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Ostrow KL, Donaldson KJ, Caterina MJ, Belzberg A, Hoke A. The Secretomes of Painful Versus Nonpainful Human Schwannomatosis Tumor Cells Differentially Influence Sensory Neuron Gene Expression and Sensitivity. Sci Rep 2019; 9:13098. [PMID: 31511601 PMCID: PMC6739480 DOI: 10.1038/s41598-019-49705-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 08/27/2019] [Indexed: 01/08/2023] Open
Abstract
Schwannomatosis is a multiple tumor syndrome in which patients develop benign tumors along peripheral nerves throughout the body. The first symptom with which schwannomatosis patients often present, prior to discovery of tumors, is pain. This pain can be debilitating and is often inadequately alleviated by pharmacological approaches. Schwannomatosis-associated pain can be localized to the area of a tumor, or widespread. Moreover, not all tumors are painful, and the occurrence of pain is often unrelated to tumor size or location. We speculate that some individual tumors, but not others, secrete factors that act on nearby nerves to augment nociception by producing neuronal sensitization or spontaneous neuronal firing. We created cell lines from human SWN tumors with varying degrees of pain. We have found that conditioned medium (CM) collected from painful SWN tumors, but not that from nonpainful SWN tumors, sensitized DRG neurons, causing increased sensitivity to depolarization by KCl, increased response to noxious TRPV1 and TRPA1 agonists and also upregulated the expression of pain-associated genes in DRG cultures. Multiple cytokines were also detected at higher levels in CM from painful tumors. Taken together our data demonstrate a differential ability of painful versus non-painful human schwannomatosis tumor cells to secrete factors that augment sensory neuron responsiveness, and thus identify a potential determinant of pain heterogeneity in schwannomatosis.
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Affiliation(s)
- Kimberly Laskie Ostrow
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Neurosurgery Pain Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Katelyn J Donaldson
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Michael J Caterina
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Neurosurgery Pain Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Allan Belzberg
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Neurosurgery Pain Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Ahmet Hoke
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
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2
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Todorovic SM. Painful Diabetic Neuropathy: Prevention or Suppression? INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 127:211-25. [PMID: 27133151 DOI: 10.1016/bs.irn.2016.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Pain-sensing sensory neurons (nociceptors) of the dorsal root ganglia (DRG) and dorsal horn (DH) can become sensitized (hyperexcitable) in response to pathological conditions such as diabetes, which in turn may lead to the development of painful peripheral diabetic neuropathy (PDN). Because of incomplete knowledge about the mechanisms underlying painful PDN, current treatment for painful PDN has been limited to somewhat nonspecific systemic drugs that have significant side effects or potential for abuse. Recent studies have established that several ion channels in DRG and DH neurons are dysregulated and make a previously unrecognized contribution to sensitization of pain responses by enhancing excitability of nociceptors in animal models of type 1 and type 2 PDN. Furthermore, it has been reported that targeting posttranslational modification of nociceptive ion channels such as glycosylation and methylglyoxal metabolism can completely reverse mechanical and thermal hyperalgesia in diabetic animals with PDN in vivo. Understanding details of posttranslational regulation of nociceptive channel activity may facilitate development of novel therapies for treatment of painful PDN. We argue that pharmacological targeting of the specific pathogenic mechanism rather than of the channel per se may cause fewer side effects and reduce the potential for drug abuse in patients with diabetes.
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Affiliation(s)
- S M Todorovic
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
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3
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Affiliation(s)
- Slobodan M Todorovic
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
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4
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Schreiber AK, Nones CFM, Reis RC, Chichorro JG, Cunha JM. Diabetic neuropathic pain: Physiopathology and treatment. World J Diabetes 2015; 6:432-444. [PMID: 25897354 PMCID: PMC4398900 DOI: 10.4239/wjd.v6.i3.432] [Citation(s) in RCA: 237] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 11/26/2014] [Accepted: 02/09/2015] [Indexed: 02/05/2023] Open
Abstract
Diabetic neuropathy is a common complication of both type 1 and type 2 diabetes, which affects over 90% of the diabetic patients. Although pain is one of the main symptoms of diabetic neuropathy, its pathophysiological mechanisms are not yet fully known. It is widely accepted that the toxic effects of hyperglycemia play an important role in the development of this complication, but several other hypotheses have been postulated. The management of diabetic neuropathic pain consists basically in excluding other causes of painful peripheral neuropathy, improving glycemic control as a prophylactic therapy and using medications to alleviate pain. First line drugs for pain relief include anticonvulsants, such as pregabalin and gabapentin and antidepressants, especially those that act to inhibit the reuptake of serotonin and noradrenaline. In addition, there is experimental and clinical evidence that opioids can be helpful in pain control, mainly if associated with first line drugs. Other agents, including for topical application, such as capsaicin cream and lidocaine patches, have also been proposed to be useful as adjuvants in the control of diabetic neuropathic pain, but the clinical evidence is insufficient to support their use. In conclusion, a better understanding of the mechanisms underlying diabetic neuropathic pain will contribute to the search of new therapies, but also to the improvement of the guidelines to optimize pain control with the drugs currently available.
