Chuluyan H E, Rosenstein R E, Cardinali D P
Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Mol Cell Endocrinol. 1989 Jun;64(1):71-80. doi: 10.1016/0303-7207(89)90066-x.
An assessment of serotonin (5HT) release was made in bovine pineal gland. Bovine pineal fragments took up [3H]5HT by a Na+-dependent process exhibiting two apparent Km, i.e. a high affinity uptake system (Km = 220 nM) and a low affinity uptake system (Km = 197 microM). A significant release of [3H]5HT was elicited by increasing K+ concentrations in the medium (20-80 mM). Exposure of bovine pineal fragments to varying doses of catecholaminergic agonists indicated that a significant [3H]5HT release was elicited at the following threshold concentrations: 10(-6) M norepinephrine (NE), 10(-7) M dopamine (DA), 10(-6) phenylephrine and 10(-6) M isoproterenol. By employing specific receptor agonists and antagonists, the 5HT release activity of adrenergic agonists was found to be mediated by alpha 1-adrenoceptors, while that of DA by D2-dopaminergic receptors. 5HT release elicited by NE or DA, as well as that by 30 mM K+, was Ca2+-dependent. Both NE and DA increase 45Ca2+ uptake in a dispersed cell preparation of bovine pineal glands. As in the case of 5HT release, the effect of NE and DA on calcium uptake was mediated by alpha 1-adrenoceptors and D2-dopaminergic receptors, respectively. These results indicate that both NE and DA control 5HT release in bovine pineal gland.
对牛松果体中的5-羟色胺（5HT）释放进行了评估。牛松果体片段通过一种依赖于钠离子的过程摄取[3H]5HT，该过程表现出两个明显的米氏常数（Km），即一个高亲和力摄取系统（Km = 220 nM）和一个低亲和力摄取系统（Km = 197 microM）。培养基中钾离子浓度升高（20 - 80 mM）会引发显著的[3H]5HT释放。将牛松果体片段暴露于不同剂量的儿茶酚胺能激动剂表明，在以下阈值浓度时会引发显著的[3H]5HT释放：10(-6) M去甲肾上腺素（NE）、10(-7) M多巴胺（DA）、10(-6) 苯肾上腺素和10(-6) M异丙肾上腺素。通过使用特异性受体激动剂和拮抗剂，发现肾上腺素能激动剂的5HT释放活性由α1 - 肾上腺素受体介导，而多巴胺的5HT释放活性由D2 - 多巴胺能受体介导。由NE或DA引发的5HT释放，以及由30 mM钾离子引发的5HT释放，均依赖于钙离子。在牛松果体的分散细胞制剂中，NE和DA均增加45Ca2+摄取。与5HT释放的情况一样，NE和DA对钙摄取的作用分别由α1 - 肾上腺素受体和D2 - 多巴胺能受体介导。这些结果表明，NE和DA均控制牛松果体中的5HT释放。
