AN ABNORMAL DISTRIBUTION OF MELATONIN RECEPTORS IN THE NEWBORN RAT WITH INHERITED PRENATAL HYDROCEPHALUS

Melatonin binding in the brain of hydrocephalic H-Tx rats was examined by autoradiography. At the time of birth, hydrocephalic animals showe d an abnormality in the distribution of high-affinity melatonin recept ors dorsal to the cerebral aqueduct when compared to controls. Whereas newborn rats of the H-Tx strain that were unaffected by hydrocephalus had melatonin receptors in a tectal midsagittal ship overlying the aq ueduct and spanning the anterior half of the tectum, hydrocephalic rat s lacked melatonin receptors in the most anterior part of this region. In these animals, the length of the aqueduct over which receptors wer e missing was compressed and was additionally occluded by dystrophic e pendyma. The first signs of ventricular expansion characteristic of hy drocephalus were evident. (C) 1997 IBRO. Published by Elsevier Science Ltd.