Bylund D B, Rudeen P K, Petterborg L J, Ray-Prenger C
Department of Pharmacology, School of Medicine, University of Missouri-Columbia 65212.
J Neurochem. 1988 Jul;51(1):81-6. doi: 10.1111/j.1471-4159.1988.tb04838.x.
The norepinephrine-induced inhibition of avian pineal N-acetyltransferase activity appears to be mediated by alpha 2-adrenergic receptors. In this study, alpha 2-adrenergic receptors in the chicken pineal gland were directly identified by radioligand binding. Membrane preparations of pineal glands from chickens from 1 to 6 weeks of age were examined using [3H]rauwolscine, a selective alpha 2-adrenergic receptor antagonist, to characterize the binding sites. The results indicate no ontological change in either the affinity (KD) or density of receptor binding sites (Bmax) during the time span examined. The binding was saturable and of high affinity with a mean KD of 0.27 +/- 0.01 nM and a mean Bmax of 242 +/- 12 fmol/mg protein. Further characterization of these binding sites indicated that the alpha 2-adrenergic receptor is of the alpha 2A subtype, since prazosin and ARC-239 bound with low affinities and oxymetazoline bound with high affinity.
去甲肾上腺素对禽类松果体N - 乙酰转移酶活性的抑制作用似乎是由α2 - 肾上腺素能受体介导的。在本研究中，通过放射性配体结合直接鉴定了鸡松果体中的α2 - 肾上腺素能受体。使用[3H]萝芙辛（一种选择性α2 - 肾上腺素能受体拮抗剂）检测1至6周龄鸡松果体的膜制剂，以表征结合位点。结果表明在所研究的时间段内，受体结合位点的亲和力（KD）或密度（Bmax）均无发育学变化。该结合具有饱和性且亲和力高，平均KD为0.27±0.01 nM，平均Bmax为242±12 fmol/mg蛋白质。对这些结合位点的进一步表征表明，α2 - 肾上腺素能受体属于α2A亚型，因为哌唑嗪和ARC - 239结合亲和力低，而羟甲唑啉结合亲和力高。
