Alibardi Lorenzo
Dipartimento di Biologia Evoluzionistica Sperimentale, Via Selmi 3, University of Bologna, 40126 Bologna, Italy.
Hear Res. 2006 Jun-Jul;216-217:73-80. doi: 10.1016/j.heares.2006.01.005. Epub 2006 Feb 28.
The goal of the present review is to summarize the main ultrastructural and immunocytochemical characteristics for glycine and GABA in commissural (COM) and tuberculo-ventral neurons (TV) of the DCN. These neurons are localized in similar areas of the DCN multipolar but are connected to different targets. About 2/3rd of COM-neurons are large to bipolar neurons, mainly glycinergic, often GABA-ergic, with scarce ergastoplasm and axo-somatic boutons. About 1/3rd of COM-neurons are glycine and GABA-negative, and show little ergastoplasm and synaptic coverage. Occasional giant COM-neurons are glycine-positive and GABA-negative, and are covered with synaptic boutons. Other infrequent large neurons, rich in dense core vesicles, glycine- and GABA-negative, are most covered with boutons. TV-neurons are most glycinergic but 9% are glycine-negative. They have little ergastoplasm and a developed Golgi apparatus. Axo-somatic terminals are scarce and mainly contain flat and pleomorphic vesicles, glycine and sometimes GABA (inhibitory). TV-neurons receive a lower number of boutons than COM, which contain mainly flat-pleomorphic terminals. Putative COM-inhibitory boutons contact excitatory pyramidal and giant neurons (monosynaptic inhibition). Some putative inhibitory COM-terminals contact inhibitory cartwheel and tuberculo-ventral neurons. This indicates direct disinhibition and therefore excitation in the DCN (di-three-synaptic). Putative COM-mossy fibers reach the granule areas of the DCN, including unipolar brush cell dendrites, another possible excitatory commissural pathway.
本综述的目的是总结背侧蜗神经核连合（COM）神经元和结节腹侧神经元（TV）中甘氨酸和γ-氨基丁酸（GABA）的主要超微结构和免疫细胞化学特征。这些神经元位于背侧蜗神经核多极的相似区域，但与不同的靶点相连。约2/3的COM神经元为大型双极神经元，主要为甘氨酸能，常为GABA能，内质网稀少，有轴体终扣。约1/3的COM神经元甘氨酸和GABA均为阴性，内质网和突触覆盖较少。偶尔出现的巨型COM神经元甘氨酸阳性、GABA阴性，被突触终扣覆盖。其他罕见的大型神经元富含致密核心囊泡，甘氨酸和GABA均为阴性，大部分被终扣覆盖。TV神经元大多为甘氨酸能，但9%为甘氨酸阴性。它们内质网较少，高尔基体发达。轴体终末稀少，主要含有扁平及多形性囊泡，含甘氨酸，有时也含GABA（起抑制作用）。TV神经元比COM神经元接受的终扣数量少，这些终扣主要是扁平多形性终末。推测的COM抑制性终扣与兴奋性锥体细胞和巨型神经元接触（单突触抑制）。一些推测的抑制性COM终末与抑制性车轮状细胞和结节腹侧神经元接触。这表明背侧蜗神经核存在直接去抑制作用，进而产生兴奋（三突触）。推测的COM苔藓纤维到达背侧蜗神经核的颗粒区，包括单极刷状细胞树突，这是另一条可能的兴奋性连合通路。