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Yang G, Shi Y, Yu J, Li Y, Yu L, Welling A, Hofmann F, Striessnig J, Juntti-Berggren L, Berggren PO, Yang SN. CaV1.2 and CaV1.3 channel hyperactivation in mouse islet β cells exposed to type 1 diabetic serum. Cell Mol Life Sci 2015; 72:1197-207. [PMID: 25292336 PMCID: PMC11113900 DOI: 10.1007/s00018-014-1737-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 09/02/2014] [Accepted: 09/22/2014] [Indexed: 11/28/2022]
Abstract
The voltage-gated Ca(2+) (CaV) channel acts as a key player in β cell physiology and pathophysiology. β cell CaV channels undergo hyperactivation subsequent to exposure to type 1 diabetic (T1D) serum resulting in increased cytosolic free Ca(2+) concentration and thereby Ca(2+)-triggered β cell apoptosis. The present study was aimed at revealing the subtypes of CaV1 channels hyperactivated by T1D serum as well as the biophysical mechanisms responsible for T1D serum-induced hyperactivation of β cell CaV1 channels. Patch-clamp recordings and single-cell RT-PCR analysis were performed in pancreatic β cells from CaV1 channel knockout and corresponding control mice. We now show that functional CaV1.3 channels are expressed in a subgroup of islet β cells from CaV1.2 knockout mice (CaV1.2(-/-)). T1D serum enhanced whole-cell CaV currents in islet β cells from CaV1.3 knockout mice (CaV1.3(-/-)). T1D serum increased the open probability and number of functional unitary CaV1 channels in CaV1.2(-/-) and CaV1.3(-/-) β cells. These data demonstrate that T1D serum hyperactivates both CaV1.2 and CaV1.3 channels by increasing their conductivity and number. These findings suggest CaV1.2 and CaV1.3 channels as potential targets for anti-diabetes therapy.
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Affiliation(s)
- Guang Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
- Jilin Academy of Traditional Chinese Medicine, Changchun, 130021 China
| | - Yue Shi
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Jia Yu
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Yuxin Li
- National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun, 130024 China
| | - Lina Yu
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Andrea Welling
- Forschergruppe, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 München, Germany
| | - Franz Hofmann
- Forschergruppe, Institut für Pharmakologie und Toxikologie, Technische Universität München, 80802 München, Germany
| | - Jörg Striessnig
- Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Lisa Juntti-Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Shao-Nian Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, 171 76 Stockholm, Sweden
- National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun, 130024 China
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Ghorbani ML, Nyborg NCB, Fjalland B, Sheykhzade M. Calcium activity of upper thoracic dorsal root ganglion neurons in zucker diabetic Fatty rats. Int J Endocrinol 2013; 2013:532850. [PMID: 23662103 PMCID: PMC3639628 DOI: 10.1155/2013/532850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 01/23/2023] Open
Abstract
The aim of the present study was to examine the calcium activity of C8-T5 dorsal root ganglion (DRG) neurons from Zucker diabetic fatty rats. In total, 8 diabetic ZDF fatty animals and 8 age-matched control ZDF lean rats were employed in the study. C8-T5 dorsal root ganglia were isolated bilaterally from 14 to 18 weeks old rats, and a primary culture was prepared. Calcium activity was measured ratiometrically using the fluorescent Ca(2+)-indicator Fura-2 acetoxymethyl ester. All neurons were stimulated twice with 20 mM K(+), followed by stimulation with either 0.3 or 0.5 μ M Capsaicin, alone or in combination with algogenic chemicals (bradykinin, serotonin, prostaglandin E2 (all 10(-5) M), and adenosine (10(-3) M)) at pH 7.4 and 6.0. Neurons from diabetic animals exhibited an overall increased response to stimulation with 20 mM K(+) compared to neurons from control. Stimulation with Capsaicin alone caused an augmented response in neurons from diabetic animals compared to control animals. When stimulated with a combination of Capsaicin and algogenic chemicals, no differences between the two groups of neurons were measured, neither at pH 7.4 nor 6.0. In conclusion, diabetes-induced alterations in calcium activity of the DRG neurons were found, potentially indicating altered neuronal responses during myocardial ischemia.
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Affiliation(s)
- Marie Louise Ghorbani
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- *Marie Louise Ghorbani:
| | | | - Bjarne Fjalland
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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Todorovic SM, Jevtovic-Todorovic V. T-type voltage-gated calcium channels as targets for the development of novel pain therapies. Br J Pharmacol 2011; 163:484-95. [PMID: 21306582 DOI: 10.1111/j.1476-5381.2011.01256.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
It is well recognized that voltage-gated calcium (Ca(2+)) channels modulate the function of peripheral and central pain pathways by influencing fast synaptic transmission and neuronal excitability. In the past, attention focused on the modulation of different subtypes of high-voltage-activated-type Ca(2+) channels; more recently, the function of low-voltage-activated or transient (T)-type Ca(2+) channels (T-channels) in nociception has been well documented. Currently, available pain therapies remain insufficient for certain forms of pain associated with chronic disorders (e.g. neuropathic pain) and often have serious side effects. Hence, the identification of selective and potent inhibitors and modulators of neuronal T-channels may help greatly in the development of safer, more effective pain therapies. Here, we summarize the available information implicating peripheral and central T-channels in nociception. We also discuss possible future developments aimed at selective modulation of function of these channels, which are highly expressed in nociceptors.
