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Carstens E, Carstens MI. Sensory Effects of Nicotine and Tobacco. Nicotine Tob Res 2022; 24:306-315. [PMID: 33955474 PMCID: PMC8842437 DOI: 10.1093/ntr/ntab086] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/28/2021] [Indexed: 12/21/2022]
Abstract
INTRODUCTION Ingestion of nicotine by smoking, vaping, or other means elicits various effects including reward, antinociception, and aversion due to irritation, bitter taste, and unpleasant side effects such as nausea and dizziness. AIMS AND METHODS Here we review the sensory effects of nicotine and the underlying neurobiological processes. RESULTS AND CONCLUSIONS Nicotine elicits oral irritation and pain via the activation of neuronal nicotinic acetylcholine receptors (nAChRs) expressed by trigeminal nociceptors. These nociceptors excite neurons in the trigeminal subnucleus caudalis (Vc) and other brainstem regions in a manner that is significantly reduced by the nAChR antagonist mecamylamine. Vc neurons are excited by lingual application of nicotine and exhibit a progressive decline in firing to subsequent applications, consistent with desensitization of peripheral sensory neurons and progressively declining ratings of oral irritation in human psychophysical experiments. Nicotine also elicits a nAChR-mediated bitter taste via excitation of gustatory afferents. Nicotine solutions are avoided even when sweeteners are added. Studies employing oral self-administration have yielded mixed results: Some studies show avoidance of nicotine while others report increased nicotine intake over time, particularly in adolescents and females. Nicotine is consistently reported to increase human pain threshold and tolerance levels. In animal studies, nicotine is antinociceptive when delivered by inhalation of tobacco smoke or systemic infusion, intrathecally, and by intracranial microinjection in the pedunculopontine tegmentum, ventrolateral periaqueductal gray, and rostral ventromedial medulla. The antinociception is thought to be mediated by descending inhibition of spinal nociceptive transmission. Menthol cross-desensitizes nicotine-evoked oral irritation, reducing harshness that may account for its popularity as a flavor additive to tobacco products. IMPLICATIONS Nicotine activates brain systems underlying reward and antinociception, but at the same time elicits aversive sensory effects including oral irritation and pain, bitter taste, and other unpleasant side effects mediated largely by nicotinic acetylcholine receptors (nAChRs). This review discusses the competing aversive and antinociceptive effects of nicotine and exposure to tobacco smoke, and the underlying neurobiology. An improved understanding of the interacting effects of nicotine will hopefully inform novel approaches to mitigate nicotine and tobacco use.
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Affiliation(s)
- Earl Carstens
- Department of Neurobiology, Physiology and Behavior University of California, Davis, CA, USA
| | - M Iodi Carstens
- Department of Neurobiology, Physiology and Behavior University of California, Davis, CA, USA
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Schwartz A, Bellissimo N. Nicotine and energy balance: A review examining the effect of nicotine on hormonal appetite regulation and energy expenditure. Appetite 2021; 164:105260. [PMID: 33848592 DOI: 10.1016/j.appet.2021.105260] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 03/31/2021] [Accepted: 04/06/2021] [Indexed: 12/15/2022]
Abstract
Nicotine has been shown to decrease appetite, food intake (FI) and body weight, but the mechanisms are unclear. The purpose of this review was to examine research on the effects of nicotine on energy balance by exploring physiological mechanisms and hormone regulation related to FI, subjective appetite and energy expenditure (EE). We searched PubMed and MEDLINE, and included articles investigating the effects of nicotine on central appetite regulation, FI, leptin, peptide-YY (PYY), ghrelin, glucagon-like peptide-1 (GLP-1), adiponectin, cholecystokinin (CCK), orexin, and EE. A total of 65 studies were included in the qualitative synthesis and review. Our findings suggest that the decrease in appetite and FI may be attributed to nicotinic alterations of neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) but the effect of nicotine on FI remains unclear. Furthermore, nicotine increases resting EE (REE) and physical activity EE (PAEE) in both smokers and non-smokers; and these increases may be a result of the catecholaminergic effect of nicotine. Decreases in body weight and appetite experienced by nicotine users results from increased EE and changes in the central hypothalamic regulation of appetite. There is not enough evidence to implicate a relationship between peripheral hormones and changes in appetite or FI after nicotine use. Although nicotine increases REE and PAEE, the effect of nicotine on other components of EE warrants further research. We conclude that further research evaluating the effect of nicotine on appetite hormones, FI and EE in humans is warranted.
