Prenatal melatonin exposure affects luteinizing hormone and hypothalamic and striatal neuropeptide Y in the male rat offspring

The present study examines the influence of prenatal melatonin on the hypot halamic and striatal neuropeptide Y (NPY) concentrations as well as on lute inizing hormone (LH) levels. Male rat offspring of control and melatonin tr eated mother rats were studied at different ages of the sexual development: infantile, prepubertal, pubertal and adult ages. Hypothalamic NPV levels w ere much higher during the juvenile than throughout the infantile period. A fter prenatal melatonin treatment significantly higher values since day 15 up to 35, also at 60 days of age were found, as compared with controls. Str iatal NPY levels were lower than in hypothalamus. Again, NPY in the striatu m from offspring of melatonin treated mother rats showed significantly high er values than the respective controls at most of the ages studied. However , prenatal melatonin exerted an inhibitory influence upon LH secretion patt ern, since decreased concentrations up to 25 days of age and delayed peak v alues at pubertal age were observed. The present study also suggest that th e effect of NPY upon LH secretion is related to sexual development, since N PY exerted opposite effect in infantile than in pubertal period and melaton in administration during intrauterine life prevented this effect. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.