INFLUENCE OF MATERNAL MELATONIN ON MELATONIN RECEPTORS IN RAT OFFSPRING

Using quantitative autoradiography, we have studied the influence of m aternal plasma melatonin on the expression and density of melatonin re ceptors in the brain and pituitary of rat offspring. At birth, the sam e structures displayed melatonin receptors whether the rats were born to and reared by intact or pinealectomized dams. The receptor density was, however, about 20% lower in the group born to pinealectomized dam s. At postnatal day 9, when the pups of both groups synthetize rhythmi cally their own melatonin, this difference was suppressed. These resul ts indicate that melatonin does not appear to be a requirement for the expression of its receptors, but seems to play a stimulatory role in their synthesis.