FIG. 8.

ICER overexpression abrogates GnRH pulse frequency-dependent effects on FSHβ transcription. (A) LβT2 cells were transfected with −140/+15 rFSHβLuc (4 μg) and with 2 μg of an expression vector encoding ICER II or with empty vector (pcDNA3), followed by perifusion and stimulation with low (∧__∧; every 120 min) or high (∧∧∧; every 30 min) GnRH pulse frequencies. Bar graphs show the fold stimulation (means ± the SEM) relative to unstimulated levels. Significant differences (P < 0.05), as measured by one-way ANOVA with a post hoc Tukey-Kramer multiple-comparison test, are denoted by different letters. (B) LβT2 cells were transfected with the ICER II expression vector and exposed to either high or low GnRH pulse frequencies in two separate experiments, repeated on three separate occasions with each individual experiment done in triplicate. Paired t tests, performed on experimental data with connected data points denoting paired experiments, revealed a significant effect at low, but not high, GnRH pulse frequencies.