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Latham LE, Wang C, Patterson TA, Slikker W, Liu F. Neuroprotective Effects of Carnitine and Its Potential Application to Ameliorate Neurotoxicity. Chem Res Toxicol 2021; 34:1208-1222. [PMID: 33570912 DOI: 10.1021/acs.chemrestox.0c00479] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Carnitine is an essential metabolite that is absorbed from the diet and synthesized in the kidney, liver, and brain. It ferries fatty acids across the mitochondrial membrane to undergo β-oxidation. Carnitine has been studied as a therapy or protective agent for many neurological diseases and neurotoxicity (e.g., prolonged anesthetic exposure-induced developmental neurotoxicity in preclinical models). Preclinical and clinical data support the notion that carnitine or acetyl carnitine may improve a patient's quality of life through increased mitochondrial respiration, release of neurotransmitters, and global gene expression changes, showing the potential of carnitine beyond its approved use to treat primary and secondary carnitine deficiency. In this review, we summarize the beneficial effects of carnitine or acetyl carnitine on the central nervous system, highlighting protective effects against neurotoxicity-induced damage caused by various chemicals and encouraging a thorough evaluation of carnitine use as a therapy for patients suffering from neurotoxicant exposure.
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Affiliation(s)
- Leah E Latham
- Division of Neurotoxicology, National Center for Toxicological Research/FDA, Jefferson, Arkansas 72079, United States
| | - Cheng Wang
- Division of Neurotoxicology, National Center for Toxicological Research/FDA, Jefferson, Arkansas 72079, United States
| | - Tucker A Patterson
- Office of Director, National Center for Toxicological Research/FDA, Jefferson, Arkansas 72079, United States
| | - William Slikker
- Office of Director, National Center for Toxicological Research/FDA, Jefferson, Arkansas 72079, United States
| | - Fang Liu
- Division of Neurotoxicology, National Center for Toxicological Research/FDA, Jefferson, Arkansas 72079, United States
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Singh P, Walia V. Anxiolytic like effect of L-Carnitine in mice: Evidences for the involvement of NO-sGC-cGMP signaling pathway. Behav Brain Res 2020; 391:112689. [PMID: 32417275 DOI: 10.1016/j.bbr.2020.112689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/26/2020] [Accepted: 05/02/2020] [Indexed: 12/20/2022]
Abstract
L-Carnitine (LC) is an endogenous compound synthesized from the essential amino acids lysine and methionine. LC act as an antioxidant and modulates the levels of neurochemicals such as glutamate, GABA, NO etc. implicated in the regulation of anxiety and related behavior. However its exact role in the anxiety is not known. The present study was designed to investigate the anxiolytic like effect of LC in mice. LC (2.5, 5.0 and 10 mg/kg, i.p.) was administered to the mice and the anxiety related behavior was determined using light and dark box (LDB) and elevated plus maze (EPM) tests. The whole brain nitrite level was also determined. The results obtained demonstrated that LC (10 mg/kg, i.p.) exerted anxiolytic like effect in mice, accompanied by the reduction of whole brain nitrite level significantly as compared to control. Further, the influence of NO and GABA modulators pretreatments on the effect of subtherapeutic dose of LC was also determined. The results obtained demonstrated that NO donor/cGMP modulator counteracted while NO inhibitor potentiated the effect confers by the subtherapeutic dose of LC mice. Pretreatment of diazepam (1 mg/kg, i.p.) further potentiated the effect of subtherapeutic dose of LC (5 mg/kg, i.p.) in EPM and LDB tests and further reduced the brain nitrite level significantly as compared to LC (5 mg/kg, i.p.) alone treatment. Thus, LC exerted anxiolytic like effect in mice and NO-sGC-cGMP signaling pathway influences the anxiolytic like effect of LC in mice.
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Affiliation(s)
- Poonam Singh
- Department of Pharmaceutical Sciences, Maharshi Dayanand University, Rohtak, 124001, Haryana, India.
| | - Vaibhav Walia
- Faculty of Pharmacy, DIT University, Dehradun, India.
