The effect of postnatal exposure to lead on the electroretinogram in young rats.

The morphological and electrophysiological effects on the retina resulting from lead exposure were assessed in neonatal rats. The electroretinogram (ERG), light and electron microscopy and morphometry of the retina were evaluated at 9, 11 and 13 days of age. The lead concentration in the blood was on average between 276 and 311 micrograms/100 ml in the different age groups. The brain concentration of lead varied on average between 102 and 104 micrograms/100 g. A reduction in amplitude, a prolonged latency and an elevated threshold sensitivity of the a-wave was observed in the 11 days old lead-exposed pups. The 13 days old lead-fed rats showed depressed amplitudes and delayed peak times of both the a- and b-waves. The latency of the a-wave was also longer in the lead-treated 13 days old animals. No ERG was recorded at the age of 9 days in neither the lead-exposed or control animals. No significant change in the morphology of the retina was found. We propose that lead exposure seem to induce a change primarily in the electrophysiological function of the photoreceptors. There was no evidence for a direct retardation of the development of the retina by the administration of lead.