MPTP treatment selectively decreases the high-affinity E11A-sensitive α6β2* nAChR population in monkey striatum
125I-α-CtxMII competition curves with varying concentration of E11A were done as described under Materials and Methods using striatal sections from unlesioned and MPTP-lesioned monkeys. Biphasic inhibition of 125I-α-CtxMII by E11A (data best fit to a two-site model) suggests the presence of two α6β2* nAChR populations in unlesioned monkey striatum. Competition analyses of 125I-α-CtxMII by E11A of the data obtained from either lesioned group yielded monophasic curves, with the loss of the very high affinity component, in all striatal areas. Each value represents the mean ± S.E.M. of four to six monkeys. Numbers in parentheses are the 95% confidence intervals (CI).
Region & Group | Preferred Model (No. of Sites) | E11A | Ratio (IC502/IC501) | Fraction of receptors | ||||
|---|---|---|---|---|---|---|---|---|
| IC501 (CI) | IC502 (CI) | f1 | f2 | |||||
| pM | % | |||||||
| Medial caudate | ||||||||
| Monkey-unlesioned | Two | 0.0097 (0.0028-0.033) | 51 (32-80) | 5600 | 34 | 66 | ||
| Monkey-lesion 1 | One | 38 (24-60) | 100 | |||||
| Monkey-lesion 2 | One | 11 (3.9-30) | 100 | |||||
| Lateral caudate | ||||||||
| Monkey-unlesioned | Two | 0.0083 (0.0021-0.032) | 56 (34-91) | 7000 | 35 | 65 | ||
| Monkey-lesion 1 | One | 5.6 (2.1-15) | 100 | |||||
| Monkey-lesion 2 | One | 31 (13-71) | 100 | |||||
| Ventral putamen | ||||||||
| Monkey-unlesioned | Two | 0.0085 (0.0021-0.033) | 38 (27-54) | 4800 | 27 | 73 | ||
| Monkey-lesion 1 | One | 29 (17-49) | 100 | |||||
| Monkey-lesion 2 | One | 13 (4.4-37) | 100 | |||||
| Dorsal putamen | ||||||||
| Monkey-unlesioned | Two | 0.0049 (0.0015-0.016) | 33 (22-50) | 6800 | 37 | 63 | ||
| Monkey-lesion 1 | One | 3.2 (1.2-8.7) | 100 | |||||
| Monkey-lesion 2 | One |
| 2.8 (0.78-10) |
|
| 100 | ||