Effects of Dietary Polychlorinated Biphenyl Exposure on Energetics of White-Footed Mouse, Peromyscus Leucopus

Abstract

Abstract-Energy budgets have provided physiological ecologists with a vital link between environmental variables and individual performance and should also prove useful to ecotoxicologists in understanding the effects of sublethal exposure in the field. Exposure to toxic compounds is likely to be metabolically expensive and may result in a trade-off between energy spent to detoxify and excrete contaminants and energy allocated to growth or reproduction. To quantify the energetic cost of polychlorinated biphenyl (PCB) exposure, we fed captive white-footed mice (Peromyscus leucopus) diets containing PCBs (2:1 Aroclor 1242:1254) at levels of 0, 0.1, 10, and 25 ppm (mg PCBs/kg food). After six weeks on the diets, there were no differences in food intake (g/d), diet digestibility (%), or body mass related to the level of dietary PCBs. This indicated that short-term exposure to PCBs did not cause a detectable increase in energy need as measured by voluntary food intake. We continued to feed mice the PCB-containing diets for one year, at which time we repeated the food intake trial, and also measured oxygen consumption at 20 and 30ЊC. After one year, all mice had gained mass, but mice on the 25-ppm diet tended to be heavier than mice in the other groups. Compared to the control group, mice on the 25-ppm diet had higher food intake (4.1 vs 3.7 g/d; p ϭ 0.06) and higher oxygen consumption at 30ЊC (40.1 vs 36.6 ml O 2 /h; p ϭ 0.01). These results suggest that there is an energetic cost to long-term contaminant exposure that, when combined with other environmental stresses, may influence patterns of energy acquisition and allocation.

Effects of perchlorate exposure on resting metabolism, peak metabolism, and thyroid function in the prairie vole (Microtus ochrogaster)

“…Energy expenditure, as measured by oxygen consumption, has been a useful endpoint in linking environmental contaminant exposure to a measure of individual performance. For example, terrestrial organisms exposed to contaminants such as polychlorinated biphenyls incur greater maintenance costs and may be adversely affected by cold stress [26][27][28]. However, the present study did not provide evidence for energetic costs associated with perchlorate exposure at the individual level.…”

“…Other species, such as Peromyscus sp., may be better models to use when investigating the effects of contaminants on metabolic function [25,26]. The configuration of the respirometry system and confounding factors such as long wash times (i.e., time taken for recirculation of gas in a chamber) made the process of collecting metabolic rates relatively difficult.…”

“…For example, terrestrial organisms exposed to contaminants such as polychlorinated biphenyls incur greater maintenance costs and may be adversely affected by cold stress [26][27][28]. For example, terrestrial organisms exposed to contaminants such as polychlorinated biphenyls incur greater maintenance costs and may be adversely affected by cold stress [26][27][28].…”

Contaminants and energy expenditure in an Arctic seabird: Organochlorine pesticides and perfluoroalkyl substances are associated with metabolic rate in a contrasted manner

“…In contrast, other studies have reported an increased metabolic rate in response to contamination, as in DDT-exposed short-tailed shrews (Blarina brevicauda, Braham and Neal, 1974) and PCB-exposed white-footed mice (Peromyscus leucopus) (Voltura and French, 2000).…”

PCBs and the energy cost of migration in the European eel (Anguilla anguilla L.)

“…It is estim ated that over 30% of the one million tons of PCBs produced are still present in aquatic and terrestrial ecosys tem s (Voltura and French, 2000). Exposure to PHAHs, especially 'dioxins' and dioxin-like PCBs, leads to adverse effects in many species, including disturbance of retinoid and thyroid hormone endocrinology, adverse effects on male and female reproduction, G Model AQTOX-2512;N o .ofP ages8 …”