Abstract:
Many compounds of plant origin with the ability to bind to the estrogen
receptor have been identified in the last decades. There is evidence that
the consumption of some of these phytoestrogens may have beneficial effects
but it also seems possible that others may act as endocrine disrupters. For
this reason there is a need to characterise the estrogenic potency of these
substances. In vitro test systems offer the possibility
to screen compounds very efficiently. Routinely in use and widespread for
the determination of estrogenicity are: (I) receptor binding assays, (II)
cell-proliferation assays (E-screens), (III) reporter gene assays, and (IV)
the analysis of the regulation of endogenous estrogen sensitive genes in cell
lines. The basis of all these test systems are molecular mechanisms which
are involved in the classical estrogen action. In addition, in the last years
several test systems for the investigation of non-classical estrogenic effects
have been established. An example for such an effect is the modulation of
the expression of interleukin-6, a cytokine that appears to be a key molecule
in the osteoporotic process, by estrogens. Summarising the advantages and
the issues of all presented in vitro test systems,
it seems to be evident that only the analysis of results obtained in a combination
of several in vitro test systems may validly predict
effcts in vivo.
Key words:
Estrogens - phytoestrogens - interleukin-6 - reporter gene assay - MCF-7 cell - E-screen
