinergic stimulation of the NRM promoted analgesia and a reduction in the duration of TI in guinea pigs. These data indicate that the NRM possibly contributes to the modulation of defensive and nociceptive behavioral responses, probably by modulating the activity of neurons in the ventral and dorsal horn of the spinal cord, respectively.
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Affiliation(s)
- Luis Felipe Souza da Silva
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, 14049-900 Ribeirão Preto, SP, Brazil
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Buhler AV, Proudfit HK, Gebhart GF. Separate populations of neurons in the rostral ventromedial medulla project to the spinal cord and to the dorsolateral pons in the rat. Brain Res 2004; 1016:12-9. [PMID: 15234247 DOI: 10.1016/j.brainres.2004.04.060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2004] [Indexed: 11/24/2022]
Abstract
Activation of neurons in the rostral ventromedial medulla (RVM) directly modulates spinal nociceptive transmission by projections to the spinal cord dorsal horn and indirectly by projections to neurons in the dorsolateral pons (DLP) that project to the spinal cord dorsal horn. However, it is not known whether the same neurons in the RVM produce both direct and indirect modulation of nociception. Deposits of the retrograde tracers Fluoro-Gold (FG) in the spinal cord dorsal horn and DiI in the DLP were used to determine whether the same RVM neurons project to both of these regions. Only 0.9+/-0.1% of RVM neurons retrogradely labeled with Fluoro-Gold from the spinal cord were also labeled with DiI placed in the DLP. In addition, spinally projecting RVM neurons were significantly larger than RVM neurons that project to the DLP. Finally, spinally projecting neurons were found predominantly on the midline and within the RVM; neurons that project to the DLP had a wider distribution and were present both within and outside of the RVM. Thus, separate and morphologically distinct populations of RVM neurons appear to modulate nociception by direct and indirect descending pathways.
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Affiliation(s)
- A V Buhler
- Department of Pharmacology, Carver College of Medicine, The University of Iowa, Bowen Science BLD 2-351, Iowa City, IA 52242, USA.
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Skyba D, Radhakrishnan R, Rohlwing J, Wright A, Sluka K. Joint manipulation reduces hyperalgesia by activation of monoamine receptors but not opioid or GABA receptors in the spinal cord. Pain 2004; 106:159-68. [PMID: 14581123 PMCID: PMC2732015 DOI: 10.1016/s0304-3959(03)00320-8] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Joint manipulation has long been used for pain relief. However, the underlying mechanisms for manipulation-related pain relief remain largely unexplored. The purpose of the current study was to determine which spinal neurotransmitter receptors mediate manipulation-induced antihyperalgesia. Rats were injected with capsaicin (50 microl, 0.2%) into one ankle joint and mechanical withdrawal threshold measured before and after injection. The mechanical withdrawal threshold decreases 2 h after capsaicin injection. Two hours after capsaicin injection, the following drugs were administered intrathecally: bicuculline, blocks gamma-aminobutyric acid (GABAA) receptors; naloxone, blocks opioid receptors; yohimbine blocks, alpha2-adrenergic receptors; and methysergide, blocks 5-HT(1/2) receptors. In addition, NAN-190, ketanserin, and MDL-72222 were administered to selectively block 5-HT1A, 5-HT2A, and 5-HT3 receptors, respectively. Knee joint manipulation was performed 15 min after administration of drug. The knee joint was flexed and extended to end range of extension while the tibia was simultaneously translated in an anterior to posterior direction. The treatment group received three applications of manipulation, each 3 min in duration separated by 1 min of rest. Knee joint manipulation after capsaicin injection into the ankle joint significantly increases the mechanical withdrawal threshold for 45 min after treatment. Spinal blockade of 5-HT(1/2) receptors with methysergide prevented, while blockade of alpha2-adrenergic receptors attenuated, the manipulation-induced antihyperalgesia. NAN-190 also blocked manipulation-induced antihyperalgesia suggesting that effects of methysergide are mediated by 5-HT1A receptor blockade. However, spinal blockade of opioid or GABAA receptors had no effect on manipulation induced-antihyperalgesia. Thus, the antihyperalgesia produced by joint manipulation appears to involve descending inhibitory mechanisms that utilize serotonin and noradrenaline.
