Young K A, Wilcox R E
Texas A&M University College of Medicine, Department of Pharmacology, Temple 76508.
Life Sci. 1991;48(19):1845-52. doi: 10.1016/0024-3205(91)90240-c.
We kinetically characterized D2 receptors in thalami pooled from a group of Sprague-Dawley rats and then determined thalamic levels of dopamine (DA), homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), and norepinephrine (NE) in relation to a measure of thalamic DA D2 receptor densities in another group of rats. The equilibrium dissociation constant (kd) was estimated as 0.1 nM by three independent methods, while the Bmax for thalamic D2 receptors was found to be 6.4 fmol/mg p using 3H-spiperone as ligand and ketanserin to occlude 5HT2 binding. Kinetic constants were in agreement with previously reported kinetic data from rodent caudate-putamen. This suggests that thalamic D2 receptors are similar to D2 receptors from other brain areas. Mean thalamic levels of DA (22.6 ng/mg p), DOPAC (1.19 ng/mg p) and HVA (0.31 ng/mg p) concur with previous reports of a sparse distribution of thalamic DA neurons. D2 receptor densities were positively correlated with DA metabolites DOPAC (P less than .05; r = 0.423) and HVA (P less than .05; r = 0.368), but not DA or NE. These results establish fundamental characteristics of thalamic DA neurotransmission to assist in the investigation of behavioral pharmacology of this area.
我们对一组斯普拉格-道利大鼠的丘脑进行了D2受体的动力学特性分析，然后在另一组大鼠中测定了丘脑多巴胺（DA）、高香草酸（HVA）、二羟基苯乙酸（DOPAC）和去甲肾上腺素（NE）的水平，并将其与丘脑DA D2受体密度的测量值相关联。通过三种独立方法估计平衡解离常数（kd）为0.1 nM，而使用3H-司来吉兰作为配体并使用酮色林阻断5HT2结合时，丘脑D2受体的Bmax为6.4 fmol/mg p。动力学常数与先前报道的啮齿动物尾状核-壳核的动力学数据一致。这表明丘脑D2受体与其他脑区的D2受体相似。DA（22.6 ng/mg p）、DOPAC（1.19 ng/mg p）和HVA（0.31 ng/mg p）的丘脑平均水平与先前关于丘脑DA神经元分布稀疏的报道一致。D2受体密度与DA代谢物DOPAC（P小于0.05；r = 0.423）和HVA（P小于0.05；r = 0.368）呈正相关，但与DA或NE无关。这些结果确立了丘脑DA神经传递的基本特征，以协助该领域行为药理学的研究。
