Aged ; Aged, 80 and over ; Alzheimer Disease ; metabolism ; pathology ; Brain ; metabolism ; Dentate Gyrus ; metabolism ; Dynamin I ; metabolism ; Hippocampus ; metabolism ; Humans ; Monomeric Clathrin Assembly Proteins ; metabolism ; Neuropil ; metabolism ; Synaptophysin ; metabolism

Objective To observe the learning and memory changes in coal-burning type of fluorosis rats, detect the expressions of neuronal nicotinic acetylcholine receptor(nAChR) at mRNA and protein levels in rat brains and to reveal the mechanism of changed learning and memory ability. Methods Twenty-four healthy SD rats, weighting 100 - 120 g, were randomly divided into three groups(8 in each). Control group was fed with normal diet, and low- and high-dose fluoride groups were fed with corn polluted with high fluoride (fluoride were 11.30,104.20 mg/kg, respectively) during drying processes with local burning-coal from the areas of endemic fluorosis to established rat model of chronic fluorosis. After exposed to fluoride for 6 months, behavioral changes were measured by Morris water maze. Animals were sacrificed, the brain was taken, after homogenizing the fluoride content of brain tissue was determined by fluoride ion selective electrode. The α3, α4 and α7 nAChR subunits at mRNA and protein levels were analyzed by real-time PCR and Western blotting, respectively. Results For rats in low- and high-fluoride groups, the escape latency time[(12.42 ± 8.03),(17.48 ± 8.05)s] was significantly longer than that in the control[(7.04 ± 3.29)s, all P< 0.05]. For rats in high-fluoride group, the numbers of crossing the platforms (1.62 ± 0.87) and the time of staying at the platforms[(16.70 ± 5.02)s] were significantly decreased as compared to that of control[3.53 ± 1.67, (23.33 ± 5.35)s, all P < 0.05]. The fluoride content in rat brain tissue in low- or high-fluoride groups [(1.14 ± 0.04), (1.79 ± 0.04)mg/kg] was significantly higher than that of control [ (0.52 ± 0.05) mg/kg, all P < 0.05]; in addition, the amount of fluoride in brain tissue of high-fluoride group was significantly higher than that of low-fluoride group(P < 0.05). In high-fluoride group, the mRNA expressions of α3, α4 and α7 nAChR subunits in rat brains(1.51 ± 0.20,1.45 ± 0.06,1.63 ± 0.08) were significantly lower as compared to controls (1.79 ± 0.11,1.66 ± 0.14,1.83 ± 0.06, all P< 0.05); whereas there were no significant changes in mRNA levels of these receptor subunits of the rat brains between low-fluoride group(1.65 ± 0.17,1.59 ± 0.09,1.71 ± 0.03) and controls (all P > 0.05). Furthermore, the protein levels of α3, α4 and α7 nAChR subunits in rat brains of highfluoride group(0.58 ± 0.13,0.16 ± 0.03,1.41 ± 0.38) and low-fluoride group(0.56 ± 0.23,0.08 ± 0.02,0.51 ± 0.16) were significantly lower than those of controls( 1.48 ± 0.42,0.57 ± 0.21,2.56 ± 0.26, P<0.05 or < 0.01). Conclusions Decreased ability of learning and memory in coal-burning type of fluorosis rats may be associated with declined expressions of nAChR at proteins and mRNA levels, which might be the main mechanism of the behavior change.

Alzheimer Disease ; genetics ; metabolism ; therapy ; Humans ; tau Proteins ; genetics ; metabolism

Objective To investigate the expressions of receptor for advanced glycation endproducts (RAGE) and nuclear factor κB(NF-κB) in brain hippocampus of rat with chronic fluorosis,and to reveal the mechanism of brain damage resulted from chronic fluorosis.Methods Sixty clean grade SD rats were randomly divided to three groups(20 rats in each group,10 female and 10 male) fed with different contents of fluoride,control group with normal tap-water(＜ 0.5 mg/L fluoride),small dosage of fluoride exposure group(10 mg/L fluoride in tap-water) and large dosage of fluoride exposure group(50 mg/L fluoride) for six months.Then the rats were killed by femoral artery bleeding and hippocampus was removed.Protein and mRNA levels of RAGE and NF-κB in the hippocampus were determined by Western blotting and quantitative real time PCR,respectively.Results As compared to the control groups[(100.00 ± 2.60)％,(100.00 ± 7.80)％],the expressions of RAGE and NF-κB at protein level in the hippocampus were significantly increased in the small dosage of fluoride exposure groups [(205.00 ± 15.30)％,(156.00 ± 12.20)％] and the large dosage of fluoride exposure groups[(232.00 ± 10.90)％,(162.00 ± 9.80)％,all P ＜ 0.05]; for the mRNA level of RAGE and NF-κB,the expressions were higher in the small dosage of fluoride exposure groups(1.27 ± 0.09,0.83 ± 0.15) and the large dosage of fluoride exposure groups (2.60 ± 0.19,1.27 ± 0.19) than those of the control groups(0.66 ± 0.18,0.32 ± 0.08,all P＜ 0.05).Conclusions The increased expressions of RAGE and NF-κB in the hippocampus of rat brain are caused by chronic fluorosis,and these changes may be associated with the mechanism of nerve injury.

