Enzyme Induction and Acute Endocrine Effects in Prepubertal Female Rats Receiving Environmental PCB/PCDF/PCDD Mixtures

Abstract

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Responses of Prepubertal Female Rats to Environmental PCBs with High and Low Dioxin Equivalencies

“…The profile of airborne PCBs was similar to that in the soil extract, but lower PCDFs and PCDDs contributed to a lower TEQ Hansen and O'Keefe, 1996). The female rats responded differently to the these extracts in terms of enzyme induction and uterotropic effects, but had very similar decreases in serum T4 (Li and Hansen, 1996a).…”

“…The soil extract was exchanged to hexane and contained 43 mg PCB/ml, 761.6 /ig PCDF/ml, and 47.2 ^g PCDD/ml. The TCDD equivalence of this extract was 0.62 /xg TCDD/mg PCB (Li and Hansen, 1996a).…”

“…UDP glucuronyltransferase (UDPGT) activity in the microsomal suspension was measured using 4-nitrophenol (4-NP) and phenolphthalein (PP) as substrates (Li and Hansen, 1996a). In brief, the volume of the incubation was 0.5 ml, containing 0.1 M Tris (pH 7.4), microsomal suspension (0.1 to 0.25 mg microsomal protein), 0.5 mg BSA, 5 mM MgC12, 0.05% Brij 58, 3 mM UDP glucuronic acid, and 0.25 mM phenolphthalein in DMSO or 0.5 mM 4-nitrophenol in 0.01 M Tris.…”

Understanding the human health effects of chemical mixtures.

“…Probably the best example of the activation of multiple receptor pathways after exposure to a chemical mixture is that elicited by Aroclor formulations of PCBs because they comprise complex mixtures of various di-ortho-, mono-ortho-, and non-ortho-substituted congeners with differing degrees of chlorine substitution. Aroclors elicit 3-MC-, PB-, and PCN-type responses in rodents (231,232), and PCBexposed humans appear to show a similar mixed pattern of enzyme induction (233).…”

Acute Effects of Polychlorinated Biphenyl-Containing and -Free Transformer Fluids on Rat Testicular Steroidogenesis

“…The mono-ortho-substituted PCB congeners also exhibit Ah receptor agonist activity (7), but with lower potency than coplanar congeners. The less chlorinated and ortho-substituted PCBs (with two or more ortho chlorines) have low or no affinity for the Ah receptors (8)(9)(10). However, they have a profile of hormone and neurotransmitter disrupters that account for their toxicity (9,11).…”