GABAergic neurons and neuropeptide receptor in the mouse trigeminal subnucleus caudalis

降钙素基因相关肽（CGRP）是三叉神经痛感受器表达的一种重要的神经递质，在口腔颌面部疼痛和偏头痛中起重要作用。本研究观察了GAD 67-GFP基因敲入小鼠三叉神经脊束核尾侧亚核（Sp 5c）内CGRP、CGRP受体（CRLR）与GABA能神经元的定位关系。CGRP免疫反应阳性神经元位于Sp 5c的背外侧周围层，而不在Sp 5c内部。在Sp 5C内约30%的GFP阳性（GABA能）神经元和许多GFP阴性（非GABA能）神经元中出现了CRLR免疫反应，表明CRLR免疫反应神经元是Sp 5C内的二级伤害感受神经元。我们认为，CRLR的激活导致了Sp 5c神经元的过度兴奋，即所谓的发条现象或中枢敏化。

Calcitonin gene related peptide (CGRP), which is expressed by trigeminal nociceptors, has considered as an important mediator in orofacial pain and migraine. We investigated the relationship between localization of CGRP, CGRP receptors (CRLR) and GABAergic neurons in the spinal trigeminal subnucleus caudalis (Sp5c) of GAD67-GFP knock-in mice. The CGRP-immunoreactive neurons were located in the dorsolateral surrounding layer of the Sp5c, but not in the inside of the Sp5c. The CRLR-immunoreactions appeared in about 30% of GFP-positive (GABAergic) neurons and many GFP-negative (non-GABAergic) neurons of the Sp5c, suggesting that the CRLR-immunoreactive neurons are second-order of nociceptive neurons in the Sp5C. We suggest that activation of CRLR result in the neural hyperexcitability, the so-called wind-up phenomenon or central sensitization in the Sp5c.