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Affiliation(s)
- Slobodan M Todorovic
- Department of Anesthesiology and Neuroscience, University of Virginia School of Medicine, Charlottesville, 22908-0710, USA.
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8
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Can ÖD, Öztürk Y, Öztürk N, Sagratini G, Ricciutelli M, Vittori S, Maggi F. Effects of treatment with St. John's Wort on blood glucose levels and pain perceptions of streptozotocin-diabetic rats. Fitoterapia 2011; 82:576-84. [DOI: 10.1016/j.fitote.2011.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/04/2011] [Accepted: 01/17/2011] [Indexed: 12/24/2022]
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Jagodic MM, Pathirathna S, Nelson MT, Mancuso S, Joksovic PM, Rosenberg ER, Bayliss DA, Jevtovic-Todorovic V, Todorovic SM. Cell-specific alterations of T-type calcium current in painful diabetic neuropathy enhance excitability of sensory neurons. J Neurosci 2007; 27:3305-16. [PMID: 17376991 PMCID: PMC6672477 DOI: 10.1523/jneurosci.4866-06.2007] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recent data indicate that T-type Ca2+ channels are amplifiers of peripheral pain signals, but their involvement in disorders of sensory neurons such as those associated with diabetes is poorly understood. To address this issue, we used a combination of behavioral, immunohistological, molecular, and electrophysiological studies in rats with streptozotocin (N-[methylnitrosocarbamoil]-D-glucosamine)-induced early diabetic neuropathy. We found that, in parallel with the development of diabetes-induced pain, T-type current density increased by twofold in medium-size cells from L4-L5 dorsal root ganglia (DRG) with a depolarizing shift in steady-state inactivation. This not only correlated closely with more prominent afterdepolarizing potentials (ADPs) but also increased cellular excitability manifested as a lower threshold for burst firing in diabetic than in control cells. T-type currents and ADPs were potently inhibited by nickel and enhanced by L-cysteine, suggesting that the Ca(V)3.2 T-type channel isoform was upregulated. Both control and diabetic DRG cells with ADPs stained positively for isolectin B4, but only diabetic cells responded robustly to capsaicin, suggesting enhanced nociceptive function. Because increased excitability of sensory neurons may result in such pathological perceptions of pain as hyperalgesia and allodynia, upregulation of T-type Ca2+ currents and enhanced Ca2+ entry into these cells could contribute to the development of symptoms in diabetic neuropathy.
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Affiliation(s)
| | | | - Michael T. Nelson
- Departments of Anesthesiology
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia 22908
| | | | | | | | - Douglas A. Bayliss
- Departments of Anesthesiology
- Pharmacology and
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia 22908
| | - Vesna Jevtovic-Todorovic
- Departments of Anesthesiology
- Neuroscience, and
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia 22908
| | - Slobodan M. Todorovic
- Departments of Anesthesiology
- Neuroscience, and
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, Virginia 22908
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10
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Torres-López JE, Juárez-Rojop IE, Granados-Soto V, Diaz-Zagoya JC, Flores-Murrieta FJ, Ortíz-López JUS, Cruz-Vera J. Peripheral participation of cholecystokinin in the morphine-induced peripheral antinociceptive effect in non-diabetic and diabetic rats. Neuropharmacology 2006; 52:788-95. [PMID: 17157334 DOI: 10.1016/j.neuropharm.2006.09.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 09/12/2006] [Accepted: 09/25/2006] [Indexed: 10/23/2022]
Abstract
The effects of cholecystokinin (CCK-8) and the CCK receptor antagonist proglumide, on antinociception induced by local peripheral (subcutaneous) injected morphine in non-diabetic (ND) and streptozotocin-induced diabetic (D) rats, were examined by means of the formalin test. Morphine induced dose-dependent antinociception both in ND and D rats. However, in D rats, antinociceptive morphine potency was about twofold less than in ND rats. Pre-treatment with CCK-8 abolished the antinociceptive effect of morphine in a dose-dependent manner in both groups of rats. Additionally, proglumide enhanced the antinociceptive effect induced by all doses of morphine tested. Both CCK-8 and proglumide had no effect on flinching behaviour when given alone to ND rats. Unlike ND rats, in D rats proglumide produced dose-dependent antinociception and CCK-8 enhanced formalin-evoked flinches, as observed during the second phase of the test. In conclusion, our data show a decrease in peripheral antinociceptive potency of morphine when diabetes was present. Additionally, peripheral CCK plays an antagonic role to the peripheral antinociceptive effect of morphine, additional to the well known CCK/morphine interaction at spinal and supraspinal level.
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Affiliation(s)
- Jorge E Torres-López
- Laboratorio Mecanismos del Dolor, Centro de Investigación y Posgrado, División Académica de Ciencias de la Salud, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico.
