Table 1.

Effects of MPTP Treatment on Number of TH⁺-Neurons in SNc and VTA of C57BL/6 mice.

Treatment	TH+/NeuN+ Cells
	In SNc Number % of Control		In VTA Number % of Control
Experiment 1:
Control	89 ± 12 (8)	-	not determined
MPTP, 24 hrs	46 ± 2 (6) 52%		not determined
MPTP, 48 hr	52 ± 11 (5) 58%		not determined
Experiment 2:
Control	114 ± 3 (6)	-	27 ± 3 (6)
MPTP, 7 days	25 ± 1 (8) 22%		13 ± 2 (8) 49%

This table reports the number of TH⁺ and NeuN⁺ cells within the defined boundaries of the SNc or VTA (based on Paxinos & Franklin, 2001) of C57BL/6 mice, in 20 μm sections cut through the SNc at AP levels −2.98, −3.08, −3.16 (levels corresponding to the levels at which ppN/OFQ mRNA expression was evaluated). The data from two experiments with different MPTP treatment times are reported separately. Data are presented as the mean number of TH⁺ cells in the SNc or VTA averaged across the three AP levels (mean ± s.e.m), with the number of animals indicated in parentheses. The reduction in TH⁺/NeuN⁺ cell number in the SNc after MPTP treatment at 24 and 48 hrs was significant by analysis of variance [F(2,18) = 4.59, p< 0.0265]; the reductions in TH⁺/NeuN⁺ cell number after MPTP treatment at 7 days were also significant (t-test; p<0.0001 for SNc and VTA).