Figure 4.

. Targeted inactivation of the Nr4a2 locus in mouse lactotropes results in a decrease in PRL+ cells and a reciprocal increase in cells that are POU1F1+ but lack both PRL and GH. A. Co-immunofluorescent analyses of POUF1, PRL, and GH in pituitary cells from Nr4a2^fl/fl (top panel) and Nr4a2^fl/fl/Prl-Cre (bottom panel) mice. A single field of disaggregated cells is show for each sample. The cells were stained with a nuclear dye (DAPI) and immunostained for POU1F1, PRL, and GH proteins. The final frame in each of the 2 studies superimposes the POU1F1, PRL, or GH stains. Pou1f1+ cells that coexpress GH or PRL or are negative for both of these hormones were quantified. White arrows indicate POU1F1+ cells that express either GH or PRL, while red arrows indicate POU1F1+ cells that do not express either of the 2 hormones. N = 2 mice used per group. B. Percentage of total POU1F1+ pituitary cells (200 cells counted per genotype, n = 1 for each sample) that express the indicated combinations of GH, PRL, and/or POIU1f1. DAPI, 4′,6-diamidino-2-phenylindole dihydrochloride; GH, growth hormone; POU1F1, pituitary-specific master regulatory transcription factor; PRL, prolactin.