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Fink MA, Paland H, Herzog S, Grube M, Vogelgesang S, Weitmann K, Bialke A, Hoffmann W, Rauch BH, Schroeder HWS, Bien-Möller S. L-Carnitine-Mediated Tumor Cell Protection and Poor Patient Survival Associated with OCTN2 Overexpression in Glioblastoma Multiforme. Clin Cancer Res 2019; 25:2874-2886. [PMID: 30670496 DOI: 10.1158/1078-0432.ccr-18-2380] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 12/04/2018] [Accepted: 01/10/2019] [Indexed: 11/16/2022]
Abstract
PURPOSE Apoptotic dysregulation, redox adaptive mechanisms, and resilience to hypoxia are major causes of glioblastoma (GBM) resistance to therapy. Commonly known as crucial factors in energy metabolism, OCTN2 (SLC22A5) and its substrate L-carnitine (LC) are increasingly recognized as actors in cytoprotection. This study provides a comprehensive expression and survival analysis of the OCTN2/LC system in GBM and clarifies the system's impact on GBM progression. EXPERIMENTAL DESIGN OCTN2 expression and LC content were measured in 121 resected human GBM specimens and 10 healthy brain samples and analyzed for prognostic significance. Depending on LC administration, the effects of hypoxic, metabolic, and cytotoxic stress on survival and migration of LN18 GBM cells were further studied in vitro. Finally, an orthotopic mouse model was employed to investigate inhibition of the OCTN2/LC system on in vivo GBM growth. RESULTS Compared with healthy brain, OCTN2 expression was increased in primary and even more so in recurrent GBM on mRNA and protein level. High OCTN2 expression was associated with a poor overall patient survival; the unadjusted HR for death was 2.7 (95% CI, 1.47-4.91; P < 0.001). LC administration to GBM cells increased their tolerance toward cytotoxicity, whereas siRNA-mediated OCTN2 silencing led to a loss of tumor cell viability. In line herewith, OCTN2/LC inhibition by meldonium resulted in reduced tumor growth in an orthotopic GBM mouse model. CONCLUSIONS Our data indicate a potential role of the OCTN2/LC system in GBM progression and resistance to therapy, and suggests OCTN2 as a prognostic marker in patients with primary GBM.
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Affiliation(s)
- Matthias A Fink
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany.,Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Heiko Paland
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany.,Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Susann Herzog
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany
| | - Markus Grube
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany
| | - Silke Vogelgesang
- Institute of Pathology, Department of Neuropathology, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Weitmann
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Angela Bialke
- Independent Trusted Third Party, University Medicine Greifswald, Greifswald, Germany
| | - Wolfgang Hoffmann
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Bernhard H Rauch
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany
| | - Henry W S Schroeder
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Sandra Bien-Möller
- Department of Pharmacology/C_DAT, University Medicine Greifswald, Greifswald, Germany. .,Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
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Aydin A, Halici Z, Albayrak A, Polat B, Karakus E, Yildirim OS, Bayir Y, Cadirci E, Ayan AK, Aksakal AM. Treatment with Carnitine Enhances Bone Fracture Healing under Osteoporotic and/or Inflammatory Conditions. Basic Clin Pharmacol Toxicol 2015; 117:173-9. [PMID: 25625309 DOI: 10.1111/bcpt.12384] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/12/2015] [Indexed: 01/20/2023]
Abstract
The aim of this study was to examine the effects of carnitine on bone healing in ovariectomy (OVX) and inflammation (INF)-induced osteoporotic rats. The rats were randomly divided into nine groups (n = 8 animals per group): sham-operated (Group 1: SHAM); sham + magnesium silicate (Mg-silicate) (Group 2: SHAM + INF); ovariectomy (Group 3: OVX); ovariectomy + femoral fracture (Group 4: OVX + FRC); ovariectomy + femoral fracture + Mg-silicate (Group 5: OVX + FRC + INF); ovariectomy + femoral fracture + carnitine 50 mg/kg (Group 6: OVX + FRC + CAR50); ovariectomy + femoral fracture + carnitine 100 mg/kg (Group 7: OVX + FRC + CAR100); ovariectomy + femoral fracture + Mg-silicate + carnitine 50 mg/kg (Group 8: OVX + FRC + INF + CAR50); and ovariectomy + femoral fracture + Mg-silicate + carnitine 100 mg/kg (Group 9: OVX + FRC + INF + CAR100). Eight weeks after OVX, which allowed for osteoporosis to develop, INF was induced with subcutaneous Mg-silicate. On day 80, all of the rats in groups 4-9 underwent fracture operation on the right femur. Bone mineral density (BMD) showed statistically significant improvements in the treatment groups. The serum markers of bone turnover (osteocalcin and osteopontin) and pro-inflammatory cytokines (tumour necrosis factor α, interleukin 1β and interleukin 6) were decreased in the treatment group. The X-ray images showed significantly increased callus formation and fracture healing in the groups treated with carnitine. The present results show that in a rat model with osteoporosis induced by ovariectomy and Mg-silicate, treatment with carnitine improves the healing of femur fractures.
