大鼠三叉神经脊束核尾侧亚核Ⅱ层内CB样、PV样阳性终末与向臂旁核投射神经元的突触联系

为了观察三叉神经脊束核尾侧亚核 层神经元与向臂旁核投射神经元的突触关系 ,选用 Calbindin D-2 8k和 Parvalbu-min作为标志物 ,采用 HRP逆行追踪与免疫组织化学技术相结合的双重反应技术对 层内的 Calbindin D-2 8k样和 Parvalbumin样阳性神经元与三叉神经脊束核尾侧亚核向臂旁核投射神经元之间的突触联系进行了观察。HRP注入臂旁核后 ,逆标神经元主要位于同侧三叉尾侧亚核 层至 层。Calbindin D-2 8k和 Parvalbumin样阳性胞体、纤维和终末主要集中在 层内侧带。电镜下观察 ,此二者的阳性反应产物呈弥散分布 ;两者的阳性终末与 HRP逆标神经元的胞体和树突之间主要形成轴 -树突触 ,偶见轴 -体突触 ;Calbindin D-2 8k样阳性终末与 HRP逆标神经元的树突形成的非对称性突触占 83% ,Parvalbumin样阳性终末与 HRP逆标神经元的树突形成的对称性突触占 85 %。此外 ,还观察到参与突触小球组成的初级传入纤维终末与 HRP逆标神经元的树突形成突触联系。以上结果提示 :(1)三叉神经脊束核尾侧亚核 层的 Calbindin D-2 8k样或 Parvalbumin样阳性神经元可通过突触传递机制对三叉神经脊束核尾侧亚核向臂旁核投射的神经元进行调控 ,影响外周伤害性信息向上位脑结构的传递 ;(2 )三叉神经脊束核尾侧亚核向臂旁核投?

SYNAPTIC CONNECTIONS BETWEEN CALBINDIN D-28k- OR PARVALBUMIN-LIKE IMMUNOREACTIVE TERMINALS AND PARABRACHIAL-PROJECTING NEURONS IN LAMINA II OF THE TRIGEMINAL SUBNUCLEUS CAUDALIS IN THE RAT

Recent studies have shown that the parabrachial nucleus (PBN) is closely related to the noxious stimulation information transmission and receives the ascending projections from the superficial laminae of the Vc. To investigate synaptic relations between the laminaⅡneurons and projecting neurons in the trigeminal subnucleus caudalis (Vc), we employ retrograde tracing and electronmicroscopy methods to examine the CB-LI and PV-LI positive synaptic connections with projecting neurons from Vc. After injecting horseradish peroxidase (HRP) into the parabrachial nucleus(PBN), the retrogradely labeled neuronal cell bodies and dendrites were found richly in the laminaⅠand Ⅱof Vc. We also observed there are two kinds of synapses. First, CB-LI axon terminals made asymmetrical (n=19) and symmetrical (n=4) axodendritic synapsese with HRP retrogeradely labeled dendrites. Second, PV-LI axon terminals made symmetrical (n=27) and asymmetrical (n=5) synapses with HRP retrogradely labeled dendrites. It is also exhibited that primary afferent central terminals made synapses with HRP retrogradely labeled dendrites. These results support the suggestions that some CB-LI neurons were interneurons that might have presynaptic excitatory or inhibitory effects on other neurons (interneurons or projecting neurons); PV-LI neurons were mostly inhibitory interneurons. Our results gave a further morphological evidence that laminaⅡneurons play important roles in transmitting and modulating orofacial noxious information.