Maffei L, Berardi N, Domenici L, Parisi V, Pizzorusso T
Istituto di Neurofisiologia del CNR, Pisa, Italy.
J Neurosci. 1992 Dec;12(12):4651-62. doi: 10.1523/JNEUROSCI.12-12-04651.1992.
The hypothesis that NGF could play a role in the plasticity of the developing mammalian visual cortex was tested in monocularly deprived (MD) rats. In particular, we have asked whether an exogenous supply of NGF could prevent the changes in ocular dominance distribution induced by monocular deprivation. Hooded rats were monocularly deprived for 1 month, starting at postnatal day 14 (P14), immediately before eye opening, by means of eyelid suture. In eight rats, only monocular deprivation was performed; in eight rats, monocular deprivation was combined with intraventricular injections of beta-NGF, and in three rats, with intraventricular injections of cytochrome C. Injections (2 microliters) were given every other day for a period of 1 month. Single neuron activity was recorded in the primary visual cortex of MD rats, MD rats treated with NGF, and MD rats treated with cytochrome C at the end of the deprivation period, and in normal rats of the same age. We found that monocular deprivation caused a striking change in the ocular dominance distribution of untreated MD rats, reducing binocular cells by a factor of two and increasing by a factor of eight the number of cells dominated by the nondeprived eye. In MD NGF-treated rats, the ocular dominance distribution was indistinguishable from the normal. Cytochrome C treatment was completely ineffective in preventing the ocular dominance shift induced by monocular deprivation. To test whether NGF affected cortical physiology or interfered with transmission of visual information, we evaluated in NGF-treated rats the spontaneous discharge and the orientation selectivity. We found these functional properties to be in the normal range. We conclude that NGF is effective in preventing the effects of monocular deprivation in the rat visual cortex and suggest that NGF is a crucial factor in the competitive processes leading to the stabilization of functional geniculocortical connections during the critical period.
在单眼剥夺（MD）大鼠中，对神经生长因子（NGF）可能在发育中的哺乳动物视觉皮层可塑性中发挥作用这一假说进行了验证。具体而言，我们探究了外源性补充NGF是否能够预防单眼剥夺引起的眼优势分布变化。从出生后第14天（P14），即睁眼之前，通过眼睑缝合对带帽大鼠进行单眼剥夺1个月。8只大鼠仅进行单眼剥夺；8只大鼠单眼剥夺的同时进行脑室内注射β-NGF；3只大鼠单眼剥夺的同时进行脑室内注射细胞色素C。每隔一天注射（2微升），持续1个月。在剥夺期结束时，记录了未处理的MD大鼠、用NGF处理的MD大鼠和用细胞色素C处理的MD大鼠以及同年龄正常大鼠初级视觉皮层中的单神经元活动。我们发现，单眼剥夺使未处理的MD大鼠的眼优势分布发生显著变化，双眼细胞数量减少了一半，而非剥夺眼主导的细胞数量增加了八倍。在用NGF处理的MD大鼠中，眼优势分布与正常情况无异。细胞色素C处理在预防单眼剥夺引起的眼优势转移方面完全无效。为了测试NGF是否影响皮层生理或干扰视觉信息传递，我们评估了用NGF处理的大鼠的自发放电和方向选择性。我们发现这些功能特性在正常范围内。我们得出结论，NGF可有效预防大鼠视觉皮层中单眼剥夺的影响，并表明NGF是关键期内导致功能性膝状体-皮层连接稳定的竞争过程中的一个关键因素。
