OBJECTIVE: To investigate effects of benzo(a)pyrene (BaP) on expressions of insulin-degrading enzyme (IDE) and neprilysin (NEP) which have the ability to degrade β-amyloid (Aβ) in neuroglia cells. METHODS: Primary mix-neuroglia cells were cultured from newborn SD rats. After exposure to BaP, Aβ_1-42 oligomer or Aβ_1-42 fiber individually or jointly for 24 h, the cell survival rate was measured by cell counting kit-8 (CCK-8). Afterwards, the primary mix-neuroglia cells were divided randomly into six groups: Control group, BaP group (2.00 μmol/L), Aβ_1-42 oligomer group (20.00 mg/L), BaP plus Aβ_1-42 oligomer group, Aβ_1-42 fiber group (20.00 mg/L) and BaP plus Aβ_1-42 fiber group, of which BaP was pretreated for 12 h followed by cotreatment with different aggregated Aβ_1-42. The expressions of IDE and NEP were measured by quantitative real-time polymerase chain reaction (qRT-PCR) for mRNA level and Western blotting for protein level. RESULTS: The cell survival rate showed no significant differences after treatment with BaP (≤20.00 μmol/L), Aβ_1-42 oligomer (20.00, 40.00 mg/L), Aβ_1-42 fiber (20.00, 40.00 mg/L) or cotreatment with BaP and Aβ_1-42 oligomer or BaP and Aβ_1-42 fiber. Compared with the control group, expressions of IDE and NEP in BaP-treated alone group had no obvious change; however, exposure to Aβ_1-42 oligomer alone significantly increased the mRNA and protein level of IDE (P<0.05), and the BaP pretreatment could significantly inhibit the up-regulated expressions of IDE by Aβ_1-42 oligomer (P<0.05); on the other hand, exposure either to Aβ_1-42 fiber alone or under the BaP pretreatment did not change the mRNA and protein level of IDE and NEP obviously. CONCLUSION On the premise of no significant change of cell survival rate, BaP pretreatment inhibited the up-regulated expressions of IDE in primary mixed neuroglia cells under cotreatment with Aβ oligomer, indicating that BaP may disturb degradation of Aβ oligomer and cause deposition of β-amyloid and further induce cognitive decline and acceleration of Alzheimer.
Amyloid beta-Peptides ; Animals ; Benzo(a)pyrene ; Blotting, Western ; Insulysin/metabolism* ; Neprilysin/metabolism* ; Neuroglia/metabolism* ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the effect of Tongluo Xingnao effervescent tablet on learning and memory of dementia rats induced by injection of Abeta25-35 in hippocampus and expression of insulin-degrading enzyme in hippocampus, in order to provide basis for preventing and treating senile dementia.

METHODThe dementia rat model was established by injecting Abeta25-35 in hippocampus. The rats were divided into the model control group, the Aricept (1.4 mg x kg(-1)) group, and Tongluo Xingnao effervescent tablet high dose (7.56 g x kg(-1)), middle dose (3.78 g x kg(-1)) and low dose (1.59 g x kg(-1)) groups. A sham operation group was established by injecting normal saline in hippocampus. The rats were orally given drugs for 90 days, once a day. Their learning and memory were tested by using Morris water maze. Immunohistochemistry and image analysis were utilized for a quantitative analysis on the expression of insulin-degrading enzyme in hippocampus.

RESULTTongluo Xingnao effervescent tablet could significantly shorten the escape latency of rats in the directional navigation test, prolong the retention time in the first quadrant dwell, decrease the retention time in the third quadrant dwell, increase the frequency of crossing the platform, show a more notable statistical significance than the model control group (P < 0.05). Additionally, it could also remarkably increase the average optical density of insulin-degrading enzyme in hippocampus, promote the expression of insulin-degrading enzyme in hippocampus, and show a more notable statistical significance than the model control group (P < 0.05).

