RESUMO
The hippocampus role in sensory-motor integration remains unclear. In these experiments we study its function in the locomotor control. To establish the connection between the hippocampus and the locomotor system, electrical stimulation in the CA1 region was applied and EMG recordings were obtained. We also evaluated the hindlimbs and forelimbs kinematic patterns in rats with a penetrating injury (PI) in the hippocampus as well as in a cortex-injured group (CI), which served as control. After the PI, tamoxifen a selective estrogen receptor modulator (SERM) that has been described as a neuroprotector and antiinflammatory drug, or vehicle was administered. Electrical stimulation in the hippocampus produces muscle contractions in the contralateral triceps, when 6 Hz or 8 Hz pulse trains were applied. The penetrating injury in the hippocampus reduced the EMG amplitude after the electrical stimulation. At 7 DPI (days post-injury) we observed an increase in the strides speed in all four limbs of the non-treated group, decreasing the correlation percentage of the studied joints. After 15 DPI the strides speed in the non-treated returned to normal. These changes did not occur in the tamoxifen group nor in cortex-injured group. After 30 days, the nontreated group presented a reduction in the number of pyramidal cell layer neurons at the injury site, in comparison to the tam-treated group. The loss of neurons, may cause the interruption of the trisynaptic circuit and changes in the locomotion speed. Tamoxifen preserves the pyramidal neurons after the injury, probably resulting in the strides speed recovery.
Assuntos
Hipocampo/fisiologia , Locomoção/fisiologia , Animais , Antígenos Nucleares/metabolismo , Fenômenos Biomecânicos , Contagem de Células , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/lesões , Córtex Cerebral/patologia , Córtex Cerebral/fisiologia , Modelos Animais de Doenças , Estimulação Elétrica , Eletromiografia , Feminino , Membro Anterior/fisiologia , Membro Posterior/fisiologia , Hipocampo/efeitos dos fármacos , Hipocampo/lesões , Hipocampo/patologia , Imuno-Histoquímica , Locomoção/efeitos dos fármacos , Músculo Esquelético/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Fármacos Neuroprotetores/farmacologia , Células Piramidais/efeitos dos fármacos , Células Piramidais/patologia , Células Piramidais/fisiologia , Ratos , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Tamoxifeno/farmacologiaRESUMO
Measurement of neurotransmitters during normal or altered function in cerebral slices could be an important tool to better understand the relationship between biochemical changes and electrophysiological activity. Some attempts of this analysis have been made; however, the current techniques do not have the appropriate time resolution to establish this relationship. The use of electrochemical biosensors has allowed for good time resolution, but problems related to the reduction of signal noise and biofouling of the electrode surface could be an important issue. In this work, we propose a new alternative to simultaneously measure glutamate and electrical activity with a high temporal resolution in brain slices. This approach is based on the use of enzymatic reactors that generate a fluorescent derivative from glutamate that can be measured at high temporal resolution. The results presented here show a reliable measurement of this neurotransmitter in brain slices obtained from intact animals under the effect of a glutamate transporter blocker DL-threo-beta-benzyloxyaspartate as well as the potassium channel blocker 4-aminopyridine. Differences in the levels of glutamate and high frequency and amplitude discharges as an effect of drug administration were found in brain slices obtained from epileptic rats (p<0.05). In conclusion, this method could be used to measure neurotransmitter concentration online at a near physiological temporal resolution, which can then be correlated to the electrical activity that is simultaneously recorded.
