title: Effect of three different intensities of infrared laser energy on the levels of amino acid neurotransmitters in the cortex and hippocampus of rat brain.
abstract: OBJECTIVE
  The aim of this study is to investigate the effects of three different intensities of infrared diode laser radiation on amino acid neurotransmitters in the cortex and hippocampus of rat brain.
  
  
  BACKGROUND
  Lasers are known to induce different neurological effects such as pain relief, anesthesia, and neurosuppressive effects; however, the precise mechanisms of these effects are not clearly elucidated. Amino acid neurotransmitters (glutamate, aspartate, glutamine, gamma-aminobutyric acid [GABA], glycine, and taurine) play vital roles in the central nervous system (CNS).
  
  
  METHODS
  The shaved scalp of each rat was exposed to different intensities of infrared laser energy (500, 190, and 90 mW) and then the rats were sacrificed after 1 h, 7 d, and 14 d of daily laser irradiation. The control groups were exposed to the same conditions but without exposure to laser. The concentrations of amino acid neurotransmitters were measured by high-performance liquid chromatography (HPLC).
  
  
  RESULTS
  The rats subjected to 500 mW of laser irradiation had a significant decrease in glutamate, aspartate, and taurine in the cortex, and a significant decrease in hippocampal GABA. In the cortices of rats exposed to 190 mW of laser irradiation, an increase in aspartate accompanied by a decrease in glutamine were observed. In the hippocampus, other changes were seen. The rats irradiated with 90 mW showed a decrease in cortical glutamate, aspartate, and glutamine, and an increase in glycine, while in the hippocampus an increase in glutamate, aspartate, and GABA were recorded.
  
  
  CONCLUSIONS
  We conclude that daily laser irradiation at 90 mW produced the most pronounced inhibitory effect in the cortex after 7 d. This finding may explain the reported neurosuppressive effect of infrared laser energy on axonal conduction of hippocampal and cortical tissues of rat brain.
authors.affiliation: Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt.
authors.forename: Nawal Abd El Hay
authors.initials: NA
authors.lastname: Ahmed
authors.forename: Nasr Mahmoud
authors.initials: NM
authors.lastname: Radwan
authors.forename: Khayria Mansour
authors.initials: KM
authors.lastname: Ibrahim
authors.forename: Mona Emam
authors.initials: ME
authors.lastname: Khedr
authors.forename: Mona A
authors.initials: MA
authors.lastname: El Aziz
authors.forename: Yasser Ashry
authors.initials: YA
authors.lastname: Khadrawy
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism / Q000528:radiation effects*; D006624:Hippocampus / Q000378:metabolism / Q000528:radiation effects*; D007259:Infrared Rays; D054023:Lasers, Semiconductor; D028022:Low-Level Light Therapy; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats
chemical_list: D000596:Amino Acids; D018377:Neurotransmitter Agents