Chen K, Waller H J, Godfrey D A
Department of Otolaryngology, Medical College of Ohio, Toledo 43699.
Hear Res. 1994 Jun 15;77(1-2):168-76. doi: 10.1016/0378-5955(94)90264-x.
Extracellular recordings were made from brain stem slices to test the effects of bath application of cholinergic agonists and antagonists on the firing rates of spontaneously active dorsal cochlear nucleus neurons. About 90% of neurons responded to carbachol. A higher proportion responded to muscarine than to nicotine. Muscarine elicited larger responses at lower concentrations than nicotine. Responses to either carbachol or muscarine were always blocked by atropine or scopolamine. The nicotinic antagonists d-tubocurarine, hexamethonium, and mecamylamine blocked the responses to nicotine, but did not decrease the responses to carbachol. Regularly firing neurons showed only increases of firing rate during exposure to cholinergic agonists. About half of responsive bursting neurons showed increased firing; half showed increased followed by decreased firing to 10 microM carbachol or muscarine. All phases of the responses of most bursting neurons were greatly decreased or abolished in low calcium, high magnesium medium, while responses of regular neurons were not detectably affected. Thus, cholinergic agonists appear to act directly on regularly firing neurons, while their actions on bursting neurons may require synaptic activity. The data suggest that cholinergic transmission in the dorsal cochlear nucleus is predominantly muscarinic, and that most regularly firing spontaneously active neurons have muscarinic receptors.
通过对脑干切片进行细胞外记录，以测试浴用胆碱能激动剂和拮抗剂对自发活动的背侧耳蜗核神经元放电率的影响。约90%的神经元对卡巴胆碱有反应。对毒蕈碱有反应的神经元比例高于对烟碱有反应的神经元。毒蕈碱在较低浓度时比烟碱引发的反应更大。对卡巴胆碱或毒蕈碱的反应总是被阿托品或东莨菪碱阻断。烟碱拮抗剂d -筒箭毒碱、六甲铵和美加明阻断了对烟碱的反应，但并未降低对卡巴胆碱的反应。在暴露于胆碱能激动剂期间，规律放电的神经元仅表现出放电率增加。约一半有反应的爆发性神经元放电增加；另一半对10微摩尔卡巴胆碱或毒蕈碱的反应先是放电增加，随后放电减少。在低钙、高镁培养基中，大多数爆发性神经元反应的所有阶段都大大降低或消失，而规律神经元的反应未受到明显影响。因此，胆碱能激动剂似乎直接作用于规律放电的神经元，而它们对爆发性神经元的作用可能需要突触活动。数据表明，背侧耳蜗核中的胆碱能传递主要是毒蕈碱型的，并且大多数自发活动的规律放电神经元具有毒蕈碱受体。
