Search

Fatal familial insomnia (FFI) is a dominantly inherited prion disease linked to the D178N mutation in the gene encoding the prion protein (PrP). Symptoms, including insomnia, memory loss and motor abnormalities, appear around 50 years of age, leading to death within two years. No treatment is available. A ten-year clinical trial of doxycycline (doxy) is under way in healthy individuals at risk of FFI to test whether presymptomatic doxy prevents or delays the onset of disease. To assess the drug's effect in a tractable disease model, we used Tg(FFI-26) mice, which accumulate aggregated and protease-resistant PrP in their brains and develop a fatal neurological illness highly reminiscent of FFI. Mice were treated daily with 10 mg/kg doxy starting from a presymptomatic stage for twenty weeks. Doxy rescued memory deficits and restored circadian motor rhythmicity in Tg(FFI-26) mice. However, it did not prevent the onset and progression of motor dysfunction, clinical signs and progression to terminal disease. Doxy did not change the amount of aggregated and protease-resistant PrP, but reduced microglial activation in the hippocampus. Presymptomatic doxy treatment rescues cognitive impairment and the motor correlates of sleep dysfunction in Tg(FFI-26) mice but does not prevent fatal disease., Highlights • Early doxycycline treatment improves memory in fatal familial insomnia mice. • Doxycycline restores normal circadian motor rhythmicity. • Doxycycline reduces microglial activation in the hippocampus. • Doxycycline does not reduce mutant prion protein aggregation or protease resistance. • Doxycycline does not delay disease onset or prolong survival of the mice.

Highlights • Ovariectomy accelerates doxycycline-induced acute liver injury. • The expression levels of IL-6, IL-10, c-fos, cox-2 and HO-1 genes were strongly upregulated in ovx mice. • Apocynin, totally improved DOXY-induced liver injury in both sham and ovx mice. • NADPH oxidase is responsible for the development of drug-induced acute liver injury, To determine the physiological role of estrogen in the development of liver injury, we examined the sensitivities of sham and ovariectomy (ovx) mice against doxycycline (DOXY)-induced acute liver injury. Ovx or sham operation was performed in C57BL/6J wild-type female mice of eight weeks of age. Sham mice and ovx mice were treated with DOXY (240 mg/kg ip) 8 weeks after the operation, 30 min after apocynin (5 mg/kg) or saline administration. Blood and liver samples were obtained at 3 and 6 h after DOXY administration. Liver dysfunction occurred soon after DOXY administration and became more severe in ovx mice than in sham mice. At early phase after DOXY injection, TNF-α and iNOS inductions upregulated almost the same levels in sham and ovx mice. On the other hand, expression levels of IL-6, IL-10, c-fos, cox-2 and HO-1, downstream genes of TNF-α, were significantly increased in ovx mice compared to those in sham mice, correlated with liver dysfunction. In addition, apocynin, a NADPH oxidase (Nox) inhibitor, totally improved DOXY-induced liver injury in both sham and ovx mice, indicating that reactive oxygen species generated through Nox activation by DOXY are responsible for development of acute liver injury.

Many data suggest that alpha synuclein (α-syn) aggregation is involved in Parkinson's disease (PD) neurotoxicity and is accelerated by the pathogenetic point mutation A30P. The triplication of α-syn gene has been linked to early-onset familial PD, suggesting that the cellular dosage of α-syn is an important modulator of its toxicity. To verify this point, we developed an inducible model of α-syn expression (both wild type [WT] and mutated A30P) in rat PC12/TetOn cells. At low expression level, both α-syn(WT) and (A30P) did not aggregate, were not toxic, and displayed a protective action against oxidative stress triggered by hydrogen peroxide (H2O2). By increasing α-syn expression, its antioxidant function was no longer detectable as for the A30P form, but again no aggregation and cell death were present both for the WT and the mutated protein. To clarify why α-syn did not accumulate at high expression level, we inhibited macroautophagy by 3-methyladenine (3-MA) and the proteasome by MG132. In presence of 3-MA, α-syn(WT) accumulated, A11 anti-oligomer antibody-positive aggregates were detectable, and cell toxicity was evident, while proteasome inhibition did not increase α-syn(WT) accumulation. Macroautophagy or proteasome inhibition slightly increased α-syn(A30P) toxicity, with no detectable aggregation. This model can provide useful details about α-syn function, aggregation, and degradation pathways., Graphical abstract Graphical abstract summarizing the main findings of the article. The red flow chart describes the system when α-syn expression was induced at low level, while the green part splits the different scenario for α-syn(WT) and α-syn(A30P) at high expression level. The slot blot shows the appearance of A11 immunoreactivity. 3-MA, 3-methyladenine; doxy, doxycycline. For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article. Highlights ▶We developed a model of alpha-synuclein (wild type or A30P) expression in PC12 cells. ▶At low alpha-synuclein expression, we found no aggregation but neuroprotection. ▶At high alpha-synuclein expression macroautophagy was activated without aggregation. ▶Macroautophagy inhibition lead to alpha-synuclein wild type aggregation and toxicity. ▶The A30P form was not toxic and its removal involved also the proteasome.