一氧化氮合酶阳性结构在大鼠三叉神经感觉核簇内的分布及其与面部伤害性刺激诱发的FOS蛋白表达的关系

用还原型尼克酰胺腺嘌呤二核苷酸脱氢酶组织化学技术与ＦＯＳ免疫组化（ＡＢＣ法）相结合的方法，观察了大鼠三叉神经感觉核簇内一氧化氮合酶阳性神经元和纤维的分布及其与面部伤害性刺激诱发的ｃ－ｆｏｓ原癌基因蛋白表达的关系．证明，浓密的一氧化氮合酶阳性纤维和终末分布于三叉神经脊束核尾侧亚核的Ⅰ和Ⅱ层，阳性成分呈蓝黑色的带状分布，而在三叉神经感觉核簇的其余核区内很稀疏．一氧化氮合酶阳性神经元胞体与面部伤害性刺激诱发的ｃ－ｆｏｓ原癌基因蛋白表达的阳性神经元在此核簇内的分布节段非常相似，都主要存在于与伤害性传入传递和调控有关的三叉神经脊束核尾侧亚核，并且二者都主要分布于与痛觉调控有关的浅层．约有１０～１５％的一氧化氮合酶阳性神经元同时呈ｃ－ｆｏｓ原癌基因蛋白表达．在三叉脊束核尾侧亚核的Ⅲ～Ⅴ层仅出现散在的阳性细胞，除在吻侧亚核的背内缘与孤束核交界处有少量一氧化氮合酶同性神经元外，在三叉神经感觉核簇的其余核区两者均几无表达．本文及文献结果提示，一氧化氮可能对面部伤害性信息的传递和调控起重要作用．

LOCALIZATION OF NITRIC OXIDE SYNTHASE POSITIVE STRUCTURES IN Vcx AND THEIR RELATIONSHIP TO NOXIOUS STIMULATION-IUDUCED FOS EXPRESSION IN THE RAT

It is well known that trigeminal sensory complex(Vcx) is the first relay station for oro-facial noxious afferent transmission in central nervous system (CNS), and noxious stimulation exerted in oro-afacial region can induce protooncogene c-fos protein (FOS) expression in the nuclear complex. At present, nitric oxide(NO) is considered to be a novel neurotransmitter and evidence suggests that NO is involved in nociceptive processing in CNS. Thus, to study the relationship between oro-facial noxious stimulation-induced FOS expression and the distribution of nitric oxide synthase (NOS) is helpful for understanding the role of NO in modulation of oro-facial nociceptive afferent information. It is believed that visualization of NADPH-diaphorase (NADPH-d) by histochemistry can reflect the localization of NOS. Twenty five adult male SD rats were used. A subcutaneous injection of 150 μl of 10% formalin in the left perioral and facial regions was made under methoxyflurane anesthesia. After 2 hours survival, the rats were Perfused and the brains were removed and sectioned. The sections were processed for NADPH-d bistochemistry in a solution containing β-NADPH and nitroblue tetrazolium (NBT) to demonstrate NOS positive reactivity. NOS positive staining, black-blue in color, was seen in the cytoplasm,whereas brown FOS-like immunoreactivity was localized inside the nucleus. The results showed that NOS reactive fibers and terminals were mainly found in laminae Ⅰand Ⅱ of the caudal subnucleus(Vc) of the trigeminal spinal nucleus (Vsp) and in the trigeminal interstitial nucleus(TIN), whereas they were scarcely seen in other parts of Vcx. In the caudal portion of Vcx, NOS positive neurons were concentrated in Lamina Ⅱ and sparsely distributed in faminae Ⅲ, Ⅳ, Ⅴ of Vc and TIN. In rostral part of Vcx, except a few positive cells in the dorsomedial area of oral subnucleus of Vsp near the nucleus of solitary tract, neurons in most nuclei, including the interpolar and oral subnuclei of Vsp and the principal sensory trigeminal nucleus, did not show NOS reactivity. FOS-like immunoreactive neurons(FLN) were only found in Vex on the injection side. They had a similar distribution with NOS cells, mainly seen in laminae Ⅰ and Ⅱ of Vc, fewer in laminae Ⅲ, Ⅳ, Ⅴ and adjacent lateral reticular formation, and alment none in rostral nuclei of Vcx. Approximately 10～15% of NOS positive neurons in lamina Ⅱ of Vc also showed FOS-like immunoreactivity. The results demonstrated that the distribution of NOS neurons was in similar segment of Vcx with that of FLN induced by formalin stimulation in oro-facial area.Both Of them were mainly in Vc which is believed to be a chief part in Vex related to nociceptive transmission.These data strongly suggest tbat NO might play a pivotal role in maculating nociceptive information processing. In addition, since the number of neurons in which NOS reactivity and FOS immunoreactivity co-exist was fewer in this experiment, we inclined to support the hypothesis that after its production,NO rapidly diffuses to enter the presynaptic or adjacent neurons where it modulates excitability and enhances the activity of synaptic connections, but does not act in postsynaptic neuron where it is prepuced.