Morgan P J, Williams L M, Lawson W, Riddoch G
Rowett Research Institute, Bucksburn, Aberdeen, U.K.
Brain Res. 1988 May 3;447(2):279-86. doi: 10.1016/0006-8993(88)91130-4.
In vitro autoradiography of [125I]cyanopindolol ([125I]cyp) binding to sections of ovine pineal reveals a uniform distribution of beta-adrenergic receptors throughout the gland. Norepinephrine (NE) stimulated cyclic AMP production in pineal slices in both a time- and dose-dependent manner, producing a maximal two-fold increase. NE, isoproterenol (ISO) and epinephrine (E) stimulate cyclic AMP (cAMP) production with equal potency. NE stimulation of cAMP was totally blocked by propranolol (beta antagonist) but only partially blocked by practolol (a beta 1 preferential antagonist) indicating a mixed population of beta 1 and beta 2 receptor subtypes. Displacement of [125I]cyp binding by either practolol or zinterol (preferential beta 2 agonist) revealed IC50s of 1.3 x 10(-5) M and 9.95 x 10(-8) M respectively, confirming a mixed population of beta 1 and beta 2 receptors. A range of peptides previously localised within the pineal by immunocytochemistry were tested at a concentration of 10(-5) M for their effect on cyclic AMP production in pineal homogenates. Only vasoactive intestinal peptide (VIP) was effective showing a dose-dependent stimulation. ISO and VIP stimulation of cAMP were additive indicating action via independent receptors.
[125I]氰基吲哚洛尔（[125I]cyp）与绵羊松果体切片结合的体外放射自显影显示，β-肾上腺素能受体在整个腺体中分布均匀。去甲肾上腺素（NE）以时间和剂量依赖性方式刺激松果体切片中环状AMP的产生，最大增加两倍。NE、异丙肾上腺素（ISO）和肾上腺素（E）以同等效力刺激环状AMP（cAMP）的产生。普萘洛尔（β拮抗剂）完全阻断了NE对cAMP的刺激，但普拉洛尔（一种β1选择性拮抗剂）仅部分阻断，表明存在β1和β2受体亚型的混合群体。普拉洛尔或齐特罗尔（选择性β2激动剂）对[125I]cyp结合的置换显示IC50分别为1.3×10（-5）M和9.95×10（-8）M，证实了β1和β2受体的混合群体。以10（-5）M的浓度测试了一系列先前通过免疫细胞化学定位在松果体内的肽对松果体匀浆中环状AMP产生的影响。只有血管活性肠肽（VIP）有效，表现出剂量依赖性刺激。ISO和VIP对cAMP的刺激是相加的，表明通过独立受体起作用。
