Effects of a hydroxy-cinnamoyl conjugate of spermidine on arthropod neuromuscular junctions.
N1-coumaroyl spermidine is structurally similar to acylpolyamines found in spider and wasp venoms, which are known to block arthropod glutamate receptors. N1-coumaroyl spermidine reduced the amplitude of excitatory postsynaptic potentials recorded in crayfish muscle. This effect was dose dependent, with an IC50 value of 70 micromol l(-1). N1-coumaroyl spermidine reversibly reduced the amplitude of potentials elicited by iontophoretic application of L-glutamate, indicating a direct effect on postsynaptic glutamate receptors. Neither 1 mmol l(-1) spermidine nor 1 mmol l(-1) coumaric acid altered excitatory postsynaptic potential amplitude, indicating that blockage requires the conjugated phenolic polyamine. N1-coumaroyl spermine, a slightly longer phenolic polyamine, reduced excitatory postsynaptic potential amplitude with approximately the same potency as N1-coumaroyl spermidine. Thus, potency of blockage does not appear to be affected in this experimental preparation by small changes in length of the polyamine. N1-coumaroyl spermidine also reduced excitatory postsynaptic potentials in muscles of the insect Drosophila. The ability of N1-coumaroyl spermidine to attenuate synaptic transmission at insect neuromuscular synapses lends support to the notion that plant-derived phenolic polyamines might serve as natural insecticides.
Klose
M K
MK
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada. klosem@biology.queensu.ca
Atkinson
J K
JK
Mercier
A J
AJ
D000818:Animals; D003400:Astacoidea; D002934:Cinnamates / Q000737:chemistry / Q000494:pharmacology; D003373:Coumaric Acids / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004330:Drosophila; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism; D006571:Heterocyclic Compounds / Q000737:chemistry / Q000494:pharmacology; D007306:Insecticides / Q000494:pharmacology; D007478:Iontophoresis; D009469:Neuromuscular Junction / Q000187:drug effects*; D011073:Polyamines / Q000737:chemistry / Q000494:pharmacology; D017470:Receptors, Glutamate / Q000378:metabolism*; D013095:Spermidine / Q000031:analogs & derivatives / Q000737:chemistry* / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects
D002934:Cinnamates; D003373:Coumaric Acids; D006571:Heterocyclic Compounds; D007306:Insecticides; C426071:NSTX-3; D011073:Polyamines; D017470:Receptors, Glutamate; D018698:Glutamic Acid; D013095:Spermidine