Nicotinic acetylcholine receptor subtypes in the rat sympathetic ganglion: pharmacological characterization, subcellular distribution and effect of pre- and postganglionic nerve crush.
Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission in autonomic ganglia, which innervate and control the activity of most visceral organs. By combining ultrastructural, immunocytochemical, and pharmacological analyses, we characterized the nAChR subtypes in the rat superior cervical ganglion (SCG) and the effect of pre- and postganglionic nerve crush on their number in the ganglion and their distribution at the intraganglionic synapses. Binding with radioactive nicotinic ligands, immunoprecipitation, and immunolocalization experiments revealed the presence of different nAChR subtypes: those containing the alpha3 subunit associated with beta4 and/or beta2 subunits that bind 3H-Epibatidine with high affinity, and those containing the alpha7 subunit that bind 125I-alphaBungarotoxin. After postganglionic nerve crush, the number of nicotinic receptors and immunopositive intraganglionic synapses for each nAChR subunit strongly decreased. Both the number of nAChRs and immunoreactivity recovered 26 days after injury, when regenerating postganglionic fibers had reinnervated the peripheral target organs, as shown by the restoration of tyrosine hydroxylase immunoreactivity in the iris. This observation and the lack of any effect of preganglionic nerve crush on the number of nicotinic receptors suggest that the peripheral targets affect the organization of intraganglionic synapses in adult SCG.
Dipartimento di Biologia Cellulare e dello Sviluppo, Università "La Sapienza", Rome, Italy.
Arianna
A
Del Signore
Cecilia
C
Gotti
Angela
A
Rizzo
Milena
M
Moretti
Paola
P
Paggi
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000493:pharmacokinetics*; D002038:Bungarotoxins / Q000493:pharmacokinetics*; D002452:Cell Count; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000293:injuries / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007456:Iodine Isotopes / Q000493:pharmacokinetics; D008297:Male; D051379:Mice; D016253:Microscopy, Immunoelectron; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000502:physiology; D018722:Nicotinic Agonists / Q000493:pharmacokinetics*; D021122:Protein Subunits / Q000378:metabolism; D011725:Pyridines / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000145:classification / Q000378:metabolism* / Q000648:ultrastructure; D013347:Subcellular Fractions; D017783:Superior Cervical Ganglion / Q000187:drug effects / Q000293:injuries / Q000378:metabolism / Q000648:ultrastructure; D013569:Synapses / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D013997:Time Factors; D014316:Tritium / Q000493:pharmacokinetics; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D019086:Bridged Bicyclo Compounds, Heterocyclic; D002038:Bungarotoxins; D007456:Iodine Isotopes; D018722:Nicotinic Agonists; D021122:Protein Subunits; D011725:Pyridines; D011978:Receptors, Nicotinic; D014316:Tritium; D014446:Tyrosine 3-Monooxygenase; C082748:epibatidine