Skeletal changes in multiparous mice fed a nutrient-sufficient diet containing cadmium

Area of Science:

• Environmental toxicology
• Skeletal biology
• Reproductive physiology

Background:

• Cadmium (Cd) is a toxic heavy metal found in the environment.
• Pregnancy and lactation place significant metabolic demands on the dam.
• The skeletal effects of cadmium exposure during reproductive cycles are not fully understood.

Purpose of the Study:

• To investigate the impact of dietary cadmium on the skeletal health of female mice during repeated cycles of pregnancy and lactation.
• To compare the effects of cadmium in pregnant/lactating mice versus non-pregnant controls.
• To assess the dose-dependent effects of cadmium on bone parameters.

Main Methods:

• Female mice were fed diets with varying cadmium concentrations (0.25, 5, or 50 ppm).
• Mice were divided into pregnant/lactating (PL) groups undergoing 6 reproductive cycles and non-pregnant (NP) control groups.
• Skeletal parameters including body weight, femur calcium content, and calcium/dry weight ratio were measured after 1, 2, 4, or 6 cycles.

Main Results:

• Non-pregnant mice showed no significant cadmium-dependent changes in body weight or femur calcium.
• Pregnant/lactating mice exposed to 50 ppm cadmium exhibited significant decreases in body weight (3-11%) and femur calcium content (15-27%) compared to controls.
• Cadmium exposure demonstrated a dose-dependent effect on femur calcium in PL mice, with higher doses causing greater reductions.

Conclusions:

• Dietary cadmium exposure negatively impacts skeletal health more severely in mice undergoing repeated pregnancy and lactation than in non-pregnant controls.
• The combination of cadmium exposure and multiparity may be a contributing factor to the development of bone diseases such as Itai-Itai disease.
• These findings highlight the vulnerability of the maternal skeleton to environmental toxicants during reproductive stress.