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Affiliation(s)
| | - Nick Bellissimo
- School of Nutrition, Ryerson University, Toronto, Ontario, Canada.
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Ni F, Ogura T, Lin W. Electronic Cigarette Liquid Constituents Induce Nasal and Tracheal Sensory Irritation in Mice in Regionally Dependent Fashion. Nicotine Tob Res 2021; 22:S35-S44. [PMID: 33320249 PMCID: PMC7737480 DOI: 10.1093/ntr/ntaa174] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/01/2020] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Electronic cigarettes (e-cigs) are currently used by millions of adults and adolescents worldwide. Major respiratory symptoms, such as coughing reported by e-cig users, including patients with e-cig, or vaping, product use-associated lung injury (EVALI), indicate e-cig constituent-induced sensory irritation. However, e-cig constituent-induced nociceptive activity in nasal and tracheal respiratory epithelia (RE) and neuronal activation in the trigeminal ganglia and brainstem nuclei, which receive airway chemosensory inputs have not been examined and compared. Comparisons of physiological responses between freebase nicotine and nicotine salts are also missing. AIMS AND METHODS Event-related potential (ERP) was recorded electrophysiologically to assess mouse nasal and tracheal RE chemosensory responses to various flavorings, nicotine, including freebase and nicotine salts, e-liquid mixtures, and tussigenic stimuli. Also, mice were subjected to inhalation exposure to aerosol of a vanilla-flavored e-liquid or air (control), and the activated-trigeminal nociceptive neurons and brainstem neurons were examined using immunohistochemistry. RESULTS Individual constituents and mixtures of e-liquids, capsaicin, and citric and acetic acids evoked significantly larger ERP in the nose than in the trachea with the exception of menthol. ERP responses to freebase nicotine were significantly larger than protonated nicotine. Four nicotine salts (benzoate, lactate, levulinate, and salicylate) induced similar responses. Compared with air-exposed mice, e-liquid aerosol-exposed mice showed a significant increase in numbers of activated trigeminal nociceptive neurons and brainstem neurons in the spinal trigeminal nucleus, paratrigeminal nucleus, and nucleus tractus solitarius. CONCLUSIONS E-liquid constituents region-dependently stimulate airway nociceptive chemosensory systems, and freebase nicotine is more potent than protonated nicotine. IMPLICATIONS Neural abnormalities have been implicated in the development of nasal and respiratory illnesses. The higher sensitivity of the nasal nociceptive chemosensory system to nicotine and flavorings may indicate a health risk for e-liquid aerosol-induced upper airway illnesses via neurogenic alteration and warrants further investigation.
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Affiliation(s)
- Fenge Ni
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD
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Panneton WM, Pan B, Gan Q. Somatotopy in the Medullary Dorsal Horn As a Basis for Orofacial Reflex Behavior. Front Neurol 2017; 8:522. [PMID: 29066998 PMCID: PMC5641296 DOI: 10.3389/fneur.2017.00522] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/19/2017] [Indexed: 11/24/2022] Open
Abstract
The somatotopy of the trigeminocervical complex of the rat was defined as a basis for describing circuitry for reflex behaviors directed through the facial motor nucleus. Thus, transganglionic transport of horseradish peroxidase conjugates applied to individual nerves/peripheral receptive fields showed that nerves innervating oropharyngeal structures projected most rostrally, followed by nerves innervating snout, periocular, and then periauricular receptive fields most caudally. Nerves innervating mucosae or glabrous receptive fields terminated densely in laminae I, II, and V of the trigeminocervical complex, while those innervating hairy skin terminated in laminae I-V. Projections to lamina II exhibited the most focused somatotopy when individual cases were compared. Retrograde transport of FluoroGold (FG) deposited into the facial motor nucleus resulted in labeled neurons almost solely in lamina V of the trigeminocervical complex. The distribution of these labeled neurons paralleled the somatotopy of primary afferent fibers, e.g., those labeled after FG injections into a functional group of motoneurons innervating lip musculature were found most rostrally while those labeled after injections into motoneurons innervating snout, periocular and preauricular muscles, respectively, were found at progressively more caudal levels. Anterograde transport of injections of biotinylated dextran amine into lamina V at different rostrocaudal levels of the trigeminocervical complex confirmed the notion that the somatotopy of orofacial sensory fields parallels the musculotopy of facial motor neurons. These data suggest that neurons in lamina V are important interneurons in a simple orofacial reflex circuit consisting of a sensory neuron, interneuron and motor neuron. Moreover, the somatotopy of primary afferent fibers from the head and neck confirms the "onion skin hypothesis" and suggests rostral cervical dermatomes blend seamlessly with "cranial dermatomes." The transition area between subnucleus interpolaris and subnucleus caudalis is addressed while the paratrigeminal nucleus is discussed as an interface between the somatic and visceral nervous systems.
