Fiszer de Plazas S, Conterjnic D, Flores V
Instituto de Biologia Celular, Facultad de Medicina, Universidad de Buenos Aires, Paraguay, Argentina.
Int J Dev Neurosci. 1991;9(3):195-201. doi: 10.1016/0736-5748(91)90040-s.
It is known that manipulation of the visual environment results in changes in the developmental pattern of several neurotransmitter receptors and that the GABA receptor shows a high degree of plasticity in differential illumination experiments. In the present paper we investigated whether exposure to a visual pattern has a developmental effect on GABA receptor expression during early postnatal life. Two groups of newly hatched chicks were used: one was exposed to a simple and specific visual pattern and the other was deprived of any visual pattern. GABA receptors at each developmental stage were determined by binding experiments performed in a crude membrane fraction. Saturation studies were carried out in a fraction enriched in synaptic membranes. The developmental pattern of both high and low affinity GABA binding sites was affected by the visual pattern. This effect displays its maximal expression by the end of the first postnatal week. The modification in receptor expression was due to a change in the receptor density while the affinity was not affected. The change in receptor density induced by the presence of a visual pattern was highest at the end of the first postnatal week suggesting that at that time there is a brief period of higher plasticity for GABA receptor expression in the visual system than at other times. Our results also suggest that variations in GABA receptor density could be instrumental in adaptative changes in the visual system in response to variations in the environmental stimulation.
已知对视觉环境的操控会导致几种神经递质受体的发育模式发生变化，并且在差异光照实验中，GABA受体表现出高度的可塑性。在本文中，我们研究了在出生后早期接触视觉模式是否对GABA受体表达有发育影响。使用了两组新孵出的小鸡：一组暴露于简单且特定的视觉模式，另一组则没有任何视觉模式。通过在粗制膜组分中进行的结合实验来测定每个发育阶段的GABA受体。在富含突触膜的组分中进行饱和研究。高亲和力和低亲和力GABA结合位点的发育模式均受视觉模式影响。这种影响在出生后第一周结束时表现出最大程度的表达。受体表达的改变是由于受体密度的变化，而亲和力未受影响。由视觉模式的存在引起的受体密度变化在出生后第一周结束时最高，这表明在那个时候，视觉系统中GABA受体表达的可塑性比其他时候更高。我们的结果还表明，GABA受体密度的变化可能有助于视觉系统响应环境刺激变化而发生适应性改变。
