Effects of prenatal and postnatal exposure to amitraz on norepinephrine, serotonin and dopamine levels in brain regions of male and female rats

The effects of maternal exposure to amitraz on brain region monoamine levels of male and female offspring rats at 60 days of age were observed. Maternal and offspring body weight, physical and general activity development were unaffected by the exposure of dams to amitraz (20mg/kgbw, orally on days 6-21 of pregnancy and 1-10 of lactation). Male and female offspring were sacrificed at 60 days of age and possible alterations in the content and metabolism of NE, DA and 5-HT were determined in brain regions by HPLC. The results showed that all these neurotransmitter systems were altered in a brain regional-related manner. In male and female offspring, amitraz induced a significant decrease in the prefrontal cortex 5-HT and its metabolite 5-HIAA and DA and its metabolites DOPAC and HVA levels with interaction of sex. Nevertheless, we verified that striatum DA and 5-HT and corresponding metabolite contents decreased in male and female offspring without statistical distinction of sex. In contrast, amitraz did not modify 5-HT content, but caused an increase in 5-HIAA content in the medulla oblongata and hippocampus in male and female offspring. Alterations in the hippocampus DA, DOPAC and HVA levels after amitraz exposure were also observed displaying a sex interaction. NE levels also showed a decrease after amitraz treatment in the prefrontal cortex and striatum without statistical sex interaction, but MHPG levels decreased in both regions with a sex interaction. Amitraz evoked increases in 5-HT turnover in the prefrontal cortex as well as in DA turnover in the striatum and hippocampus but decreases in NE turnover in the hypothalamus, prefrontal cortex and striatum. The present findings indicated that maternal exposure to amitraz altered noradrenergic, serotonergic and dopaminergic neurochemistry in their offspring in the prefrontal cortex, striatum and hippocampus, and those variations could be related to several alterations in the functions in which these brain regions are involved.

Toxicokinetics of glyphosate and its metabolite aminomethyl phosphonic acid in rats

The toxicokinetics of glyphosate after single 100 mgkg(-1) intravenous (i.v.) and 400 mgkg(-1) oral doses were studied in rats. Serial blood samples were obtained after i.v. and oral administration. Plasma concentrations of glyphosate and its metabolite amiomethyl phosphonic acid (AMPA) were determined by HPLC method. After i.v. and oral administration, plasma concentration-time curves were best described by a two-compartment open model. For glyphosate, the elimination half-lives (T(1/2beta)) from plasma were 9.99 h after i.v. and 14.38 h after oral administration. The total plasma clearance was not influenced by dose concentration or route and reached a value of 0.995 l h(-1)kg(-1). After i.v. administration, the apparent volume of distribution in the second compartment (V(2)) and volume of distribution at steady state (V(ss)) were 2.39 and 2.99 l kg(-1), respectively, suggesting a considerable diffusion of the herbicide into tissues. After oral administration, glyphosate was partially and slowly absorbed with a T(max) of 5.16 h. The oral bioavailability of glyphosate was found to be 23.21%. Glyphosate was converted to AMPA. The metabolite AMPA represented 6.49% of the parent drug plasma concentrations. The maximum plasma concentrations of glyphosate and AMPA were 4.62 and 0.416 microg ml(-1), respectively. The maximum plasma concentration of AMPA was achieved at 2.42 h. For AMPA, the elimination half-life (T(1/2beta)) was 15.08 h after oral administration of glyphosate parent compound.

Pharmacokinetics of amoxycillin and the rate of depletion of its residues in pigs

Six pigs were used in a two-period crossover study to investigate the pharmacokinetics of amoxycillin after single intravenous and oral doses of 20 mg/kg bodyweight. Twelve pigs were used to study the residues of the drug in muscle, kidney, liver and fat after they had received daily oral doses of 20 mg/kg amoxycillin for five days. The mean (sd) elimination half life (t1/2beta) and mean residence time of amoxycillin in plasma were 3.38 (0.30) and 3.54 (0.43) hours, respectively, after intravenous administration and 4.13 (0.50) and 4.47 (0.30) hours, respectively, after oral administration. After oral administration, the maximum plasma concentration (Cmax) was 7.37 (0.42) microg/ml and it was reached after 0.97 (0.29) hours. Six days after the last oral dose, the mean concentration of amoxycillin in the pigs' kidneys was 21.38 ng/g and in the liver it was 12.32 ng/g, but no amoxycillin could be detected in fat or muscle; the concentrations of amoxycillin in edible tissues were less than the European Union maximal residue limit of 50 microg/kg.