Alibardi L
Dipartimento di Biologia evoluzionistica e sperimentale, University of Bologna, Italy.
Ann Anat. 1998 Oct;180(5):427-38. doi: 10.1016/S0940-9602(98)80103-9.
Medium to large-giant multipolar neurons in the rat ventral cochlear nucleus were retrograde labelled after injection of the tracer Wheat Germ Agglutinin conjugated to Horse Radish Peroxidase into the contralateral cochlear nucleus. Light microscopy immunocytochemistry showed that 42.45% of these retrograde labelled neurons, generally strongly labelled with the tracer, were markedly glycine immunopositive, and that 57.55%, usually weakly retrograde labelled neurons, were immunonegative or weakly positive for glycine. These commissural neurons were generally GABA negative and variably immunopositive for glutamate. About 1/3rd of the commissural neurons had variably developed a rough endoplasmic reticulum whilst axo-somatic boutons covered 20-40% of the cell body. These cells were recognized as multipolar neurons of type I. Most of them were weakly glycine positive or even negative and a few appeared glycinergic. A little less than the remaining 2/3rds of the whole commissural population in the postero-ventral cochlear nucleus presented a surface which was 65-85% covered with synaptic boutons, among which some also appeared labelled. These cells were recognized as multipolar neurons of type II. Many microtubules and neurofilaments were present, free ribosomes being more numerous around Nissl bodies with short cisternae. A few low retrograde labelled type II were weakly or non glycinergic. A small number of large to giant neurons type II, strongly retrograde labelled, appeared to be glycine positive, consistently GABA negative and variably glutamate positive. A very small proportion of retrograde labelled neurons appeared having the characteristics of globular bushy neurons. Their weak labelling, however, suggests that they project by collaterals or thin axons to the contralateral cochlear nucleus. Spherical bushy cells in the rat anteroventral cochlear nucleus lack the nuclear capping of rough endoplasmic reticulum observed in the cat, and none was labelled after injection into the contralateral cochlear nucleus. Globular and spherical neurons were variably glutamate positive but glycine and GABA negative. In conclusion, the present study suggests that commissural neurons include a small number of strongly labelled large to giant glycinergic and presumably inhibitory type II and, less frequently type I. A large group of less heavily labelled commissural neurons of type I and II contain low levels or no glycine, which is probably used for metabolic purposes rather than as a neurotransmitter. This suggests that these neurons are presumably excitatory.
将与辣根过氧化物酶结合的示踪剂小麦胚凝集素注射到对侧耳蜗核后，大鼠腹侧耳蜗核中的中到大巨型多极神经元被逆行标记。光学显微镜免疫细胞化学显示，这些逆行标记的神经元中，42.45%（通常被示踪剂强烈标记）对甘氨酸呈明显免疫阳性，57.55%（通常逆行标记较弱）对甘氨酸免疫阴性或弱阳性。这些连合神经元通常对GABA呈阴性，对谷氨酸呈可变免疫阳性。约1/3的连合神经元有不同程度发育的粗面内质网，轴体终扣覆盖细胞体的20 - 40%。这些细胞被识别为I型多极神经元。它们大多数对甘氨酸呈弱阳性甚至阴性，少数表现为甘氨酸能。后腹侧耳蜗核中，略少于其余2/3的整个连合神经元群体的表面有65 - 85%被突触终扣覆盖，其中一些也显示有标记。这些细胞被识别为II型多极神经元。存在许多微管和神经丝，游离核糖体在短池状尼氏体周围较多。少数逆行标记较弱的II型神经元对甘氨酸呈弱阳性或无反应。少数大到巨型的II型神经元，逆行标记强烈，似乎对甘氨酸呈阳性，始终对GABA呈阴性，对谷氨酸呈可变阳性。极少数逆行标记的神经元呈现球状浓密神经元的特征。然而，它们的弱标记表明它们通过侧支或细轴突投射到对侧耳蜗核。大鼠前腹侧耳蜗核中的球状浓密细胞缺乏猫中观察到的粗面内质网的核帽，注射到对侧耳蜗核后无一被标记。球状和球型神经元对谷氨酸呈可变阳性，但对甘氨酸和GABA呈阴性。总之，本研究表明，连合神经元包括少数强烈标记的大到巨型甘氨酸能且可能是抑制性的II型，较少见的是I型。一大组标记较轻的I型和II型连合神经元含有低水平或不含甘氨酸，这可能用于代谢目的而非作为神经递质。这表明这些神经元可能是兴奋性的。