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11
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Yang SN, Berggren PO. The role of voltage-gated calcium channels in pancreatic beta-cell physiology and pathophysiology. Endocr Rev 2006; 27:621-76. [PMID: 16868246 DOI: 10.1210/er.2005-0888] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Voltage-gated calcium (CaV) channels are ubiquitously expressed in various cell types throughout the body. In principle, the molecular identity, biophysical profile, and pharmacological property of CaV channels are independent of the cell type where they reside, whereas these channels execute unique functions in different cell types, such as muscle contraction, neurotransmitter release, and hormone secretion. At least six CaValpha1 subunits, including CaV1.2, CaV1.3, CaV2.1, CaV2.2, CaV2.3, and CaV3.1, have been identified in pancreatic beta-cells. These pore-forming subunits complex with certain auxiliary subunits to conduct L-, P/Q-, N-, R-, and T-type CaV currents, respectively. beta-Cell CaV channels take center stage in insulin secretion and play an important role in beta-cell physiology and pathophysiology. CaV3 channels become expressed in diabetes-prone mouse beta-cells. Point mutation in the human CaV1.2 gene results in excessive insulin secretion. Trinucleotide expansion in the human CaV1.3 and CaV2.1 gene is revealed in a subgroup of patients with type 2 diabetes. beta-Cell CaV channels are regulated by a wide range of mechanisms, either shared by other cell types or specific to beta-cells, to always guarantee a satisfactory concentration of Ca2+. Inappropriate regulation of beta-cell CaV channels causes beta-cell dysfunction and even death manifested in both type 1 and type 2 diabetes. This review summarizes current knowledge of CaV channels in beta-cell physiology and pathophysiology.
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Affiliation(s)
- Shao-Nian Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology L1:03, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden.
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Sutachan JJ, Montoya G JV, Xu F, Chen D, Blanck TJJ, Recio-Pinto E. Pluronic F-127 affects the regulation of cytoplasmic Ca2+ in neuronal cells. Brain Res 2006; 1068:131-7. [PMID: 16387285 DOI: 10.1016/j.brainres.2005.11.003] [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] [Received: 03/09/2005] [Revised: 10/31/2005] [Accepted: 11/09/2005] [Indexed: 01/28/2023]
Abstract
Fura-2 is one of the most widely used cytoplasmic Ca2+ ([Ca2+]cyt) sensors. In studies using isolated dorsal root ganglion (DRG) neurons, the loading of Fura-2 AM is often facilitated by the use of pluronic F-127. In preliminary studies, we detected that the use of pluronic F-127 appeared to be affecting the depolarization-evoked [Ca2+]cyt transient in DRG neurons. To determine whether this was the case, we conducted a systematic study. Adult rat DRG neurons were cultured, and their response to 50 mM KCl was measured in sister cultured cells (isolated on the same day) that were loaded with 5 microM Fura-2AM in the absence or in the presence of 0.02% pluronic F-127. In the absence of pluronic F-127, the KCl-evoked [Ca2+]cyt transient changed with time, being wider on day 1 than on day 2 after plating. On day 2, the KCl-evoked [Ca2+]cyt transient was wider in neurons Fura-2 loaded in the presence of pluronic F-127. These results indicate that pluronic F-127 significantly alters depolarization-evoked [Ca2+]cyt transients, which may reflect alteration in regulation of [Ca2+]cyt in neuronal cells.
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Affiliation(s)
- Jhon-Jairo Sutachan
- Department of Anesthesiology, New York University School of Medicine, 550 First Avenue, RR605, New York, NY 10016, USA
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Abstract
BACKGROUND Diabetes remains the most common cause of neuropathy in the United States and is a significant source of morbidity and mortality, accounting for substantial suffering and billions of dollars in health care expenditures each year. REVIEW SUMMARY Our insight into the pathophysiology of the diabetic neuropathies has increased considerably over the last decade. aided by advances in the basic science of diabetes itself. A wide variety of potential mechanisms for nerve injury in diabetes has been identified, including the polyol pathway of glucose metabolism, oxidative nerve injury, the deposition of advanced glycosylation end products within the nerve and the effects of vascular insufficiency, among others. Diabetic neuropathy may take a variety of clinical forms beyond the well-known distal symmetric neuropathy, many of which are often misdiagnosed or overlooked entirely, sometimes with serious consequences for the patient. Proper therapy after diagnosis is also critical and may include not only primary management, but also treatment of painful diabetic neuropathy through an expanding repertoire of increasingly effective pharmacologic agents. Though primary treatment trials have not yet provided effective therapies, ongoing and future trials offer continuing promise. CONCLUSIONS The diabetic neuropathies are exceedingly common, but often improperly diagnosed and incompletely treated. A proper understanding of the mechanisms underlying these diseases and the clinical recognition of their various forms is highly important as appropriate primary and symptomatic management can substantially reduce the morbidity and mortality associated with these disorders.
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Affiliation(s)
- Clifton Gooch
- Electromyography Laboratory, Columbia University College of Physicians and Surgeons, Columbia Presbyterian Medical Center, 710 West 168th Street, 13th Floor, New York, NY 10032, USA.
