López-Sañudo S, Arilla E
Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
Neurosci Lett. 1994 Jan 3;165(1-2):27-32. doi: 10.1016/0304-3940(94)90701-3.
Interaction of beta-adrenergic and somatostatinergic systems in the hippocampus has not been investigated fully. We studied the influence of DL-isoproterenol (ISO), a beta-adrenergic agonist and DL-propranolol (PRO), a beta-adrenergic blocking agent, on the somatostatinergic system in the rat hippocampus. The short-(5h) and long-term (14 days) administration of ISO (5 mg/kg i.p.) or of PRO (10 mg/kg i.p.) did not affect somatostatin-like immunoreactivity (SSLI) content in the hippocampus of male Wistar rats. Both short- and long-term ISO administration decreased the number of specific [125I]Tyr11-somatostatin ([125I]Tyr11-SS) receptors in synaptosomes from hippocampus (29%, P < 0.05 and 34%, P < 0.05, after short- and long-term administration, respectively) without changing the affinity constant. This decrease in the number of [125I]Tyr11-SS receptors was not due to a direct effect of ISO on these receptors since no decrease in binding was produced by high concentrations of ISO (10(-5) M) when added in vitro. In addition, this decrease could be blocked by pretreatment with PRO. Short- and long-term administration of PRO alone increased the [125I]Tyr11-SS binding in hippocampus (42%, P < 0.05 and 33%, P < 0.05, after short- or long-term administration, respectively) without changing the affinity constant. Although there is no direct evidence that the regulation of SS receptors by the beta-adrenergic system has a physiological significance, this mechanism may provide a means by which the brain environment could modulate SS receptor number and, therefore, sensitivity to SS in a subset of SS-sensitive neurons.
海马体中β-肾上腺素能系统与生长抑素能系统之间的相互作用尚未得到充分研究。我们研究了β-肾上腺素能激动剂DL-异丙肾上腺素（ISO）和β-肾上腺素能阻滞剂DL-普萘洛尔（PRO）对大鼠海马体中生长抑素能系统的影响。短期（5小时）和长期（14天）给予ISO（5毫克/千克腹腔注射）或PRO（10毫克/千克腹腔注射）均未影响雄性Wistar大鼠海马体中生长抑素样免疫反应性（SSLI）的含量。短期和长期给予ISO均可降低海马体突触体中特异性[125I]酪氨酸11-生长抑素（[125I]酪氨酸11-SS）受体的数量（短期和长期给药后分别降低29%，P<0.05和34%，P<0.05），而亲和力常数不变。[125I]酪氨酸11-SS受体数量的减少并非由于ISO对这些受体的直接作用，因为在体外加入高浓度ISO（10^-5 M）时未导致结合减少。此外，这种减少可被PRO预处理阻断。单独短期和长期给予PRO可增加海马体中[125I]酪氨酸11-SS的结合（短期或长期给药后分别增加42%，P<0.05和33%，P<0.05），而亲和力常数不变。虽然没有直接证据表明β-肾上腺素能系统对SS受体的调节具有生理意义，但这种机制可能提供了一种大脑环境调节SS受体数量的方式，从而调节一部分对SS敏感神经元对SS的敏感性。
