Received for publication June 5, 2006.
Revised July 24, 2006.
Accepted for publication August 1, 2006.

Heterogeneity of Nicotinic Cholinergic Receptors in Rat Superior Cervical and Nodose Ganglia

Abstract

Nicotinic receptors (nAChRs) are present in ganglia in the peripheral nervous system. In autonomic ganglia, they are responsible for fast synaptic transmission, while 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 3 and 4 subunits, but a significant percentage of the nAChRs in these ganglia also contain 5 and 2 subunits. A small percentage of the nAChRs in nodose ganglia also contain 2 and 4 subunits. Sequential immunoprecipitation assays indicated that in the SCG all 5 subunits are associated with 3 and 4 subunits, forming the mixed heteromeric 345 subtype. A receptor comprised of 3, 2 and 4 subunits in the SCG was also detected. In rat SCG, we found the following distribution of nAChRs subtypes: 55-60% simple 34 subtype, 25-30% 345 subtype, 10-15% 342 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.

Key words: Nicotinic cholinergic, Receptor binding studies, Antibody