Objective Aim of the study is to investigate the expression of syndecan-4 and nuclear factor κB(NF-κB) in the kidney of rat with chronic fluorosis,and to reveal the mechanism of kidney damage resulted from the toxicity of excessive amount of fluoride.Methods According to body mass and sex,sixty SD rats were randomly divided to three groups according to body mass and fed with different contents of fluoride:control group with normal tap-water(＜ 0.5 mg/L fluoride),small dosage of fluoride exposure group (adding 10 mg/L fluoride in tap-water) and large dosage of fluoride exposure group (50 mg/L fluoride) for six months.The protein level of syndecan-4 and NF-κB in the kidney was detected by Western blotting and syndecan-4 mRNA level by quantitative real time PCR.Results As compared to the control group[(100.0 + 8.1)％],the expression of syndecan-4 at protein level in the kidney of rat was significantly increased in the small dosage of fluoride exposure group [(198.5 + 5.6)％,P ＜ 0.05] and large dosage of fluoride exposure group [(209.2 + 13.0)％,P ＜ 0.05]; the protein levels of NF-κB in the small dosage of fluoride exposure group[(284.4 + 11.1)％,P ＜ 0.05] and in the large dosage of fluoride exposure group[(343.2 + 2.9)％,P ＜ 0.05] were significantly increased than that of the control group[(100.0 ± 10.7)％].The mRNA levels of syndecan-4 in the kidney in the small dosage of fluoride exposure group and large dosage of fluoride exposure group(0.431 + 0.058 and 0.453 ± 0.065,both P ＜ 0.05,respectively) were significantly increased than that of the control(0.128 + 0.026).Conclusions The increased expression of NF-κB in the kidney is induced by increased expression of syndecan-4,which may be involved in kidney damage of chronic fluorosis.

Objective To investigate the effect of fluoride on the expression of a subunit of calcium/calmodulin-dependent protein kinase- Ⅱ (α-CaMK Ⅱ ) at both mRNA and protein levels in human neuroblastoma cells were cultured in DMEM with final concentrations of NaF 0(control) ,0.05,0.50,2.00,5.00 mmol/L, respectively, for 48 hours. Then quantitative RT-PCR and Western blot were performed to detect the expression level of α-CaMK Ⅱ P1 (postnatal day 1) pups together with their mothers were randomly divided into three groups. Lactating rats were given drinking water containing NaF at concentrations 0(control) ,2,3 mmol/L. And pups were exposed to NaF through milk. In each group, 8 pups were sacrificed on day 14 after birth. In post-weaning period, another 8 pups in each group were given drinking water with the same dose of fluoride as their mother's 21 day after birth. After then, these pups were killed on day 28, and hippocampus was dissected immediately and Western blot was conducted mRNA and protein levels were decreased. When NaF concentrations were 0,0.05,0.50,2.00,5.00 mmol/L, the mRNA relative ratios of α-CaMKⅡ in SY5Y cells were 1.00 ± 0.00,0.77 ± 0.18,0.40 ± 0.11,0.22 ± 0.06 and 0.15 ± 0.03, and protein levels of α-CaMK Ⅱ were 100.00 ± 0.00,76.17 ± 2.08,59.16 ± 2.12,48.52 ± 2.71 and 43.51 ± 2.57, any mmol/L group, hippocampus α-CaMK Ⅱ protein levels on day 14 and 28(75.02 ± 2.88,73.83 ± 3.88 and 81.00 ± 2.54,45.70 ± 2.34) were significantly lower than that of control groups(100.00 ± 0.00,100.00 ± 0.00, all P < 0.01). In 3 mmol/L group, hippocampus α-CaMKⅡ protein level on day 28 was lower than that of 2 mmol/L group (P < 0.01). Conclusion Fluoride can decrease mRNA and protein levels of α-CaMK Ⅱ in nerve cells and hippocampus, which may be one of the mechanisms of learning and memory impairment by fluorosis.

