Maternal melatonin treatment influences rates of neonatal development of meadow vole pups.

Meadow vole dams, housed in a 14L:10D photoperiod were injected daily 3 h before onset of darkness with 10 micrograms melatonin. Treatment during gestation or lactation produced offspring that exhibited altered somatic, testicular, and pelage growth. Gestational melatonin treatment decreased preweaning weight gain, delayed testicular development, and increased pelage growth in offspring, whereas melatonin treatment during lactation increased pelage depth at weaning and increased post-weaning somatic growth. These results suggest that pre- and postnatal maternal melatonin secretory patterns influence postnatal development of photosensitive traits in offspring.