Morphine induces reproductive changes in female rats and their male offspring.

The effect of intrauterine morphine exposure on the development of reproductive functions has been investigated in the rat. Female rats were treated daily ip with morphine sulfate, doses increasing at 10-d intervals from 5, 7.5, 10, to 15 mg/kg. These rats were mated between day 38 and 45, and morphine treatment continued at 20 and 30 mg/kg over pregnancy and at up to 40 mg/kg for 10 d postpartum. The treatment mainly disrupted ovarian cyclicity; only 48% exhibited normal cyclicity. Of these, 43% became pregnant when mature male rats were placed with them. Litter size was normal but with significantly more stillbirths in each litter and live pups had decreased body weights. Male offspring had reduced body weight at the time of weaning that persisted until 60 d of age. At 120 d, animals showed complete abolition of spermatogenesis and drastically reduced testicular steroidogenesis. Plasma LH levels were low, and hypothalamic noradrenaline was high.