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Li F, Obrosova IG, Abatan O, Tian D, Larkin D, Stuenkel EL, Stevens MJ. Taurine replacement attenuates hyperalgesia and abnormal calcium signaling in sensory neurons of STZ-D rats. Am J Physiol Endocrinol Metab 2005; 288:E29-36. [PMID: 15585600 DOI: 10.1152/ajpendo.00168.2004] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The etiology of painful diabetic neuropathy is poorly understood, but may result from neuronal hyperexcitability secondary to alterations of Ca2+ signaling in sensory neurons. The naturally occurring amino acid taurine functions as an osmolyte, antioxidant, Ca2+ modulator, inhibitory neurotransmitter, and analgesic such that its depletion in diabetes may predispose one to neuronal hyperexcitability and pain. This study reports the effects of taurine replacement on hyperalgesia and sensory neuron Ca2+ homeostasis in streptozotocin-diabetic (STZ-D) rats. Nondiabetic and STZ-D rats were treated with a 2% taurine-supplemented diet for 6-12 wk. Thermal hyperalgesia and mechanical allodynia were determined by measuring hindpaw withdrawal latency to radiant heat and the withdrawal threshold to the von Frey anesthesiometer. Intracellular Ca2+ signaling was explored in neurons from L4-L6 dorsal root ganglia (DRG), using fura 2 fluorescence. Taurine replacement of diabetic rats attenuated deficits of nerve conduction and prevented reductions of mechanical and thermal withdrawal threshold and latency, respectively. In small DRG sensory neurons from diabetic rats, recovery of intracellular Ca2+ concentration ([Ca2+]i) in response to KCl was slowed and 73% corrected by taurine. The amplitudes of caffeine and ATP-induced [Ca2+]i transients were decreased by 47 and 27% (P < 0.05), respectively, in diabetic rat DRG sensory neurons and corrected by 74 and 93% (P < 0.05), respectively, by taurine replacement. These data indicate that taurine is important in the regulation of neuronal Ca2+ signaling and that taurine deficiency may predispose one to nerve hyperexcitability and pain, complicating diabetes.
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Affiliation(s)
- Fei Li
- Department of Internal Medicine, Michigan Diabetes Research and Training Center, University of Michigan, Ann Arbor Veterans Administration Hospitals, Ann Arbor, Michigan, USA
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15
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Corrales A, Montoya G JV, Sutachan JJ, Cornillez-Ty G, Garavito-Aguilar Z, Xu F, Blanck TJJ, Recio-Pinto E. Transient increases in extracellular K+ produce two pharmacological distinct cytosolic Ca2+ transients. Brain Res 2005; 1031:174-84. [PMID: 15649442 DOI: 10.1016/j.brainres.2004.10.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2004] [Indexed: 11/24/2022]
Abstract
Transient increases in extracellular K+ are observed under various conditions, including repetitive neuronal firing, anoxia, ischemia and hypoglycemic coma. We studied changes in cytoplasmic Ca2+ ([Ca2+]cyt) evoked by pulses of KCl in human neuroblastoma SH-SY5Y cells and rat dorsal root ganglia (DRG) neurons at 37 degrees C. A "pulse" of KCl evoked two transient increases in [Ca2+]cyt, one upon addition of KCl (K+on) and the other upon removal of KCl (K+off). The K+on transient has been described in many cell types and is initiated by the activation of voltage-dependent Ca2+ channels followed by Ca2+-evoked Ca2+ release from intracellular Ca2+ stores. The level of KCl necessary to evoke the K+off transient depends on the type of neuron, in SH-SY5Y cells it required 100 mM KCl, in most (but not all) of dorsal root ganglia neurons it could be detected with 100-200 mM KCl and in a very few dorsal root ganglia neurons it was detectable at 20-50 mM KCl. In SH-SY5Y cells, reduction of extracellular Ca2+ inhibited the K+on more strongly than the K+off and slowed the decay of K+off. Isoflurane (1 mM) reduced the K+on)- but not the K+off-peak. However, isoflurane slowed the decay of K+off. The nonspecific cationic channel blocker La3+ (100 microM) had an effect similar to that of isoflurane. Treatment with thapsigargin (TG) at a concentration known to only deplete IP3-sensitive Ca2+ stores did not affect K+on or K+off, suggesting that Ca2+ release from the IP3-sensitive Ca2+ stores does not contribute to K+on and K+off transients and that the thapsigargin-sensitive Ca2+ ATPases do not contribute significantly to the rise or decay rates of these transients. These findings indicate that a pulse of extracellular K+ produces two distinct transient increases in [Ca2+]cyt.
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Affiliation(s)
- Alexandra Corrales
- Anesthesiology Department, New York University School of Medicine, 550 First Avenue, RR605, New York, NY 10016, USA
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16
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Abstract
Diabetes mellitus is a common cause of peripheral nervous system disorders that manifest in a variety of clinical forms, many of which are often misdiagnosed. Over the past two decades, our understanding of the pathophysiology of diabetic nerve injury has improved remarkably through the elucidation of the important roles of the polyol pathway of glucose metabolism, oxidative injury, advanced glycosylation end-products, vascular insufficiency, and other mechanisms. A large number of clinical treatment trials based upon this abundant scientific data have met with limited success, but ongoing and future trials offer promise for more dramatic success in treating this common cause of morbidity and mortality in the diabetic population.
