Strejcková A, Mares P, Raevsky V
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Exp Neurol. 1987 Dec;98(3):555-62. doi: 10.1016/0014-4886(87)90264-0.
Acetylcholine was applied microiontophoretically by means of multibarrel electrodes to neurons in the sensorimotor cortex of adult, 18-, 15-, 12-, and 9-day-old rats anesthetized with urethane. A total of 229 neurons was recorded; only 22 of them were in 18- and 15-day-old rats because of similarity of results with those from adult as well as 12-day-old animals. In adult rats 43 of 58 neurons recorded in infragranular layers responded to acetylcholine with a marked increase in their firing. In 12-day-old rats the incidence of excitatory responses to acetylcholine was also high: 59 of 86 cells again were localized predominantly in deep cortical layers (V and VI). A marked difference was observed in 9-day-old rats: only 15 of 63 neurons were excited by acetylcholine. A majority of cells did not respond at all--including units localized in infragranular layers. Two cells in layer V responded to acetylcholine by an inhibition. Our results indicate that there is a marked increase in cholinoceptivity of cortical neurons between postnatal days 9 and 12. This finding is in agreement with the finding that local application of acetylcholine can elicit an epileptogenic focus in 12-day but not in 9-day-old rat pups.
通过多管电极以微离子电泳方式将乙酰胆碱施加于用氨基甲酸乙酯麻醉的成年、18日龄、15日龄、12日龄和9日龄大鼠的感觉运动皮层神经元。共记录了229个神经元；由于18日龄和15日龄大鼠的结果与成年及12日龄动物的结果相似，因此其中只有22个神经元来自这两个年龄段的大鼠。在成年大鼠中，在颗粒下层记录的58个神经元中有43个对乙酰胆碱有反应，其放电明显增加。在12日龄大鼠中，对乙酰胆碱的兴奋性反应发生率也很高：86个细胞中有59个主要位于皮层深层（V层和VI层）。在9日龄大鼠中观察到明显差异：63个神经元中只有15个被乙酰胆碱兴奋。大多数细胞根本没有反应，包括位于颗粒下层的细胞。V层中的两个细胞对乙酰胆碱有抑制反应。我们的结果表明，出生后第9天至第12天之间，皮层神经元的胆碱敏感性显著增加。这一发现与以下发现一致，即局部应用乙酰胆碱可在12日龄但不能在9日龄的幼鼠中引发癫痫病灶。
