Kaplan A M, Vigna S R
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
Peptides. 1994;15(2):297-302. doi: 10.1016/0196-9781(94)90016-7.
Synthetic porcine gastric inhibitory polypeptide (GIP) was iodinated and purified by reverse-phase HPLC and used to localize saturable [125I]GIP binding sites by radioligand binding to frozen sections of rat brain followed by autoradiography. Saturable [125I]GIP binding sites were expressed in several brain regions including cerebral cortex, anterior olfactory nucleus, lateral septal nucleus, subiculum, inferior colliculus, and inferior olive. Saturable [125I]GIP binding was time dependent, reversible, high affinity, and specific for GIP. Scatchard analysis of equilibrium binding resulted in an estimated dissociation constant (Kd) of 16-62 pM for the rat brain [125I]GIP binding sites. Peptides with amino acid sequences similar to GIP such as secretin, vasoactive intestinal polypeptide (VIP), glucagon, and peptide histidine isoleucine (PHI) only partially inhibited saturable [125I]GIP binding at concentrations approximately 10,000-100,000-fold higher than GIP. Saturable [125I]GIP binding was not observed in other rat organs surveyed such as spinal cord, pituitary, stomach, small intestine, colon, pancreas, liver, heart, or skeletal muscle. We conclude that a saturable [125I]GIP binding site with the pharmacological properties of an authentic GIP receptor is expressed in certain regions of the rat brain.
合成猪胃抑制多肽（GIP）经碘化后通过反相高效液相色谱法纯化，并用于通过放射性配体与大鼠脑冰冻切片结合后进行放射自显影来定位可饱和的[125I]GIP结合位点。可饱和的[125I]GIP结合位点在包括大脑皮层、前嗅核、外侧隔核、海马下脚、下丘和下橄榄核在内的几个脑区中表达。可饱和的[125I]GIP结合具有时间依赖性、可逆性、高亲和力且对GIP具有特异性。对平衡结合进行Scatchard分析得出，大鼠脑[125I]GIP结合位点的估计解离常数（Kd）为16 - 62 pM。与GIP氨基酸序列相似的肽，如促胰液素、血管活性肠多肽（VIP）、胰高血糖素和肽组氨酸异亮氨酸（PHI），在浓度比GIP高约10,000 - 100,000倍时仅部分抑制可饱和的[125I]GIP结合。在所检测的其他大鼠器官如脊髓、垂体、胃、小肠、结肠、胰腺、肝脏、心脏或骨骼肌中未观察到可饱和的[125I]GIP结合。我们得出结论，在大鼠脑的某些区域表达了具有真实GIP受体药理学特性的可饱和[125I]GIP结合位点。