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Affiliation(s)
- David Podwall
- Department of Neurology, Columbia University College of Physicians & Surgeons, 710 West 168th Street, 13th Floor, New York, NY 10032, USA
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17
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Shangguan Y, Hall KE, Neubig RR, Wiley JW. Diabetic neuropathy: inhibitory G protein dysfunction involves PKC-dependent phosphorylation of Goalpha. J Neurochem 2003; 86:1006-14. [PMID: 12887697 DOI: 10.1046/j.1471-4159.2003.01912.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We examined the hypothesis that decreased inhibitory G protein function in diabetic neuropathy is associated with increased protein kinase C (PKC)-dependent phosphorylation of the Goalpha subunit. Streptozotocin-induced diabetic rats were studied between 4 and 8 weeks after onset of diabetes and compared with aged-matched healthy animals as controls. Opioid-mediated inhibition of forskolin-stimulated cyclic AMP was significantly less in dorsal root ganglia (DRGs) from diabetic rats compared with controls. Activation of PKC in DRGs from control rats was associated with a significant decrease in opioid-mediated inhibition of forskolin-stimulated cyclic AMP that was similar to the decrease in inhibition observed in DRGs from diabetic rats. Both basal and PKC-mediated labeling of Goalpha with 32Pi was significantly less in DRGs from diabetic rats, supporting increased endogenous PKC-dependent phosphorylation of Goalpha. Probing of immunoprecipitated Goalpha with an anti-phospho-serine/threonine specific antibody revealed a significant increase in baseline phosphorylation in diabetic DRGs. Activation of PKC produced a significant increase in phosphorylation in control DRGs but no significant increase in Goalpha in diabetic DRGs. Phosphorylation of PKC-alpha was increased, PKC-betaII was unchanged and PKC-delta decreased in diabetic DRGs. These results suggest that diminished inhibitory G protein function observed in DRGs neurons from diabetic rats involves an isoform-specific PKC-dependent pathway.
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Affiliation(s)
- Yu Shangguan
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, USA
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18
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Kim H, Sasaki T, Maeda K, Koya D, Kashiwagi A, Yasuda H. Protein kinase Cbeta selective inhibitor LY333531 attenuates diabetic hyperalgesia through ameliorating cGMP level of dorsal root ganglion neurons. Diabetes 2003; 52:2102-9. [PMID: 12882929 DOI: 10.2337/diabetes.52.8.2102] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Streptozocin (STZ)-induced diabetic rats show hyperalgesia that is partially attributed to altered protein kinase C (PKC) activity. Both attenuated neuronal nitric oxide synthase (nNOS)-cGMP system and tetrodotoxin-resistant (TTX-R) Na channels in dorsal root ganglion neurons may be involved in diabetic hyperalgesia. We examined whether PKCbeta inhibition ameliorates diabetic hyperalgesia and, if so, whether the effect is obtained through action on neurons by testing nociceptive threshold in normal and STZ-induced diabetic rats treated with or without PKCbeta-selective inhibitor LY333531 (LY) and by assessing the implication of LY in either nNOS-cGMP system or TTX-R Na channels of isolated dorsal root ganglion neurons. The decreased nociceptive threshold in diabetic rats was improved either after 4 weeks of LY treatment or with a single intradermal injection into the footpads. The treatment of LY for 6 weeks significantly decreased p-PKCbeta and ameliorated a decrease in cGMP content in dorsal root ganglia of diabetic rats. The latter effect was confirmed in ex vivo condition. The treatment with NO donor for 4 weeks also normalized both diabetic hyperalgesia and decreased cGMP content in dorsal root ganglions. The expressions of nNOS and TTX-R Na channels were not changed with LY treatment. These results suggest that LY is effective for treating diabetic hyperalgesia through ameliorating the decrease in the nNOS-cGMP system.
