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Asiedu K. Neurophysiology of corneal neuropathic pain and emerging pharmacotherapeutics. J Neurosci Res 2024; 102:e25285. [PMID: 38284865 DOI: 10.1002/jnr.25285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/12/2023] [Accepted: 12/02/2023] [Indexed: 01/30/2024]
Abstract
The altered activity generated by corneal neuronal injury can result in morphological and physiological changes in the architecture of synaptic connections in the nervous system. These changes can alter the sensitivity of neurons (both second-order and higher-order projection) projecting pain signals. A complex process involving different cell types, molecules, nerves, dendritic cells, neurokines, neuropeptides, and axon guidance molecules causes a high level of sensory rearrangement, which is germane to all the phases in the pathomechanism of corneal neuropathic pain. Immune cells migrating to the region of nerve injury assist in pain generation by secreting neurokines that ensure nerve depolarization. Furthermore, excitability in the central pain pathway is perpetuated by local activation of microglia in the trigeminal ganglion and alterations of the descending inhibitory modulation for corneal pain arriving from central nervous system. Corneal neuropathic pain may be facilitated by dysfunctional structures in the central somatosensory nervous system due to a lesion, altered synaptogenesis, or genetic abnormality. Understanding these important pathways will provide novel therapeutic insight.
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Affiliation(s)
- Kofi Asiedu
- School of Optometry & Vision Science, University of New South Wales, Sydney, New South Wales, Australia
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García-López C, Gómez-Huertas C, Sánchez-González JM, Borroni D, Rodríguez-Calvo-de-Mora M, Romano V, Rachwani-Anil R, Ramos-López JF, Ortiz-Pérez S, Rocha-de-Lossada C. Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons. J Clin Med 2022; 11:jcm11051424. [PMID: 35268515 PMCID: PMC8911328 DOI: 10.3390/jcm11051424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/02/2022] [Accepted: 03/03/2022] [Indexed: 12/01/2022] Open
Abstract
This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.
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Affiliation(s)
- Celia García-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Carmen Gómez-Huertas
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - José-María Sánchez-González
- Department of Physics of Condensed Matter, Optics Area, University of Seville, 41004 Seville, Spain
- Correspondence: ; Tel.: +34-955-42-08-61
| | - Davide Borroni
- Department of Doctoral Studies, Riga Stradins University, LV-1007 Riga, Latvia;
- Cornea Research Unit, ADVALIA Vision, 20145 Milan, Italy
| | - Marina Rodríguez-Calvo-de-Mora
- Department of Ophthalmology, Hospital Regional Universitario de Málaga, 29010 Málaga, Spain;
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
| | - Vito Romano
- Department of Eye and Vision Science Ophthalmology, St Paul’s Eye Hospital, Liverpool L7 8XP, UK;
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK
- Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, 25121 Brescia, Italy
| | | | - Juan-Francisco Ramos-López
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
| | - Santiago Ortiz-Pérez
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Surgery, Faculty of Medicine, University of Granada, 18010 Granada, Spain
| | - Carlos Rocha-de-Lossada
- Department of Ophthalmology, Hospital Universitario Virgen de las Nieves, 18014 Granada, Spain; (C.G.-L.); (C.G.-H.); (J.-F.R.-L.); (S.O.-P.); (C.R.-d.-L.)
- Department of Ophthalmology (Qvision), Vithas Almería, 04120 Almería, Spain
- Department of Ophthalmology, Ceuta Medical Center, 51001 Ceuta, Spain
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Wu F, Zhao Y, Zhang H. Ocular Autonomic Nervous System: An Update from Anatomy to Physiological Functions. Vision (Basel) 2022; 6:vision6010006. [PMID: 35076641 PMCID: PMC8788436 DOI: 10.3390/vision6010006] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 11/16/2022] Open
Abstract
The autonomic nervous system (ANS) confers neural control of the entire body, mainly through the sympathetic and parasympathetic nerves. Several studies have observed that the physiological functions of the eye (pupil size, lens accommodation, ocular circulation, and intraocular pressure regulation) are precisely regulated by the ANS. Almost all parts of the eye have autonomic innervation for the regulation of local homeostasis through synergy and antagonism. With the advent of new research methods, novel anatomical characteristics and numerous physiological processes have been elucidated. Herein, we summarize the anatomical and physiological functions of the ANS in the eye within the context of its intrinsic connections. This review provides novel insights into ocular studies.
