title: Microinjection of l-arginine into corpus callosum cause reduction in myelin concentration and neuroinflammation.
abstract: Role of nitric oxide (NO) in inflammationary diseases such as multiple sclerosis (MS) has been proposed previously. We sought to examine if NO plays centrally a key role in MS related phenomena; demyelination or neuroinflammation. Female Wistar rats (weighing 200-250 g) were mounted in a stereotaxic apparatus and received injections of l-arginine aimed at corpus callosum (AP: 1.2, L: ±1.8, V: 3.2). The drug (50-200 μg/rat) was microinjected intra-corpus callosum repeatedly (3-5 times/each per day). Control groups solely received saline (1 μg/rat) into the corpus callosum. The animals were tested for the novelty seeking behavior using the conditioning task. Memory impairment was examined using the shuttle box and Y-maze. l-NAME was pre-injected to l-arginine to involve the NO. All animals' brains were also processed for histological evaluation. l-arginine produced significant changes in the novelty seeking behavior but not in the memory formation, evidenced by passive avoidance and alternation behaviors. Pre-injection of l-NAME reversed the response to l-arginine. Present study further revealed a prominent inflammation as well as myelin elimination in the l-arginine treated rats' brains. These data suggest that the NO infusion in the myelin rich areas such as corpus callosum may lead to MS signs centrally.
authors: Department of Biology, Faculty of Basic Sciences, Shahed University, Tehran, Iran.
authors: Samaneh Sheikhi
authors: SS
authors: Kouhsar
authors: Manizheh
authors: M
authors: Karami
authors: Azita Parvaneh
authors: AP
authors: Tafreshi
authors: Mehrdad
authors: M
authors: Roghani
authors: Mohammad-Reza Jalali
authors: MR
authors: Nadoushan
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D003337:Corpus Callosum / Q000187:drug effects*; D003711:Demyelinating Diseases / Q000139:chemically induced; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004660:Encephalitis / Q000139:chemically induced*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D018782:Maze Learning / Q000187:drug effects; D008569:Memory Disorders / Q000139:chemically induced; D008845:Microinjections / Q000379:methods; D009186:Myelin Sheath / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester