Influence of chlorinated hydrocarbons, Hg2+ and methyl-Hg+ on steroid hormone receptors from eggshell gland mucosa of domestic fowls and ducks

Abstract

A series of chlorinated hydrocarbons were investigated for their ability to inhibit the binding of tritiated progesterone, dexamethasone and testosterone to their respective cytoplasmic receptors, prepared from the eggshell gland mucosa of the domestic fowl. o,p'-DDE and toxaphene were most potent in inhibiting the binding of progesterone and testosterone to their receptors, while p,p'-DDE was most potent in inhibiting the binding of dexamethasone. The effect of the latter compound on dexamethasone binding was biphasic. There were significant differences between ducks and domestic fowls in the dissociation constant (KD) and maximal number of binding sites (Bmax) for several of the steroid hormones. No effect of steroid binding was observed in the p,p'-DDE-treated ducks that were laying thin-shelled eggs. Some metals were also tested for their ability to inhibit progesterone binding. Hg2+ was most potent (IC50 = 5.8 x 10(-5) M) in this respect, while Cd2+, Pb2+ and Al3+ inhibited the binding only when administered in very high concentrations (10(-3) M). Me-Hg+ was less potent than Hg2+. It is concluded that chlorinated hydrocarbon pesticides may interact with several different steroid hormone receptors. These findings are discussed in relation to some reproductive and other hormonal disturbances observed in birds and mammals.