Differential transcription outputs of ultradian and constant hormone treatments. (a) Two pulses of corticosterone induce characteristic pulsatile release of nascent RNA, whereas constant treatment induces continuous release of Per1 transcript. (b–d) Constant treatment leads to accumulation of higher levels of mature RNA from GR-regulated genes, Per1 (b), Mt2 (c) and Fkbp5 (d), than pulsatile treatment. Error bars represent the mean ± s.e.m. n = 4. (e) Western blot (WB) experiments demonstrate that the Fkbp5 protein level after constant treatment is higher than the protein level after pulsatile treatment (600 nM corticosterone for 8 h). Lane 1, pulsatile treatment; Lane 2, constant treatment.