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Strohmaier CA, Kiel JW, Reitsamer HA. Episcleral venous pressure response to brain stem stimulation: Effect of topical lidocaine. Exp Eye Res 2021; 212:108766. [PMID: 34529959 DOI: 10.1016/j.exer.2021.108766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/28/2021] [Accepted: 09/12/2021] [Indexed: 11/16/2022]
Abstract
Episcleral venous pressure (EVP) is important for steady state intraocular pressure (IOP), as it has to be overcome by aqueous humor in order to leave the eye. Recent evidence suggests a neuronal tone being present, as topical anesthesia lowered EVP. The superior salivatory nucleus in the brainstem could be identified to elicit increases in EVP during electrical stimulation. In the present study the effect of topical anesthesia on the stimulation effect was investigated. 8 Spraque Dawley rats were anesthetized, artificially ventilated with CO2 monitoring and continuous blood pressure monitoring. Intraocular pressure was measured continuously through a cannula in the vitreous body. Episcleral venous pressure was measured by direct cannulation of an episcleral vein via a custom made glass pipette connected to a servonull micropressure system. Electrical stimulation of the superior salivatory nucleus (9 μA, 200 pulses of 1 ms duration) increased EVP from 8.51 ± 1.82 mmHg to 10.97 ± 1.93 mmHg (p = 0.004). After application of topical lidocaine EVP increased from 7.42 ± 1.59 mmHg to 9.77 ± 1.65 mmHg (p = 0.007). The EVP response to stimulation before and after lidocaine application was not statistically significantly different (2.45 ± 0.5 vs 2.35 ± 0.49 mmHg, p = 0.69), while the decrease in baseline EVP was (8.51 vs. 7.42 mmHg, p = 0.045). The present data suggest that distinct neuronal mechanisms controlling the episcleral circulation of rats exist. This is in keeping with previous reports of two distinct arterio-venous anastomoses, one in the limbal circulation and one in the conjunctival/episcleral circulation.
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Affiliation(s)
- Clemens A Strohmaier
- Ophthalmology/Optometry, Johannes Kepler University, Linz, Austria; Ophthalmology/Optometry, Paracelsus Medical University, Salzburg, Austria; Ophthalmology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
| | - Jeffrey W Kiel
- Ophthalmology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
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Dual enkephalinase inhibitor PL265: a novel topical treatment to alleviate corneal pain and inflammation. Pain 2019; 160:307-321. [PMID: 30412056 DOI: 10.1097/j.pain.0000000000001419] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ocular pain is a core symptom of inflammatory or traumatic disorders affecting the anterior segment. To date, the management of chronic ocular pain remains a therapeutic challenge in ophthalmology. The main endogenous opioids (enkephalins) play a key role in pain control but exhibit only transient analgesic effects due to their rapid degradation. The aim of this study was to explore the antinociceptive and anti-inflammatory effects of topical administration of PL265 (a dual enkephalinase inhibitor) on murine models of corneal pain. On healthy corneas, chronic PL265 topical administration did not alter corneal integrity nor modify corneal mechanical and chemical sensitivity. Then, on murine models of corneal pain, we showed that repeated instillations of PL265 (10 mM) significantly reduced corneal mechanical and chemical hypersensitivity. PL265-induced corneal analgesia was completely antagonized by naloxone methiodide, demonstrating that PL265 antinociceptive effects were mediated by peripheral corneal opioid receptors. Moreover, flow cytometry (quantification of CD11b+ cells) and in vivo confocal microscopy analysis revealed that instillations of PL265 significantly decreased corneal inflammation in a corneal inflammatory pain model. Chronic PL265 topical administration also decreased Iba1 and neuronal injury marker (ATF3) staining in the nucleus of primary sensory neurons of ipsilateral trigeminal ganglion. These results open a new avenue for ocular pain treatment based on the enhancement of endogenous opioid peptides' analgesic effects in tissues of the anterior segment of the eye. Dual enkephalinase inhibitor PL265 seems to be a promising topical treatment for safe and effective alleviation of ocular pain and inflammation.
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Abstract
This study provides evidence for the presence of opioid-receptors in the retina, optic nerve, and optic nerve head astrocytes. These receptors were measured by more than one technique including Western blotting, immunohistochemistry, and functional assays such as scotopic electroretinogram (ERG) and Pattern ERG. I also have provided evidence in recently published work from my laboratory that opioid receptors, more specifically δ-opioid receptors, play crucial roles in retina neuroprotection against ischemic and glaucomatous injuries. This chapter provides detailed procedures to measure opioid receptor activation and their roles in retina neuroprotection using functional assays such as scotopic ERG and pattern ERG.
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Jin J, Xu GX, Yuan ZL. Influence of the hypothalamic arcuate nucleus on intraocular pressure and the role of opioid peptides. PLoS One 2014; 9:e82315. [PMID: 24691128 PMCID: PMC3972173 DOI: 10.1371/journal.pone.0082315] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 10/22/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND An opioid peptide neuron/humoral feedback regulation might be involved in changes of intraocular pressure (IOP). The aims of this study are to investigate the effects of arcuate nucleus (ARC) and opioid peptides on intraocular pressure (IOP). METHODS Fifty-four healthy purebred New Zealand white rabbits (108 eyes) were randomly divided into 4 groups, including control group, electrical stimulation group, [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) group, and [D-Pen 2, D-Pen5]- enkephalin (DPDPE) group. Bilateral IOP was measured after unilateral electrical stimulation of the ARC or unilateral microinjection into the ARC of the selective μ-opioid receptor agonist DAMGO or the selective δ opioid receptor agonist DPDPE, both alone and after pre-administration of either the non-selective opioid receptor antagonist naloxone or saline. RESULTS Both electrical stimulation in ARC and micro-injection either or opioid receptor agonists, DAMGO or DPDPE, respectively, caused a significant bilateral reduction in IOP (P<0.05) which was more pronounced in the ipsilateral than in the contralateral eye. Pretreatment with naloxone prevented some, but not all IOP reductions. CONCLUSION The ARC takes part in the negative regulation of IOP, an action that may involve opioid neurons.
