Frog retinal ganglion cells projecting to the tectum layer F release acetylcholine as co-mediator.
Neurons may release more than one classical neurotransmitter (co-mediator). It has been demonstrated in a recent study that a burst of action potentials in frog retina ganglion cells induces an after-burst increase (phasic potentiation) of the retinotectal transmission that lasts tens of seconds. This increase is mediated by presynaptic nicotinic acetylcholine receptors that are activated by the endogenous acetylcholine released during the burst of action potentials of the retinotectal fiber. The objective of the present study was to find out the origin of acetylcholine release. We show that reduction of the retinotectal transmission to the subthreshold level by application of moderate concentrations of kynurenic acid or CNQX had no effect on the phasic nicotinic potentiation of the retinotectal transmission. This demonstrates that the retinotectal terminals are the source of acetylcholine - responsible for the phasic potentiation of retinotectal transmission. The acetylcholine is thus co-released with glutamate.
Laboratory of Neurophysiology, Neuroscience Institute, Medical Academy, Lithuanian University of Health Sciences, Eiveniu 4, Kaunas LT 50009, Lithuania.
Armantas
A
Baginskas
Vilija
V
Kuraite
Antanas
A
Kuras
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism*; D000200:Action Potentials; D000818:Animals; D018698:Glutamic Acid / Q000378:metabolism*; D007736:Kynurenic Acid / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000502:physiology; D011896:Rana temporaria; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D055366:Synaptic Potentials; D009435:Synaptic Transmission; D003336:Tectum Mesencephali / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*
D018377:Neurotransmitter Agents; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D007736:Kynurenic Acid; D000109:Acetylcholine