Splenomegaly and adrenal weight changes in isolated adult mice chronically exposed to lead

The combined effect of lead exposure and high or low dietary calcium on health and immunocompetence in the zebra finch (Taeniopygia guttata)

The widespread contamination by lead and the acidification of the environment ask for a better understanding of the effects of the interaction between lead and calcium on various aspects of health, including disease defense, in wildlife. Here, we investigated the effects of chronic exposure to sublethal levels of lead, combined with high or low dietary calcium, on health and several components of immunity in male and female zebra finches (Taeniopygia guttata). Thirty individuals of each sex were randomly assigned to three groups: a control group, a group exposed to lead with an additional calcium source (i.e. grit) and a group exposed to lead without access to an extra calcium source. Lead was administered as lead acetate via the drinking water (20 ppm) for 38 consecutive days. Exposure to lead increased significantly the concentrations of lead in kidney and bone in individuals of the experimental groups. Furthermore, the lack of a calcium supplement significantly enhanced the uptake of lead. Lead did not affect health indices such as hematocrit, spleen mass and body mass, nor the adrenal stress response. Cell-mediated immune responsiveness, assessed by a delayed-type hypersensitivity response to phytohaemagglutinin, was also not affected by lead exposure. On the other hand, lead exposure did significantly suppress the secondary humoral immune response towards sheep red blood cells in females, but only when the additional calcium source was not available. This effect was not found in males, suggesting sexual differences in susceptibility of humoral immunity to lead treatment in zebra finches.

The effect of inorganic lead and/or a polychlorinated biphenyl on the developing immune system of mice

Approximately 200 female Swiss-Webster mice, six to eight weeks of age, were divided into eight groups. Three of these groups were fed 10, 100, or 250 ppm Aroclor 1254. One group was treated with 1000 ppm lead. Three groups were exposed simultaneously to lead and Aroclor 1254 at concentrations of 10 ppm PCB + 1000 ppm Pb, 100 ppm PCB + 1000 ppm Pb, and 250 ppm PCB + 1000 ppm Pb. Control mice received deionized water and rat food only. All groups were exposed for a period of 12 wk, then bred, with exposure continued throughout gestation and lactation. Offspring were weaned onto the control diet at 3 wk of age. Results from this study indicate a varied effect of lead and/or PCBs on body and organ weights of both dams and their pups, no noticeable detrimental effect on reproduction, and very little effect on the pups' ability to mount an immune response upon challenge with foreign antigens.

Aggression and open-field activity of lead-exposed mice

Blood lead levels were increased 11 to 18 times in mice that ingested a 5 mg/ml solution of lead acetate for 2 or 4 weeks, with no effect on weight gain. Although the lead treatment produced neither mortality nor obvious abnormalities, it nevertheless inhibited the development of isolation-induced aggression which was characteristic on the basis of changes in motor activity.