title: Effect of tooth loss on spatial memory and trkB-mRNA levels in rats.
abstract: The mechanism by which tooth loss accelerates spatial memory impairment is unknown. The purpose of this study was to test the hypothesis that tooth loss affects trkB-mRNA levels and leads to an accelerated decrease in the hippocampal cell density in rats. A radial maze was used to evaluate the spatial memory of male Wistar rats that were categorized based on the number of extracted molar teeth. Number of hippocampal pyramidal cells and the trkB-mRNA expressions in the amygdala, perirhinal cortex, thalamus, and the hippocampal CA1, CA3, and CA4 areas, were evaluated using molecular biological techniques. Seven weeks after tooth extraction, maze performance was significantly lower in each tooth loss group than in the control group, and the number of extracted teeth was inversely proportional to the induction of the trkB-mRNA and the hippocampal cell density. The average weight of rats increased by controlled feeding throughout the experiment without showing a significant difference between the control and experimental groups. The results indicated that, in rats, the spatial memory-linked trkB-mRNA was reduced in association with the tooth loss; this supports the hypothesis and suggests that teeth have a role in the prevention of spatial memory impairment.
authors.affiliation: Department of Removable Prosthodontics, School of Dentistry, Iwate Medical University, Japan.
authors.forename: Kaoruko
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Wakabayashi
authors.forename: Takuya
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000344:Afferent Pathways / Q000503:physiopathology; D000679:Amygdala / Q000378:metabolism / Q000473:pathology; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000502:physiology*; D018728:Entorhinal Cortex / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000502:physiology*; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008409:Mastication / Q000502:physiology; D018782:Maze Learning / Q000502:physiology; D008569:Memory Disorders / Q000209:etiology* / Q000235:genetics / Q000473:pathology / Q000523:psychology; D008963:Molar; D010513:Periodontal Ligament / Q000293:injuries / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020813:Receptor, trkB / Q000096:biosynthesis* / Q000235:genetics; D009435:Synaptic Transmission; D013787:Thalamic Nuclei / Q000378:metabolism / Q000473:pathology; D014081:Tooth Extraction / Q000009:adverse effects; D016388:Tooth Loss / Q000150:complications / Q000235:genetics / Q000523:psychology*; D014276:Trigeminal Nerve / Q000502:physiology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger; D020813:Receptor, trkB