Debeir T, Benavides J, Vigé X
Synthelabo Recherche CNS Research Department, Bagneux, France.
Neuroscience. 1998 Feb;82(3):739-52. doi: 10.1016/s0306-4522(97)00317-5.
In situ hybridization studies have revealed high levels of protease (thrombin)-activated receptor-1 messenger RNA in the mesencephalon of rats, suggesting that dopaminergic neurons are a target for thrombin's actions. We have evaluated the effect of thrombin receptor activation, either by thrombin or by thrombin receptor agonist peptide, a 14 amino acid agonist of protease-activated receptor-1, on tyrosine hydroxylase-positive neurons. Pure cultures of rat mesencephalic neurons or co-cultures of mesencephalic neurons and glial cells were treated with either thrombin or thrombin receptor agonist peptide the day after plating. Tyrosine hydroxylase-positive cell counting, [3H]dopamine uptake and morphometric analysis were performed on day 5. Thrombin and thrombin receptor agonist peptide influenced neurite elongation, branching and the number of primary, secondary and tertiary neurites of tyrosine hydroxylase-positive neurons. In pure cultures, the most significant effects of thrombin and thrombin receptor agonist peptide were to delay branching and to increase the centrifugal growth of neurites without affecting the total neuritic length. Thrombin (up to 10 nM) and thrombin receptor agonist peptide did not affect the number of tyrosine hydroxylase-positive neurons or [3H]dopamine uptake. Neurotrophin-4 also influenced the morphology of tyrosine hydroxylase-positive neurons. The increase of neuritic length initiated by this neurotrophin is complementary to the radial elongation induced by protease-activated receptor-1 activation. When neurons were cultured in the presence of glial cells, the effects of thrombin and thrombin receptor agonist peptide on most of these parameters were larger than those observed with pure cultures. Thus, thrombin is able to initiate a complex remodelling of the architecture of tyrosine hydroxylase-positive neurons through the activation of protease-activated receptor-1. These results provide further support for the involvement of protease-activated receptor-1 activation in the development and differentiation of the central nervous system.
原位杂交研究显示，大鼠中脑中蛋白酶（凝血酶）激活的受体-1信使核糖核酸水平很高，这表明多巴胺能神经元是凝血酶作用的靶点。我们评估了凝血酶受体激活（通过凝血酶或凝血酶受体激动肽，一种14个氨基酸的蛋白酶激活受体-1激动剂）对酪氨酸羟化酶阳性神经元的影响。在接种后的第二天，用凝血酶或凝血酶受体激动肽处理大鼠中脑神经元的纯培养物或中脑神经元与神经胶质细胞的共培养物。在第5天进行酪氨酸羟化酶阳性细胞计数、[3H]多巴胺摄取和形态计量分析。凝血酶和凝血酶受体激动肽影响酪氨酸羟化酶阳性神经元的神经突伸长、分支以及一级、二级和三级神经突的数量。在纯培养物中，凝血酶和凝血酶受体激动肽最显著的作用是延迟分支并增加神经突的离心生长，而不影响神经突的总长度。凝血酶（高达10 nM）和凝血酶受体激动肽不影响酪氨酸羟化酶阳性神经元的数量或[3H]多巴胺摄取。神经营养因子-4也影响酪氨酸羟化酶阳性神经元的形态。这种神经营养因子引发的神经突长度增加与蛋白酶激活受体-1激活诱导的径向伸长互补。当神经元在神经胶质细胞存在的情况下培养时，凝血酶和凝血酶受体激动肽对大多数这些参数的影响比在纯培养物中观察到的更大。因此，凝血酶能够通过激活蛋白酶激活受体-1引发酪氨酸羟化酶阳性神经元结构的复杂重塑。这些结果为蛋白酶激活受体-1激活参与中枢神经系统的发育和分化提供了进一步的支持。
