Institute of Neuroscience, Consiglio Nazionale delle Ricerche, 56100 Pisa, Italy.
Cereb Cortex. 2012 Mar;22(3):725-34. doi: 10.1093/cercor/bhr158. Epub 2011 Jun 17.
The ocular dominance (OD) shift induced by monocular deprivation (MD) during the critical period is mediated by an initial depression of deprived-eye responses followed by an increased responsiveness to the nondeprived eye. It is not fully clear to what extent these 2 events are correlated and which are their physiological and molecular mediators. The extracellular synaptic environment plays an important role in regulating visual cortical plasticity. Matrix metalloproteinases (MMPs) are a family of activity-dependent zinc-dependent extracellular endopeptidases mediating extracellular matrix remodeling. We investigated the effects of MMP inhibition on OD plasticity in juvenile monocularly deprived rats. By using electrophysiological recordings, we found that MMP inhibition selectively prevented the potentiation of neuronal responses to nondeprived-eye stimulation occurring after 7 days of MD and potentiation of deprived-eye responses occurring after eye reopening. Three days of MD only resulted in a depression of deprived-eye responses insensitive to MMP inhibition. MMP inhibition did not influence homeostatic plasticity tested in the monocular cortex but significantly prevented an increase in dendritic spine density present after 7 days MD in layer II-III pyramids.
在关键期内，单眼剥夺（MD）诱导的眼优势（OD）转移是由剥夺眼反应的初始抑制，随后对非剥夺眼的反应增强介导的。这两个事件在多大程度上相关，以及它们的生理和分子介质是什么，目前还不完全清楚。细胞外突触环境在调节视觉皮层可塑性方面起着重要作用。基质金属蛋白酶（MMPs）是一类活性依赖的锌依赖性细胞外内肽酶，介导细胞外基质重塑。我们研究了 MMP 抑制对幼年单眼剥夺大鼠 OD 可塑性的影响。通过电生理记录，我们发现 MMP 抑制选择性地阻止了 MD 后 7 天发生的非剥夺眼刺激引起的神经元反应增强，以及眼重开后发生的剥夺眼反应增强。仅 3 天的 MD 仅导致对 MMP 抑制不敏感的剥夺眼反应抑制。MMP 抑制不影响单眼皮层中的同型可塑性，但显著阻止了 MD 后 7 天在 II-III 层锥体中存在的树突棘密度增加。