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Affiliation(s)
- Hyoh Kim
- Division of Neurology, Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
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19
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McCormack K. A New Perspective on Signal Transduction in Neuropathic Pain The Emerging Role of the G Protein By Dimer in Transducing and Modulating Opioid Signaling. Pain 2003. [DOI: 10.1201/9780203911259.ch5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Hall KE, Liu J, Sima AA, Wiley JW. Impaired inhibitory G-protein function contributes to increased calcium currents in rats with diabetic neuropathy. J Neurophysiol 2001; 86:760-70. [PMID: 11495948 DOI: 10.1152/jn.2001.86.2.760] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
There is a growing body of evidence that sensory neuropathy in diabetes is associated with abnormal calcium signaling in dorsal root ganglion (DRG) neurons. Enhanced influx of calcium via multiple high-threshold calcium currents is present in sensory neurons of several models of diabetes mellitus, including the spontaneously diabetic BioBred/Worchester (BB/W) rat and the chemical streptozotocin (STZ)-induced rat. We believe that abnormal calcium signaling in diabetes has pathologic significance as elevation of calcium influx and cytosolic calcium release has been implicated in other neurodegenerative conditions characterized by neuronal dysfunction and death. Using electrophysiologic and pharmacologic techniques, the present study provides evidence that significant impairment of G-protein-coupled modulation of calcium channel function may underlie the enhanced calcium entry in diabetes. N- and P-type voltage-activated, high-threshold calcium channels in DRGs are coupled to mu opiate receptors via inhibitory G(o)-type G proteins. The responsiveness of this receptor coupled model was tested in dorsal root ganglion (DRG) neurons from spontaneously-diabetic BB/W rats, and streptozotocin-induced (STZ) diabetic rats. Intracellular dialysis with GTPgammaS decreased calcium current amplitude in diabetic BB/W DRG neurons compared with those of age-matched, nondiabetic controls, suggesting that inhibitory G-protein activity was diminished in diabetes, resulting in larger calcium currents. Facilitation of calcium current density (I(DCa)) by large-amplitude depolarizing prepulses (proposed to transiently inactivate G proteins), was significantly less effective in neurons from BB/W and STZ-induced diabetic DRGs. Facilitation was enhanced by intracellular dialysis with GTPgammaS, decreased by pertussis toxin, and abolished by GDPbetaS within 5 min. Direct measurement of GTPase activity using opiate-mediated GTPgamma[(35)S] binding, confirmed that G-protein activity was significantly diminished in STZ-induced diabetic neurons compared with age-matched nondiabetic controls. Diabetes did not alter the level of expression of mu opiate receptors and G-protein alpha subunits. These studies indicate that impaired regulation of calcium channels by G proteins is an important mechanism contributing to enhanced calcium influx in diabetes.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Biological Transport/drug effects
- Biological Transport/physiology
- Calcium/metabolism
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/metabolism
- Diabetic Neuropathies/metabolism
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- GTP Phosphohydrolases/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Ganglia, Spinal/cytology
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- Guanosine Diphosphate/analogs & derivatives
- Guanosine Diphosphate/pharmacology
- In Vitro Techniques
- Male
- Neural Conduction/physiology
- Neurons/physiology
- Patch-Clamp Techniques
- Pertussis Toxin
- Rats
- Rats, Inbred BB
- Rats, Sprague-Dawley
- Receptors, Opioid, mu/metabolism
- Sulfur Radioisotopes
- Thionucleotides/pharmacology
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- K E Hall
- Veterans Affairs Ann Arbor Healthcare System, Geriatric Research Education Clinical Center, Michigan 48105, USA.
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Lelkes E, Unsworth BR, Lelkes PI. Reactive oxygen species, apoptosis and alte1red NGF-induced signaling in PC12 pheochromocytoma cells cultured in elevated glucose: AnIn Vitro cellular model for diabetic neuropathy. Neurotox Res 2001; 3:189-203. [PMID: 14715473 DOI: 10.1007/bf03033191] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Diabetic neuropathies, affecting the autonomic, sensory, and motor peripheral nervous system, are among the most frequent complications of diabetes. The symptoms of diabetic polyneuropathies are multi-faceted; the etiology and the underlying mechanisms are as yet unclear. Clinical studies established a significant correlation between the control of the patients' blood glucose level and the severity of the damage to the peripheral nervous system. Recent in vitro studies suggest that elevated glucose levels induced dysfunction and apoptosis in cultured cells of neuronal origin, possibly through the formation of reactive oxygen species (ROS). Based on these results, we hypothesized that elevated glucose levels impair neuronal survival and function via ROS dependent intracellular signaling pathways. In order to test this hypothesis, we cultured neural crest-derived PC12 pheochromocytoma cells under euglycemic (5 mM) and hyperglycemic (25 mM) conditions. Continuous exposure of undifferentiated PC12 cells for up to 72 h to elevated glucose induced the enhanced generation of ROS, as assessed from the increase in the cell-associated fluorescence of the ROS-sensitive fluorogenic indicator, 2,7-dichlorodihydrofluorescein diacetate. In cells cultured in high glucose, both basal and secretagogue-stimulated catecholamine release were enhanced. Furthermore, high glucose, reduced (by ca. 30%) the rate of cell proliferation and enhanced the occurrence of apoptosis, as assessed by DNA fragmentation, TUNEL assay and the activation of an apoptosis-specific protease, caspase CCP32. Elevated glucose levels significantly attenuated nerve growth factor (NGF)-induced neurite extension, as quantitated by computer-aided image analysis. Culturing PC12 cells in high glucose resulted in alterations in basal and NGF-stimulated mitogen-activated protein kinase (MAPK) signaling pathways, specifically in a switch from the neuronal survival/differentiation-associated MAPK ERK to that of apoptosis/stress-associated MAPK p38 and JNK. Based on our results we present a model in which the prolonged, excess formation of ROS represents a common mechanism for hyperglycemia-induced damage to neuronal cells. We propose that this simple in vitro system might serve as an appropriate model for evaluating some of the effects of elevated glucose on cultured cells of neuronal origin.
