Article Figures & Data
Figures
- Fig. 1.
Immunoprecipitation analysis of the subunit content of α6β2* and α4(nonα6)β2* nAChR subtypes immunopurified through affinity column from striatal extracts and labeled with 2 nm3H-Epi. The results are expressed as percentage of total 3H-Epi binding present in the solution before immunoprecipitation. Each data point is the mean ± SEM of five determinations performed in triplicate.
- Fig. 2.
Inhibition of 125I-Epi binding to native immunoimmobilized α6β2* (a) and α4(nonα6)β2* (b) nAChRs by several nicotinic ligands, including nicotine (Nic), acetylcholine (ACh), cytisine (Cyt), dihydro-β-erythroidine (DHBE),d-tubocurarine (dTC) (a, b), α-CntxMII (c), and MLA (d). The curves were obtained by fitting three or four separate experiments using the LIGAND program (Munson and Rodbard, 1980).
- Fig. 3.
a, b,3H-WIN-35,428 (a) and3H-Epi binding (b) in rat striatal membranes obtained from control and 6-OHDA lesioned rats.c, Immunoprecipitation of nAChR subunits in 2% Triton X-100 extracts from control and 6-OHDA lesioned striata. Each value represents the mean ± SEM of three separate experiments. Statistical analysis according to Mann–Whitney U test, **p < 0.01.
Tables
- Table 1.
Affinity of nicotinic agonists and antagonists for immunoimmobilized nAChR subtypes
α6β2* α4(non α6)β2* Kd (nm) 125I-Epibatidine 0.034 (34) 0.041 (25) Ki (nm) Cytisine 0.65 (18) 0.19 (16) Nicotine 2.5 (23) 1.75 (23) Acetylcholine 8.0 (34) 8.6 (23) Dihydro-β-erythroidine 524 (25) 274 (21) d-Tubocurarine 3,110 (20) 16,100 (28) α-Conotoxin MII 1.3 (45) – >10,000 >10,000 Methyllycaconitine 40 (47) – 20,800 (18) 25,000 (23) Kd and Ki values were derived from curves of 125I-Epi saturation and competition binding, respectively, to α6β2* or α4(nonα6)β2
↵* immunoimmobilized receptors. Curves obtained from three or four separate experiments were fitted using a nonlinear least-squares analysis program. For both α-conotoxin MII and methyllycaconitine, a two-site model was statistically significant (F test), whereas for d-tubocurarine and cytisine the data were better fitted with a one-site model. Numbers in parentheses represent percentage of coefficient of variation.
