The conventional anti-psychotic, haloperidol, increases H3 phospho-acetylation in bulk chromatin. (a) The nine site-specific modifications at N-terminal tails of histone H3 and H4 that were examined in the present study. Ac, acetylation; me, methylation; p, phosphorylation. Single letter code: K, lysine; R, arginine; S, serine. Upward arrows mark association with open chromatin and the transcriptional state, downward arrows mark assocation with silenced and inactive chromatin, combined arrows mark more generalized function independent of transcription (Jenuwein and Allis, 2001). (b) Representative immunoblots from acid extracted proteins from striatum of mice killed 120 min after a single dose of haloperidol or saline, showing immunoreactivities for the total of nine site- and modificationspecific histone epitopes shown in (a). Notice increased H3 phosphoacetylation (H3pS10-acK14) in striatum of haloperidol-treated animals (top), but no differences to controls for H3 acetylation (H3acK9/14 and H3acK14), methylation (H3meK4, H3meK9, H3meR17) and phosphorylation (H3pS10) and for H4 acetylation, (H4acK8, H4acK12). (c) Levels of immunoreactivity (mean ± S.E.M.) for each of the nine histone epitopes in striatum of mice 120 min after a single dose of haloperidol. Levels are normalized to saline-treated littermate controls. Notice 2-fold increase in H3pS10-acK14 in striatum of haloperidol-treated animals, but no difference to controls for the remaining eight H3/H4 epitopes.