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Affiliation(s)
- E Lelkes
- Department of Medicine and Medical Scholars Program, University of Wisconsin Medical School, Madison, WI 53706, USA
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22
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Pieper GM, Mizoguchi H, Ohsawa M, Kamei J, Nagase H, Tseng LF. Decreased opioid-induced antinociception but unaltered G-protein activation in the genetic-diabetic NOD mouse. Eur J Pharmacol 2000; 401:375-9. [PMID: 10936496 DOI: 10.1016/s0014-2999(00)00459-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous evaluation of antinociceptive action in experimental diabetes has been conducted almost exclusively in chemically induced diabetes mellitus. The purpose of the present study was to evaluate antinociceptive response and G-protein activation by mu-opioid receptor and delta-opioid receptor agonists in the genetic non-obese diabetic (NOD) mouse, a model of type I insulin-dependent diabetes mellitus (IDDM). Tail-flick latency before and after hyperglycemia was unaltered. Hyperglycemic NOD mice were hyporesponsive to intracerebroventricular (i.c.v.) injections of [D-Ala(2)]deltorphin II but not to [D-Ala(2), N-MePhe(4), Gly-ol(5)]enkephalin (DAMGO); however, G-protein activation in pons/medulla assessed by [35S]GTPgammaS binding was not diminished. This suggests that a G-protein defect in signaling cannot account for the hyporesponsiveness of antinociception in this genetic model of IDDM.
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Affiliation(s)
- G M Pieper
- Department of Surgery, Division of Transplant Surgery, Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, 9200 West Wisconsin Avenue, 53226, Milwaukee, WI, USA.
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23
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Receptor-Mediated Modulation of Voltage-Dependent Ca2+ Channels via Heterotrimeric G-proteins in Neurons. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0021-5198(19)30742-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Srinivasan S, Stevens MJ, Sheng H, Hall KE, Wiley JW. Serum from patients with type 2 diabetes with neuropathy induces complement-independent, calcium-dependent apoptosis in cultured neuronal cells. J Clin Invest 1998; 102:1454-62. [PMID: 9769338 PMCID: PMC508993 DOI: 10.1172/jci2793] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We hypothesized that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that promotes complement-independent, calcium-dependent apoptosis in neuronal cell lines. Neuronal cells were cultured in the presence of complement-inactivated sera obtained from patients with type 2 diabetes with and without neuropathy and healthy adult control patients. Serum from diabetic patients with neuropathy was associated with a significantly greater induction of apoptosis, compared to serum from diabetic patients without neuropathy and controls. In the presence of calcium channel antagonists, induction of apoptosis was reduced by approximately 50%. Pretreatment of neuronal cells with serum from diabetic patients with neuropathy was associated with a significant increase in elevated K+-evoked cytosolic calcium concentration. Serum-induced enhancement in cytosolic calcium and calcium current density was blocked by treatment with trypsin and filtration of the serum using a 100,000-kd molecular weight filter. Treatment with an anti-human IgG antibody was associated with intense fluorescence on the surface of neuronal cells exposed to sera from patients with type 2 diabetes mellitus with neuropathy. We conclude that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that induces complement-independent, calcium-dependent apoptosis in neuronal cells.
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Affiliation(s)
- S Srinivasan
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical Center and the Ann Arbor Veterans Affairs Medical Center, Ann Arbor, Michigan 48105, USA
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25
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Ristic H, Srinivasan S, Hall KE, Sima AA, Wiley JW. Serum from diabetic BB/W rats enhances calcium currents in primary sensory neurons. J Neurophysiol 1998; 80:1236-44. [PMID: 9744935 DOI: 10.1152/jn.1998.80.3.1236] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the hypothesis that exposure of nondiabetic rat dorsal root ganglion (DRG) neurons to sera from diabetic BB/W rats would produce an increase in calcium currents associated with impaired regulation of the inhibitory G protein-calcium channel complex. Acutely dissociated rat DRGs were incubated for 18-24 h in medium supplemented with sera (10% vol/vol) from either diabetic rats with neuropathy or age-matched, nondiabetic controls. Exposure of DRG neurons to sera from diabetic BB/W rats resulted in a surface membrane immunofluorescence pattern when treated with an anti-rat light-chain antibody that was not observed in neurons exposed to control sera. Calcium current density (IDCa) was assessed with the use of the whole cell variation of the patch-clamp technique. IDCa in neurons exposed to diabetic sera was significantly increased compared with neurons exposed to control sera. Guanine nucleotide-binding (G) protein regulation of calcium channel function was examined with the use of a two-pulse "facilitation" or IDCa enhancement protocol in the presence of activators [guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S)] or antagonists [guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) and pertussis toxin (PTX)] of G protein function. Facilitation was significantly decreased in neurons exposed to diabetic sera. Intracellular diffusion of neurons with GDP beta s blocked facilitation, whereas dialysis with GTP gamma s increased facilitation to a similar magnitude in neurons exposed to either diabetic or control sera. Treatment with PTX resulted in a significant increase in IDCa and approximately 50% decrease in facilitation in neurons treated with control sera but no significant changes in neurons exposed to diabetic sera. We conclude that serum from diabetic BB/W rats with neuropathy contains an autoimmune immunoglobulin that impairs regulation of the inhibitory G protein-calcium channel complex, resulting in enhanced calcium influx. Regulation of the inhibitory G protein-calcium channel complex involves PTX-sensitive and -insensitive G proteins.
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Affiliation(s)
- H Ristic
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, USA
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27
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Abstract
This paper is the nineteenth installment of our annual review of research concerning the opiate system. It summarizes papers published during 1996 reporting the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress, tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.
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Affiliation(s)
- G A Olson
- Department of Psychology, University of New Orleans, LA 70148, USA
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