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Affiliation(s)
- Ali Aydin
- Department of Orthopedics and Traumatology, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Zekai Halici
- Department of Pharmacology, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Abdulmecit Albayrak
- Department of Pharmacology, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Beyzagul Polat
- Department of Pharmacology, Ataturk University Faculty of Pharmacy, Erzurum, Turkey
| | - Emre Karakus
- Department of Pharmacology, Ataturk University Faculty of Veterinary Medicine, Erzurum, Turkey
| | - Omer Selim Yildirim
- Department of Orthopedics and Traumatology, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Yasin Bayir
- Department of Biochemistry, Ataturk University Faculty of Pharmacy, Erzurum, Turkey
| | - Elif Cadirci
- Department of Pharmacology, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Arif Kursad Ayan
- Department of Nuclear Medicine, Ataturk University Faculty of Medicine, Erzurum, Turkey
| | - Ahmet Murat Aksakal
- Department of Orthopedics and Traumatology, Sevket Yilmaz Education and Research Hospital, Bursa, Turkey
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Yamashita D, Sun GW, Cui Y, Mita S, Otsuki N, Kanzaki S, Nibu KI, Ogawa K, Matsunaga T. Neuroprotective effects of cutamesine, a ligand of the sigma-1 receptor chaperone, against noise-induced hearing loss. J Neurosci Res 2015; 93:788-95. [PMID: 25612541 DOI: 10.1002/jnr.23543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 10/28/2014] [Accepted: 11/21/2014] [Indexed: 11/10/2022]
Abstract
The sigma-1 receptor, which is expressed throughout the brain, provides physiological benefits that include higher brain function. The sigma-1 receptor functions as a chaperone in the endoplasmic reticulum and may control cell death and regeneration within the central nervous system. Cutamesine (1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl) piperazine dihydrochloride) is a ligand selective for this receptor and may mediate neuroprotective effects in the context of neurodegenerative disease. We therefore assessed whether cutamesine protects the inner ear from noise-induced or aging-associated hearing loss. Immunohistochemistry and Western blotting revealed that the sigma-1 receptor is present in adult cochlea. We treated mice with 0, 3, or 30 mg/kg cutamesine from 10 days before noise exposure until the end of the study. All subjects were exposed to a 120-dB, 4-kHz octave-band noise for 2 hr. We assessed auditory thresholds by measuring the auditory-evoked brainstem responses at 4, 8, and 16 kHz, prior to and 1 week, 1 month, or 3 months following noise exposure. For the aging study, measurements were made before treatment was initiated and after 3 or 9 months of cutamesine treatment. Damage to fibrocytes within the cochlear spiral limbus was assessed by quantitative histology. Cutamesine significantly reduced threshold shifts and cell death within the spiral limbus in response to intense noise. These effects were not dose or time dependent. Conversely, cutamesine did not prevent aging-associated hearing loss. These results suggest that cutamesine reduces noise-induced hearing loss and cochlear damage during the acute phase that follows exposure to an intense noise.
