Holden-Dye L, Franks C J, Williams R G, Walker R J
Department of Physiology and Pharmacology, University of Southampton.
Parasitology. 1995 May;110 ( Pt 4):449-55. doi: 10.1017/s0031182000064787.
The action of two peptides isolated from the nematode Panagrellus redivivus, PF1 (SDPNFLRFamide) and PF2 (SADPNFLRFamide) have been studied on synaptic transmission in the motornervous system of the parasitic nematode Ascaris suum. Intracellular recordings were made from Ascaris somatic muscle cells and excitatory junction potentials (EJPs) elicited by stimulation of the ventral nerve cord. The EJPs were cholinergic as they were blocked by the Ascaris nicotinic receptor antagonist, benzoquinonium. PF1 caused a slow hyperpolarization, similar to the action of this peptide first reported by Bowman, Geary & Thompson (1990) and further characterized by Franks et al. (1994). The hyperpolarization was accompanied by a marked decrease in the amplitude of the EJPs with an EC50 of 311 +/- 30 nM (n = 5). This inhibition is unlikely to be due to a post-synaptic site of action of the peptide as the muscle cell input conductance was not significantly altered by PF1 and furthermore the response to bath-applied acetylcholine was not inhibited by PF1 at concentrations up to 10 microM (n = 6). PF2 also inhibited the EJPs in a similar manner to PF1. These studies indicate that both of the peptides isolated from the free-living nematode Panagrellus redivivus have biological activity in the parasitic nematode Ascaris suum. PF1 and PF2 have inhibitory actions in contrast to the predominantly excitatory actions of the Ascaris endogenous peptides AF1 (KNEFIRFamide) and AF2 (KHEYLRFamide). The potent actions of the Panagrellus neuropeptides PF1 and PF2 in Ascaris suggest that peptides with a similar or identical sequence may also occur in Ascaris and have an inhibitory role in the motornervous system.
从线虫小杆线虫（Panagrellus redivivus）中分离出的两种肽PF1（SDPNFLRFamide）和PF2（SADPNFLRFamide）对寄生线虫猪蛔虫（Ascaris suum）运动神经系统突触传递的作用已得到研究。从猪蛔虫体壁肌肉细胞进行细胞内记录，并通过刺激腹神经索诱发兴奋性接头电位（EJP）。这些EJP是胆碱能的，因为它们被猪蛔虫烟碱受体拮抗剂苯醌铵所阻断。PF1引起缓慢的超极化，类似于Bowman、Geary和Thompson（1990年）首次报道并由Franks等人（1994年）进一步表征的这种肽的作用。超极化伴随着EJP幅度的显著降低，EC50为311±30 nM（n = 5）。这种抑制不太可能是由于该肽的突触后作用位点，因为PF1并未显著改变肌肉细胞的输入电导，此外，在浓度高达10 μM时，PF1并未抑制对浴加乙酰胆碱的反应（n = 6）。PF2也以与PF1类似的方式抑制EJP。这些研究表明，从小杆线虫中分离出的这两种肽在寄生线虫猪蛔虫中均具有生物活性。与猪蛔虫内源性肽AF1（KNEFIRFamide）和AF2（KHEYLRFamide）主要的兴奋作用相反，PF1和PF2具有抑制作用。小杆线虫神经肽PF1和PF2在猪蛔虫中的强效作用表明，具有相似或相同序列的肽可能也存在于猪蛔虫中，并在运动神经系统中发挥抑制作用。
