PH03 Perchlorate
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH050) Kidney lesions induced by ammonium perchlorate in adult zebrafish.
Capps, T1, Patino, R2, Blazer, V3, 1 Texas Tech Institute of Environmental and Human Health, Lubbock, Texas, USA2 USGS Texas Cooperative Fish and Wildlife Research Unit, Lubbock, Texas, USA3 USGS National Fish Health Laboratory, Kearneysville, West Virginia, USA
ABSTRACT- Perchlorate derived from ammonium perchlorate (AP), and other perchlorate species, inhibits iodide uptake by the thyroid follicles thus impairing the production of thyroid hormones and disrupting regulatory feedback mechanisms. As a result, the secretion of thyroid-stimulating hormone (TSH) by the pituitary gland increases. A well-known consequence of these events is the hyperstimulation of thyroid follicles. Effects of AP on other physiological systems, such as the renal system, are not well understood. The mammalian kidney is known to contain TSH receptors as well as iodide transport mechanisms similar to those of the thyroid follicle. Therefore, the kidney is also a potential target of direct (association with iodide transporters) or indirect (increased TSH) actions of perchlorate. This study examined the effects of AP on the zebrafish kidney using histopathological methods. Adult zebrafish were exposed to water-borne perchlorate at environmentally relevant concentrations (18 ppm) for eight weeks using a static-renewal system. Control fish were maintained in water without AP. At the end of the exposure period, fish were processed for histological analyses of the trunk region of the kidney. Preliminary observations suggested the presence of higher numbers of macrophage aggregates, putative tissue markers of contaminant exposure or disease, in kidneys of AP-exposed fish. Quantitative observations were then made with an ocular lens grid by determining the relative number of crosshairs that fell on macrophage aggregates. These observations indicated that exposure to AP caused a significant increase in the incidence of renal macrophage aggregates (Student′s t-test; P < 0.05). This is the first documentation of histopathological effects of AP in kidney.
Key words: kidney, ammonium perchlorate, zebrafish, macrophage aggregate