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Affiliation(s)
- D.A. Skyba
- Neuroscience Graduate Program, University of Iowa, Iowa City, IA, USA
- Pain Research Program, University of Iowa, Iowa City, IA, USA
| | - R. Radhakrishnan
- Physical Therapy and Rehabilitation Science Graduate Program, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
- Pain Research Program, University of Iowa, Iowa City, IA, USA
| | - J.J. Rohlwing
- Physical Therapy and Rehabilitation Science Graduate Program, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
| | - A. Wright
- School of Physiotherapy, Curtin University of Technology, Perth, WA, Australia
| | - K.A. Sluka
- Neuroscience Graduate Program, University of Iowa, Iowa City, IA, USA
- Physical Therapy and Rehabilitation Science Graduate Program, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
- Pain Research Program, University of Iowa, Iowa City, IA, USA
- Corresponding author. Address: Physical Therapy and Rehabilitation Science Graduate Program, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA. Tel.: +1-319-335-9791; fax: +1-319-335-9707. E-mail address: (K.A. Sluka)
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Roles of alpha1- and alpha2-adrenoceptors in the nucleus raphe magnus in opioid analgesia and opioid abstinence-induced hyperalgesia. J Neurosci 2003. [PMID: 12944526 DOI: 10.1523/jneurosci.23-21-07950.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Noradrenaline and alpha-adrenoceptors have been implicated in the modulation of pain in various behavioral conditions. Noradrenergic neurons and synaptic inputs are present in neuronal circuits critical for pain modulation, but their actions on neurons in those circuits and consequently the mechanisms underlying noradrenergic modulation of pain remain unclear. In this study, both recordings in vitro and behavioral analyses in vivo were used to examine cellular and behavioral actions mediated by alpha1- and alpha2-adrenoceptors on neurons in the nucleus raphe magnus. We found that alpha1- and alpha2-receptors were colocalized in the majority of a class of neurons (primary cells) that inhibit spinal pain transmission and are excited during opioid analgesia. Activation of the alpha1-receptor depolarized whereas alpha2-receptor activation hyperpolarized these neurons through a decrease and an increase, respectively, in potassium conductance. Blockade of the excitatory alpha1-receptor or activation of the inhibitory alpha2-receptor significantly attenuated the analgesia induced by local opioid application, suggesting that alpha1-receptor-mediated synaptic inputs in these primary cells contribute to their excitation during opioid analgesia. In the other cell class (secondary cells) that is thought to facilitate spinal nociception and is inhibited by analgesic opioids, only alpha1-receptors were present. Blocking the alpha1-receptor in these cells significantly reduced the hyperalgesia (increased pain) induced by opioid abstinence. Thus, state-dependent activation of alpha1-mediated synaptic inputs onto functionally distinct populations of medullary pain-modulating neurons contributes to opioid-induced analgesia and opioid withdrawal-induced hyperalgesia.
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26
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Cucchiaro G, Commons KG. Alpha 4 nicotinic acetylcholine receptor subunit links cholinergic to brainstem monoaminergic neurotransmission. Synapse 2003; 49:195-205. [PMID: 12774304 DOI: 10.1002/syn.10218] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Agonists of nicotinic receptors containing the alpha4-subunit produce antinociception accompanied by several adverse side effects. The purpose of this study was to determine the distribution of the alpha4-subunit of nicotinic acetylcholine receptors (nAChR) in brainstem monoaminergic nuclei that may contribute to these effects using dual labeling immunofluorescence methods. The alpha4-subunit immunoreactivity was enriched in serotonergic (nucleus raphe magnus, pallidus, obscurus, and dorsalis) and noradrenergic (A5, locus coeruleus (LC), A7) areas associated with antinociception, where it was commonly colocalized with serotonin (5-HT) or tyrosine hydroxylase (TH) immunoreactivity. However, it was also noted that alpha4 was present in all other brainstem monoaminergic nuclei examined (adrenergic C1-C3, noradrenergic A1-alpha4, dopamine A9 and A10, nucleus raphe medianus). To determine if alpha4 agonists could impact neural activity in brainstem, monoaminergic nuclei that are associated with antinociception, the expression of c-Fos in response to the systemic administration of epibatidine (2.5, 5, or 10 microg/kg) was examined. Epibatidine produced a robust (2-5-fold) increase in c-Fos expression, which was not dose dependent, in all of these areas examined except the nucleus raphe magnus. These results suggest that the alpha4 subunit is positioned to mediate the effects of acetylcholine widely across many, if not all, monoaminergic neurons in the brainstem. These observations emphasize the potential involvement of noradrenergic, as well as serotonergic mechanisms in epibatidine's analgesic effects, and they also suggest that even selective alpha4 ligand may have widespread effects on brain monoamine neurotransmission.
