Modulation of the effects of methylmercury on rat neurodevelopment by co-exposure with Labrador Tea (Rhododendron tomentosum ssp. subarcticum)

Abstract

Seafood is an important source of nutrients for many populations worldwide. Unfortunately the contamination of seafood with methylmercury (MeHg) has raised health concerns, particularly for developing infants. The modification of MeHg toxicity by nutrients, including antioxidants, has been reported in both epidemiological and animal exposure studies. We used a rat perinatal exposure model to investigate the modulation of developmental MeHg toxicity by an extract of Rhododendron tomentosum ssp. subarcticum, a plant rich in antioxidants traditionally consumed by Inuit. Sprague-Dawley rat dams were exposed daily to 2 mg MeHg/kg bw and 100 mg R. tomemtosum extract/kg bw administered either separately or jointly, from the first day of gestation until weaning. MeHg exposure was associated with impaired pup growth and survival, decreased grip strength, hyperactivity and altered exploratory behaviour, delayed acoustic startle response, elevated brain N-methyl-D-aspartate receptor (NMDA-R) levels, and increased serum lipid peroxidation. R. tomemtosum extract co-exposure modulated MeHg's effects on oxidative stress and brain NMDA-R levels and may have affected MeHg pharmacokinetic. However, modulation of these molecular endpoints did not lead to significant alterations of MeHg's effects on rat neurobehaviour.