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Affiliation(s)
- Daisuke Yamashita
- Department of Otolaryngology, School of Medicine, Kobe University, Kobe, Japan; Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan; Department of Otolaryngology, School of Medicine, Keio University, Tokyo, Japan
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Du X, Chen K, Choi CH, Li W, Cheng W, Stewart C, Hu N, Floyd RA, Kopke RD. Selective degeneration of synapses in the dorsal cochlear nucleus of chinchilla following acoustic trauma and effects of antioxidant treatment. Hear Res 2011; 283:1-13. [PMID: 22178982 DOI: 10.1016/j.heares.2011.11.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 11/18/2011] [Accepted: 11/30/2011] [Indexed: 12/20/2022]
Abstract
The purpose of this study was to reveal synaptic plasticity within the dorsal cochlear nucleus (DCN) as a result of noise trauma and to determine whether effective antioxidant protection to the cochlea can also impact plasticity changes in the DCN. Expression of synapse activity markers (synaptophysin and precerebellin) and ultrastructure of synapses were examined in the DCN of chinchilla 10 days after a 105 dB SPL octave-band noise (centered at 4 kHz, 6 h) exposure. One group of chinchilla was treated with a combination of antioxidants (4-hydroxy phenyl N-tert-butylnitrone, N-acetyl-l-cysteine and acetyl-l-carnitine) beginning 4 h after noise exposure. Down-regulated synaptophysin and precerebellin expression, as well as selective degeneration of nerve terminals surrounding cartwheel cells and their primary dendrites were found in the fusiform soma layer in the middle region of the DCN of the noise exposure group. Antioxidant treatment significantly reduced synaptic plasticity changes surrounding cartwheel cells. Results of this study provide further evidence of acoustic trauma-induced neural plasticity in the DCN and suggest that loss of input to cartwheel cells may be an important factor contributing to the emergence of hyperactivity in the DCN after noise exposure. Results further suggest that early antioxidant treatment for acoustic trauma not only rescues cochlear hair cells, but also has impact on central auditory structures.
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Affiliation(s)
- Xiaoping Du
- Hough Ear Institute, Oklahoma, OK 73112, USA
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Chronic pretreatment with acetyl-L-carnitine and ±DL-α-lipoic acid protects against acute glutamate-induced neurotoxicity in rat brain by altering mitochondrial function. Neurotox Res 2010; 19:319-29. [PMID: 20217290 DOI: 10.1007/s12640-010-9165-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 12/23/2009] [Accepted: 02/20/2010] [Indexed: 01/05/2023]
Abstract
Cellular oxidative stress and energy failure were shown to be involved in Glutamate (L-Glu) neurotoxicity, whereas, acetyl-L-carnitine (ALCAR) and ±DL-α-lipoic acid (LA) are known to be key players in the mitochondrial energy production. To evaluate the effects of the above antioxidants, adult rats were pretreated with ALCAR (100 mg/kg i.p for 21 days) and both ALCAR and LA (100 mg/kg i.p + 50 mg/kg i.p for 21 days), before stereotactically administering L-Glu bolus (1 μmole/1 μl) in the cerebral cortex. Results showed that acute L-Glu increased ROS (P < 0.001), LPO (P < 0.001), Ca(2+) (P < 0.001), TNF-α (P < 0.001), IFN-γ (P < 0.001), NO (P < 0.001) levels and mRNA expression of Caspase-3, Casapase-9, iNOS, and nNOS genes with respect to saline-injected control group. Key antioxidant parameters such as SOD, CAT, GSH, GR along with mitochondrial transmembrane potential (Ψ∆m) were decreased (P < 0.05), while ALCAR pretreatment prevented these effects by significantly inhibiting ROS (P < 0.001), LPO (P < 0.001), Ca(2+) (P < 0.05), TNF-α (P < 0.05), IFN-γ (P < 0.001), NO (P < 0.01) levels and expression of the above genes. This chronic pretreatment of ALCAR also increased SOD, CAT, GSH, GR, and Ψ∆m (P < 0.0.01, P < 0.0.01, P < 0.05, P < 0.05, and P < 0.001, respectively) with respect to L: -Glu group. The addition of LA to ALCAR resulted in further increases in CAT (P < 0.05), GSH (P < 0.01), GR (P < 0.05), Ψ∆m (P < 0.05) and additional decreases in ROS (P < 0.001), LPO (P < 0.05), Ca(2+) (P < 0.05), TNF-α (P < 0.05) and mRNA expression of iNOS and nNOS genes with respect to ALCAR group. Hence, this "one-two punch" of ALCAR + LA may help in ameliorating the deleterious cellular events that occur after L-Glu.
