Assuntos
Encéfalo/fisiologia , Oclusão Dentária , Mastigação/fisiologia , Animais , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Infarto Cerebral , Comportamento Alimentar/fisiologia , Expressão Gênica , Humanos , Aprendizagem , Memória , Ratos , Transmissão Sináptica/fisiologia , Dente/fisiologiaRESUMO
OBJECTIVES: The present study aimed to identify the effect of memory-related genes on male rats tested for spatial memory with either molar teeth extraction or its restoration by occlusal support using experimental dentures. DESIGN: Memory-related genes were detected from hippocampi of male Wistar rats (exposed to teeth extraction with or without dentures, or no extraction (control)) (7-week old) after behavioural testing (via the radial maze task) using a DNA microarray. The time course of the expression of these genes was evaluated by quantitative real-time polymerase chain reaction (PCR) (on 49-week-old rats). RESULTS: In preliminary experiments, to determine which memory genes are affected by spatial memory training, DNA microarray analysis revealed that thyrotropin-releasing hormone (Trh) and tenascin XA (Tnxa) were up-regulated and neuronatin (Nnat) and S100a9 were down-regulated after the maze training. The expression of Tnxa, Nnat and S100a9 of 49-week-old rats (during the time course) via quantitative real-time PCR was consistent with the results of microarrays of the preliminary experiment. Expression of Trh that was evaluated by quantitative real-time PCR did not agree with the results for this gene from the microarray for all groups. Therefore, expression of Trh may have increased in only young, trained rats. The expression of S100a9 prior to the maze task was down-regulated in only the extraction group. CONCLUSION: These results demonstrated that Trh, Tnxa and Nnat genes were affected according to the degree of memory in male rats. This study also indicated that S100a9 is a memory-related gene, which is affected by the presence of occlusal support.
Assuntos
Calgranulina B/genética , Perfilação da Expressão Gênica , Hipocampo/metabolismo , Memória/fisiologia , Tenascina/genética , Hormônio Liberador de Tireotropina/genética , Extração Dentária , Ácido gama-Aminobutírico/genética , Aminas/metabolismo , Animais , Calgranulina B/metabolismo , Ácidos Cicloexanocarboxílicos/metabolismo , Oclusão Dentária , Gabapentina , Masculino , Aprendizagem em Labirinto , Análise de Sequência com Séries de Oligonucleotídeos , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Tenascina/metabolismo , Hormônio Liberador de Tireotropina/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
The objectives of this study were (1) to establish a reliable method for detecting the force threshold of the tooth tactile sensation while avoiding experimenter bias and (2) to examine the effect of occlusal force loading on the threshold for impulsive force stimulation in subjects with normal dentition. Twenty volunteers participated in this study (10 males and 10 females; mean age, 26.6 ± 2.9 years). To simulate the bite force during occlusal tapping, a force-loading device was designed to exert impulsive force to the occlusal surface in the direction parallel to the tooth axis. The impulsive force detection threshold of the periodontal sensation was measured before and after loading 98 N of occlusal force on the left upper first molar for 1 min. Transient mechanical loading of the upper first molar caused an increase in the absolute threshold for impulsive force. This increase did not vanish immediately, and the increment of the threshold was maintained during the remainder of the experiment. A computer-controlled method for the evaluation of tooth tactile sensation using impulsive stimulation was established. Transient occlusal force loading parallel to the tooth axis increases the threshold of periodontal sensation for mechanical impulsive stimulation.
