Luccardini C, Barilà B, Cupello A, Robello M, Mainardi P
Centro di Neurofisiologia Cerebrale, CNR, Genova, Italy.
Amino Acids. 2001;21(2):119-28. doi: 10.1007/s007260170019.
GABAA receptors of cerebellar granule cells obtained from neonatal rats and kept in culture were studied by labelled muscimol binding. The data show that, according to the maturational state of those cells in vivo, one or two binding components appear. The low affinity component seems to be the one appearing later. The expression of this component seems to be regulated by protein tyrosine phosphorylation. In fact, its expression is down regulated by the protein tyrosine kinase (PTK) inhibitor, genistein. Viceversa, its expression is upregulated by insulin like growth factor I (IGF-I), most probably via PTK activation. A possible interpretation of the data is that in vivo IGF-I is one of the endogenous messages leading to the expression of this component during development. Another endogenous factor involved may be GABA itself. Low affinity GABAA receptors appear to be the ones involved in inhibitory synaptic transmission at glomeruli. Whereas the high affinity ones probably correspond to extrasynaptic GABAA receptors mediating the tonic form of inhibition in cerebellar granules.
通过标记的蝇蕈醇结合研究了从新生大鼠获得并培养的小脑颗粒细胞的GABAA受体。数据表明，根据这些细胞在体内的成熟状态，会出现一个或两个结合成分。低亲和力成分似乎是较晚出现的那个。该成分的表达似乎受蛋白质酪氨酸磷酸化调节。事实上，蛋白质酪氨酸激酶（PTK）抑制剂金雀异黄素会下调其表达。反之，胰岛素样生长因子I（IGF-I）很可能通过激活PTK上调其表达。对这些数据的一种可能解释是，在体内IGF-I是发育过程中导致该成分表达的内源性信号之一。另一个可能涉及的内源性因素可能是GABA本身。低亲和力GABAA受体似乎参与了小球处的抑制性突触传递。而高亲和力受体可能对应于介导小脑颗粒细胞紧张性抑制形式的突触外GABAA受体。