Objective To investigate expression of glutathione S-transferase(GST) mRNA in peripheral blood of the population in coal-burning fluorosis area and to evaluate the effect of comprehensive control intervention. Methods Fifty samples of peripheral blood from patients in the coal-buring fluorosis area in Bijie county of Guizhou province were selected as fluorasis group and 50 samples of peripheral blood from patients in area with comprehensive management were selected as intervention group, respectively. Fifty samples from non-endemic fluorosis area were selected as the control group. Total RNA from blood was extracted and purified by the Trizol- Phenol-Chloroform one-step method. Expression of GST mRNA was detected by using SYBR Green I real-time fluorescence quantitative PCR. Results The data of GST mRNA in fluorosis group, intervention group and control group was 38.28±27.22,70.56±37.23 and 103.46 ± 46.62, respectively. There was a significant difference between the groups(F = 3.75, P < 0.05). Decreased expression of GST mRNA in fluorosis group and intervention group as compare to control was detected(all P < 0.05), and the expression of GST mRNA in intervention group was higher than that in fluorosis group(P < 0.05). Conclusion Coal-burning fluorosis possibly led to the decreased expression of GST mRNA in peripheral blood, and comprehensive control maybe prevent the decreased expression of GST in mRNA level.

OBJECTIVESTo investigate the neuroprotective function of alpha7 nicotinic receptor (nAChR) and its roles in the pathogenesis of Alzheimer's disease (AD).

METHODSpecific RNA interference to alpha7 nAChR mRNA expression was performed by gene specific small interference RNA (siRNA). SH-SY5Y cells were transfected with the siRNA or treated with 20 micromol/L 3-[2, 4-dimethoxybenzylidene] anabaseine (DMXB), an alpha7 nAChR agonist. After 48 hrs culture, levels of alpha7 nAChR mRNA and protein were monitored by RT-PCR and Western blotting, respectively. In the second experiment, SH-SYSY cells treated with siRNA or DMXB were exposed to 1 micromol/L Abeta(25-35), followed by protein analysis of alpha-form of secreted beta-amyloid precursor peptide (alphaAPPs), and total APP was assayed by Western blotting. In addition, lipid peroxidation and MTT [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] reduction were measured by spectrophotometry.

RESULTIn RNA interference group, as compared with controls, alpha7 nAChR mRNA and protein levels were decreased with inhibitory efficiency by 80% and 69%, respectively, along with a decrease in protein levels of alphaAPP and reduction of MTT. However the product of lipid peroxidation was increased. There was an enhanced gene inhibition of alpha7 nAChR by Abeta. While cells treated with DMXB, the alpha7 nAChR protein was increased by 23% as compared with that of the control, along with decrease of alphaAPP and ERK 1/2 at the protein level. The enhanced expression of alpha7 nAChR reduced the neurotoxic effects resulted from Abeta.

CONCLUSIONThe findings indicate that alpha7 nAChR may play a significant neuroprotective role by enhancing cleavage of APP, improving antioxidant defenses and limiting the toxicity of Abeta, which has been implied in the pathogenesis of AD.

Acetylcholine ; pharmacology ; Alzheimer Disease ; pathology ; physiopathology ; Amyloid beta-Peptides ; metabolism ; toxicity ; Amyloid beta-Protein Precursor ; pharmacology ; Cells, Cultured ; Humans ; Lipid Peroxidation ; Neurons ; drug effects ; pathology ; Neuroprotective Agents ; pharmacology ; Nicotinic Agonists ; pharmacology ; Protease Nexins ; RNA Interference ; RNA, Messenger ; drug effects ; metabolism ; RNA, Small Interfering ; pharmacology ; Receptors, Cell Surface ; Receptors, Nicotinic ; metabolism ; physiology ; alpha7 Nicotinic Acetylcholine Receptor

OBJECTIVESTo investigate the changes of nuclear factor (NF-)κBp65 and inflammatory chemotactic factors including monocyte chemoattractant protein 1 (MCP-1/CCL-2), macrophage inflammatory protein 1α (MIP-1α/CCL-3), glial fibrillary acidic protein (GFAP) in brains of the patients with Alzheimer's disease (AD) and reveal the correlation of these factors.

METHODSTen patients with AD and 8 age-matched control subjects were selected in the study. Immunohistochemistry was performed to determine the protein expression of NF-κBp65, MCP-1, MIP-1α and GFAP. Double-immunohistochemistry was used to detect the expression of GFAP and β-amyloid peptide 1-42 (Aβ(1-42)) in the hippocampus, temporal and frontal cortices.

