Wolf S S, Moody T W, Quirion R, O'Donohue T L
Brain Res. 1985 Apr 22;332(2):299-307. doi: 10.1016/0006-8993(85)90598-0.
The binding of [125I]physalaemin to rat brain slices was investigated. Radiolabeled physalaemin bound with high affinity (Kd = 0.3 nM) to a single class of sites (Bmax = 22 fmol/mg protein). Kinetic studies indicated that binding was time-dependent and all specific binding was reversible. Pharmacology studies indicated that specific [125I]physalaemin binding was inhibited by structurally related peptides such as substance P and eledoisin. Biochemical studies indicated that specific binding of radiolabeled physalaemin was greatly reduced if the brain slices were pretreated with heat, trypsin or N-ethyl maleimide. Autoradiographic studies indicated that the [125I]physalaemin binding sites were discretely distributed throughout the brain. Highest grain densities were present in the olfactory bulb, dentate gyrus, amygdala, superficial layers of the superior colliculus, subiculum, dorsal parabrachial nucleus, locus coeruleus, nucleus tractus solitarii and dorsal horn of the spinal cord. Moderate grain densities were present in the nucleus accumbens, olfactory tubercle, pyriform cortex, striatum, hippocampus, inferior colliculus and central gray of the midbrain. Low grain densities were present in most thalamic nuclei, the substantia nigra and cerebellum. The corpus callosum and controls treated with 1 microM unlabeled physalaemin had negligible levels of binding. The unique pharmacological and regional distribution data obtained suggest that [125I]physalaemin may serve as a valuable probe to study central substance P receptors.
研究了[125I]雨蛙肽与大鼠脑片的结合情况。放射性标记的雨蛙肽以高亲和力（Kd = 0.3 nM）与一类位点结合（Bmax = 22 fmol/mg蛋白质）。动力学研究表明，结合具有时间依赖性，且所有特异性结合都是可逆的。药理学研究表明，特异性[125I]雨蛙肽结合受到结构相关肽（如P物质和eledoisin）的抑制。生化研究表明，如果脑片用热、胰蛋白酶或N-乙基马来酰亚胺预处理，放射性标记的雨蛙肽的特异性结合会大大降低。放射自显影研究表明，[125I]雨蛙肽结合位点在整个大脑中呈离散分布。嗅球、齿状回、杏仁核、上丘表层、海马下脚、臂旁背核、蓝斑、孤束核和脊髓背角存在最高的颗粒密度。伏隔核、嗅结节、梨状皮质、纹状体、海马、下丘和中脑中央灰质存在中等颗粒密度。大多数丘脑核、黑质和小脑存在低颗粒密度。胼胝体和用1 microM未标记雨蛙肽处理的对照结合水平可忽略不计。所获得的独特药理学和区域分布数据表明，[125I]雨蛙肽可能是研究中枢P物质受体的有价值探针。