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Affiliation(s)
- W. Michael Panneton
- Department of Anesthesiology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - BingBing Pan
- Department of Anesthesiology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Anesthesiology, Hunan Provincial People’s Hospital, Changsha, China
| | - Qi Gan
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
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Stojakovic A, Espinosa EP, Farhad OT, Lutfy K. Effects of nicotine on homeostatic and hedonic components of food intake. J Endocrinol 2017; 235:R13-R31. [PMID: 28814527 PMCID: PMC5578410 DOI: 10.1530/joe-17-0166] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 07/17/2017] [Indexed: 12/30/2022]
Abstract
Chronic tobacco use leads to nicotine addiction that is characterized by exaggerated urges to use the drug despite the accompanying negative health and socioeconomic burdens. Interestingly, nicotine users are found to be leaner than the general population. Review of the existing literature revealed that nicotine affects energy homeostasis and food consumption via altering the activity of neurons containing orexigenic and anorexigenic peptides in the brain. Hypothalamus is one of the critical brain areas that regulates energy balance via the action of these neuropeptides. The equilibrium between these two groups of peptides can be shifted by nicotine leading to decreased food intake and weight loss. The aim of this article is to review the existing literature on the effect of nicotine on food intake and energy homeostasis and report on the changes that nicotine brings about in the level of these peptides and their receptors that may explain changes in food intake and body weight induced by nicotine. Furthermore, we review the effect of nicotine on the hedonic aspect of food intake. Finally, we discuss the involvement of different subtypes of nicotinic acetylcholine receptors in the regulatory action of nicotine on food intake and energy homeostasis.
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Affiliation(s)
- Andrea Stojakovic
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
- Mitochondrial Neurobiology and Therapeutics LaboratoryMayo Clinic, Rochester, Minnesota, USA
| | - Enma P Espinosa
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
- Faculty of MedicineSchool of Clinica Biochemistry, Pontifical Catholic University of Ecuador (PUCE), Quito, Ecuador
| | - Osman T Farhad
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
| | - Kabirullah Lutfy
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
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Magara J, Michou E, Raginis-Zborowska A, Inoue M, Hamdy S. Exploring the effects of synchronous pharyngeal electrical stimulation with swallowing carbonated water on cortical excitability in the human pharyngeal motor system. Neurogastroenterol Motil 2016; 28:1391-400. [PMID: 27061591 DOI: 10.1111/nmo.12839] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 03/17/2016] [Indexed: 01/30/2023]
Abstract
BACKGROUND Previous reports have revealed that excitation of human pharyngeal motor cortex can be induced by pharyngeal electrical stimulation (PES) and swallowing carbonated water (CW). This study investigated whether combining PES with swallowing (of still water, SW or CW) can potentiate this excitation in either cortical and/or brain stem areas assessed with transcranial and transcutaneous magnetic stimulation (TMS). METHODS Fourteen healthy volunteers participated and were intubated with an intraluminal catheter to record pharyngeal electromyography and deliver PES. Each participant underwent baseline corticopharyngeal, hand and craniobulbar motor-evoked potential (MEP) measurements. Subjects were then randomized to receive each of four 10-min interventions (PES only, ShamPES+CW, PES+CW, and PES+SW). Corticobulbar, craniobulbar and hand MEPs were then remeasured for up to 60 min and data analyzed using anova and post hoc t-tests. KEY RESULTS A two-way rmanova for Interventions × Time-point showed a significant corticopharyngeal interaction (p = 0.010). One-way anova with post hoc t-tests indicated significant cortical changes with PES only at 45 (p = 0.038) and 60 min (p = 0.023) and ShamPES+CW immediately (p = 0.008) but not with PES+CW or PES+SW. By contrast, there were immediate craniobulbar amplitude changes only with PES+CW (p = 0.020) which were not sustained. CONCLUSIONS & INFERENCES We conclude that only PES produced long-term changes in corticopharyngeal excitability whereas combination stimuli were less effective. Our data suggest that PES alone rather than in combination, may be better for the patients who have difficulty in performing voluntary swallows.
