title: Delayed hippocampal effects from a single exposure of prepubertal guinea pigs to sub-lethal dose of chlorpyrifos: a magnetic resonance imaging and spectroscopy study.
abstract: This study was designed to test the hypothesis that in vivo magnetic resonance imaging (MRI) and spectroscopy (MRS) can detect in adulthood the neurotoxic effects of a single exposure of prepubertal guinea pigs to the organophosphorus pesticide chlorpyrifos. Twelve female guinea pigs were given either a single dose of chlorpyrifos (0.6×LD50 or 300mg/kg, sc) or peanut oil (vehicle; 0.5ml/kg, sc) at 35-40 days of age. One year after the exposure, the animals were tested in the Morris water maze. Three days after the end of the behavioral testing, the metabolic and structural integrity of the brain of the animals was examined by means of MRI/MRS. In the Morris water maze, the chlorpyrifos-exposed guinea pigs showed significant memory deficit. Although no significant anatomical differences were found between the chlorpyrifos-exposed guinea pigs and the control animals by in vivo MRI, the chlorpyrifos-exposed animals showed significant decreases in hippocampal myo-inositol concentration using MRS. The present results indicate that a single sub-lethal exposure of prepubertal guinea pigs to the organophosphorus pesticide chlorpyrifos can lead to long-term memory deficits that are accompanied by significant reductions in the levels of hippocampal myo-inositol.
authors: Department of Diagnostic Radiology & Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, United States.
authors: Roger J
authors: RJ
authors: Mullins
authors: Su
authors: S
authors: Xu
authors: Edna F R
authors: EF
authors: Pereira
authors: Jacek
authors: J
authors: Mamczarz
authors: Edson X
authors: EX
authors: Albuquerque
authors: Rao P
authors: RP
authors: Gullapalli
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D004390:Chlorpyrifos / Q000633:toxicity*; D005260:Female; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism*; D007294:Inositol / Q000378:metabolism*; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D018782:Maze Learning / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D014316:Tritium
chemical_list: D007306:Insecticides; D014316:Tritium; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D004390:Chlorpyrifos