Effects of subchronic benzoapyrene exposure on hippocampal cholinergic system in rats / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe the effects of subchronic benzo[a]pyrene (B[a]P) exposure on the neurobehavior and hippocampal acetylcholine (Ach) level, acetylcholinesterase (AChE) activity, and mRNA and protein expression of nicotinic acetylcholine receptor α7 subtype (nAChR α7) in rats, and to investigate the neurotoxic mechanism of B[a]P.</p><p><b>METHODS</b>Sixty healthy male SD rats were randomly divided into blank control group, solvent control group, and B [a]P exposure groups. Each rat in the exposure groups was intraperitoneally injected with B[a]P at 1.0, 2.5, or 6.25 mg/kg once every other day for 90 days. The learning and memory ability of the rats was examined by Morris water maze test and step-down test; the hippocampal Ach level was measured by alkaline hydroxylamine method; the AChE activity was measured by DNTB method; the mRNA and protein expression levels of hippocampal nAChR α7 were measured by quantitative PCR and Western blot.</p><p><b>RESULTS</b>The 2.5 and 6.25 mg/kg B[a]P exposure groups showed significantly lower learning and memory abilities than the blank control group and solvent control group (P < 0.05); also, the two groups had significantly lower hippocampal Ach levels than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The 6.25 mg/kg B[a]P exposure group showed significantly lower hippocampal AChE activity than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). There were no significant differences in the mRNA and protein expression levels of nAChR α7 among all groups (P > 0.05). The hippocampal Ach level was negatively correlated with the mean escape latency period and total distance travelled (r = -0.567, P < 0.01; r = -0.503, P < 0.01) but positively correlated with the time in platform quadrant (r = 0.800, P < 0.01).</p><p><b>CONCLUSION</b>Subchronic B[a]P exposure may impair the learning and memory ability in rats, which is related to the downregulation of hippocampal Ach level.</p>

The modification of apoptosis correlated gene, protein and protein activity in rat hippocampus induced by benzoa pyrene sub-chronic exposure / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To observe the effects of subchronic exposure to benzo[a]pyrene (B[a]P) on the mRNA and protein expression levels of apoptosis-related genes (bax, bcl-2, caspase-3, caspase-6, and caspase-9) and the activities of Caspase-3, Caspase-6, and Caspase-9 in the hippocampal neurons of rats and to investigate the neurotoxic mechanism by which B[a]P induces the apoptosis of neurons.</p><p><b>METHODS</b>Fifty-two healthy SD rat were randomly divided into five groups according to preliminary neurobehavioral test results: blank control group, solvent control group, and 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups; the rats in exposure groups were intraperitoneally injected with B[a]P every other day for 90 days. The Morris water maze was used to test the learning and memory ability of rats; flow cytometry was used to measure the apoptosis ratio of hippocampal neurons; real-time quantitative PCR and Western blot were used to measure the mRNA and protein expression levels of apoptosis-related genes; spectrophotometry was used to measure the activities of their en-coded proteins.</p><p><b>RESULTS</b>Compared with the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group, the 2.5 and 6.25 mg/kg B[a]P exposure groups hada significantly longer mean escape latency period (P < 0.05) and a significantly increased number of times of platform crossing (P < 0.05), and the 6.25 mg/kg B[a]P exposure group had significantly lower length and percentage of time spent in the platform quadrant (P < 0.05). The early apoptosis ratio rose as the dose of B[a]P increased (P trend < 0.05); the early apoptosis ratios of 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups were significantly higher than those of blank control group and solvent control group (P < 0.05). Compared with the blank control group, solvent control group, and 1.0 and 2.5 mg/kg B[a]P exposure groups, the 6.25 mg/kg B[a]P exposure group had significantly increased Bax expression (P < 0.05) and significantly decreased Bcl-2 expression and Bcl-2/Bax ratio (P < 0.05). The 2.5 and 6.25 mg/kg B[a]P exposure groups had significantly higher expression levels of Caspase-3 and Caspase-6 than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The activities of Caspase-3, Caspase-6, and Caspase-9 were significantly higher in the 2.5 and 6.25 mg/kg B[a]P exposure groups than in the blank control group and solvent control group (P < 0.05). There was a positive correlation between the activities of Caspase-3, Caspase-6, and Caspase-9 and early apoptosis ratio of hippocampal neurons in rats (r = 0.793, P = 0.019; r = 0.886, P = 0.006; r = 0.773, P = 0.025). There were no significant differences in the mRNA expression of Bax, Bcl-2, Caspase-3, Caspase-6, and Caspase-9 among these groups (P > 0.05).</p><p><b>CONCLUSION</b>Subchronic exposure to B[a]P can induce apoptosis of hippocampal neurons; its mechanism may be related to the fact that B[a]P can induce upregulated expression of Bax, inhibit expression of Bcl-2, lead to decrease in Bcl-2/Bax ratio, induce upregulated expression of Caspase-3 and Caspase-6, and cause increase in the activities of Caspase-3, Caspase-6, and Caspase-9.</p>

Effects of iodine deficient and hypothyroid on protein expression of extracellular signal-regulate kinase (ERK1/2) in the cerebellum of rats / 中国地方病学杂志

