Neuroprotective Effects of Dexmedetomidine against Thapsigargin-induced ER-stress via Activity of α<sub>2</sub>-adrenoceptors and Imidazoline Receptors

Manami Inagaki; Masayuki Somei; Tatsunori Oguchi; Ran Ono; Sachie Fukutaka; Ikumi Matsuoka; Mayumi Tsuji; Katsuji Oguchi; Manami Inagaki; Masayuki Somei; Tatsunori Oguchi; Ran Ono; Sachie Fukutaka; Ikumi Matsuoka; Mayumi Tsuji; Katsuji Oguchi

doi:10.3934/Neuroscience.2016.2.237

AIMS Neuroscience

2016, Volume 3, Issue 2: 237-252. doi: 10.3934/Neuroscience.2016.2.237

Previous Article Next Article

Research article

Neuroprotective Effects of Dexmedetomidine against Thapsigargin-induced ER-stress via Activity of α₂-adrenoceptors and Imidazoline Receptors

1.
Department of Pharmacology, School of Medicine, Showa University, Tokyo, Japan
2.
Department of Pharmacology, School of Pharmacy, Showa University, Tokyo, Japan

Received: 26 May 2016 Accepted: 08 July 2016 Published: 26 May 2016

Dexmedetomidine is a potent and highly selective α₂-adrenoceptor agonist with sedative, analgesic, and sympatholytic properties, though it also exhibits some affinity for imidazoline binding sites. In addition to its sedative effects, dexmedetomidine exerts neuroprotective effects under ischemic conditions. Invasive incidents such as ischemia or hypoxia induce dysfunctions in energy production or depletion of ATP as well as accumulation and aggregation of abnormal proteins in the endoplasmic reticulum (ER), leading to an ER-stress response. In the present study, we examined whether dexmedetomidine exerts inhibitory effects on apoptosis mediated by thapsigargin-induced ER-stress in SH-SY5Y cells, and proposed a possible underlying mechanism for its neuroprotective effects. We used thapsigargin (TG) to generate an ER-stress response in SH-SY5Y cells. SH-SY5Y cells were pretreated with Dex (1–1000 nM) or receptor antagonists (atipamezole, efaroxan, BU99006, and 2’,5’-dideoxyadenosine) for 1 hour before co-treatment with 1 mM TG for 20 hours. Co-incubation with dexmedetomidine suppressed thapsigargin-induced increases in cytosolic Ca²⁺, caspase-4 and -3 activity, eIF2α phosphorylation, and expression of ER-stress biomarkers. Dexmedetomidine treatment also decreased cAMP levels. In the presence of atipamezole or efaroxan, but not BU99006, inhibition of eIF2α phosphorylation and CHOP expression significantly increased following treatment with dexmedetomidine in thapsigargin-treated cells. However, pretreatment with BU99006 enhanced the increase in mitochondrial membrane potential associated with dexmedetomidine treatment. The results of the present study demonstrate that dexmedetomidine at clinically relevant concentrations suppresses ER-stress-induced apoptosis in SH-SY5Y cells. Some neuroprotective effects of dexmedetomidine may be mediated by α₂-adrenoceptor and I₁- and I₂-receptors.
- dexmedetomidine,
- α₂-agonist,
- imidazoline receptor,
- ER-stress-mediated apoptosis,
- ischemia,
- neurodegeneration
Citation: Manami Inagaki, Masayuki Somei, Tatsunori Oguchi, Ran Ono, Sachie Fukutaka, Ikumi Matsuoka, Mayumi Tsuji, Katsuji Oguchi. Neuroprotective Effects of Dexmedetomidine against Thapsigargin-induced ER-stress via Activity of α2-adrenoceptors and Imidazoline Receptors[J]. AIMS Neuroscience, 2016, 3(2): 237-252. doi: 10.3934/Neuroscience.2016.2.237

Related Papers:

Abstract

Dexmedetomidine is a potent and highly selective α₂-adrenoceptor agonist with sedative, analgesic, and sympatholytic properties, though it also exhibits some affinity for imidazoline binding sites. In addition to its sedative effects, dexmedetomidine exerts neuroprotective effects under ischemic conditions. Invasive incidents such as ischemia or hypoxia induce dysfunctions in energy production or depletion of ATP as well as accumulation and aggregation of abnormal proteins in the endoplasmic reticulum (ER), leading to an ER-stress response. In the present study, we examined whether dexmedetomidine exerts inhibitory effects on apoptosis mediated by thapsigargin-induced ER-stress in SH-SY5Y cells, and proposed a possible underlying mechanism for its neuroprotective effects. We used thapsigargin (TG) to generate an ER-stress response in SH-SY5Y cells. SH-SY5Y cells were pretreated with Dex (1–1000 nM) or receptor antagonists (atipamezole, efaroxan, BU99006, and 2’,5’-dideoxyadenosine) for 1 hour before co-treatment with 1 mM TG for 20 hours. Co-incubation with dexmedetomidine suppressed thapsigargin-induced increases in cytosolic Ca²⁺, caspase-4 and -3 activity, eIF2α phosphorylation, and expression of ER-stress biomarkers. Dexmedetomidine treatment also decreased cAMP levels. In the presence of atipamezole or efaroxan, but not BU99006, inhibition of eIF2α phosphorylation and CHOP expression significantly increased following treatment with dexmedetomidine in thapsigargin-treated cells. However, pretreatment with BU99006 enhanced the increase in mitochondrial membrane potential associated with dexmedetomidine treatment. The results of the present study demonstrate that dexmedetomidine at clinically relevant concentrations suppresses ER-stress-induced apoptosis in SH-SY5Y cells. Some neuroprotective effects of dexmedetomidine may be mediated by α₂-adrenoceptor and I₁- and I₂-receptors.