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Affiliation(s)
- J Magara
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.,Centre for Gastrointestinal Sciences, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, Salford, UK
| | - E Michou
- Centre for Gastrointestinal Sciences, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, Salford, UK
| | - A Raginis-Zborowska
- Centre for Gastrointestinal Sciences, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, Salford, UK
| | - M Inoue
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - S Hamdy
- Centre for Gastrointestinal Sciences, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, University of Manchester, Salford, UK
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Gees M, Alpizar YA, Luyten T, Parys JB, Nilius B, Bultynck G, Voets T, Talavera K. Differential Effects of Bitter Compounds on the Taste Transduction Channels TRPM5 and IP3 Receptor Type 3. Chem Senses 2014; 39:295-311. [DOI: 10.1093/chemse/bjt115] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Abstract
INTRODUCTION The ability of nicotine, the primary psychoactive substance in tobacco smoke, to regulate appetite and body weight is one of the factors cited by smokers that prevents them from quitting and is the primary reason for smoking initiation in teenage girls. The regulation of feeding and metabolism by nicotine is complex, and recent studies have begun to identify nicotinic acetylcholine receptor (nAChR) subtypes and circuits or cell types involved in this regulation. DISCUSSION We will briefly describe the primary anatomical and functional features of the input, output, and central integration structures of the neuroendocrine systems that regulate energy homeostasis. Then, we will describe the nAChR subtypes expressed in these structures in mammals to identify the possible molecular targets for nicotine. Finally, we will review the effects of nicotine and its withdrawal on feeding and energy metabolism and attribute them to potential central and peripheral cellular targets.
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Affiliation(s)
- Michele Zoli
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41125, Modena, Italy.
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Pascual-Font A, Hernández-Morato I, McHanwell S, Vázquez T, Maranillo E, Sañudo J, Valderrama-Canales FJ. The central projections of the laryngeal nerves in the rat. J Anat 2011; 219:217-28. [PMID: 21599662 DOI: 10.1111/j.1469-7580.2011.01390.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The larynx serves respiratory, protective, and phonatory functions. The motor and sensory innervation to the larynx controlling these functions is provided by the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). Classical studies state that the SLN innervates the cricothyroid muscle and provides sensory innervation to the supraglottic cavity, whereas the RLN supplies motor innervation to the remaining intrinsic laryngeal muscles and sensory innervation to the infraglottic cavity, but recent data suggest a more complex anatomical and functional organisation. The current neuroanatomical tracing study was undertaken to provide a comprehensive description of the central brainstem connections of the axons within the SLN and the RLN, including those neurons that innervate the larynx. The study has been carried out in 41 adult male Sprague-Dawley rats. The central projections of the laryngeal nerves were labelled following application of biotinylated dextran amines onto the SLN, the RLN or both. The most remarkable result of the study is that in the rat the RLN does not contain any afferent axons from the larynx, in contrast to the pattern observed in many other species including man. The RLN supplied only special visceromotor innervation to the intrinsic muscles of the larynx from motoneurons in the nucleus ambiguus (Amb). All the afferent axons innervating the larynx are contained within the SLN, and reach the nucleus of the solitary tract. The SLN also contained secretomotor efferents originating from motoneurons in the dorsal motor nucleus of the vagus, and special visceral efferent fibres from the Amb. In conclusion, the present study shows that in the rat the innervation of the larynx differs in significant ways from that described in other species.
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Affiliation(s)
- Arán Pascual-Font
- Departamento de Anatomía y Embriología Humana I, Facultad de Medicina, Universidad Complutense de Madrid, Spain
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Nakatsuka M, Iwai Y. Expression of TRPV4 in the stimulated rat oral mucous membrane--nociceptive mechanisms of lingual conical papillae. Okajimas Folia Anat Jpn 2009; 86:45-54. [PMID: 19877445 DOI: 10.2535/ofaj.86.45] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The study was supported by 2006-2007 Aid Program for Overseas Training of the Promotion and Mutual Aid Corporation for Private School of Japan and International Exchange Grant, Osaka Dental University. We studied the function of TRPV4 expression and its neuronal activation in response to noxious stimulation of oral mucosa. The intermolar region of dorsal lingual eminence (IDLE) of rats was stimulated with 10 microl of either normal saline or 5% formalin. Immunohistological studies of the TRPV4, pERK and serotonin (5HT) expression in designated regions of tongues and brainstems were performed for studying the descending pain modulatory system in response to nociception. Specimens of the experimental IDLE demonstrated a significant increase of TRPV4 activity in particular in stratum basale of conical papillae (p < 0.01). pERK-IR positive neurons were significantly increased in the RMg (p < 0.05), Sp5C (p < 0.05) and Md (p < 0.01); TRPV4-IR neurons were found to show a similar distribution with pERK-IR cells in the peripheral Sp5C (p < 0.05). A significant increase of 5HT expression was observed in the RMg (p < 0.01), RPa (p < 0.01) and ROb (p < 0.05). The results suggest that TRPV4 in the oral mucosa is nociceptor of peripheral hyperalgesia, and pERK expression in the Sp5C is closely related with central hyperalgesia of the nociception. Furthermore, pERK-IR cells of the central 5HT nervous system are activated to accelerate 5HT release for neuronal modulation of the descending pain modulatory system in response to nociception.
