Saideman Shari R, Ma Mingming, Kutz-Naber Kimberly K, Cook Aaron, Torfs Pieter, Schoofs Liliane, Li Lingjun, Nusbaum Michael P
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074, USA.
J Neurophysiol. 2007 Jan;97(1):579-95. doi: 10.1152/jn.00772.2006. Epub 2006 Oct 25.
Pyrokinin (PK) peptides localize to the central and peripheral nervous systems of arthropods, but their actions in the CNS have yet to be studied in any species. Here, we identify PK peptide family members in the crab Cancer borealis and characterize their actions on the gastric mill (chewing) and pyloric (filtering) motor circuits in the stomatogastric ganglion (STG). We identified PK-like immunolabeling in the STG neuropil, in projection neuron inputs to this ganglion, and in the neuroendocrine pericardial organs. By combining MALDI mass spectrometry (MS) and ESI tandem MS techniques, we identified the amino acid sequences of two C. borealis pyrokinins (CabPK-I, CabPK-II). Both CabPKs contain the PK family-specific carboxy-terminal amino acid sequence (FXPRLamide). PK superfusion to the isolated STG had little influence on the pyloric rhythm but excited many gastric mill neurons and consistently activated the gastric mill rhythm. Both CabPKs had comparable actions in the STG and these actions were equivalent to those of Pevpyrokinin (shrimp) and Leucopyrokinin (cockroach). The PK-elicited gastric mill rhythm usually occurred without activation of the projection neuron MCN1. MCN1, which does not contain CabPKs, effectively drives the gastric mill rhythm and at such times is also a gastric mill central pattern generator (CPG) neuron. Because the PK-elicited gastric mill rhythm is independent of MCN1, the underlying core CPG of this rhythm is different from the one responsible for the MCN1-elicited rhythm. Thus neuromodulation, which commonly alters motor circuit output without changing the core CPG, can also change the composition of this core circuit.
促激肽（PK）肽定位于节肢动物的中枢和外周神经系统，但它们在中枢神经系统中的作用尚未在任何物种中得到研究。在这里，我们鉴定了北方黄道蟹中的PK肽家族成员，并描述了它们对胃神经节（STG）中胃磨（咀嚼）和幽门（过滤）运动回路的作用。我们在STG神经纤维网、该神经节的投射神经元输入以及神经内分泌心包器官中鉴定出了PK样免疫标记。通过结合基质辅助激光解吸电离质谱（MALDI-MS）和电喷雾串联质谱技术，我们鉴定了两种北方黄道蟹促激肽（CabPK-I、CabPK-II）的氨基酸序列。两种CabPK都含有PK家族特异性的羧基末端氨基酸序列（FXPRLamide）。将PK灌注到分离的STG对幽门节律影响很小，但能兴奋许多胃磨神经元并持续激活胃磨节律。两种CabPK在STG中的作用相当，且这些作用与对虾促激肽（Pevpyrokinin）和蟑螂促亮氨酸激肽（Leucopyrokinin）的作用相同。PK引发的胃磨节律通常在投射神经元MCN1未激活的情况下出现。不含有CabPK的MCN1能有效驱动胃磨节律，此时它也是胃磨中枢模式发生器（CPG）神经元。由于PK引发的胃磨节律独立于MCN1，这种节律的潜在核心CPG与负责MCN1引发节律的核心CPG不同。因此，神经调节通常在不改变核心CPG的情况下改变运动回路输出，也能改变这个核心回路的组成。
