Table 1

[³H]WIN 35,428 binding parameters from quantitative autoradiographic analysis

Region (n)	IC₅₀		B_max	High-Affinity Site
Region (n)	High	Low	B_max	High-Affinity Site
	nM		pmol/mg	%
Striatum
6 mo (9)	1.79 ± 0.28	289 ± 59	2.78 ± 0.60	59 ± 1
12 mo (9)	2.37 ± 0.30	226 ± 30	2.27 ± 0.22	46 ± 1
18 mo (9)	3.27 ± 0.45^*	164 ± 20	1.44 ± 0.09^*	46 ± 1
24 mo (9)	3.29 ± 0.47^*	190 ± 37	1.33 ± 0.21^*	45 ± 2
Nucleus accumbens
6 mo (9)	2.77 ± 0.28	221 ± 16	2.36 ± 0.17	43 ± 2
12 mo (9)	4.50 ± 0.40	215 ± 28	2.04 ± 0.28	48 ± 2
18 mo (9)	5.55 ± 1.40	240 ± 46	1.61 ± 0.28	47 ± 2
24 mo (9)	4.26 ± 0.72	185 ± 26	1.41 ± 0.17^*	42 ± 2
Substantia nigra
6 mo (7)	2.22 ± 0.32	301 ± 67	1.09 ± 0.20	49 ± 1
12 mo (9)	1.36 ± 0.13^*	331 ± 55	0.64 ± 0.09^*	59 ± 1
18 mo (9)	1.33 ± 0.17^*	202 ± 21	0.40 ± 0.05^***	59 ± 1
24 mo (7)	1.66 ± 0.07^*	195 ± 19	0.29 ± 0.03^***	62 ± 1
Ventral tegmental area
6 mo (7)	1.71 ± 0.19	404 ± 64	1.25 ± 0.17	61 ± 1
12 mo (9)	1.68 ± 0.17	339 ± 59	0.86 ± 0.18	55 ± 2
18 mo (9)	1.90 ± 0.21	288 ± 43	0.47 ± 0.04^**	59 ± 1
24 mo (7)	1.50 ± 0.15	250 ± 22	0.42 ± 0.07^**	57 ± 1

See Fig. 2 for details. In all brain regions of each age group studied, the two-site binding model was statistically preferred (p < .01). See Experimental Procedures forB_max calculation. Each value is mean ± S.E.M. from seven to nine rats per group.

Significance is denoted for within-region comparisons with 6-month-old rats: * p < .05, ** p < .01, *** p < .001.