Functional properties of neuronal nicotinic acetylcholine receptors in the chick retina during development.
Acetylcholine (ACh) has been recognized for a long time as a major neurotransmitter in the retina, however, little is known about the contribution of acetylcholine receptors in synaptic processing. Moreover, even less information is available concerning their role during development. To address this question further, we examined the physiological and pharmacological properties of neuronal nicotinic acetylcholine receptors (nAChRs) in retinal ganglion cells from embryonic (E) 12-18-day-old Leghorn chicks. Patch-clamp recordings in whole-cell configuration revealed that at E12 approximately 21% of the ganglion cells responded to acetylcholine pulses with inward currents. The number of responsive cells progressively increased to 57% at E15 to reach up to 15 positive cells out of 15 cells tested at E18. Acetylcholine-evoked responses could be subdivided, according to their time course, into fast and slowly desensitizing. Taking advantage of the selectivity of the frog toxin epibatidine (Epi), that preferentially activates heteromeric neuronal nicotinic acetylcholine receptors, we compared the currents evoked by this toxin vs. the effects of acetylcholine. A further characterization of the receptor diversity during development was to assess their sensitivity to the alpha-conotoxin MII (alpha-CTX-MII), which has been shown to preferentially block alpha6- and alpha3beta2-containing receptors. These data demonstrate that ganglion cells of the chick retina express multiple receptor subtypes that progressively develop as a function of retina maturation.
Department of Neurosciences, Faculty of Medicine, CMU, 1 rue Michel Servet, CH-1211 Geneva, Switzerland. lecci1@etu.unige.ch
Marzia
M
Lecchi
J Michael
JM
McIntosh
Sonia
S
Bertrand
Avinoam B
AB
Safran
Daniel
D
Bertrand
D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D002642:Chick Embryo; D020916:Conotoxins / Q000494:pharmacology; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018722:Nicotinic Agonists / Q000494:pharmacology; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D011725:Pyridines / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000196:embryology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism*; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D019086:Bridged Bicyclo Compounds, Heterocyclic; D020916:Conotoxins; D018722:Nicotinic Agonists; D011725:Pyridines; D011978:Receptors, Nicotinic; C098872:alpha-conotoxin MII; C419362:nicotinic receptor alpha3beta2; C104518:nicotinic receptor alpha6; C082748:epibatidine; D000109:Acetylcholine