Table 1.

α 4YFP intensities in ventral midbrain neurons

	Saline	Nicotine	Nicotine, % of saline	p value	Cell-based measurements (no. of cells)
					Saline (6 mice)		Nicotine (6 mice)
					Total	α4+	Total	α4+
VTA (TH+)	826 ± 22	902 ± 23	109 ± 3	NS	640	610	655	648
VTA (GAD+)	268 ± 25	363 ± 18	136 ± 7	0.002	73	67	100	99
SNC (TH+)	1052 ± 23	1117 ± 25	106 ± 2	NS	612	610	581	579
SNR (GAD+)	503 ± 17	735 ± 18	146 ± 4	<0.001	256	254	237	237

Measurements of α4YFP fluorescence in various brain regions and changes with chronic nicotine (2 mg · kg⁻¹ · h⁻¹ for 10 d). Procedures were applied to each of the six mice in each group. Unless otherwise stated, analyses were performed on one brain section per mouse. In VTA, all TH⁺ or GAD⁺ somata were measured. In SNC, TH⁺ or GAD⁺ cell bodies were measured in one of two lobes. NS, Not significant; no., number.