LEAD-EXPOSURE ALTERS THE DRUG METABOLIC-ACTIVITY AND THE HOMEOSTASIS OF ESSENTIAL METAL-IONS IN THE LENTICULAR SYSTEM OF THE RAT

Potential lead exposure to the eyes as a result of the use of traditio nal cosmetic Kohl in Asia, Africa and the Middle East has been a subje ct of recent debate to the scientific community. In continuation of ou r earlier work we therefore examine in the present study, the drug met abolic activity and the homeostasis of essential metal ions in the len ticular system of adult rats exposed to long term low level lend (lean acetate 0.1% w/v). The results of out investigation demonstrate that long term low level lead exposure impaired the phase I & phase II meta bolic activity of the lenticular system when assessed by amino-pyrine demethylase, benzo[a]pyrene hydroxylase, aniline hydroxylase and UDP g lucuronyl transferase (UDPGT), glutathione S-transferase (GST), respec tively. A more pronounced decrease (55%) in GST was noticed compared t o UDPGT, aminopyrene demethylase, benzo[a]pyrene hydroxylase ann anili ne hydroxylase (20-30%). Increased lead concentration in the lenticula r system of the rats as monitored by atomic absorption spectroscopy re sulted in a significant decrease (15-32%) in the levels of Ca, Cu, Zn and Fe, along with a progressive loss in body weight. Respective incre ase in blood lead level was also monitored parallel to increase in len ticular lead concentration at different time points in lean treated ra ts. The present investigation, therefore, demonstrates that long term low level lead exposure to rats results in a profound impairment in th e homeostasis of essential metal ions, lenticular drug metabolizing en zymatic activity and significant loss in body weight when compared to untreated control rats. Whether such a decrease in these functions ref lects an inhibition of protein synthesis at transcriptional/post trans criptional levels or gene regulation at molecular level remains to be established. Copyright (C) 1996 Elsevier Science Ltd.