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Affiliation(s)
- Giovanni Cucchiaro
- Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
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Abstract
Chronic pain is a complex problem with staggering negative health and economic consequences. The complexity of chronic pain is presented within Cervero and Laird's model that describes three phases of pain, including pain without tissue damage, pain with tissue damage and inflammation, and neuropathic pain. The increased afferent input in phases 2 and 3 of chronic pain produces marked changes in primary afferents, dorsal root ganglia, and spinal cord dorsal horn. These changes promote the symptoms of chronic pain, including spontaneous pain, hyperalgesia, and allodynia. Increased afferent input also evokes supraspinal input to the dorsal horn, including biphasic innervation from the ventromedial medulla and A7 catecholamine cell group, that promotes hyperalgesia and allodynia. More rostral brain structures, such as the lateral hypothalamus, amygdala, and hippocampus, may also play a role in chronic pain. Although much has been discovered about the multiple pathological mechanisms involved in chronic pain, further research is needed to fully comprehend these mechanisms.
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Affiliation(s)
- Janean E Holden
- The University of Illinois at Chicago, 718 College of Nursing, Chicago, IL 60612-7350, USA.
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Miranda HF, Sierralta F, Pinardi G. Carbachol interactions with nonsteroidal anti-inflammatory drugs. Can J Physiol Pharmacol 2002; 80:1173-9. [PMID: 12564643 DOI: 10.1139/y02-145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The inhibition of cyclooxygenase enzymes by nonsteroidal anti-inflammatory drugs (NSAIDs) does not completely explain the antinociceptive efficacy of these agents. It is known that cholinergic agonists are antinociceptive, and this study evaluates the interactions between carbachol and some NSAIDs. Antinociceptive activity was evaluated in mice by the acetic acid writhing test. Dose-response curves were constructed for NSAIDs and carbachol, administered either intraperitoneally (i.p.) or intrathecally (i.t.). The interactions of carbachol with NSAIDs were evaluated by isobolographic analysis after the simultaneous administration of fixed proportions of carbachol with each NSAID. All of the drugs were more potent after spinal than after systemic administration. The combinations of NSAIDs and carbachol administered i.p. were supra-additive; however, the i.t. combinations were only additive. Isobolographic analysis of the coadministration of NSAIDs and carbachol and the fact that atropine antagonized the synergistic effect suggest that carbachol may strongly modulate the antinociceptive activity of NSAIDs; thus, central cholinergic modulation would be an additional mechanism for the antinociceptive action of NSAIDs, unrelated to prostaglandin biosynthesis inhibition.
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Affiliation(s)
- H F Miranda
- Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Independencia 1027, Santiago 7, Chile.
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Holden JE, Van Poppel AY, Thomas S. Antinociception from lateral hypothalamic stimulation may be mediated by NK(1) receptors in the A7 catecholamine cell group in rat. Brain Res 2002; 953:195-204. [PMID: 12384253 DOI: 10.1016/s0006-8993(02)03285-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Stimulation of the lateral hypothalamus (LH) produces antinociception that is modified by intrathecal alpha-adrenergic antagonists. Spinally-projecting noradrenergic neurons in the LH have not been identified, suggesting that the LH may innervate brainstem noradrenergic neurons, such as the A7 catecholamine cell group in the dorsolateral pontine tegmentum, that modify nociception at the level of the spinal cord dorsal horn. Recently we demonstrated in neuroanatomical studies that substance P-immunoreactive neurons in the LH project the A7 area. To identify a functional connection between substance P neurons in the LH and the A7 cell group, the cholinergic agonist carbachol (125 nmol) was microinjected into the LH of female Sprague-Dawley rats and antinociception was obtained on the tail flick or foot withdrawal test. Cobalt chloride (100 nM) was then microinjected near the A7 cell group to block synaptic activation of spinally-projecting A7 neurons, which were identified using tyrosine-hydroxylase immunoreactivity. Within 5 min of the cobalt chloride injection, the antinociceptive effect of carbachol stimulation was blocked. In another set of experiments, the NK(1) receptor antagonist L-703-606 (5 microg) was microinjected near the A7 cell group following LH stimulation with carbachol. L-703-606 also abolished LH-induced antinociception. These results support the conclusion that antinociception produced by activating substance P neurons in the LH is mediated in part by the subsequent activation of spinally-projecting noradrenergic neurons in the A7 cell group.
