Effect of RGS3 on LH content and GnRH receptor binding. Pituitary cells were infected or not with adeno-RGS3 or adeno-βgal (5 M.O.I.) and 72 h later were used for measurement of LH content or of GnRH receptors. Upper panel: LH content of pituitary cells was measured after repeated freezing and thawing to release LH for measurement by RIA. There were no significant differences among the groups (p > 0.05). Lower panel: Pituitary cell membranes were prepared for measurement of GnRH receptors by binding to 125I-GnRH-A. There were no significant differences among the groups. Our earlier report that adeno-βgal (60 M.O.I.) increased receptor binding by 100% (23) was not observed here because of the lower dose of adeno-βgal (5 M.O.I.) used. Data are mean ± SEM of three independent experiments.