Effects of low level manganese exposure on the serum neuroendocrine hormones in the welders / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the effects of low level manganese (Mn) exposure on the serum neuroendocrine hormones levels of the welders.</p><p><b>METHODS</b>The exposure group consisted of 41 male welders, 40 male workers without exposing to harmful agents served as controls. The serum contents of prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (TST) and thyroid stimulating hormone (TSH) of 81 subjects were detected by chemiluminescence immunoassay.</p><p><b>RESULTS</b>The geometric mean value of airborne Mn concentrations was 0.03 mg/m(3) (0.003 - 0.519 mg/m(3)) in the welding circumstances. The levels of Mn in red blood cells (RBCs) and urinary Mn of the exposure group were significantly higher than those of control group (P < 0.01). The contents of serum LH and TSH of the exposure group were 2.89 ± 0.69 mIU/ml and 1.45 ± 0.56 uIU/ml, which were significantly lower than those (3.82 ± 1.61 mIU/ml and 2.19 ± 1.28 µIU/ml) of control group (P < 0.01). The serum contents of LH, FSH and TSH of the group exposed to Mn for < 5 years were significantly lower than those of the control group, The serum TST level of the group exposed to Mn for < 5 years was significantly higher than those of the control group and group exposed to Mn for 5 ∼ years, the serum FSH level of the group exposed to Mn for < 5 years was significantly lower than that of the group exposed to Mn for 10 years (P < 0.05 or P < 0.01). The serum contents of LH and TSH of the group exposed to Mn for 5 ∼ years were significantly lower than those of the control group (P < 0.05 or P < 0.01). The serum contents of PRL, LH and TSH of the group exposed to Mn for 10 years were significantly lower than those of the control group (P < 0.05). There was negative correlation between blood (RBC) Mn and urinary Mn (r = -0.310, P < 0.05), also there was negative correlation between serum PRL and serum TST (r = -0.409, P < 0.01), the positive correlation between serum LH and serum FSH was observed (r = 0.361, P < 0.05).</p><p><b>CONCLUSION</b>The results of present study showed that the long exposure to low level of Mn may decrease the levels of serum PRL, LH and TSH in workers occupationally exposed to Mn, which can influence the metabolism of neuroendocrine hormones to certain extent.</p>

Effect of sodium para-aminosalicylic on concentrations of amino acid neurotransmitters in basal ganglia of manganese-exposed rats / 中华预防医学杂志

<p><b>OBJECTIVE</b>To probe the effect of sodium para-aminosalicylate (PAS-Na) on concentration of amino acid neurotransmitters including glutamate (Glu), glutamine (Gln), glycine (Gly) and gamma-aminobutyric acid (GABA) in basal ganglia of subacute manganese (Mn)-exposed rats.</p><p><b>METHODS</b>Forty Sprague-Dawley male rats were randomly divided into the control, Mn-exposed, low dose PAS-Na (L-PAS) and high dose PAS-Na (H-PAS) groups. Rats in experiment groups received daily intraperitoneally injections of manganese chloride (MnCl₂ · 4H₂O, 15 mg/kg), while rats in control group received daily intraperitoneally injections of normal saline (NS), all at 5 days/week for 4 weeks. Then the rats in PAS groups followed by a daily subcutaneously dose of PAS-Na (100 and 200 mg/kg as the L-PAS and H-PAS groups, respectively) for another 3 and 6 weeks; while the rats in Mn-exposed and control group received NS. The concentrations of Glu, Gln, Gly and GABA in basal ganglia of rat was detected by the high performance liquid chromatography fluorescence detection technique.</p><p><b>RESULTS</b>After treating with PAS-Na for 3 weeks, the concentration of Gly in the Mn-exposed rats decreased to (0.165 ± 0.022) µmol/L (control = (0.271 ± 0.074) µmol/L, Mn vs control, t = 4.65, P < 0.05). After the further 6-week therapy with PAS-Na, the concentrations of Glu, Gln, Gly in the Mn-exposed rats were lower than those of the control rats ((0.942 ± 0.121), (0.377 ± 0.070), (0.142 ± 0.048), (1.590 ± 0.302), (0.563 ± 0.040), (0.247 ± 0.084) µmol/L; t = 7.72, 5.85, 4.30, P < 0.05); and also lower than in L-PAS and H-PAS groups, whose concentrations were separately (1.268 ± 0.124), (1.465 ± 0.196), (0.497 ± 0.050), (0.514 ± 0.103), (0.219 ± 0.034) µmol/L (L-PAS Glu and Gln vs Mn, t = 3.87, 3.77, P < 0.05; H-PAS Glu, Gln and Gly vs Mn, t = 6.78, 4.70, 3.42, P < 0.05).</p><p><b>CONCLUSION</b>The toxic effect of manganese on Glu, Gln and Gly in basal ganglia of Mn-exposed rats is obvious, especially appears earlier on Gly. The toxic effect still continues to develop when relieved from the exposure. PAS-Na may play an antagonism role in toxic effect of manganese on concentration of Glu, Gln and Gly in basal ganglia of Mn-exposed rats.</p>