Abstract
Nicotinic cholinergic receptors (nAChRs) are present in ganglia in the peripheral nervous system. In autonomic ganglia, they are responsible for fast synaptic transmission, whereas in the sensory ganglia and sensory neurons, they may be involved in modulation of neurotransmission. The present study measured nAChRs in several rat autonomic ganglia: the superior cervical ganglia (SCG), sensory nodose ganglia, stellate ganglia, and pelvic ganglia. The densities of the heteromeric nAChRs determined by receptor binding assay in those four ganglia are 481, 45, 9, and 11 fmol/mg protein, respectively. Immunoprecipitation studies with subunit-specific antibodies showed that a majority of the nAChRs in the SCG and nodose ganglia contain the α3 and β4 subunits, but a significant percentage of the nAChRs in these ganglia also contain α5 and β2 subunits. A small percentage of the nAChRs in nodose ganglia also contain α2 and α4 subunits. Sequential immunoprecipitation assays indicated that in the SCG, all α5 subunits are associated with α3 and β4 subunits, forming the mixed heteromeric α3β4α5 subtype. A receptor composed of α3, β2, and β4 subunits in the SCG was also detected. In rat SCG, we found the following distribution of nAChRs subtypes: 55 to 60% simple α3β4 subtype, 25 to 30% α3β4α5 subtype, and 10 to 15% α3β4β2 subtype. These findings indicate that the nAChRs in SCG and nodose ganglia are heterogeneous, which suggests that different receptor subtypes may play different roles in these ganglia or may be activated under different conditions.
Footnotes
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This research was supported by National Institutes of Health grant DA12976.
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ABBREVIATIONS: nAChR, neuronal nicotinic acetylcholine receptor; A-85380, 3-2(S)-azetidinylmethoxy)pyridine; EB, epibatidine; NRS, normal rabbit serum; SCG, superior cervical ganglia; Ab, antibody; NRS, normal rabbit serum; NGF, nerve growth factor.
- Received June 2, 2006.
- Accepted August 1, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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