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Affiliation(s)
- Janean E Holden
- Department of Medical-Surgical Nursing, The University of Illinois at Chicago, 718 College of Nursing (M/C 802), 845 S. Damen Avenue, Chicago, IL 60612-7350, USA.
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Proudfit HK. The challenge of defining brainstem pain modulation circuits. THE JOURNAL OF PAIN 2002; 3:350-4; discussion 358-9. [PMID: 14622736 DOI: 10.1054/jpai.2002.127777] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Chiang CY, Hu B, Hu JW, Dostrovsky JO, Sessle BJ. Central sensitization of nociceptive neurons in trigeminal subnucleus oralis depends on integrity of subnucleus caudalis. J Neurophysiol 2002; 88:256-64. [PMID: 12091551 DOI: 10.1152/jn.00944.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our recent studies have shown that application to the tooth pulp of the inflammatory irritant mustard oil (MO) produces a prolonged (>40 min) "central sensitization" reflected in neuroplastic changes in the mechanoreceptive field (RF) and response properties of nociceptive brain stem neurons in subnuclei oralis (Vo) and caudalis (Vc) of the trigeminal spinal tract nucleus. In view of the previously demonstrated ascending modulatory influence of Vc on Vo, our aim was to determine whether the Vo neuroplastic changes induced by MO application to the tooth pulp depend on an ascending influence from Vc. In chloralose/urethan-anesthetized rats, MO application to the pulp produced significant increases in Vo nociceptive neuronal orofacial RF size and responses to mechanical noxious stimuli that lasted as long as 40-60 min. These changes were not affected by vehicle (saline) microinjected into Vc at 20 min after MO application, but 0.3 microl of a 5 mM CoCl(2) solution microinjected into the ipsilateral Vc produced a reversible blockade of the MO-induced Vo neuroplastic changes. A similar volume and concentration of CoCl(2) solution injected into subnucleus interpolaris of the trigeminal spinal tract nucleus did not affect the MO-induced neuroplastic changes in Vo. These findings indicate that inflammatory pulp-induced central sensitization in Vo is dependent on the functional integrity of Vc.
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Affiliation(s)
- Chen Yu Chiang
- Faculty of Dentistry, University of Toronto, Ontario M5G 1G6, Canada
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Miranda HF, Sierralta F, Pinardi G. Neostigmine interactions with non steroidal anti-inflammatory drugs. Br J Pharmacol 2002; 135:1591-7. [PMID: 11934798 PMCID: PMC1573279 DOI: 10.1038/sj.bjp.0704599] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2001] [Revised: 11/28/2001] [Accepted: 01/08/2002] [Indexed: 12/21/2022] Open
Abstract
1. The common mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs) is the inhibition of the enzyme cyclo-oxygenase (COX), however, this inhibition is not enough to completely account for the efficacy of these agents in several models of acute pain. 2. It has been demonstrated that cholinergic agents can induce antinociception, but the nature of the interaction between these agents and NSAIDs drugs has not been studied. The present work evaluates, by isobolographic analysis, the interactions between the cholinergic indirect agonist neostigmine (NEO) and NSAIDs drugs, using a chemical algesiometric test. 3. Intraperitoneal (i.p.) or intrathecal (i.t.) administration of NEO and of the different NSAIDs produced dose-dependent antinociception in the acetic acid writhing test of the mouse. 4. The i.p. or i.t. co-administration of fixed ratios of ED(50) fractions of NSAIDs and NEO, resulted to be synergistic or supra-additive for the combinations ketoprofen (KETO) and NEO, paracetamol (PARA) and NEO) and diclofenac (DICLO) and NEO administered i.p. However, the same combinations administered i.t. were only additive. In addition, the combinations meloxicam (MELO) and NEO and piroxicam (PIRO) and NEO, administered either i.p. or i.t., were additive. 5. The results suggest that the co-administration of NEO with some NSAIDs (e.g. KETO, PARA or DICLO) resulted in a synergistic interaction, which may provide evidence of supraspinal antinociception modulation by the increased acetylcholine concentration in the synaptic cleft of cholinergic interneurons. The interaction obtained between neostigmine and the NSAIDs could carry important clinical implications.
