Vitamin D metabolism impairment in the rat’s offspring following maternal exposure to ¹³⁷cesium

Previous works clearly showed that chronic contamination by (137)cesium alters vitamin D metabolism. Since children are known to be a high-risk group for vitamin D metabolism disorders, effects of Cs-137 on vitamin D biosynthetic pathway were investigated in newborn rats. The experiments were performed in 21-day-old male offspring of dams exposed to Cs-137 in their drinking water at a dose of 6,500 Bq/l (150 Bq/rat/day) during the lactation period. Significant modifications of blood calcium (-7%, P < 0.05), phosphate (+80%, P < 0.01) and osteocalcin (-25%, P < 0.05) levels were observed in contaminated offspring, associated with an increase of blood vitamin D-3 (+25%, P < 0.01). Besides, decreased expression levels of cyp2r1 and cyp27b1 (-26 and -39%, respectively, P < 0.01) were measured in liver and kidney suggesting a physiological adaptation in response to the rise in vitamin D level. Expressions of vdr, ecac1, cabp-d28k, ecac2 and cabp-9k involved in renal and intestinal calcium transport were unaffected. Altogether, these data show that early exposure to post-accidental doses of Cs-137 induces the alteration of vitamin D metabolism, associated with a dysregulation of mineral homeostasis.