大鼠脊髓背角CGRP、IB4阳性终末与GABA能神经元之间的联系及GABA_BR1阳性终末的超微结构观察

THE RELATIONSHIPS BETWEEN CGRP,IB4 IMMUNOREACTIVE CENTRAL TERMINALS WITH GABAERGIC NEURONS AND ULTRASTRUCTURAL STUDY OF GABA_BR1 IMMUNOREACTIVE CENTRAL TERMINALS IN THE RAT SPINAL DORSAL HORN

背根神经节小型神经元初级传入末梢上的GABAB受体在脊髓背角接受中间神经元的突触前抑制,是脊髓水平痛觉调节的途径之一。为研究大鼠脊髓背角胶状质中背根神经节神经元传入纤维末梢同脊髓背角GABA能中间神经元之间的联系,本实验用免疫组织化学法,通过激光共聚焦显微镜观察了正常大鼠CGRP阳性和IB4阳性背根节神经元的中枢突同脊髓背角GA-BA能中间神经元之间的联系。同时,用免疫电镜(IEM)技术研究了脊髓背角GABABR1阳性的背根神经节神经元中枢突末梢形成突触的特点。结果显示:CGRP阳性和IB4阳性背根节神经元的中枢突和脊髓背角GABA能中间神经元之间形成密切联系;电镜下许多脊髓背角胶状质中突触小球的中央末梢为GABABR1免疫阳性,并作为突触前或突触后成分与周围末梢之间形成对称性和非对称性突触。提示脊髓背角GABA能中间神经元可能通过分布在背根节神经元初级传入末梢上的GABAB受体产生突触前抑制,参与脊髓水平的痛觉调制。

The metabotropic type-B γ-aminobutyric acid receptors （ GABABR） on the central teminals of the small sized dorsal root ganglion （DRG） neurons play an important role in pain regulation by presynaptic mechanism at spinal level. Laser confecal scanning microscopy was employed to study the relationships between the central teminals originated small sized DRG neurons with the GABA-IR neurons in spinal dorsal bern. Immunoelectron microscopy （IEM） was used to study the ultrastructures of GABABR-IR central terminals. The results revealed that CGRP-IR and IB4-IR central terminals had close contacts with the GABA-IR neurons, and the GABABR-IR central terminals established synapses as pre- and postsynaptic structures with the shapes of synaptic glomerulus. These results suggest GABABR might play an important role in the regulation of pain via presynaptic mechanism at the spinal level.