References

[1]	Ramsay MA, Luterman DL (2004) Dexmedetomidine as a total intravenous anesthetic agent. Anesthesiology 101: 787-790. doi: 10.1097/00000542-200409000-00028
[2]	Jalowiecki P, Rudner R, Gonciarz M, et al. (2005) Sole use of dexmedetomidine has limited utility for conscious sedation during outpatient colonoscopy. Anesthesiology 103: 269-273. doi: 10.1097/00000542-200508000-00009
[3]	Martin E, Ramsay G, Mantz J, et al. (2003) The role of the alpha2-adrenoceptor agonist dexmedetomidine in postsurgical sedation in the intensive care unit. J Intensive Care Med 18: 29-41. doi: 10.1177/0885066602239122
[4]	Kamibayashi T, Maze M (2000) Clinical uses of alpha2 -adrenergic agonists. Anesthesiology 93: 1345-1349. doi: 10.1097/00000542-200011000-00030
[5]	Walker SM, Howard RF, Keay KA, et al. (2005) Developmental age influences the effect of epidural dexmedetomidine on inflammatory hyperalgesia in rat pups. Anesthesiology 102: 1226-1234. doi: 10.1097/00000542-200506000-00024
[6]	Hoffman WE, Kochs E, Werner C, et al. (1991) Dexmedetomidine improves neurologic outcome from incomplete ischemia in the rat. Reversal by the alpha 2-adrenergic antagonist atipamezole. Anesthesiology 75: 328-332.
[7]	Dahmani S, Rouelle D, Gressens P, et al. (2010) Characterization of the postconditioning effect of dexmedetomidine in mouse organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation. Anesthesiology 112: 373-383. doi: 10.1097/ALN.0b013e3181ca6982
[8]	Engelhard K, Werner C, Eberspacher E, et al. (2003) The effect of the alpha 2-agonist dexmedetomidine and the N-methyl-D-aspartate antagonist S(+)-ketamine on the expression of apoptosis-regulating proteins after incomplete cerebral ischemia and reperfusion in rats. Anesthesia Analgesia 96: 524-531, table of contents.
[9]	Sato K, Kimura T, Nishikawa T, et al. (2010) Neuroprotective effects of a combination of dexmedetomidine and hypothermia after incomplete cerebral ischemia in rats. Acta anaesthesiologica Scandinavica 54: 377-382. doi: 10.1111/j.1399-6576.2009.02139.x
[10]	Wikberg JE, Uhlen S, Chhajlani V (1991) Medetomidine stereoisomers delineate two closely related subtypes of idazoxan (imidazoline) I-receptors in the guinea pig. Europ J Pharmacol 193: 335-340. doi: 10.1016/0014-2999(91)90148-J
[11]	Virtanen R, Savola JM, Saano V, et al. (1988) Characterization of the selectivity, specificity and potency of medetomidine as an alpha 2-adrenoceptor agonist. Europ J Pharmacol 150: 9-14. doi: 10.1016/0014-2999(88)90744-3
[12]	Savola MK, Savola JM (1996) [3H]dexmedetomidine, an alpha 2-adrenoceptor agonist, detects a novel imidazole binding site in adult rat spinal cord. Europ J Pharmacol 306: 315-323. doi: 10.1016/0014-2999(96)00224-5
[13]	Dahmani S, Paris A, Jannier V, et al. (2008) Dexmedetomidine increases hippocampal phosphorylated extracellular signal-regulated protein kinase 1 and 2 content by an alpha 2-adrenoceptor-independent mechanism: evidence for the involvement of imidazoline I1 receptors. Anesthesiology 108: 457-466. doi: 10.1097/ALN.0b013e318164ca81
[14]	Kalimo H, Paljarvi L, Vapalahti M (1979) The early ultrastructural alterations in the rabbit cerebral and cerebellar cortex after compression ischaemia. Neuropathol App Neurobiol 5: 211-223. doi: 10.1111/j.1365-2990.1979.tb00620.x
[15]	Morimoto K, Yanagihara T (1981) Cerebral ischemia in gerbils: polyribosomal function during progression and recovery. Stroke J Cerebral Circulation 12: 105-110. doi: 10.1161/01.STR.12.1.105
[16]	Jevtovic-Todorovic V, Hartman RE, Izumi Y, et al. (2003) Early exposure to common anesthetic agents causes widespread neurodegeneration in the developing rat brain and persistent learning deficits. J Neurosci 23: 876-882.
[17]	Loop T, Dovi-Akue D, Frick M, et al. (2005) Volatile anesthetics induce caspase-dependent, mitochondria-mediated apoptosis in human T lymphocytes in vitro. Anesthesiology 102: 1147-1157. doi: 10.1097/00000542-200506000-00014
[18]	Nath R, Raser KJ, Hajimohammadreza I, et al. (1997) Thapsigargin induces apoptosis in SH-SY5Y neuroblastoma cells and cerebrocortical cultures. Biochem Mol Biol Int 43: 197-205.
[19]	Nakajima A, Tsuji M, Inagaki M, et al. (2014) Neuroprotective effects of propofol on ER stress-mediated apoptosis in neuroblastoma SH-SY5Y cells. Europ J Pharmacol 725: 47-54. doi: 10.1016/j.ejphar.2014.01.003
[20]	Zhang M, Shan X, Gu L, et al. (2013) Dexmedetomidine causes neuroprotection via astrocytic α2- adrenergic receptor stimulation and HB-EGF release. J Anesthesiology Clinical Sci 2: 6. doi: 10.7243/2049-9752-2-6
[21]	Zhang F, Ding T, Yu L, et al. (2012) Dexmedetomidine protects against oxygen-glucose deprivation-induced injury through the I2 imidazoline receptor-PI3K/AKT pathway in rat C6 glioma cells. J Pharm Pharmacol 64: 120-127. doi: 10.1111/j.2042-7158.2011.01382.x
[22]	Salvioli S, Maseroli R, Pazienza TL, et al. (1998) Use of flow cytometry as a tool to study mitochondrial membrane potential in isolated, living hepatocytes. Biochemistry (Mosc) 63: 235-238.
[23]	Gertler R, Brown HC, Mitchell DH, et al. (2001) Dexmedetomidine: a novel sedative-analgesic agent. Proceedings 14: 13-21.
[24]	Wikberg JE, Uhlen S, Chhajlani V (1991) Medetomidine stereoisomers delineate two closely related subtypes of idazoxan (imidazoline) I-receptors in the guinea pig. Eur J Pharmacol 193: 335-340. doi: 10.1016/0014-2999(91)90148-J
[25]	Lee YS, Silva AJ (2009) The molecular and cellular biology of enhanced cognition. Nat Rev Neurosci 10: 126-140.
[26]	Ho AK, Ogiwara T, Chik CL (1996) Thapsigargin modulates agonist-stimulated cyclic AMP responses through cytosolic calcium-dependent and -independent mechanisms in rat pinealocytes. Mol Pharmacol 49: 1104-1112.
[27]	Kishikawa H, Kobayashi K, Takemori K, et al. (2008) The effects of dexmedetomidine on human neutrophil apoptosis. Biomed Res 29: 189-194. doi: 10.2220/biomedres.29.189
[28]	Paris A, Mantz J, Tonner PH, et al. (2006) The effects of dexmedetomidine on perinatal excitotoxic brain injury are mediated by the alpha2A-adrenoceptor subtype. Anesthesia Analgesia 102: 456-461. doi: 10.1213/01.ane.0000194301.79118.e9
[29]	Fujita Y, Inoue K, Sakamoto T, et al. (2013) A comparison between dosages and plasma concentrations of dexmedetomidine in clinically ill patients: a prospective, observational, cohort study in Japan. J Intensive Care 1: 15. doi: 10.1186/2052-0492-1-15
[30]	Masayuki Somei MI, Tatsunori Oguchi, Ran Ono, , Sachie Fukutaka MT, Katsuji Oguchi (2016) Combined neuroprotective effects of propofol and dexmedetomidine on endoplasmic reticulum stress-meditated apoptosis in SH-SY5Y cells. Showa Uni J Med Sci 28.
[31]	Tesson F, Limon-Boulez I, Urban P, et al. (1995) Localization of I2-imidazoline binding sites on monoamine oxidases. J Biol Chem 270: 9856-9861. doi: 10.1074/jbc.270.17.9856

Reader Comments

Your name:*

Email:*
© 2016 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)