Electrophysiological effects of tachykinin analogues on ganglion cell activity in cyprinid fish retina.
Electrical spike activity of ganglion cells has been recorded extracellularly in the teleost (roach) retina, and effects of a variety of tachykinins studied at a working concentration of 1 microM. Application of substance P mostly caused a slow and prolonged increase in background activity. In contrast, the response to carbachol was very brisk and short-lasting. Substance P and physalaemin predominantly induced an enhancement of 'On' and 'Off' components of light-evoked responses, whilst eledoisin and neurokinin A were mostly inhibitory. All effects were independent of chromatic and spatial aspects of the responses. Interestingly, in the presence of a tachykinin antagonist, 'Spantide' [D-Arg1,D-Pro2, D-Trp7.9, Leu11]SP, the profile of the effect of substance P reversed, inhibitory actions becoming much more common. Taken together, the results suggest that a tachykinin system utilising two subtypes of the receptor may be active in the roach retina and these may be involved in differential control of visual sensitivity.
Downing
J E
JE
Department of Biology, Imperial College of Science, London, UK.
Djamgoź
M B
MB
D000200:Action Potentials / Q000187:drug effects / Q000528:radiation effects; D000818:Animals; D003530:Cyprinidae / Q000502:physiology*; D004600:Eledoisin / Q000494:pharmacology; D015288:Neurokinin A / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D010803:Physalaemin / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology; D018039:Receptors, Tachykinin; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D013045:Species Specificity; D013373:Substance P / Q000031:analogs & derivatives* / Q000494:pharmacology; D015320:Tachykinins / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D010446:Peptide Fragments; D011480:Protease Inhibitors; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D015320:Tachykinins; D010803:Physalaemin; D013373:Substance P; D004600:Eledoisin; C032720:substance P (5-11), pGlu(5)-MePhe(8)-MeGly(9)-; D015288:Neurokinin A; C042867:spantide; D011761:Pyrrolidonecarboxylic Acid