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Robertson CL, Scafidi S, McKenna MC, Fiskum G. Mitochondrial mechanisms of cell death and neuroprotection in pediatric ischemic and traumatic brain injury. Exp Neurol 2009; 218:371-80. [PMID: 19427308 DOI: 10.1016/j.expneurol.2009.04.030] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 04/23/2009] [Accepted: 04/28/2009] [Indexed: 11/30/2022]
Abstract
There are several forms of acute pediatric brain injury, including neonatal asphyxia, pediatric cardiac arrest with global ischemia, and head trauma, that result in devastating, lifelong neurologic impairment. The only clinical intervention that appears neuroprotective is hypothermia initiated soon after the initial injury. Evidence indicates that oxidative stress, mitochondrial dysfunction, and impaired cerebral energy metabolism contribute to the brain cell death that is responsible for much of the poor neurologic outcome from these events. Recent results obtained from both in vitro and animal models of neuronal death in the immature brain point toward several molecular mechanisms that are either induced or promoted by oxidative modification of macromolecules, including consumption of cytosolic and mitochondrial NAD(+) by poly-ADP ribose polymerase, opening of the mitochondrial inner membrane permeability transition pore, and inactivation of key, rate-limiting metabolic enzymes, e.g., the pyruvate dehydrogenase complex. In addition, the relative abundance of pro-apoptotic proteins in immature brains and neurons, and particularly within their mitochondria, predisposes these cells to the intrinsic, mitochondrial pathway of apoptosis, mediated by Bax- or Bak-triggered release of proteins into the cytosol through the mitochondrial outer membrane. Based on these pathways of cell dysfunction and death, several approaches toward neuroprotection are being investigated that show promise toward clinical translation. These strategies include minimizing oxidative stress by avoiding unnecessary hyperoxia, promoting aerobic energy metabolism by repletion of NAD(+) and by providing alternative oxidative fuels, e.g., ketone bodies, directly interfering with apoptotic pathways at the mitochondrial level, and pharmacologic induction of antioxidant and anti-inflammatory gene expression.
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Affiliation(s)
- Courtney L Robertson
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, 21201, USA
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Lamhonwah AM, Hawkins CE, Tam C, Wong J, Mai L, Tein I. Expression patterns of the organic cation/carnitine transporter family in adult murine brain. Brain Dev 2008; 30:31-42. [PMID: 17576045 DOI: 10.1016/j.braindev.2007.05.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 04/30/2007] [Accepted: 05/01/2007] [Indexed: 12/16/2022]
Abstract
UNLABELLED Organic cation/carnitine transporters transport carnitine, drugs, and xenobiotics (e.g. choline, acetylcarnitine, betaine, valproic acid), and are expressed in muscle, heart, blood vessels, kidney, gut, etc. OBJECTIVE To characterize expression patterns of mOctn1, -2 and -3 in murine brain. METHODS We applied our transporter-specific antibodies to mOctn1, -2 and -3, followed by 2 0 antibody and DAB peroxidase detection to serial adult murine brain sections counterstained with hematoxylin. RESULTS All three transporters showed strong expression in the external plexiform layer of the olfactory bulb and in olfactory nerve, the molecular layer and neuronal processes of input fibres extending vertically in motor cortex, in the dendritic arborization of the cornu ammonis and dendate gyrus (hippocampus), neuronal processes in the arcuate nucleus (hypothalamus), choroid plexus cells, and neuronal cell bodies and dendrites of cranial nerve nuclei V and VII. In the cerebellum, all three transporters were strongly expressed in dendritic processes of Purkinje cells, but Octn1 and -2 were expressed more strongly than Octn3 in Purkinje cell bodies. In spinal cord, Octn1, -2 and -3 were prominent in axons and dendritic end-arborizations of spinal cord neurons in both ascending and descending white matter tracts, whereas Octn3 was also strongly expressed in grey matter, specifically in anterior horn cell bodies. Octn3 was weakly expressed in glomerular layer neuronal cell bodies of olfactory bulb. CONCLUSIONS hOCTN2 deficiency presents with carnitine-responsive cardiomyopathy, myopathy and hypoglycemic, hypoketotic coma with strokes, seizures and delays. In mouse, Octn1, -2 and -3 are expressed in many regions throughout the central nervous system with a pattern suggestive of roles in modulating cerebral bioenergetics and in acetylcholine generation for neurotransmission in olfactory, satiety, limbic, memory, motor and sensory functions. This distribution may play a role in the pattern of neurological injury that occurs in hOCTN2 deficiency during catabolic episodes of hypoglycemic, hypoketotic encephalopathy and which may manifest with cognitive impairment, hypotonia and seizures.
