The Effects of the Soy
Isoflavone Genistein on the Reproductive Development of Striped Bass
S.J. Pollack, M.A. Ottinger, C.V. Sullivan, L. Curry
Woods, III-2003
North American Journal of Aquaculture, 65(3):
226–234
Abstract:
The aquaculture industry has made great strides
toward developing diets for finfish that provide adequate nutrition for the
animals being maintained while minimizing the cost to the farmer.
Alternative, plant-derived protein sources are used to minimize cost.
Soybean meal is the plant protein most commonly used because it maintains
adequate growth. However, soy is rich in phytoestrogens, the most abundant
of which is genistein. Studies have shown variable physiological effects
associated with exposure to genistein. The objective of this research was to
investigate the effects of feeding genistein to juvenile striped bass Morone
saxatilis at varying concentrations in the diet. The first
experiment was designed to determine whether juvenile striped bass are
capable of responding to estrogen exposure. Juvenile striped bass were given
weekly injections of estradiol benzoate for 3 weeks and showed a significant
response to the estrogen via expression of vitellogenin. In two additional
experiments, genistein was fed to striped bass fingerlings (approximately
120 d old and 60–100 d old) in varying concentrations (0, 2, 4, and 8 mg/g
of diet) to determine whether a similar response would be elicited. No
significant differences were found among the growth variables and
histological endpoints, although a significant vitellogenin response was
observed at the 2-mg/g and 8-mg/g doses. These results show that the
juvenile striped bass did respond to the estrogen-like function of genistein
and that the genistein induced a U-shaped response curve that is
characteristic of the low-dose effects of some endocrine-disrupting
chemicals.
(Department of Animal and Avian Sciences, University
of Maryland–College Park, College Park, Maryland 20742, USA)