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Affiliation(s)
- Ji Jin
- Department of Ophthalmology, the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Guo-xu Xu
- Department of Ophthalmology, the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Zhi-lan Yuan
- Department of Ophthalmology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China
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Ribeiro AP, Silva ML, Araújo RL, Ferrucci DL, Mineo T, Thiesen R, Bandarra MB, Laus JL. Expression of matrix metalloproteinases, type IV collagen, and interleukin-10 in rabbits treated with morphine after lamellar keratectomy. Vet Ophthalmol 2011; 15:153-63. [DOI: 10.1111/j.1463-5224.2011.00954.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Neuhuber W, Schrödl F. Autonomic control of the eye and the iris. Auton Neurosci 2010; 165:67-79. [PMID: 21071284 DOI: 10.1016/j.autneu.2010.10.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 08/08/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
Abstract
The vertebrate eye receives innervation from ciliary and pterygopalatine parasympathetic and cervical sympathetic ganglia as well as sensory trigeminal axons. The sympathetic and parasympathetic pathways represent the classical "core" of neural regulation of ocular homeostasis. Sensory trigeminal neurons are also involved in autonomic regulation by both providing the afferent limb of various reflexes and exerting their peptide-mediated local effector function. This arrangement is remarkably conserved throughout vertebrate classes although significant modifications are observed in anamniotes, in particular their irises. In higher primates and birds, intrinsic choroidal neurons emerged as a significant additional innervation component. They most likely mediate local vascular regulation and other local homeostatic tasks in foveate eyes. This review across the vertebrate classes outfolds the complex neuronal regulatory underpinnings across vertebrates that ensure proper visual function.
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Zhuravleva ZN, Kositsyn NS. Morphofunctional interactions of peripheral nerve fibers of the iris with neurons developing in the anterior chamber of the eye in rats. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2010; 40:615-9. [PMID: 20535569 DOI: 10.1007/s11055-010-9304-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 12/29/2008] [Indexed: 11/26/2022]
Abstract
Electron microscopic studies were performed on intraocular transplants of embryonic septal and hippocampal tissue developing in the anterior chamber of the eye in rats for 3-4 months. The aim of the study was to seek ultrastructural identification of peripheral nerve fibers entering transplants from the iris, and to assess their ability to establish true synaptic contacts with transplanted CNS neurons. Bundles of myelinated and unmyelinated axons surrounded by Schwann cell cytoplasm were seen within the perivascular spaces of ingrowing blood vessels. Both types of peripheral fiber were also identified in the neuropil areas of transplants. At the ultrastructural level, unmyelinated axons were found to be free of glial Schwann cell sheaths and to form typical asymmetrical synapses with the dendrites and dendritic spines of transplant neurons. These results provide evidence of the high morphofunctional plasticity of both parts (central, peripheral) of the nervous system.
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Affiliation(s)
- Z N Zhuravleva
- Laboratory for the Systemic Organization of Neurons, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia.
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Husain S, Potter DE. The opioidergic system: potential roles and therapeutic indications in the eye. J Ocul Pharmacol Ther 2008; 24:117-40. [PMID: 18355128 DOI: 10.1089/jop.2007.0112] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Shahid Husain
- Department of Ophthalmology, Storm Eye Institute, Hewitt Laboratory of the Ola B Williams Glaucoma Center, Medical University of South Carolina, Charleston, SC 29425, USA.
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Abstract
This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Abstract
Neurotrophic keratopathy is an ocular pathological condition that remains difficult to treat. The loss of trigeminal nerve function and corneal sensation that underlies this condition can lead to the development of various disorders of the cornea. Substance P, a sensory neurotransmitter produced by the trigeminal nerve, has been investigated for its effect on corneal epithelial wound healing. Substance P by itself has no direct effect on corneal epithelial migration, but it manifests a synergistic action with insulin-like growth factor-1 (IGF-1) in both epithelial migration in vitro and corneal wound healing in vivo. The minimal amino acid sequences of both substance P and IGF-1 that are required for such effects have been determined. With use of these minimal amino acid sequences, the potential adverse consequences of treatment with the full-length polypeptides may be avoided. The application of eye drops containing a substance P-derived peptide and IGF-1 has proved clinically effective for the treatment of patients with persistent epithelial defects of the cornea.
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Affiliation(s)
- Teruo Nishida
- Department of Biomolecular Recognition and Ophthalmology, Yamaguchi University School of Medicine, Ube City, Yamaguchi 755-8505, Japan.
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