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Dietary supplements containing plant materials of Annonaceae species (Annona muricata L., A. squamosa L., A. mucosa JACQ., A. squamosa × cherimola Mabb.) were extracted by hot, pressurized ethyl acetate and analyzed for their effect in vitro on Lund human mesencephalic neurons. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and cell death was determined by lactate dehydrogenase levels. Three supplements strongly decreased the cell viability at extract concentrations of 1 µg/mL, of which 1 decreased cell viability at 0.1 µg/µL. Also, strong neuronal toxicities of these supplements were found. Cell death was observed at concentrations of 10 µg/mL. The degree of toxicity was comparable to the ones found in Annonaceous fruit extracts. Two fruit pulps of Annonaceae (A. muricata and A. squamosa) showed a reduction in cell viability at lower concentrations. The fruit pulp extract of A. muricata revealed the strongest neurotoxic effect, with 67% cell death at a concentration of 1 µg/mL. A high reduction in cell viability coupled with pronounced cell death was found at 0.1 µg/mL for an Annonaceous seed extract. These results demonstrate that the intake of dietary supplements containing plant material from Annonaceae may be hazardous to health in terms of neurotoxicity. [ABSTRACT FROM AUTHOR]

Aim P301 S MAPT transgenic mice ( P301 S mice) are a widely used model of frontotemporal dementia and parkinsonism linked to chromosome 17 with tau pathology ( FTDP-17-tau). However, a systematic correlation between cognitive deficits and cellular tau pathology at different ages is still missing. Therefore, our study investigated memory deficits of P301 S mice in relation to pathological tau species and dendritic spine pathology throughout adulthood. Methods We analysed P301 S mice behaviourally with the novel open field, rotarod, and Morris water maze tests to measure deficits in locomotion, balance and cognition, respectively; immunohistochemically with different tau antibodies for specific tau species; and with Golgi staining for dendritic spine pathology. Results We confirmed the occurrence of locomotor deficits at an age of 5 months and newly report memory deficits from 2.5 months of age onwards. At this early age, MC1 and CP13, but not AT180 immunoreactivity, was prominent in the hippocampus of P301 S mice. Neuronal cell loss in the hippocampus of P301 S mice was not observed to occur till 6 months of age. However, there was a significant reduction in the density of dendritic spines from young adulthood onwards in hippocampal pyramidal neurones. Conclusion In P301 S mice, memory deficits precede the onset of locomotor dysfunction and coincide with the appearance of conformationally changed, S202-phosphorylated tau and reduced spine density in the absence of neuronal cell loss in the hippocampus. Our finding provides insights into the toxic effects of different tau species in vivo and may facilitate the development of new therapies against neurodegenerative tauopathies. [ABSTRACT FROM AUTHOR]

Suppression of tau protein expression has been shown to improve behavioral deficits in mouse models of tauopathies, offering an attractive therapeutic approach. Experimentally this had been achieved by switching off the promoters controlling the transgenic human tau gene (MAPT), which is not possible in human patients. The aim of the present study was therefore to evaluate the effectiveness of small interfering RNAs (siRNAs) and their cerebral delivery to suppress human tau expression in vivo, which might be a therapeutic option for human tauopathies. We used primary cortical neurons of transgenic mice expressing P301S-mutated human tau and Lund human mesencephalic (LUHMES) cells to validate the suppressive effect of siRNA in vitro. For measuring the effect in vivo, we stereotactically injected siRNA into the brains of P301S mice to reveal the suppression of tau by immunochemistry (AT180, MC1, and CP13 antibodies). We found that the Accell™ SMART pool siRNA against MAPT can effectively suppress tau expression in vitro and in vivo without a specific delivery agent. The siRNA showed a moderate distribution in the hippocampus of mice after single injection. NeuN, GFAP, Iba-1, MHC II immunoreactivities and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay showed neither signs of neurotoxicity or neuroinflammation nor apoptosis when MAPT siRNA is present in the hippocampus. Our data suggest that siRNA against MAPT can serve as a potential tool for gene therapy in tauopathies.