Abstract
Gibberellic acid (GA3), a plant growth regulator, has registered in Taiwan for shoot growth, floral development and fruit set in celery, spinach, grapes, wax apples and pears. It was determined to be safe as its low acute toxicity and specified usage. Several literatures, however, raised its concern about potential endocrine disrupting effects of GA3 on estrogenic response in animal tests. Therefore, the aim of this study is to explore possible mechanism of GA3 regarding endocrine disruption with two kinds of well-known in vitro estrogen activity-detecting systems, i.e. estrogen receptor (ER)-mediated transcriptional activation assay and MCF-7 cell proliferation assay (E-screen). The results indicated that significant transactive and cell proliferative responses were observed at 0.1 to 1000 uM of GA3 in both assays. In the meantime, those responses were demonstrated that it can be inhibited with an ER antagonist, 4-hydroxytamoxifen. In conclusion, GA3 can elicit estrogenic activity via receptor-mediated pathway in human cells.
