Cocaine increases endoplasmic reticulum stress protein expression in striatal neurons.
Cocaine administration upregulates the levels of extracellular glutamate and dopamine in the striatum. Activation of the receptors alters calcium homeostasis in striatal neurons leading to the expression of the endoplasmic reticulum (ER) stress proteins. It was therefore hypothesized that cocaine upregulates the expression of the ER stress proteins, immunoglobulin heavy chain binding protein (BiP), Ire1alpha and perk via glutamate and dopamine receptor activation. A novel glutamate microbiosensor and Western immunoblot analyses were mainly performed to test the hypothesis in the rat dorsal striatum. The results showed that i.p. injection of repeated cocaine (20 mg/kg) for nine consecutive days significantly increased extracellular glutamate levels while acute cocaine injection did not. However, the immunoreactivities (IR) of the ER stress proteins in the dorsal striatum were significantly increased by either acute or repeated cocaine injections as compared with saline controls. Intrastriatal injection (i.s.) of the selective group I metabotropic glutamate receptor (mGluR) antagonist N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC; 25 nmol) or the mGluR5 subtype antagonist 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP; 2 and 25 nmol) significantly decreased repeated cocaine-induced increases in the IR of the ER stress proteins in the injected dorsal striatum. Similarly, the selective D1 antagonist (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390; 0.1 mg/kg, i.p.) or the N-methyl-d-aspartate antagonist dizocilpine/(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-ibenzo[a,d]cyclohepten-5,10-imine maleate (MK801; 2 nmol, i.s.) decreased acute or repeated cocaine-induced the IR of the ER stress proteins in the dorsal striatum. These data suggest that cocaine upregulates expression of the ER stress proteins in striatal neurons via a mechanism involving activation of glutamate and dopamine receptors.
Shin
E H
EH
Department of Biology and Center for Innovative BioPhysio Sensor Technology, Pusan National University, 30 Jangjeon-dong, Kumjeong-gu, C6-311, Pusan 609-735, Korea.
Bian
S
S
Shim
Y-B
YB
Rahman
M A
MA
Chung
K T
KT
Kim
J Y
JY
Wang
J Q
JQ
Choe
E S
ES
D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000378:metabolism* / Q000503:physiopathology; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D018492:Dopamine Antagonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism; D018832:Molecular Chaperones / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000187:drug effects / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013312:Stress, Physiological / Q000139:chemically induced* / Q000378:metabolism / Q000503:physiopathology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D019892:eIF-2 Kinase / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP
D003042:Cocaine; D018492:Dopamine Antagonists; D018765:Dopamine Uptake Inhibitors; D018691:Excitatory Amino Acid Antagonists; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D017346:Protein Serine-Threonine Kinases; D017447:Receptors, Dopamine D1; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D019892:eIF-2 Kinase; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C486557:Ern2 protein, rat