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Affiliation(s)
- Hugo F Miranda
- Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, Casilla 70.000, Santiago 7, Chile.
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Abstract
Upon receipt in the dorsal horn (DH) of the spinal cord, nociceptive (pain-signalling) information from the viscera, skin and other organs is subject to extensive processing by a diversity of mechanisms, certain of which enhance, and certain of which inhibit, its transfer to higher centres. In this regard, a network of descending pathways projecting from cerebral structures to the DH plays a complex and crucial role. Specific centrifugal pathways either suppress (descending inhibition) or potentiate (descending facilitation) passage of nociceptive messages to the brain. Engagement of descending inhibition by the opioid analgesic, morphine, fulfils an important role in its pain-relieving properties, while induction of analgesia by the adrenergic agonist, clonidine, reflects actions at alpha(2)-adrenoceptors (alpha(2)-ARs) in the DH normally recruited by descending pathways. However, opioids and adrenergic agents exploit but a tiny fraction of the vast panoply of mechanisms now known to be involved in the induction and/or expression of descending controls. For example, no drug interfering with descending facilitation is currently available for clinical use. The present review focuses on: (1) the organisation of descending pathways and their pathophysiological significance; (2) the role of individual transmitters and specific receptor types in the modulation and expression of mechanisms of descending inhibition and facilitation and (3) the advantages and limitations of established and innovative analgesic strategies which act by manipulation of descending controls. Knowledge of descending pathways has increased exponentially in recent years, so this is an opportune moment to survey their operation and therapeutic relevance to the improved management of pain.
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Affiliation(s)
- Mark J Millan
- Department of Psychopharmacology, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy/Seine, Paris, France.
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34
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Svokos K, Nalwalk JW, Leurs R, Menge WM, Timmerman H, Hough LB. A role for spinal, but not supraspinal, alpha(2) adrenergic receptors in the actions of improgan, a powerful, non-opioid analgesic. Brain Res 2001; 923:12-9. [PMID: 11743967 DOI: 10.1016/s0006-8993(01)03191-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Improgan is a derivative of cimetidine that induces non-opioid antinociception after intracerebroventricular (i.c.v.) administration, but the mechanism of action of this compound remains unknown. Since activation of either supraspinal or spinal alpha(2) adrenergic receptors can induce antinociception, and since improgan showed affinity for these receptors in vitro, the effects of the alpha(2) antagonist yohimbine on improgan antinociception were presently studied in rats on the hot plate and tail flick tests. Systemic yohimbine pretreatment (4 mg/kg, i.p.) completely blocked improgan antinociception (80 microg, i.c.v.), suggesting a mediator role for alpha(2) receptors. However, i.c.v. pretreatment with yohimbine (30 microg) had no effect on improgan antinociception. Since this treatment completely antagonized clonidine antinociception (40 microg, i.c.v.), supraspinal alpha(2) receptors seem to mediate the antinociceptive effects of clonidine, but not that produced by improgan. In contrast, intrathecal (i.t.) yohimbine pretreatment (30 microg) completely blocked the antinociception elicited by i.c.v. improgan and i.c.v. morphine. These results suggest that spinal (but not supraspinal) alpha(2) adrenergic receptors play a significant role in the pain-relieving actions of improgan. Furthermore, although improgan shows some affinity at alpha(2) receptors, this drug does not act directly at these receptors to induce antinociceptive responses. Like several other classes of analgesics, improgan-like drugs seem to activate non-opioid, descending pain-relieving circuits.
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Affiliation(s)
- K Svokos
- Center for Neuropharmacology and Neuroscience, Albany Medical College MC-136, Albany, NY 12208, USA
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35
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Decker MW, Meyer MD, Sullivan JP. The therapeutic potential of nicotinic acetylcholine receptor agonists for pain control. Expert Opin Investig Drugs 2001; 10:1819-30. [PMID: 11772288 DOI: 10.1517/13543784.10.10.1819] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Due to the limitations of currently available analgesics, a number of novel alternatives are currently under investigation, including neuronal nicotinic acetylcholine receptor (nAChR) agonists. During the 1990s, the discovery of the antinociceptive properties of the potent nAChR agonist epibatidine in rodents sparked interest in the analgesic potential of this class of compounds. Although epibatidine also has several mechanism-related toxicities, the identification of considerable nAChR diversity suggested that the toxicities and therapeutic actions of the compound might be mediated by distinct receptor subtypes. Consistent with this view, a number of novel nAChR agonists with antinociceptive activity and improved safety profiles in preclinical models have now been identified, including A-85380, ABT-594, DBO-83, SIB-1663 and RJR-2403. Of these, ABT-594 is the most advanced and is currently in Phase II clinical evaluation. Nicotinically-mediated antinociception has been demonstrated in a variety of rodent pain models and is likely mediated by the activation of descending inhibitory pathways originating in the brainstem with the predominant high-affinity nicotine site in brain, the alpha4beta2 subtype, playing a critical role. Thus, preclinical findings suggest that nAChR agonists have the potential to be highly efficacious treatments in a variety of pain states. However, clinical proof-of-principle studies will be required to determine if nAChR agonists are active in pathological pain.
