ABSTRACT
Objective To investigate the neurotoxic effects ofLDN-57444, a specific ubiquitin C-termiual hydrolase L1 (UCH-L1) inhibitor, on dopaminergic neurons and the possible mechanism. Methods The viability of SK-N-SH cells exposed to 5, 10, 25, 50, 75 or 100 μmol/L LDN-57444 for 24 h was assessed using MTT assay, and the cell apoptosis was detected with Hoechst staining. Western blot was performed to identify the expressions of UCH-L1 protein, ubiquitin monomer and polyubiquitinated proteins, and the activity of the ubiquitin-proteasome system (UPS) was evaluated with fluorometry. Results After exposure to UCH-LI inhibitor for 24 h, the cell process-like structures of SK-N-SH cells diminished, and the cell body shrank and became spherical. Exposure to LDN-57444 resulted in concentration-dependent reduction of the cell viability, and the reduction became statistically significant following the exposure to 50 μmol/L LDN-57444, as compared with that in the control group (P<0.05). The exposure also resulted in obvious cell apoptosis as shown by nuclear fragmentation and presence of the apoptotie bodies. Western blot detected no obvious changes in UCH-L1 protein expression but identified reduced ubiquitin monomer and increased polyubiquitinated protein expression in the cells. Fluorometry showed reduced activity of UPS in the exposed cells. Conclusion UCH-L1 inhibitor produces neurotoxicity to dopaminergie neurons and induces cell apoptosis possibly as the result of impaired UPS activity and intracellular accumulation of polyubiquitinated proteins following the exposure.
ABSTRACT
Objective To investigate the effects of different doses of pituitary adenylate cyclase- activating polypeptide(PACAP)on the functional and morphological outcome in a mice model of Parkinson' s disease(PD)rendered by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).Methods Male mice were treated with PACAP 0.02, 0.20 or 2.00 ?g by iv bolus for 7 days after MPTP was administered, and were compared with the saline-treated mice.The immunohistochemistry and Western blot were used to detect the alterations of PD biomarker including tyrosine hydroxylase(TH), dopamine transporter(DAT)and vesicular monoamine transporter2(VAMT2).In addition, monoamine neurotransmitters in the striatum of mice were measured by the high performance liquid chromatography (HPLC).Results TH immunohistochemistry indicated that the number of TH-positive neurons in the substantia nigra was increased in all PACAP-treated mice(PACAP(0.02 ?g/d)group was 93.33?4.87, F=85.85,P