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Affiliation(s)
- Anne Marie Lamhonwah
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, 555 University Avenue, University of Toronto, Toronto, Ont., Canada M5G 1X8
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Le Prell CG, Yamashita D, Minami SB, Yamasoba T, Miller JM. Mechanisms of noise-induced hearing loss indicate multiple methods of prevention. Hear Res 2007; 226:22-43. [PMID: 17141991 PMCID: PMC1995566 DOI: 10.1016/j.heares.2006.10.006] [Citation(s) in RCA: 230] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2006] [Revised: 10/05/2006] [Accepted: 10/24/2006] [Indexed: 12/20/2022]
Abstract
Recent research has shown the essential role of reduced blood flow and free radical formation in the cochlea in noise-induced hearing loss (NIHL). The amount, distribution, and time course of free radical formation have been defined, including a clinically significant late formation 7-10 days following noise exposure, and one mechanism underlying noise-induced reduction in cochlear blood flow has finally been identified. These new insights have led to the formulation of new hypotheses regarding the molecular mechanisms of NIHL; and, from these, we have identified interventions that prevent NIHL, even with treatment onset delayed up to 3 days post-noise. It is essential to now assess the additive effects of agents intervening at different points in the cell death pathway to optimize treatment efficacy. Finding safe and effective interventions that attenuate NIHL will provide a compelling scientific rationale to justify human trials to eliminate this single major cause of acquired hearing loss.
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Affiliation(s)
- Colleen G Le Prell
- Kresge Hearing Research Institute, University of Michigan, 1301 East Ann Street, Ann Arbor, MI 48109-0506, USA.
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Hoang BX, Graeme Shaw D, Pham P, Levine S. Restoration of cellular energetic balance with l-carnitine in the neuro-bioenergetic approach for cancer prevention and treatment. Med Hypotheses 2007; 69:262-72. [DOI: 10.1016/j.mehy.2006.11.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 11/17/2006] [Indexed: 11/17/2022]
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Tastekin A, Gepdiremen A, Ors R, Buyukokuroglu ME, Halici Z. Protective effect of L-carnitine against bilirubin-induced neuronal cell death. Brain Dev 2006; 28:436-9. [PMID: 16516423 DOI: 10.1016/j.braindev.2006.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 01/19/2006] [Accepted: 01/20/2006] [Indexed: 10/25/2022]
Abstract
There is growing evidence that glutamate receptor-mediated injury plays a crucial role in bilirubin neurotoxicity. L-carnitine (LC) has been shown to prevent glutamate-induced toxicity in neuronal cell culture. The purpose of this study is to assess whether LC is able to prevent bilirubin neurotoxicity. Unconjugated bilirubin at different concentrations was administered to cerebellar granular cell cultures prepared from 1-day-old Sprague-Dawley rats. The neuroprotective effect of LC was examined. LC at doses of 10(-6), 10(-5), 10(-4) and 10(-3) M was applied to culture flasks. LC at a dose of 10(-4) M significantly blocked bilirubin neurotoxicity. On the other hand, LC significantly increased bilirubin toxicity at a higher dose (10(-3) M). LC at the doses of 10(-5) and 10(-6) M was found to be ineffective. 10(-4) M LC decreased bilirubin-induced neuronal cell death from 47.72+/-3.68 to 27.23+/-5.14%, (P=0.003). The present study demonstrates, for the first time, that LC protects against bilirubin neurotoxicity in a dose-dependent manner in cerebellar granular cell culture of rats. Further research is needed to confirm our findings and to clarify the mechanisms responsible for the protective effect of LC.
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Affiliation(s)
- Ayhan Tastekin
- Division of Neonatology, School of Medicine, Atatürk University, Erzurum, Turkey.
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