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Affiliation(s)
- Michiko Nakatsuka
- Dept. of Oral Anatomy, Osaka Dental University, Kuzuha Hanazono-cho 8-1, Hirakata, Osaka 573-1121, Japan.
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Felizardo R, Boucher Y, Braud A, Carstens E, Dauvergne C, Zerari-Mailly F. Trigeminal projections on gustatory neurons of the nucleus of the solitary tract: A double-label strategy using electrical stimulation of the chorda tympani and tracer injection in the lingual nerve. Brain Res 2009; 1288:60-8. [DOI: 10.1016/j.brainres.2009.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/05/2009] [Accepted: 07/01/2009] [Indexed: 11/17/2022]
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Modulation of paratrigeminal nociceptive neurons following temporomandibular joint inflammation in rats. Exp Neurol 2008; 214:209-18. [PMID: 18778706 DOI: 10.1016/j.expneurol.2008.08.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 08/07/2008] [Accepted: 08/10/2008] [Indexed: 11/23/2022]
Abstract
To evaluate the involvement of paratrigeminal nucleus (Pa5) nociceptive neurons in temporomandibular joint (TMJ) inflammation-induced pain and its autonomic correlates, we conducted behavioral, single unit recording and Fos immunohistochemical studies in anesthetized rats. Nocifensive behaviors to mechanical, heat or cold stimulation of the lateral face over the TMJ region were significantly enhanced in the TMJ-inflamed rats for 10-14 days after injection of complete Freund's adjuvant (CFA) into the TMJ and gradually decreased at the end of the 14-day observation period. Lowering of the nocifensive threshold in TMJ-inflamed rats lasted longer in vagus nerve-transected rats than vagus nerve-intact rats. A large number of Fos-like immunoreactive (LI) cells were observed in the Pa5, and half of them were retrogradely labeled with Fluorogold (FG) injected into the parabrachial nucleus. Background activity of Pa5 wide dynamic range and nociceptive specific neurons was significantly higher in the TMJ-inflamed rats when compared with controls. Responses to mechanical stimuli were significantly higher in NS neurons in the TMJ-inflamed rats. All thermal responsive Pa5 neurons were exclusively sensitive to cold and the response to cold was significantly higher in the TMJ-inflamed rats compared with control rats. Vagus nerve stimulation significantly decreased responses to mechanical and cold stimuli as well as the background activity in TMJ-treated rats but not in TMJ-untreated rats. The present findings suggest that populations of Pa5 neurons are nociceptive and involved in TMJ inflammation-induced pain as well as in autonomic processes related to TMJ pain.
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Alioto OE, Lindsey CJ, Koepp J, Caous CA. Sensory sciatic nerve afferent inputs to the dorsal lateral medulla in the rat. Auton Neurosci 2008; 140:80-7. [PMID: 18514588 DOI: 10.1016/j.autneu.2008.04.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 04/11/2008] [Accepted: 04/15/2008] [Indexed: 12/18/2022]
Abstract
Investigations show the paratrigeminal nucleus (Pa5) as an input site for sensory information from the sciatic nerve field. Functional or physical disruption of the Pa5 alters behavioral and somatosensory responses to nociceptive hindpaw stimulation or sciatic nerve electrostimulation (SNS), both contralateral to the affected structure. The nucleus, an input site for cranial and spinal nerves, known for orofacial nociceptive sensory processing, has efferent connections to structures associated with nociception and cardiorespiratory functions. This study aimed at determining the afferent sciatic pathway to dorsal lateral medulla by means of a neuronal tract-tracer (biocytin) injected in the iliac segment of the sciatic nerve. Spinal cord samples revealed bilateral labeling in the gracile and pyramidal or cuneate tracts from survival day 2 (lumbar L1/L2) to day 8 (cervical C2/C3 segments) following biocytin application. From day 10 to day 20 medulla samples showed labeling of the contralateral Pa5 to the injection site. The ipsilateral paratrigeminal nucleus showed labeling on day 10 only. The lateral reticular nucleus (LRt) showed fluorescent labeled terminal fibers on day 12 and 14, after tracer injection to contralateral sciatic nerve. Neurotracer injection into the LRt of sciatic nerve-biocytin-treated rats produced retrograde labeled neurons soma in the Pa5 in the vicinity of biocytin labeled nerve terminals. Therefore, Pa5 may be considered one of the first sites in the brain for sensory/nociceptive inputs from the sciatic nerve. Also, the findings include Pa5 and LRt in the neural pathway of the somatosympathetic pressor response to SNS and nocifensive responses to hindpaw stimulation.
