Long-term drinking purified water may aggravate the inhibition of NMDA expression and spatial learning ability induced by lead on rat / 中华预防医学杂志

<p><b>OBJECTIVE</b>To compare brain lead accumulation and neurotoxicity induced by lead under drinking purified water and tap water on rat.</p><p><b>METHODS</b>All 104 male weaning SD rats were randomly divided into eight groups, matched-four pairs according to drinking water: tap water, purified water, tap water with lead 50 mg/L(lead acetate water-solution), purified water with lead 50 mg/L, tap water with lead 200 mg/L, purified water with lead 200 mg/L, tap water with lead 800 mg/L. All were fed with normal food and environmental cognitions kept consistent Morris water maze(including Place Navigation, Spatial Probe Test, Visible Platform Trial) was measured to test rat spatial learning at the 12 and 24 week. At the end of the experiment (28 week), rats were killed and the lead of brain and blood was measured by Graphite furnace atomic absorption spectrometric method; the NR1, NR2A, NR2B of NMDAR (N-methyl-D-aspartame receptor) in hippocampus were analyzed by RT-PCR.</p><p><b>RESULTS</b>Under the same lead exposure, no significant differences were observed in blood lead, however, brain lead level showed higher in drinking purified water group than that in tap water group. Expression of NR1, NR2A and NR2B in hippocampus of the rats drinking purified water was lower than those drinking tap water, especially at low lead exposure (50 mg/L) (P < 0.05). In the 24 week Morris water maze, place navigation test's escape latency showed significantly prolonged at the rats drinking purified water as compared with those drinking tap water on the pairs of 50 mg/L and 200 mg/L pb2+ groups (P < 0.05), and the differences occurred in early 1-2 days.</p><p><b>CONCLUSION</b>Compared with drinking tap water, drinking purified water might increase the accumulation of brain lead, lower NR1, NR2A, NR2B expression and delay the spatial learning and memory ability under chronic lead exposure in water.</p>

Antagonism effects of green tea against microcystin induced oxidant damage on liver and kidney / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the antagonism effects of green tea (GT) against microcystin LR (MC-LR) induced hepatotoxicity and nephrotoxicity in mice.</p><p><b>METHODS</b>All 40 male mice were randomly divided into four groups. Mice in group III and IV were pretreated with green tea for free drink at doses of 2 g/L and 12 g/L prior to MC-LR intoxication, for consecutively 18 days. The toxin treatment mice were administered continually intraperitoneal injections of MC-LR at a dose of 10 microg x kg(-1) x d(-1) bw from day 6th till sacrifice, continually 13 days. Mice were sacrificed and immediately subjected to necropsy, and the body weight, relative organ weight, serum biochemical parameters, antioxidant enzyme levels (SOD and GSH), lipid peroxidation products (MDA) and histopathology were systematically evaluated.</p><p><b>RESULTS</b>MC-LR exposure led to increase the oxidative stress and organ injury was significantly observed through biochemical parameters and microscopic evaluation. However, high dose of GT pretreatment caused a significant elevation in serum GSH and SOD levels, and a decrease of serum MDA level as compared with MC-LR control. The mean values of GSH and SOD activities were separately 467.29 mg/L and 139.22 U/ml in group IV. Subsequently, GT pretreatment obviously diminished the serum ALT, AST and Cr activities. Those pathological damages in liver and kidney, were to a certain extent, lessened in GT pretreatment mice in correlation with the biochemical parameters.</p><p><b>CONCLUSION</b>GT might elevate antioxidant defense system, clean up free radicals, lessen oxidative damages and protect liver and kidney against MC-LR induced toxicity.</p>