ABSTRACT
Objective To observe the expression changes of 5-hydroxytryptamine (5-HT),brainderived neurotrophic factor (BDNF) in rats with chronic manganism.Methods Sixty healthy male Sprague-Dawley rats were randomly divided into control group (n =15) and experimental group (n =45).The experimental group was divided into three subgroups:low-dose group (n =15),middle-dose group (n =15),high-dose group (n =15).The rats in control group were given intraperitoneal injection of normal saline while the rats in low-dose group,middle-dose group,high-dose group were given intraperitoneal injection of 5 mg/kg,15 mg/kg and 25 mg/kg manganese chloride tetrahydrate,respectively for 5 days oncea week and lasted for 12 weeks.The depressive behavior changes of rats were observed by sucrose preference test and open field test.The concentrations of manganese in the striatum of rats were detected by inductively coupled plasma-atomic emission spectrometry.The expression of 5-HT in frontal cortex,hippocampus of rats was determined by high performance liquid chromatography.The expression of BDNF in frontal cortex,hippocampus of rats was examined by Western blotting.The expression of BDNF mRNA was detected using real-time fluorescence quantitative polymerase chain reaction.Results The chronic manganese poisoning rats presented depression-like behavior based on the sucrose preference test and open field test,which was more distinct in high-dose rats.As compared with the control group (frontal cortex (459.65 ± 16.81) ng/g,hippocampus (323.92 ± 17.41) ng/g;tissue wet weight),the expressions of 5-HT were significantly decreased in frontal cortex ((423.45 ± 17.19) ng/g,(376.89 ± 18.87) ng/g,(280.17 ± 25.46) ng/g),hippocampus ((265.71 ± 17.89) ng/g,(214.35 ±23.63) ng/g,(172.67 ± 18.24) ng/g) of the experimental group (F =132.68,69.66,both P ＜ 0.05).As compared with the control group (frontal cortex 0.962 ±0.111,hippocampus 0.873 ± 0.101;the expressions of BDNF were significantly decreased in frontal cortex (0.855 ± 0.106,0.649 ± 0.112,0.506 ± 0.121) and hippocampus (0.731 ± 0.092,0.626 ±0.104,0.544 ± 0.113) with the increasing concentration of MnCl2 which showed dose dependence (F =13.26,18.54,both P ＜ 0.05).As compared with the control group (frontal cortex 0.000 87 ± 0.000 07,hippocampus 0.000 82 ± 0.000 09),the expressions of BDNF mRNA were decreased significantly in frontal cortex (0.000 71 ± 0.000 06,0.000 48 ± 0.000 03,0.000 36 ± 0.000 03) and hippocampus (0.000 57 ± 0.000 05,0.000 49 ± 0.000 04,0.000 38 ± 0.000 05) in the treated group with the increasing concentration of manganese (F =18.46,12.76,both P ＜ 0.05).Conclusion Rats with chronic manganese poisoning could present depression-like behavior and the expression of 5-HT and BDNF is decreased in the frontal cortex and hippocampus with the increased accumulation of manganese.
ABSTRACT
<p><b>OBJECTIVE</b>To study the changes in the expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FP1) in the substantia nigra (SN) of rats with manganese-induced parkinsonism.</p><p><b>METHODS</b>Eighty Sprague-Dawley rats were randomly divided into four groups. Rats in the control group were injected intraperitoneally with saline solution. Rats in the low-dose, medium-dose, and high-dose groups were injected intraperitoneally with 5, 15, and 20 mg/kg MnC12 solution, respectively, for 16 weeks. Three behavioral tests were performed at the 16th week. The concentration of Mn2+ in the SN was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES), and the positive expression of tyrosine hydroxylase (TH) was measured by immunohistochemical staining to determine whether rats with manganese-induced parkinsonism were successfully produced. The expression of DMT1 and FP1 in SN was measured by immunohistochemical staining and fluorescent quantitative polymerase chain reaction.</p><p><b>RESULTS</b>Rats with manganese-induced parkinsonism were successfully produced using the above method. Compared with that in the control group, the concentrations of Mn2+ in the SN of rats exposed to 5, 15, and 20 mg/kg Mn2+ were significantly higher (1.72?0.33 vs 0.56 ± 0.20 µg/g, P<0.01; 2.92±0.77 vs 0.56±0.20 µg/g, P<0.01; 5.65±1.60 vs 0.56±0.20 µg/g, P<0.01). The mean ODs of TH-positive cells in the SN of rats exposed to 5, 15, and 20 mg/kg Mn+ were significantly lower than that in the control group (0.054±0.008 vs 0.109±0.019, P<0.01; 0.016±0.004 vs 0.109±0.019, P<0.01; 0.003±0.001 vs 0.109±0.019, P<0.01). Compared with that in the control group, the mean optical densities (ODs) of DMT1-positive cells in the SN of rats exposed to 15, and 20 mg/kg Mn2+ were significantly higher (0.062±0.004 vs 0.015±0.007, P<0.01; 0.116±0.064 vs 0.015±0.007, P<0.01). The mean ODs of FP1-positive cells in the SN of rats exposed to 5, 15, and 20 mg/kg Mn2+ were significantly lower than that in the control group (0.092±0.011 vs 0.306±0.081, P<0.01; 0.048±0.008 vs 0.306±0.081, P<0.01; 0.008±0.002 vs 0.306±0.081, P< 0.01). Rats exposed to 15 and 20 mg/kg Mn2+ had significantly higher expression of DMT1 mRNA in the SN than those in the control group (0.052±0.0126 vs 0.001±0.0004, P<0.05; 0.124±0.0299 vs 0.001±0.0004, P<0.05). However, rats exposed to 5, 15, and 20 mg/kg Mn2 had significantly lower expression of FP1 mRNA in the SN than those in the control group (0.059±0.0076 vs 0.162±0.0463, P<0.05; 0.033±0.0094 vs 0.162±0.0463, P< 0.05; 0.002±0.0007 vs 0.162±0.0463, P<0.05).</p><p><b>CONCLUSION</b>The increased expression of DMT1 and reduced expression of FP1 may be involved in the processes of Mn2+ accumulation in the SN and dopaminergic neuron loss in rats with manganese-induced parkinsonism.</p>