Serum proteins and disazo dye teratogenesis

Serum proteins of pregnant rats were analyzed by paper electrophoresis following administration of the teratogenic disazo dyes trypan blue, Evans blue, Niagara blue 4B, Niagara sky blue 6B, Congo red, and Niagara blue 2B. Sera were obtained from blood taken by cardiac puncture just before dye injection, 48 hours after dye injection; and again at autopsy. All of the dyes tested caused a reduction in serum albumin and total protein concentration and an elevation in the concentration of beta or alpha-2 globulins at some time during pregnancy. The remaining serum fractions reacted variably to the dye treatment. In spite of the rather consistent results presented in this paper, and similar findings reported for other teratogens, there is no direct proof that altered serum proteins, per se, are causally related to the production of malformations.