Vitamin D and calcium deficiency initiated in pregnancy and maintained after weaning accelerate auditory dysfunction in the offspring in BALB/cJ mice

Abstract

The objective of this study was to examine the effect of vitamin D and calcium deficiency initiated in pregnancy and maintained through 10 weeks of postnatal life in BALB/cJ mice on auditory thresholds measured at 5 test frequencies using auditory brainstem response procedures. The BALB/cJ strain has a genetic defect resulting in a progressive sensorineural (inner ear) hearing loss similar to that experienced by individuals of advanced age. Beginning at 14 days of pregnancy and throughout lactation, mice were fed one of the following diets: adequate in both vitamin D and calcium (0.5% Ca by weight); deficient in vitamin D and calcium (0.2% Ca); or deficient in vitamin D and calcium (0.1% Ca). Offspring were fed the same diet as the mother for 10 weeks postweaning. At weaning, auditory brainstem response thresholds at 32 kHz were significantly higher (worse) in the offspring of the vitamin D–deficient and 0.1% calcium dams as compared to those of the other 2 diet groups. At 1 week postweaning, differences in hearing sensitivity began to emerge at 4, 8, 24, and increased at 32 kHz. Four weeks after weaning, the mice fed the adequate diet had significantly better hearing than the vitamin D–deficient and 0.1% calcium group at 4, 24, and 32 kHz ( P ≤ .05). That is, the more severe the diet the greater the hearing loss. These results suggest that exposure to vitamin D and calcium deficiency early in life may accelerate hearing impairment in susceptible individuals.