Berardi N, Domenici L, Parisi V, Pizzorusso T, Cellerino A, Maffei L
Istituto di Neurofisiologia del CNR, Pisa, Italy.
Proc Biol Sci. 1993 Jan 22;251(1330):17-23. doi: 10.1098/rspb.1993.0003.
The effects of monocular deprivation done during the critical period are usually ascribed to competition between the two sets of monocular thalamic afferents taking place at cortical level. We have suggested that loss in competition for the deprived eye is explained by the lack of a neurotrophic factor, produced in the cortex and dependent on electrical activity. To test this hypothesis we have exogenously supplied nerve growth factor (NGF) to rats monocularly deprived (MD) during the critical period, and studied whether monocular deprivation still affected the functional and anatomical organization of the visual cortex. NGF is produced in the rat visual cortex during the critical period, and its expression, at least in the hippocampus, seems to be regulated by electrical activity. Ocular dominance distribution of area 17 neurons, visual acuity, and Parvalbumin immunoreactivity (Parva-LI) were determined in four sets of animals: normal rats, control untreated monocularly deprived rats, deprived rats treated with cytochrome c (to control for non-specific aspects of NGF treatment), and deprived rats treated with NGF. Parva-LI is an excellent marker for the effects of monocular deprivation on the functional organization of the rat visual cortex. We found that exogenous supply of NGF completely prevented the shift in ocular dominance distribution of visual cortical neurons, the loss of visual acuity for the deprived eye, and the strong reduction in Parva-LI induced by monocular deprivation in control rats.
关键期内单眼剥夺的影响通常归因于两组单眼丘脑传入神经在皮质水平发生的竞争。我们曾提出，剥夺眼竞争的丧失可由皮质中产生且依赖电活动的神经营养因子缺乏来解释。为验证这一假说，我们在关键期内向单眼剥夺（MD）大鼠外源供应神经生长因子（NGF），并研究单眼剥夺是否仍会影响视皮质的功能和解剖组织。关键期内大鼠视皮质会产生NGF，且其表达，至少在海马体中，似乎受电活动调控。在四组动物中测定了17区神经元的眼优势分布、视敏度和小白蛋白免疫反应性（Parva-LI）：正常大鼠、未经处理的单眼剥夺对照大鼠、用细胞色素c处理的剥夺大鼠（以控制NGF处理的非特异性方面）以及用NGF处理的剥夺大鼠。Parva-LI是单眼剥夺对大鼠视皮质功能组织影响的优良标志物。我们发现，外源供应NGF完全阻止了视皮质神经元眼优势分布的偏移、剥夺眼视敏度的丧失以及对照大鼠中由单眼剥夺诱导的Parva-LI的大幅降低。
