Cross generation lead ingestion: behavioral and physiological effects in mice

Neonatal lead exposure changes quality of sperm and number of macrophages in testes of BALB/c mice

BALB/c mice were exposed to 0.1 ppm lead acetate in the drinking water from postnatal day (PND) 1 for 6 weeks. Until PND21, lead exposure was from mother's milk; thereafter, it was directly from the drinking water. The blood lead levels were the highest in pups before weaning (59.5+/-0.9 microg/dL) and significantly lower between PND21 and PND42 (20.3+/-4.7 microg/dL). At PND42, lead-exposed male mice were tested for fertility, sperm DNA, and macrophage number. Mating of lead-treated males with non-treated females confirmed the reduction of fertility in the exposed males. Flow cytometric studies of testicular preparations indicated that the sperm count was not different between lead-exposed and control males; however, the lead-treated mice had a significant increase in the number of testicular cells having a < 1n amount of DNA, which coincided with a decrease in the number of testicular cells with a 2n and 4n amount of DNA. The number of testicular macrophages also was decreased in lead-exposed males, which could reflect altered levels of CSF-1 or response to CSF-1, as previously reported [Kowolenko, M., Tracy, L., Lawrence, D.A., 1989. Lead-induced alterations of in vitro bone marrow cell responses to colony stimulating factor-1. J. Leukoc. Biol. 45, 198-206]. Our study showed that exposure to 0.1 ppm of lead during the neonatal and adolescent period is sufficient to reduce fertility in adult male mice; however, it did not affect sperm count on PND42. The presence of an increased number of apoptotic (< 1n amount of DNA) testicular cells may be diagnostic of defective sperm function. Thus, an administered dose of 0.1 ppm via drinking water ingestion by neonatal male BALB/c mice sufficient to produce PbB of 20-60 mg/dL compromised reproductive function in these mice as adults.

Lead concentration in different compartments of the bovine eye

It is known that lead is a metabolic substitute of calcium and recently, in vitro results showed that glycosaminoglycans and proteins are capable of binding lead. Therefore, in this work, the level of lead in aqueous humor, vitreous humor, lens and sclera of bovine eyes was analyzed in order to establish a relationship between lead concentration and the contents of glycosaminoglycans, proteins, water and calcium in those structures. Lead was determined by means of atomic absorption spectrometry after acid digestion. Our results suggest a direct relationship between the contents of proteins and glycosaminoglycans, and the ability of the different eye structures to retain lead. Nevertheless, an inverse relationship between water content and lead concentration was found. No association between calcium and lead concentrations was observed.

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 traditional cosmetic Kohl in Asia, Africa and the Middle East has been a subject of recent debate to the scientific community. In continuation of our earlier work we therefore examine in the present study, the drug metabolic activity and the homeostasis of essential metal ions in the lenticular system of adult rats exposed to long term low level lead (lead acetate 0.1% w/v). The results of our investigation demonstrate that long term low level lead exposure impaired the phase I & phase II metabolic activity of the lenticular system when assessed by aminopyrine demethylase, benzo[a]pyrene hydroxylase, aniline hydroxylase and UDP glucuronyl transferase (UDPGT), glutathione S-transferase (GST), respectively. A more pronounced decrease (55%) in GST was noticed compared to UDPGT, aminopyrene demethylase, benzo[a]-pyrene hydroxylase and aniline hydroxylase (20-30%). Increased lead concentration in the lenticular system of the rats as monitored by atomic absorption spectroscopy resulted in a significant decrease (15-35%) in the levels of Ca, Cu, Zn and Fe, along with a progressive loss in body weight. Respective increase in blood lead level was also monitored parallel to increase in lenticular lead concentration at different time points in lead treated rats. The present investigation, therefore, demonstrates that long term low level lead exposure to rats results in a profound impairment in the homeostasis of essential metal ions, lenticular drug metabolizing enzymatic activity and significant loss in body weight when compared to untreated control rats. Whether such a decrease in these functions reflects an inhibition of protein synthesis at transcriptional/post transcriptional levels or gene regulation at molecular level remains to be established.