title: Effects of lead and/or zinc exposure during the second stage of rapid postnatal brain growth on delta-aminolevulinate dehydratase and negative geotaxis of suckling rats.
abstract: Lead has been shown to produce cognitive and motor deficits in young rats that could be mediated, at least in part, by inhibition of the zinc-containing heme biosynthetic enzyme delta-aminolevulinate dehydratase (ALA-D). In the present study we investigated the effects of lead and/or zinc treatment during the second stage of rapid postnatal brain development on brain, kidney and blood ALA-D specific activity, as well as the negative geotaxis behavior of rats. Eight-day-old Wistar rats were injected intraperitoneally with saline, lead acetate (8 mg/kg) and/or zinc chloride (2 mg/kg) daily for five consecutive days. Twenty-four hours after treatment, ALA-D activity was determined in the absence and presence of DL-dithiothreitol (DTT). The negative geotaxis behavior was assessed in 9- to 13-day-old rats. Treatment with lead and/or zinc did not affect body, brain or kidney weights or brain- or kidney-to-body weight ratios of the animals. In spite of the absence of effect of any treatment on ALA-D specific activity in brain, kidney and blood, the reactivation index with DTT was higher in the groups treated with lead or lead + zinc than in the control group, in brain, kidney and blood (mean +/- SEM; brain: 33.33 +/- 4.34, 38.90 +/- 8.24, 13.67 +/- 3.41; kidney: 33.50 +/- 2.97, 37.60 +/- 2.67, 15.80 +/- 2.66; blood: 63.95 +/- 3.73, 56.43 +/- 5.93, 31.07 +/- 4.61, respectively, N = 9-11). The negative geotaxis response behavior was not affected by lead and/or zinc treatment. The results indicate that lead and/or zinc treatment during the second stage of rapid postnatal brain growth affected ALA-D, but zinc was not sufficient to protect the enzyme from the effects of lead in brain, kidney and blood.
authors.affiliation: Curso de Farmácia, Universidade do Sul de Santa Catarina, Tubarão, SC, Brazil.
authors.forename: E C
authors.initials: EC
authors.lastname: Goulart
authors.forename: C A
authors.initials: CA
authors.lastname: Pereira
authors.forename: R C
authors.initials: RC
authors.lastname: Garcia
authors.forename: M B
authors.initials: MB
authors.lastname: Giacomelli
authors.forename: A L
authors.initials: AL
authors.lastname: Rodrigues
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects*; D001835:Body Weight; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D007668:Kidney / Q000201:enzymology; D007854:Lead / Q000009:adverse effects*; D008297:Male; D000623:Porphobilinogen Synthase / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015032:Zinc / Q000009:adverse effects*
chemical_list: D007854:Lead; D000623:Porphobilinogen Synthase; D015032:Zinc; D004229:Dithiothreitol