Hatton G I, Luckman S M, Bicknell R J
Department of Neuroendocrinology, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Brain Res Bull. 1991 May;26(5):765-9. doi: 10.1016/0361-9230(91)90173-h.
Neurohypophysial astrocytes, the pituicytes, are known to undergo morphological changes in vivo in response to stimuli that increase the demand for hormone secretion. Similar changes have been induced by beta-adrenergic stimulation both in the isolated, but otherwise intact, neural lobe and in pituicytes cultured from adult rats. Since the predominant beta-receptor subtype in the neural lobe is beta 2, we investigated the possibility that beta 2-receptor activation is mainly responsible for the observed pituicyte responses. In one experiment, cultured pituicytes were induced by noradrenalin to change from flattened amorphous to stellate morphology. Addition of the beta 2-antagonist IPS 339, but not the beta 1-antagonist practolol, significantly reduced (by 30-60%) the number of cells transformed by noradrenalin. In a second experiment, adrenalin, by definition a more potent beta 2-agonist, transformed significantly more pituicytes into stellate shapes than did noradrenalin at the same concentrations (100% vs. 60% increase, respectively). These results support the idea that beta 2-adrenergic receptors are involved in neurohypophysial plasticity. Also, since the neural lobe is outside of the bloodbrain barrier, these findings suggest that adrenal catecholamines participate in altering pituicyte morphology.
神经垂体星形胶质细胞，即垂体细胞，已知在体内会因增加激素分泌需求的刺激而发生形态变化。在分离但其他方面完整的神经叶以及从成年大鼠培养的垂体细胞中，β - 肾上腺素能刺激也诱导了类似的变化。由于神经叶中主要的β - 受体亚型是β2，我们研究了β2 - 受体激活是否主要负责观察到的垂体细胞反应。在一项实验中，培养的垂体细胞被去甲肾上腺素诱导从扁平无定形形态转变为星状形态。添加β2拮抗剂IPS 339，但不添加β1拮抗剂心得宁，显著减少（30% - 60%）了被去甲肾上腺素转化的细胞数量。在第二项实验中，肾上腺素（根据定义是一种更强效的β2激动剂）在相同浓度下（分别增加100%和60%）比去甲肾上腺素显著更多地将垂体细胞转化为星状形态。这些结果支持β2 - 肾上腺素能受体参与神经垂体可塑性的观点。此外，由于神经叶位于血脑屏障之外，这些发现表明肾上腺儿茶酚胺参与改变垂体细胞形态。
