Barmack N H, Fredette B J, Mugnaini E
R.S. Dow Neurological Sciences Institute, Legacy Good Samaritan Hospital, Portland, Oregon 97209, USA.
J Comp Neurol. 1998 Mar 16;392(3):352-72. doi: 10.1002/(sici)1096-9861(19980316)392:3<352::aid-cne6>3.0.co;2-0.
At least two subnuclei of the inferior olive, the beta-nucleus, and the dorsomedial cell column (dmcc), contain vestibularly responsive neurons that receive a dense descending projection that uses gamma-aminobutyric acid (GABA) as the transmitter. In contrast to the GABAergic innervation of other olivary subnuclei, the terminal boutons that terminate on neurons in the beta-nucleus and the dorsomedial cell column remain intact after cerebellectomy, ruling out both the cerebellum and the cerebellar nuclei as afferent sources. By using both immunohistochemical as well as orthograde and retrograde tracer methods, we have identified the source of the GABAergic pathway to the beta-nucleus and dmcc in both rat and rabbit. Under physiologic recording of single olivary neurons to guide electrode placement, we injected the bidirectional tracer, wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) into the beta-nucleus and dmcc of the inferior olive. These injections retrogradely labeled neurons in the parasolitary nucleus (Psol) near the vestibular complex. Psol neurons were identified as GABAergic with an antibody to glutamic acid decarboxylase (GAD). In the rat, Psol neurons are small (5-7 microm in diameter) and number approximately 1,800. In the rabbit, they are slightly larger (6-9 microm in diameter) and number approximately 2,200. WGA-HRP injections in conjunction with GAD immunohistochemistry double labeled a high percentage of neurons in both the rat and rabbit Psol. Injection of the orthograde tracer Phaseolus vulgaris-leucoagglutinin into the area of the Psol revealed a projection from this region to both the beta-nucleus and dmcc. Subtotal electrolytic lesions of this division of the Psol caused a substantial reduction in GAD-positive synaptic terminals in both the ipsilateral beta-nucleus and dmcc. The location of these GABAergic neurons, bordering both the nucleus solitarius and caudal vestibular complex, emphasizes the importance of the Psol in the processing of both vestibular and autonomic information pertinent to postural control.
下橄榄核至少有两个亚核，即β核和背内侧细胞柱（dmcc），包含前庭反应性神经元，这些神经元接受以γ-氨基丁酸（GABA）作为递质的密集下行投射。与其他橄榄亚核的GABA能神经支配不同，终止于β核和背内侧细胞柱神经元的终末小体在小脑切除术后保持完整，排除了小脑和小脑核作为传入源。通过使用免疫组织化学以及顺行和逆行示踪方法，我们在大鼠和兔子中都确定了到β核和dmcc的GABA能通路的来源。在对单个橄榄神经元进行生理记录以指导电极放置的情况下，我们将双向示踪剂，即小麦胚凝集素结合辣根过氧化物酶（WGA-HRP）注入下橄榄核的β核和dmcc。这些注射逆行标记了前庭复合体附近的孤束旁核（Psol）中的神经元。用谷氨酸脱羧酶（GAD）抗体将Psol神经元鉴定为GABA能神经元。在大鼠中，Psol神经元较小（直径5-7微米），数量约为1800个。在兔子中，它们稍大一些（直径6-9微米），数量约为2200个。WGA-HRP注射结合GAD免疫组织化学在大鼠和兔子的Psol中双重标记了高比例的神经元。将顺行示踪剂菜豆白细胞凝集素注入Psol区域显示了从该区域到β核和dmcc的投射。Psol这一区域的部分电解损伤导致同侧β核和dmcc中GAD阳性突触终末大量减少。这些GABA能神经元的位置毗邻孤束核和尾侧前庭复合体，强调了Psol在处理与姿势控制相关的前庭和自主神经信息方面的重要性。