RESULTSAs compared to age-matched controls (the numbers of the positively stained neuronal cells: 0.31 ± 0.20, 0.25 ± 0.20 and 0.25 ± 0.20, respectively), the immunoreactivities of NF-κBp65 in the hippocampus and the temporal and frontal cortices (numbers of the positively stained cells: 3.6 ± 1.5, 2.2 ± 1.2 and 2.2 ± 1.2, respectively) were significantly increased in AD brains. The levels of MCP-1 and MIP-1α in the hippocampus, and the temporal and frontal cortices (numbers of the positively stained neuronal cells: 8.0 ± 1.3, 8.8 ± 1.0, 9.3 ± 1.4, respectively;and 8.1 ± 1.5, 12.5 ± 1.1, 6.4 ± 1.1, respectively) with AD were significantly higher than those of controls (the numbers of the positive neuronal cells: 4.5 ± 0.9, 4.5 ± 0.6, 4.0 ± 1.8, respectively; and 5.0 ± 1.9, 6.3 ± 2.2, 3.8 ± 1.5, respectively). An increased number of glial cells stained with GFAP were observed to extensively distribute around the senile plaques in AD brains. There were significant correlations between NF-κBp65 and these inflammatory chemotactic factors in AD brains.

CONCLUSIONCorrelative expressions of NF and inflammatory chemotactic factors were found in the brains of AD patients, through a mechanism that may involve the inflammatory response induced by Aβ in the processing of AD.

Aged ; Aged, 80 and over ; Alzheimer Disease ; metabolism ; pathology ; Brain ; metabolism ; pathology ; Chemokine CCL2 ; metabolism ; Chemokine CCL3 ; metabolism ; Female ; Frontal Lobe ; metabolism ; pathology ; Glial Fibrillary Acidic Protein ; metabolism ; Hippocampus ; metabolism ; pathology ; Humans ; Immunohistochemistry ; Male ; Neuroglia ; metabolism ; pathology ; Plaque, Amyloid ; metabolism ; pathology ; Temporal Lobe ; metabolism ; pathology ; Transcription Factor RelA ; metabolism

Objective To investigate the expression of c-Jun-N-terminal kinase(JNK) in rat brains with chronic fluorosis and try to reveal the molecular mechanism for the neural impairment induced by the disease.Methods The rats were randomly divided into 3 groups, normal control group(drinking water containing less than 0.5 mg/L of sodium fluoride, NaF), lower fluoride exposed group(drinking water containing 5 mg/L NaF) and higher fluoride exposed group(drinking water containing 50 mg/L NaF), 24 in every group. The rats were examined at the sixth month after feeding. The concentration of fluorine in urine and blood was detected by F-ion selective electrode. The expression of JNK in brains was investigated by using Western blotting and immunohitochemistry staining, and analyze the correlation between activating of JNK and the concentration of fluorine in blood. Results The increased concentration of fluorine in urine(control: 0.92 ± 0.30, lower fluoride exposed group: 2.56 ± 0.91,higher fluoride exposed group: 5.73 ± 3.14, P ＜ 0.05) were observed when 6 months after the beginning of the experiment, and the amount of fluorine in blood was also higher in rats with fluorosis(control: 0.12 ± 0.07, lower fluoride exposed group: 0.36 ± 0.14, higher fluoride exposed group: 0.50 ± 0.18, P ＜ 0.05). The expression of phospho-JNK at protein levels were higher in the brains of rats with fluorosis than that of controls (control: 1.00 ± 0.37, lower fluoride exposed group: 1.20 ± 0.28, higher fluoride exposed group: 1.74 ± 0.69, P ＜ 0.05), whereas no change of total-JNK was found(F = 0.046, P ＞ 0.05). Furthermore, the expression of phospho-JNK in the parietal cortex(119.3 ± 14.1), occipital cortex(112.7 ± 5.4), hippocampus CA3(100.6 ± 8.9), dorsal thalamus (117.8 ± 10.4) and olivary nucleus( 112.6 ± 5.9) of rats in higher fluoride exposed group were higher than that in control( 104.1 ± 8.9,106.6 ± 9.6,106.6 ± 9.7,108.9 ± 6.4,100.3 ± 8.4, all P ＜ 0.05) and lower fluoride exposed group(96.7 ± 17.1,102.5 ± 8.3,106.4 ± 6.5,110.2 ± 9.3,102.4 ± 4.7,102.5 ± 9.8, all P＜ 0.05). The positive stained neurons of total-JNK also distributed in the same brain regions of rats, but no difference was detected between the rats with fluorosis and controls(all P ＞ 0.05). The increased level of phospho-JNK was positively correlated with the fluoride contents in blood of the rats with fluorosis (r = 0.677). Conclusions The expression of phospho-JNK in brains of rats with fluorosis was significantly increased with a correlation to fluoride content in blood, which might be connected to the mechanism of neural impairment induced by chronic fluorosis.