title: FMRF-NH2-like factor from neurohaemal organ modulates neuromuscular transmission in the locust.
abstract: YGGFMRFamide, FMRFamide and related peptides potentiate transmission at locust slow motor synapses. Since immunohistochemical evidence points to neurohaemal organs (NHO) as potential sources for endogenous RFamide-like peptides we have applied extracts from the metathoracic NHO, equivalent to 1/3 NHO, to the metathoracic extensor tibiae muscle. NHO-extract depolarizes the muscle fibre and increases its membrane resistance; enhances transmitter release; and increases the amplitude of contraction and the rate of relaxation. These effects are in good qualitative and quantitative agreement with those of YGGFMRFamide (5 X 10(-8) to 10(-7) M). Octopamine which partly acts like YGGFMRFamide cannot account for the NHO-effects.
mesh_terms: D000818:Animals; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D019835:FMRFamide; D006110:Grasshoppers; D009479:Neuropeptides / Q000494:pharmacology*; D009490:Neurosecretory Systems / Q000032:analysis*; D009655:Octopamine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D009479:Neuropeptides; D009655:Octopamine; D004744:Enkephalin, Methionine; D019835:FMRFamide; C033460:enkephalin-Met, Arg(6)-PheNH2(7)-; C028435:2-octopamine