در شكل پذيري سيناپسي قشر بينايي اثر تجربه حسي NMIDA نقش گيرنده هاي

The Role of NMDA Receptors in Synaptic Plasticity of Adult Visual Cortex: Effect of Sensory Experience

Objective: The purpose of this study was to improve our understanding of the role of NMDA class of glutamate receptors in experience-dependent synaptic plasticity of visual cortex of light (LR) and dark (DR) reared adult rats. Materials and Methods: Layer IV stimulation yeilded field potentials in layer [VIII. consisting of two excitatory postsynaptic potentials (EPSP) called EPSPI and EPSP2. To induce long-term potntiation (LTP), eight episodes of primed-bursts stimulation were delivered at {l.] Hz. Results: NMDA receptor antagonists APS and ketamine differently changed the amplitude of baseline responsesʹ in slices from LR rats but they were ineffective on those of DR ones. Whereas AP5 did not change potentiation of both responses in LR rats, it decreased the extent of LTP of EPSP2 in DR animals. These results suggest that LTP of NMDA receptor-dependent field potentials in the LR visual cortex are AP5-insensitive, while they are affected by ketamine. Also the drugs were more effective on LTP of EPSP2 in DR group than in LR one. Conclusion: Our findings indicate that dependency of LTP on NMDA receptors and/or sensitivity of the receptors to the antagonists are different in LR and DR animals. These results are consistent with the findings that composition and action of NMDA receptors changes as a function of age and sensory experience.