TABLE 2

Effect of nicotine administration on nAChRs in striatum and cortex of young mice

Mice (2–4 months old) received nicotine (300 μg/ml) in 2% saccharin drinking water for 1 to 6 weeks. Increases were observed in 125I-A85380 and 125I-epibatidine binding in cortex and striatum, with no change in 125I-α-bungarotoxin (α-Bgt) binding. 125I-α-conotoxin MII (α-CtxMII) binding sites in striatum were not significantly different from control. Control binding in striatum was 1.34 ± 0.38 fmol/mg (125I-epibatidine), 4.13 ± 0.94 fmol/mg (125I-A85380), 0.72 ± 0.05 fmol/mg (125I-α-CtxMII), and 6.37 ± 0.14 fmol/mg (125I-α-bungarotoxin) and for the cortex, 1.22 ± 0.33 fmol/mg (125I-epibatidine), 3.01 ± 0.69 fmol/mg (125I-A85380), and 7.29 ± 0.11 fmol/mg (125I-α-bungarotoxin). Values expressed as mean ± S.E.M. of the indicated number of animals.

Brain Region and Length of Nicotine Treatment No. of Mice Specific Binding
125I-α-CtxMII 125I-Epibatidine 125I-A85380 125I-α-Bgt
% control
Striatum
    0 weeks 27-34 100.0 ± 2.3 100.0 ± 1.4 100.0 ± 1.3 100.0 ± 1.5
    1 week 14 86.2 ± 3.8 108.9 ± 1.8** 125.0 ± 3.9*** 95.5 ± 2.7
    2 weeks 14 84.6 ± 7.1 94.2 ± 2.0 113.8 ± 1.1*** 101.1 ± 1.8
    4 weeks 15 93.2 ± 9.2 107.0 ± 2.9** 113.9 ± 2.0*** 103.7 ± 2.3
    6 weeks 15 89.5 ± 6.1 99.8 ± 1.3 113.6 ± 2.0*** 98.5 ± 2.1
Cortex
    0 weeks 20-27 N.D. 100.0 ± 1.5 100.0 ± 1.2 100 ± 0.9
    1 week 8-14 N.D. 121.4 ± 1.3*** 137.7 ± 2.6*** 91.8 ± 3.4
    2 weeks 8-14 N.D. 109.6 ± 1.4*** 136.3 ± 2.1*** 105.4 ± 1.2
    4 weeks 7-15 N.D. 121.5 ± 3.2*** 130.3 ± 2.2*** 106.3 ± 1.1
    6 weeks 9-15 N.D. 117.9 ± 2.2*** 128.7 ± 2.8*** 104.5 ± 1.6
  • N.D., not detected.

  • ** p < 0.01; *** p < 0.001; significance of difference from control.