Effect of excess Fe on Cd or Pb absorption by rats

Area of Science:

• Toxicology
• Environmental Health
• Nutritional Science

Background:

• Cadmium and lead are toxic heavy metals with significant public health implications.
• Gastrointestinal absorption is a critical factor determining heavy metal bioavailability and toxicity.
• Dietary factors, such as iron, can influence the absorption of other metals.

Purpose of the Study:

• To investigate the effects of fasting and iron supplementation (ferrous and ferric iron) on cadmium and lead absorption in adult rats.
• To examine the influence of iron on cadmium and lead retention in neonatal rats.
• To compare the absorption mechanisms of cadmium and lead across different age groups.

Main Methods:

• Adult and neonatal rats were gavaged with radiolabeled cadmium (109Cd) or lead (210Pb).
• Animals were subjected to different pre-gavage conditions: feeding, fasting, or fasting with iron supplementation.
• Cadmium and lead absorption and retention in the gastrointestinal tract and carcass were quantified.

Main Results:

• Fasting slightly increased cadmium absorption, while ferrous and ferric iron significantly increased it 3-fold and 14-fold, respectively.
• Fasting increased lead absorption fivefold; ferric iron blocked this effect.
• In neonatal rats, iron supplementation increased cadmium retention in the carcass and decreased GI tract retention.
• Ferric iron significantly decreased lead retention in neonatal rat carcasses and the GI tract.

Conclusions:

• Iron, particularly ferric iron, plays a crucial role in modulating cadmium and lead absorption in rats.
• The oxidizing effect of ferric iron on cadmium absorption is more pronounced in adult rats.
• Similarities in intestinal transport mechanisms for cadmium and iron suggest potential competitive or cooperative interactions.