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Affiliation(s)
- M W Decker
- Dept. 4N5, Building AP-9A/3, 100 Abbott Park Rd., Abbott Park, IL 60064-6125, USA.
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36
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Holden JE, Naleway E. Microinjection of carbachol in the lateral hypothalamus produces opposing actions on nociception mediated by alpha(1)- and alpha(2)-adrenoceptors. Brain Res 2001; 911:27-36. [PMID: 11489441 DOI: 10.1016/s0006-8993(01)02567-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Electrical stimulation of the lateral hypothalamus (LH) produces antinociception partially blocked by intrathecal alpha-adrenergic antagonists, but the mechanism underlying this effect is not clear. Evidence from immunological studies demonstrates that substance P-immunoreactive neurons in the LH project near the A7 catecholamine cell group, a group of noradrenergic neurons in the pons known to effect antinociception in the spinal cord dorsal horn. Such evidence suggests that LH neurons may activate A7 neurons to produce antinociception. To test this hypothesis, the cholinergic agonist carbachol was microinjected into the LH at doses of 63, 125 and 250 nmol and the resulting effects on tail-flick and nociceptive foot-withdrawal latencies were measured. All three doses significantly increased response latencies on both tests, with the 125-nmol dose providing the optimal effect. Intrathecal injection of the opioid antagonist naltrexone (97 nmol) partially reversed antinociception, but neither the alpha(2)-adrenoceptor antagonist yohimbine nor the alpha(1)-adrenoceptor antagonist WB4101 altered latencies. However, two sequential doses of yohimbine blocked LH-induced antinociception on both tests. In contrast, two sequential doses of WB4101 increased nociceptive responses on both the tail-flick and foot-withdrawal tests. These findings, and those of published reports, suggest that neurons in the LH activate spinally projecting methionine enkephalin neurons, as well as two populations of A7 noradrenergic neurons that exert a bidirectional effect on nociception. One of these populations increases nociception through the action of alpha(1)-adrenoceptors and the other inhibits nociception through the action of alpha(2)-adrenoceptors in the spinal cord dorsal horn.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Analgesia
- Animals
- Carbachol/pharmacology
- Cholinergic Agonists/pharmacology
- Dose-Response Relationship, Drug
- Efferent Pathways/drug effects
- Efferent Pathways/metabolism
- Female
- Hypothalamic Area, Lateral/drug effects
- Hypothalamic Area, Lateral/metabolism
- Injections, Spinal
- Nociceptors/drug effects
- Nociceptors/metabolism
- Norepinephrine/metabolism
- Pain/metabolism
- Pain/physiopathology
- Pain Measurement/drug effects
- Pons/drug effects
- Pons/metabolism
- Posterior Horn Cells/drug effects
- Posterior Horn Cells/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/metabolism
- Substance P/metabolism
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Affiliation(s)
- J E Holden
- Department of Medical-Surgical Nursing, The University of Illinois at Chicago, Chicago, IL 60612-7350, USA.