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Expression of Fos protein in brainstem after application of l-menthol to the rat nasal mucosa. Neurosci Lett 2008; 435:246-50. [PMID: 18343574 DOI: 10.1016/j.neulet.2008.02.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 02/04/2008] [Accepted: 02/20/2008] [Indexed: 11/23/2022]
Abstract
There are two functional pathways for the nasotrigeminal reflex: the spinal nucleus of trigeminal nerve (SPV) to the Kölliker-Fuse (KF) nucleus and the nucleus of solitary tract (NTS) to the lateral parabrachial nucleus (PBl). Although stimulation of the nasal mucosa by cool temperature induces respiratory depression, it is still unknown whether these nuclei are activated. In the present study, we examined the expression of Fos protein in rat brainstem neurons after nasal application of l-menthol, which is known to activate cold-sensitive nasal receptors. Application of l-menthol, but not paraffin oil, decreased the respiratory rate from 99.7+/-15.6 to 78.5+/-7.3 min(-1). Furthermore, a significantly higher density of Fos-immunoreactive cells was observed in the SPV and KF in the l-menthol rats than in the controls. In the SPV, the density of Fos-immunoreactive cells was highest at approximately 0.5mm rostral to the obex in both the l-menthol (48.5+/-11.5 cells/section) and paraffin oil (26.0+/-9.6 cells/section) groups. In the KF, the mean density of Fos-immunoreactive cells was highest at approximately 5.0mm rostral to the obex in both groups (l-menthol: 67.8+/-14.0 cells/section, control: 41.0+/-12.7 cells/section). The present study suggests that the SPV-KF pathway is important for the cold-induced respiratory depression.
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Cat odor, but not trimethylthiazoline (fox odor), activates accessory olfactory and defense-related brain regions in rats. Neuroscience 2008; 151:937-47. [DOI: 10.1016/j.neuroscience.2007.11.039] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 11/23/2007] [Accepted: 12/23/2007] [Indexed: 11/18/2022]
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Ma WL, Zhang WB, Xiong KH, Guo F. Visceral and orofacial somatic afferent fiber terminals converge onto the same neuron in paratrigeminal nucleus: An electron microscopic study in rats. Auton Neurosci 2007; 131:45-9. [PMID: 16962830 DOI: 10.1016/j.autneu.2006.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 06/17/2006] [Accepted: 06/26/2006] [Indexed: 01/02/2023]
Abstract
The paratrigeminal nucleus (Pa5) receives visceral sensory inputs through the vagus (X) and glossopharyngeal (IX) nerves and somatic sensory inputs through the trigeminal (V) nerve. In the present study, transganglionic transport of the WGA-HRP and Wallerian degeneration was used to identify whether two kinds of primary afferent fiber terminals converge onto a single neuron in the Pa5 at the utrastructural level. It was found that HRP-labeled and degenerated terminals originating from the IX and/or X nerves and infraorbital nerve formed asymmetrical synapses with unlabeled dendrites in the Pa5. Furthermore, approximately 7% (43/630) HRP-labeled and 31% (43/137) degenerated terminals formed synaptic connections with the same dendritic profiles simultaneously in the dorsal division of the Pa5. These results may provide a neuroanatomical substrate for integration of viscerosomatic sensory inputs associated with visceral and cardiovascular reflexes in the Pa5.
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Affiliation(s)
- Wen-Ling Ma
- Department of Anatomy and K K Leung Brain Research Centre, Fourth Military Medical University, Xi'an 710032, P R China.
