Mechanisms of estrogen-induced elevation of PKA activity in immortalized hippocampal neurons

In our previous studies, we confirmed that β-estradiol evoked an immediate PKA activation in the living immortalized hippocampal neural cell, H19-7 by means of DR2 fluorometry. The DR2 is a cell-permeable fluorescent PKA substrate. This study was undertaken to clarify the mechanisms of this estrogen-induced PKA elevation. Instead of β-estradiol, we added either BSA-conjugated β-estradiol or α-estradiol to H19-7 cell and then DR2 fluorometry was done. The BSA-conjugated β-estradiol caused as much PKA elevation as β-estradiol, while aestradiol induced no change in PKA activity. Intracellular Ca ion concentration was also imaged by Fura2 fluorometry on the same cell in which estrogen-stimulated PKA elevation was confirmed. As the result, it was observed that PKA activation followed Ca ion elevation. Effects of PKA inhibitor, Ca channel antagonist and ICll 82, 780 were observed in this experimental system of estrogen-induced PKA activity assay.