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Smeets WJ, González A. Catecholamine systems in the brain of vertebrates: new perspectives through a comparative approach. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 33:308-79. [PMID: 11011071 DOI: 10.1016/s0165-0173(00)00034-5] [Citation(s) in RCA: 300] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A comparative analysis of catecholaminergic systems in the brain and spinal cord of vertebrates forces to reconsider several aspects of the organization of catecholamine systems. Evidence has been provided for the existence of extensive, putatively catecholaminergic cell groups in the spinal cord, the pretectum, the habenular region, and cortical and subcortical telencephalic areas. Moreover, putatively dopamine- and noradrenaline-accumulating cells have been demonstrated in the hypothalamic periventricular organ of almost every non-mammalian vertebrate studied. In contrast with the classical idea that the evolution of catecholamine systems is marked by an increase in complexity going from anamniotes to amniotes, it is now evident that the brains of anamniotes contain catecholaminergic cell groups, of which the counterparts in amniotes have lost the capacity to produce catecholamines. Moreover, a segmental approach in studying the organization of catecholaminergic systems is advocated. Such an approach has recently led to the conclusion that the chemoarchitecture and connections of the basal ganglia of anamniote and amniote tetrapods are largely comparable. This review has also brought together data about the distribution of receptors and catecholaminergic fibers as well as data about developmental aspects. From these data it has become clear that there is a good match between catecholaminergic fibers and receptors, but, at many places, volume transmission seems to play an important role. Finally, although the available data are still limited, striking differences are observed in the spatiotemporal sequence of appearance of catecholaminergic cell groups, in particular those in the retina and olfactory bulb.
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Affiliation(s)
- W J Smeets
- Graduate School of Neurosciences of Amsterdam, Research Institute of Neurosciences, Amsterdam, The Netherlands.
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Nuseir K, Proudfit HK. Bidirectional modulation of nociception by GABA neurons in the dorsolateral pontine tegmentum that tonically inhibit spinally projecting noradrenergic A7 neurons. Neuroscience 2000; 96:773-83. [PMID: 10727795 DOI: 10.1016/s0306-4522(99)00603-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The A7 catecholamine cell group in the dorsolateral pontine tegmentum constitutes an important part of the descending pathways that modulate nociception. Evidence from immunocytochemical studies demonstrate that noradrenergic A7 neurons are densely innervated by GABA terminals arising from GABA neurons that are located in the dorsolateral pontine tegmentum medial to the A7 cell group. GABA(A) receptors are also located on the somata and dendrites of noradrenergic A7 neurons. These findings suggest that noradrenergic neurons in the A7 cell group may be under tonic inhibitory control by GABA neurons. To test this hypothesis, the GABA(A) antagonist bicuculline methiodide in doses of 0.2 or 1.0nmol was microinjected into sites located dorsal to the A7 cell group and the resulting effects on tail flick and nociceptive foot withdrawal responses were measured. Both doses of bicuculline produced significant increases in tail flick latencies and small, but significant, increases in foot withdrawal latencies. Intrathecal injection of the alpha(2)-adrenoceptor antagonist yohimbine, in a dose of 76.7nmol (30microg), attenuated the antinociceptive effect of bicuculline on both the tail and the feet. In contrast, the alpha(1)-adrenoceptor antagonist WB4101, in a nearly equimolar dose of 78.6nmol (30microg), increased the antinociceptive effect of bicuculline on both the tail and the feet. Intrathecal injection of the antagonists alone did not consistently alter nociceptive responses of either the feet or the tail. These findings suggest that noradrenergic neurons in the A7 cell group are tonically inhibited by local GABA neurons. Furthermore, these findings suggest that inhibition of GABA(A) receptors located on spinally-projecting A7 noradrenergic neurons disinhibits, or activates, two populations of A7 neurons that have opposing effects on nociception. One of these populations facilitates nociception by an action mediated by alpha(1)-adrenoceptors in the spinal cord dorsal horn and the other population inhibits nociception by an action mediated by alpha(2)-adrenoceptors.
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Affiliation(s)
- K Nuseir
- Department of Pharmacology, University of Illinois at Chicago, Chicago, IL 60612, USA
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39
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Abstract
Compounds acting at both nicotinic and muscarinic acetylcholine receptors appear to have antinociceptive activity, and acetylcholine release in the spinal cord may be involved in endogenous pain control. The therapeutic potential of most cholinergic agonists or of agents that increase synaptic acetylcholine is limited by side effect liabilities. Recent studies, however, have identified some compounds with improved safety profiles. Multiple subtypes of nicotinic and muscarinic receptors exist, and molecular and pharmacological studies are just beginning to identify which subtypes are involved in the antinociceptive effects of cholinergic receptor activation. Further advances in this area will be necessary to determine if the rational design of subtype selective cholinergic agonists will provide novel analgesic agents.
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Affiliation(s)
- M W Decker
- Neurological and Urological Diseases Research, Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, Illinois 60064-6125, USA.
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