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Koepp J, Lindsey CJ, Motta EM, Rae GA. Role of the paratrigeminal nucleus in nocifensive responses of rats to chemical, thermal and mechanical stimuli applied to the hind paw. Pain 2006; 122:235-244. [PMID: 16616416 DOI: 10.1016/j.pain.2006.01.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 12/16/2005] [Accepted: 01/25/2006] [Indexed: 11/29/2022]
Abstract
Anatomical and immunohystochemical data suggest the paratrigeminal nucleus (Pa5) may play a role in nociceptive processing. The current study examines the influence of unilateral Pa5 lesion on nocifensive responses of conscious rats to noxious thermal (Hargreaves test), mechanical (electronic von Frey and Randall-Selitto tests), and chemical (formalin 2.5%; 50 microl) stimuli applied to the hind paw. Lesion of the Pa5 induced by ibotenic acid did not affect the latency for radiant heat-induced withdrawal of either paw. In contrast, the mean mechanical threshold for withdrawal of the contralateral (but not ipsilateral) paw in Pa5-lesioned rats was reduced by approximately 45% and 20%, in electronic von Frey and Randall-Selitto tests, respectively, when compared to sham-operated animals. Conversely, animals with Pa5 lesions injected with formalin in the contralateral paw spent less time engaged in focused (licking, biting or scratching the injected paw) and total nocifensive behavior (i.e., focused nocifensive behavior plus protection of the injected paw during movements) in both the first and second phases of the test [ approximately 50% inhibition of each parameter during first phase (0-5 min) and at 20, 25, and 30 min of second phase, relative to the sham-operated group], but the number of paw-jerks was unaffected. Pa5 lesion also delayed the onset of second phase focused pain induced by formalin in the ipsilateral paw. The results suggest that the Pa5 integrates the supraspinal pain control system and plays a differential modulatory role in the central processing of mechanical and chemical nociceptive information.
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Affiliation(s)
- Janice Koepp
- Department of Pharmacology, Biological Sciences Center, Universidade Federal de Santa Catarina, Campus, Trindade, Florianópolis, SC 88010-970, Brazil Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil
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Luan F, Ma W, Zhang X, Zhang H, Liu M, Hu Z, Fan BT. Quantitative structure-activity relationship models for prediction of sensory irritants (logRD50) of volatile organic chemicals. CHEMOSPHERE 2006; 63:1142-53. [PMID: 16307788 DOI: 10.1016/j.chemosphere.2005.09.053] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 09/14/2005] [Accepted: 09/14/2005] [Indexed: 05/05/2023]
Abstract
Quantitative classification and regression models for prediction of sensory irritants (logRD50) of volatile organic chemicals (VOCs) have been developed. Each compound was represented by the calculated structural descriptors to encode constitutional, topological, geometrical, electrostatic, and quantum-chemical features. The heuristic method (HM) was then used to search the descriptor space and select the descriptors responsible for activity. The best classification results were found using support vector machine (SVM): the accuracy for training, test and overall data set is 96.5%, 85.7% and 94.4%, respectively. The nonlinear regression models were built by radial basis function neural networks (RNFNN) and SVM, respectively. The root mean squared errors (RMS) in prediction for the training, test and overall data set are 0.4755, 0.6322 and 0.5009 for reactive group, 0.2430, 0.4798 and 0.3064 for nonreactive group by RBFNN. The comparative results obtained by SVM are 0.4415, 0.7430 and 0.5140 for reactive group, 0.3920, 0.4520 and 0.4050 for nonreactive group, respectively. This paper proposes an effective method for poisonous chemicals screening and considering.
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Affiliation(s)
- Feng Luan
- Department of Chemistry, Lanzhou University, Lanzhou 730000, China
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Saxon DW, Hopkins DA. Ultrastructure and synaptology of the paratrigeminal nucleus in the rat: primary pharyngeal and laryngeal afferent projections. Synapse 2006; 59:220-34. [PMID: 16385507 DOI: 10.1002/syn.20233] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The paratrigeminal nucleus (PTN) receives primary afferent projections from the aerodigestive tract and orofacial regions and plays a role in the integration of visceral and somatic information. This study describes the fine structure of the rat PTN and the synaptology of primary afferent projections from the pharynx and larynx. Injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or cholera toxin-HRP (CT-HRP) were made into the wall of the pharynx or larynx to label primary afferent axon terminals. Light microscopic observations demonstrated that afferent axons terminated bilaterally in overlapping fields in the PTN. Electron microscopic observations of the PTN revealed that there were three distinct classes of neurons, based on morphology and axosomatic contacts. The most abundant neurons, Type 1, were fusiform in shape and received very few or no axosomatic contacts. Type 2 neurons contained prominent Nissl substance (rough endoplasmic reticulum) and few axosomatic contacts, while Type 3 neurons had many axosomatic synapses. Terminals containing round, clear vesicles and forming asymmetric contacts (round asymmetric, RA) with dendrites were the predominant synaptic type in the PTN. Primary afferent terminals from the pharynx and larynx were of the RA type and formed synaptic contacts with small-diameter (<1 microm) dendrites. Visceral primary afferent inputs from the pharynx and larynx overlap with trigeminal somatic afferents in the PTN and have similar synaptic morphology. The results support the concept that the PTN provides an anatomical substrate for mediating viscerovisceral and somatovisceral reflexes via efferent connections with autonomic centers in the brainstem.
