Levels of ERK, CREB and TH proteins in the VTA in HIV-1Tg and F344 rats (A) Representative western blots showing the protein density of CREB, pCREB, ERK1/2, pERK1/2, TH and β-tubulin in the nicotine or saline treated HIV-1Tg (HIV-1Tg-Nic, HIV-1Tg-Sal) and F344 rats (F344-Nic, F344-Sal). (B) Total and phosphorylated protein levels of ERK1, ERK2 and CREB along with levels of TH after chronic nicotine or saline injection. Ratios are expressed as the mean percentage of β-tubulin ± S.E.M. # p < 0.05 difference between the nicotine- and saline-treatment group. n=8 rats per group.