Objective To study the effects of iodine deficiency and hypothyroidism on protein expression of extracellular signal-regulate kinase(ERK1/2) in the cerebellum of rots. Methods Twenty-eight healthy Wistar rots, female, 60 days old, were randomly divided according to their body weight into control group, iodine deficient group and hypothyroidism groups. Hypothyroidism groups in accordance with drinking water containing propylthiouracil(PTU) were divided into doses of 5 mg/L and 15 mg/L groups, 7 rats in each group. Rats after pregnancy, iodine deficient rats were administered with iodine-deficient diet and hypothyroid rats were administered with PTU in drinking water. Pup's cerebellum in each group were weighed on day 14,21,28 and 42. Cerebellum tissue was observed for cerebellar morphology using silver staining and detected for ERK1/2 protein using immunohistochemistry on day 7,14,21,28 and 42. Results On day 14,21,28 and 42, cerebellum weight of pups from iodine-deficient[(0.0945±0.0233), (0.1347±0.0046), (0.1542±0.0094), (0.1949±0.0048)g]were significantly lighter than control[(0.1856±0.0123), (0.2049±0.0098), (0.2268±0.0065), (0.2606±0.0086)g, all P < 0.05]and hypothyroidism groups [for 5 mg/L group: (0.1741±0.0172), (0.1927±0.0103), (0.2181±0.0064), (0.2583±0.0054)g, all P<0.05; for 15 mg/L group: (0.1604±0.0083), (0.1682±0.0103), (0.1996±0.0073) and (0.2579±0.0067)g, all P< 0.05]the difference had statistical significance(F=6.325,8.870, 16.191 and 21.574, all P<0.05). Compared to the controls on day 7, iodine-deficient group didn't have clear layers; on day 21, disappearance of external granule cells from iodine-deficient and 15 mg/L groups was delayed, still two or three layer external granule cells remained; on day 28 and 42, molecular layer from 5, 15 mg/L and iodine-deficient groups and became thinner. Immunohistochemistry showed that on day 7, there was no statistical difference of integrated optical density average of ERK1/2, in all the groups(F=1.102, P>0.05); on day 14,21,28 and 42, integrated optical density average of ERK1/2 in iodine-deficient group[(7.3245±0.5070), (8.3606±1.0683), (9.1217±1.0402), (12.1587±0.7581), all P<0.01]and hypothyroidism groups [for 5 mg/L group: (11.4307±1.5200), (14.919±0.8497), (16.0082±1.1130), (15.7721±0.8293), all P< 0.01; for 15 mg/L group: (7.8538±0.9775), (11.2461±0.8138),(12.78±1.3783), (13.0871±1.1450), all P < 0.01]was significantly lower than those of controls [(16.2831±0.5143), (20.2653±0.9551), (22.7485±1.0267), (22.1725±0.9939), all P < 0.01], the difference having a statistical signifieance(F=16.131,13.543,26.953,41.583, all P<0.01). Conclusions Iodine deficiency and hypothyroidism during critical periods of brain development may change eerebellar morphology and down regulate the protein expression of ERK1/2, which may result in damage of cerebellum development.

Association of INF-gamma/A+874T gene polymorphisms with respiratory syncytial virus bronchiolitis / 中国当代儿科杂志

<p><b>OBJECTIVE</b>A deficient interferon-gamma (IFN-gamma) response has been involved in the pathogenesis of severe respiratory syncytial virus (RSV) infection. Gene polymorphisms in IFN-gamma/A+874T have been associated with the susceptibility to asthma and might be related to disease severity of RSV infection. This study investigated the single nucleotide polymorphisms (SNPs) of IFN-gamma/A+874T in Han children in Wenzhou area and to explore the correlation between gene polymorphisms of IFN-gamma/A+874T and the susceptibility and disease severity of RSV bronchiolitis, as well as the effect of SNPs upon nasopharyngeal secretions (NPS) IFN-gamma and total serum IgE levels.</p><p><b>METHODS</b>One hundred and fourteen hospitalized children with RSV bronchiolitis and 90 healthy controls were recruited. Sequence analysis was used for detecting the SNPs of IFN-gamma/A+874T. NPS IFN-gamma levels were measured using ELISA. Total serum IgE levels were assayed using the chemiluminescence method.</p><p><b>RESULTS</b>IFN-gamma/A+874T gene polymorphisms were present in both the patient and the control groups. AA and AT genotypes were found in both groups, with a AA frequency of 82.5% vs 77.8% and a AT frequency of 17.5% vs 21.1% (p>0.05). The frequency of allele was 90.4% (A) and 9.6% (T) in the patient group, and 88.3% (A) and 11.7% (T) in the control group, respectively. There were no significant differences in the allele frequency between the two groups. Moreover, no difference was found both in NPS IFN-gamma and total serum IgE levels between AA and AT genotypes in the patient group. There were no significant differences in the variation of IFN-gamma/+874 between mild and moderate to severe cases.</p><p><b>CONCLUSIONS</b>IFN-gamma/A+874T gene polymorphisms were present in Han children in Wenzhou area. Gene variations were not associated with the susceptibility and disease severity of RSV bronchiolitis as well as IFN-gamma and total serum IgE levels.</p>