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Affiliation(s)
- Dale W Saxon
- Department of Anatomy, Faculty of Medicine, Indiana University, Evansville Center for Medical Education, Evansville, Indiana 47712, USA
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Ma WL, Zhang WB, Feng G, Cai YL. Calbindin D28k-containing neurons in the paratrigeminal nucleus receive convergent nociceptive information and project to nucleus of the solitary tract in rat. Brain Res 2005; 1038:132-40. [PMID: 15757629 DOI: 10.1016/j.brainres.2005.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 12/21/2004] [Accepted: 01/01/2005] [Indexed: 11/21/2022]
Abstract
The paratrigeminal nucleus (PTN) receives orofacial somatic and visceral afferent fibers and contains many calbindin-D28k neurons (CB-containing neurons) that project to nucleus of the solitary tract (NTS). In the present study, retrograde and transganglionic tracing methods combined with immunofluorescence histochemistry and confocal laser scanning microscopy were used. After Fluoro-gold (FG) injection into the unilateral NTS, 74.4% FG-labeled neurons of ipsilateral PTN were double-labeled with CB. Furthermore, 41.0% and 32.5% FG/CB double-labeled neurons co-existed with Fos induced by nociceptive stimulation of the lips and the upper alimentary tract, respectively. In the PTN unilateral to FG injection site, 26.6% CB-LI neurons were double-labeled with PAG, 61.5% and 79.0% CB/PAG double-labeled neurons were triple-labeled with FG and Fos, and 22.9% FG/CB double-labeled neurons were triple-labeled with PAG, 84.3% FG/PAG double-labeled neurons expressed Fos induced by the upper alimentary tract stimulation. In the intact animals, 62.8% CB-LI neurons and 88.3% PAG-LI neurons co-existed with GABA(B)R, respectively. In addition, some terminals from the inferior alveolar nerve (IAN) were closely apposed to CB/Fos double-labeled or CB single-labeled neurons. These results suggested that CB-containing neurons in the PTN receive the nociceptive information converge from the orofacial area and visceral organs, and comprising the glutamatergic excitatory transmission pathway from the PTN to the NTS. This pathway might be modulated by GABA via the GABA(B) receptor.
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Affiliation(s)
- Wen-Ling Ma
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an 710032, PR China.
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Bae YC, Oh JM, Hwang SJ, Shigenaga Y, Valtschanoff JG. Expression of vanilloid receptor TRPV1 in the rat trigeminal sensory nuclei. J Comp Neurol 2004; 478:62-71. [PMID: 15334649 DOI: 10.1002/cne.20272] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Little is known about the central projection patterns of trigeminal afferent neurons expressing the vanilloid receptor TRPV1 and their coexpression of neuromodulatory peptides. To address these issues, we examined the distribution of TRPV1-positive neurons in the trigeminal ganglion (TG) and trigeminal sensory nuclei principalis (Vp), oralis (Vo), interpolaris (Vi), and caudalis (Vc) in the rat via light and electron microscopy. In addition, we studied the colocalization of TRPV1-positive neurons with substance P (SP) and calcitonin gene-related peptide (CGRP) via confocal microscopy. In TG, only small and medium-sized neurons were immunopositive for TRPV1. The staining for TRPV1 was found in axon collaterals in the dorsal parts of Vp, Vo, and Vi and in terminals and fibers throughout lamina I and the outer zone of lamina II (IIo) of Vc. With electron microscopy, TRPV1-positive fibers in the ascending and descending trigeminal tracts were found to be unmyelinated. Almost all TRPV1-positive terminals in Vc contained numerous large dense-core vesicles and formed synaptic contacts with single small dendrites. Multiple immunofluorescence revealed a high degree of colocalization of TRPV1 with SP and CGRP in TG neurons as well as in fibers and terminals confined to laminae I and IIo of Vc. These results suggest that the central projections of unmyelinated (C) afferents sensitive to noxious heat and capsaicin are organized differently between Vc and the rostral trigeminal nuclei and that Vc may play a role in the development of hyperalgesia.
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Affiliation(s)
- Yong Chul Bae
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea.
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