Concentration-dependent suppression by beta-adrenergic antagonists of the shift in ocular dominance following monocular deprivation in kitten visual cortex.
Concentration-dependent suppression by beta-adrenergic antagonists of the shift in ocular dominance following monocular deprivation in kitten visual cortex.
复制标题
β-肾上腺素能拮抗剂对小猫视觉皮层单眼剥夺后眼优势转变的浓度依赖性抑制。
DOI：
10.1016/0306-4522(86)90115-6
复制
发表时间：
1986
期刊：
影响因子：
3.3
通讯作者：
Kasamatsu,T
中科院分区：
文献类型：
--
作者：
Shirokawa,T;Kasamatsu,T
我们发现β-肾上腺素能受体拮抗剂阻断了小猫在短暂单眼剥夺后的眼优势转移。普萘洛尔局部微灌注到小猫视觉皮层，可减少眼优势距灌注中心2 mm的预期偏移。然而，阻断作用并没有达到距离灌注中心约5毫米的区域，这表明β受体阻滞剂在目前的范例中以浓度依赖的方式起作用。我们通过广泛改变储存在渗透微型泵中的β受体阻滞剂（心得安和索他洛尔）的浓度，进一步研究了浓度-效应关系。当普萘洛尔浓度从10−6M增加到10−2M时，双眼细胞比例由0.13增加到0.67，在普萘洛尔浓度约10−4M时达到半最大值（双眼视力为0.40）。然而，在相同条件下，索他洛尔灌注获得的最大双眼明显低于心得安（0.45）。因此，在约10−5M的温度下获得了半最大双目度（0.30）。我们还注意到β受体阻滞剂的对数浓度与眼优势转移程度之间存在线性反比关系，这是通过单眼细胞的比例来测量的，单眼细胞只对非剥夺眼的刺激作出反应。后者从0.75降低到0.25，前者从10−6M增加到10−2M（在渗透微型泵中）。两种β受体阻滞剂在这种相关性中表现相似。局部灌注[3H]心得安在皮质灌注1周结束时观察皮质内扩散情况。放射性在灌注中心处最高，随着距离的增加而迅速下降，在距灌注中心约3mm处趋于平稳。局部灌注[3H]心得安的平均“稀释系数”计算为生理记录区域（距离灌注中心约2mm）原始溶液的11/70左右。应用11/70的“稀释因子”，我们估计了在记录位点获得半最大效果所需的β受体阻滞剂的近似浓度；心得安为5.8 × 10−7M，索他洛尔为5.8 × 10−8M。综上所述，目前的结果被解释为在视觉皮层内激活的β-肾上腺素能受体的数量与单眼剥夺后眼优势的变化程度之间存在正相关。因此，我们得出结论，正常功能的β-肾上腺素能受体可能在视觉皮质可塑性的调节中起关键作用。
We showed that β-adrenergic receptor antagonists blocked the shift in ocular dominance following brief monocular deprivation in young kittens. Localized microperfusion of propranolol into the kitten visual cortex reduced the expected shift in the ocular dominance ~2 mm away from the center of perfusion. The blocking effect, however, did not reach an area ~5 mm from the perfusion center, suggesting that β blockers work in a concentration-dependent fashion in the present paradigm.We further studied the concentration-effect relationship by widely changing the concentration of β blockers (propranolol and sotalol) stored in an osmotic minipump. The proportion of binocular cells increased from 0.13 to 0.67 when the concentration of propranolol was increased from 10−6M to 10−2M, giving the half-maximum effect (binocularity, 0.40) at about 10−4M propranolol. However, the maximum binocularity obtained with the sotalol perfusion under the comparable condition was apparently much lower (0.45) than that with propranolol. Accordingly, the half-maximum binocularity (0.30) was obtained at about 10−5M sotalol. We also noted the presence of a linear, inverse relation between the logarithmic concentration of the β blockers and the extent of the shift in ocular dominance as measured by the proportion of monocular cells which responded exclusively to stimulation of the nondeprived eye. The latter decreased from 0.75 to 0.25, when the former was increased from 10−6M to 10−2M (in an osmotic minipump). The two β blockers behaved similarly in this correlation.The intracortical spread of locally perfused [3H]propranolol was studied at the end of the cortical perfusion which lasted for a week. The radioactivity was highest at the perfusion center and rapidly declined with increasing distance, leveling off ~3 mm from the perfusion center. The average “dilution factor” of locally perfused [3H]propranolol was calculated as about 11/70 of the original solution in an area of physiological recordings (~2 mm from the perfusion center). Applying the “dilution factor” of 11/70, we estimated the approximate concentration of β blockers needed at the recording sites to obtain the half-maximum effect; it was about 5.8 × 10−7M for propranolol and 5.8 × 10−8M for sotalol.Taken together, the present results were interpreted as suggesting that there is a positive correlation between the number of activated β-adrenergic receptors within the visual cortex and the extent of changes in ocular dominance following monocular deprivation. Thus, we conclude that normally functioning β-adrenergic receptors may be critically involved in the regulation of visuocortical plasticity.