Figure 5.

CREB Phosporylation Is Stimulated by Pulsatile GnRH in a Frequency-Dependent Manner That Is Attenuated by PKA Inhibition. LβT2 cells were transiently transfected with 2 μg of (A) empty vector or (B) DNPKA. Cells were perifused for 20 h and stimulated with high (black solid bars; ΛΛΛΛ; every 30 min) or low (gray shaded bars; Λ__Λ; every 120 min) frequencies of GnRH or medium alone (white solid bars; ____). Bar graphs show relative pCREB levels (mean ± SEM from three independent experiments, each performed in triplicate, normalized to CREB). Western immunoblot shown is representative of one experiment. Significant differences (P < .05), measured by one-way ANOVA with a post hoc Tukey multiple-comparison test, are indicated by different letters.