CONCLUSIONTongluo Xingnao effervescent tablet has the effects of improving learning and memory capacity of AD rats and promoting the expression of insulin-degrading enzyme in hippocampus. Its effect in promoting intelligence will be related to increased insulin-degrading enzyme in hippocampus.

Alzheimer Disease ; drug therapy ; genetics ; metabolism ; psychology ; Animals ; Female ; Hippocampus ; drug effects ; metabolism ; Humans ; Insulysin ; genetics ; metabolism ; Learning ; drug effects ; Male ; Memory ; drug effects ; Rats ; Rats, Sprague-Dawley ; Tablets ; administration & dosage

Lead exposure is a known potential risk factor for neurodegenerative diseases such as Alzheimer's disease (AD). Exposure to lead during the critical phase of brain development has been linked with mental retardation and hypophrenia in later life. This study was aimed to investigate the effects of lead exposure of pregnant mice on the expressions of insulin-degrading enzyme (IDE) and nerve growth factor (NGF) in the hippocampus of their offspring. Blood samples were collected from the tail vein, and after anesthetizing the pups, the brain was excised on postnatal day 21. Lead concentrations were determined by graphite furnace atomic absorption spectrophotometry, and the expressions of IDE and NGF were determined by immunohistochemistry and Western blotting. Results showed that the reduction in IDE and NGF expression in the hippocampus of pups might be associated with impairment of learning and memory and dementia induced by maternal lead exposure during pregnancy and lactation.
Animals ; Down-Regulation ; Female ; Gene Expression Regulation, Developmental ; drug effects ; Gene Expression Regulation, Enzymologic ; drug effects ; Hippocampus ; drug effects ; growth & development ; metabolism ; Insulysin ; genetics ; metabolism ; Lead ; toxicity ; Mice ; Pregnancy ; Prenatal Exposure Delayed Effects ; chemically induced

OBJECTIVETo study the effect of ginsenoside Rb1 on GSKbeta/IDE signal transduction pathway and Abeta protein secretion in hippocampal neurons of high glucose-treated rats.

METHODHippocampal neurons of 24 h-old newly born SD rats were primarily cultured, inoculated in culture medium under different conditions, and then divided into the normal group, the high glucose group, the LiCl group and the Rb1 group. After being cultured for 72 h, the expressions of their phosphorylated GSK3beta, total GSK3beta and IDE protein were detected by Western blotting analysis. The mRNA expressions of GSK3beta and IDE were determined by RT-PCR. The ELISA assay was used to detect the secretion of Abeta protein in cell supernatant.

RESULTCompared with the normal group, the high glucose group showed increase in the p/tGSK3beta protein ratio and the secretion of Abeta protein and decrease in IDE protein and mRNA (P < 0.05). Compared with the high glucose group, both Rb1 and LiCl groups showed decrease in the p/tGSK3beta protein ratio and the expression of Abeta protein and increase in IDE protein and mRNA expression (P < 0.05). Compared with the LiCl group, the Rb1 group showed no significant difference in the expressions of p/tGSK3beta protein, IDE protein, mRNA and Abeta protein expression. In addition, the GSK3beta mRNA expression of the four groups had no significant difference.

CONCLUSIONGinsenoside Rb1 may reduce the secretion of Abeta protein in hippocampal neurons by reducing the phosphorylation of GSK3beta, down-regulating the ratio of pGSK3beta/GSK3beta and upregulating the expression of IDE.

Amyloid beta-Peptides ; genetics ; metabolism ; secretion ; Animals ; Dietary Carbohydrates ; adverse effects ; Gene Expression Regulation ; drug effects ; Ginsenosides ; pharmacology ; Glucose ; adverse effects ; Glycogen Synthase Kinase 3 ; genetics ; metabolism ; Glycogen Synthase Kinase 3 beta ; Hippocampus ; cytology ; Insulin ; metabolism ; Insulysin ; genetics ; metabolism ; Neurons ; cytology ; drug effects ; metabolism ; secretion ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects