ABSTRACT
Objective:To study the effect of Schisandrae Chinensis Fructus lignans (SCL) on learning and memory ability of D-galactose（D-gal）-induced aging model mice. Method:ICR mice were randomly divided into 4 groups: normal group (distilled water, subcutaneous injection with normal saline), model group (distilled water, subcutaneous injection with 200 mg·kg-1D-gal), piracetam group (oral administration with 200 mg·kg-1 piracetam, subcutaneous injection with 200 mg·kg-1D-gal), low-dose SCL group (oral administration with 50 mg·kg-1·d-1 SCL, subcutaneous injection with 200 mg·kg-1·d-1 D-gal), medium-dose SCL group (oral administration with 100 mg·kg-1·d-1 SCL, subcutaneous injection with 200 mg·kg-1·d-1D-gal), high-dose SCL group (oral administration with 200 mg·kg-1·d-1 SCL, subcutaneous injection with 200 mg·kg-1·d-1 D-gal). The drugs were administered continuously for 10 weeks. Dark test and Morris water maze test were performed to observe the effect of SCL on the learning and memory ability of D-gal-induced aging mice. The activities of superoxide dismutase (SOD) and malondialdehyde (MDA) in mouse brain tissue were detected by chemical colorimetry. The expressions of peroxiredoxin-6（Prdx6） and glutathione peroxidase 1（GSH-Px1） mRNA in mouse brain tissue were detected by polymerase chain reaction (PCR). The expressions of Prdx6 and GSH-Px1 protein in mouse tissues were detected by Western blot. Result:In behavioral experiments, compared with normal group, the number of dark avoidance errors in model group significantly increased (P<0.05), the latency was significantly reduced (P<0.01), and the number of mouse passes and the target quadrant residence time were significantly reduced (P<0.01), which can be used as an indicator of successful modeling. Compared with the model group, the number of errors in the piracetam group, and medium and high-dose SCL groups was significantly reduced (P<0.05，P<0.01), and the latency was significantly prolonged (P<0.05，P<0.01). At the same time, the number of water maze passes and the target quadrant retention time in the high-dose SCL group increased significantly (P<0.01). The results of biochemical indicators showed that compared with normal group, the SOD activity in brain tissue of model group mice was significantly reduced (P<0.01), while the MDA content was increased (P<0.05). Compared with the model group, SOD activity in the brain tissues of piracetam group, and low, medium and high-dose piracetam groups was significantly increased (P<0.05), whereas the level of MDA was reduced (P<0.05). The expressions of Prdx6 and GSH-Px1 were significantly increased (P<0.05，P<0.01), indicating that the SCL administration group was dose-dependent. Conclusion:SCL can improve the learning and memory ability of D-gal-induced aging mice, which may be related to the anti-oxidation ability of SCL and the up-regulation of Prdx6 and GSH-Px1 expressions in mouse brain tissue.
ABSTRACT
<p><b>OBJECTIVE</b>To establish the biological exposure limit values of urinary S-phenylmercapturic acid (SPMA) for assessing occupational exposure to benzene.</p><p><b>METHODS</b>Study participants were selected from 55 workers of benzene exposures below 32.5 mg/m(3). The concentration of personal exposure to benzene was measured by gas chromatography and sampled with personal sampler. The urine samples were collected at the end of work shift and individual internal exposure level was evaluated by determination of SPMA in urine by HPLC/MS method. Comparison of external and internal exposure was assessed by the relative internal exposure (RIE) index.</p><p><b>RESULTS</b>The benzene exposure level ranged from 0.71 to 32.17 mg/m(3) (geometric mean 6.98 mg/m(3), median 7.50 mg/m(3)). The urinary SPMA at the end of the work shift were significantly correlated with benzene exposure, (microg/g Cr) = -8.625 + 18.367X (mg/m(3)), r = 0.8035, (P < 0.01). According to the occupational exposure limit for benzene in China and calculation of regression equation, the expected value of urinary SPMA was 101.58 microg/g Cr. Mean level of biotransformation of per mg/m(3) benzene to urinary SPMA was 18.23 microg/g Cr and the metabolic efficiencies of benzene transformation to urinary SPMA decreased with benzene exposure increased.</p><p><b>CONCLUSION</b>Based on abroad documents and data, biological limit value for occupational exposure to benzene in China is recommended as follows: 100 microg/g Cr (47 micromol/mol Cr) for SPMA in the urine at the end of shift.</p>