Chronic treatment with baicalein alleviates behavioural disorders and improves cerebral blood flow via reverting metabolic abnormalities in a J20 transgenic mouse model of Alzheimer's disease.

Baicalein (BE) has both antioxidant and anti-inflammatory effects. It has also been reported able to improve cerebral blood circulation in brain ischemic injury. However, its chronic efficacy and metabolomics in Alzheimer's disease (AD) remain unknown. In this study, BE at 80 mg/kg was administrated through the oral route in J20 AD transgenic mice aged from aged 4 months to aged 10 months. Metabolic- and neurobehavioural phenotyping was done before and after 6 months' treatment to evaluate the drug efficacy and the relevant mechanisms. Meanwhile, molecular docking was used to study the binding affinity of BE and poly (ADP-ribose) polymerase-1 (PARP-1) which is related to neuronal injury. The open field test showed that BE could suppress hyperactivity in J20 mice and increase the frequency of the target quadrant crossing in the Morris Water Maze test. More importantly, BE restored cerebral blood flow back to the normal level after the chronic treatment. A 1H NMR-based metabolomics study showed that BE treatment could restore the tricarboxylic acid cycle in plasma. And such a treatment could suppress oxidative stress, inhibit neuroinflammation, alleviate mitochondrial dysfunction, improve neurotransmission, and restore amino homeostasis via starch and sucrose metabolism and glycolipid metabolism in the cortex and hippocampus, which could affect the behavioural and cerebral blood flow. These findings showed that BE is a potential therapeutic agent for AD.

Functional effects of berberine in modulating mitochondrial dysfunction and inflammatory response in the respective amyloidogenic cells and activated microglial cells - In vitro models simulating Alzheimer's disease pathology.

AIM: Berberine (BBR) is an alkaloid extracted from Coptidis Rhizoma, also known as Huang-Lian. Huang-Lian has been used extensively in traditional Chinese medicine for the treatment of various diseases, including diabetes and dementia. Because Alzheimer's disease (AD) is a complex disease that involves various pathophysiological changes, the diverse neuroprotective effects of BBR may be useful for improving the brain's energy state at an early stage of the disease. MAIN METHODS: We performed extracellular flux and 1H NMR-based metabolic profiling analyses to investigate the effects of BBR on metabolic processes in these cells. Pioglitazone (PIO), a peroxisome proliferator-activated receptor-γ (PPARγ) agonist has been studied extensively for the treatment of AD. We explored the combination dosing effects of BBR and PIO in vitro, then leveraged computational methods to explain the experimental finding. KEY FINDINGS: BBR demonstrates potential in modulating the mitochondrial bioenergetics and attenuating dysfunction of the primary energy and glutathione metabolism pathways in an AD cell model. It also suppresses basal respiration and reduces the production of pro-inflammatory cytokines in activated microglial cells. Both experimental and computational observations indicate that BBR and PIO have comparable binding affinities to the PPARγ protein, suggesting both drugs may have some overlapping effects for AD. SIGNIFICANCE: BBR exerts beneficial effects on disrupted metabolic processes in amyloidogenic cells and activated microglial cells, which are important for preventing or delaying early-stage disease progression. The choice of BBR or PIO for AD treatment depends on their respective pharmacokinetic profiles, delivery, efficacy and safety, and warrants further study.

Metabolic Profiling of Female Tg2576 Mouse Brains Provides Novel Evidence Supporting Intranasal Low-Dose Pioglitazone for Long-Term Treatment at an Early Stage of Alzheimer's Disease.

Accumulating evidence suggests that disruptions in brain energy metabolism may be a key player in the pathogenesis of Alzheimer's disease (AD). Pioglitazone (PIO) has been found to exert beneficial effects on metabolic dysfunction in many AD preclinical studies. However, limited success in clinical trials remains an obstacle to its development for the treatment of AD. PIO's poor brain penetration was often cited as a contributing factor to the lack of clinical benefit. In this study, we prepared PIO-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles and administered them as suspended nanoparticles via nebulization. Preliminary investigation of drug distribution to the brain revealed comparatively reduced systemic exposure after administering PIO nanoparticles via the intranasal route. In vitro, extracellular flux analysis showed significantly raised spare respiratory capacity when cells were treated with low-dose PIO nanoparticles. Tg2576 transgenic mice treated with low-dose PIO nanoparticles over four months exhibited an overall trend of reduced hyperactivity in open field tests but did not show any visible effect on alternation rates in the Y-maze task. Subsequent 1H NMR-based metabolic profiling of their plasma and different brain regions revealed differences in metabolic profiles in the cerebellum, cortex, and hippocampus of Tg2576 mice after long-term PIO treatment, but not in their midbrain and plasma. In particular, the specificity of PIO's treatment effects on perturbed amino acid metabolism was observed in the cortex of transgenic mice with increases in alanine and N-acetylaspartate levels, supporting the notion that PIO treatment exerts beneficial effects on impaired energy metabolism associated with AD. In conclusion, inhalation exposure to PIO nanoparticles presents an exciting opportunity that this drug could be administered intranasally at a much lower dose while achieving a sufficient level in the brain to elicit metabolic benefits at an early stage of AD but with reduced systemic exposure.

In Vitro and In Vivo Comparison of Curcumin-Encapsulated Chitosan-Coated Poly(lactic-co-glycolic acid) Nanoparticles and Curcumin/Hydroxypropyl-ß-Cyclodextrin Inclusion Complexes Administered Intranasally as Therapeutic Strategies for Alzheimer's Disease.

Curcumin (CUR) has antioxidant and anti-inflammatory effects that are beneficial to Alzheimer's disease (AD). However, the poor solubility and high instability of CUR compromise its application greatly. In this study, CUR-encapsulated chitosan-coated poly (lactic-co-glycolic acid) nanoparticles (CUR-CS-PLGA-NPs) and hydroxypropyl-ß-cyclodextrin-encapsulated CUR complexes (CUR/HP-ß-CD inclusion complexes) were developed and compared through intranasal administration. In vitro studies indicated that CUR in CUR/HP-ß-CD inclusion complexes was stable under physiological conditions over 72 h with 95.41 ± 0.01% remaining, which was higher than 49.66 ± 3.91% remaining in CUR-CS-PLGA-NPs. Meanwhile, CUR/HP-ß-CD inclusion complexes showed a higher cellular uptake level of CUR than CUR-CS-PLGA-NPs in SH-SY5Y cells. Both formulations could reduce CUR's cellular cytotoxicity and showed a comparable antioxidant effect. Both formulations displayed the anti-inflammatory effect at 20 µM CUR in BV-2 cells, which decreased TNF-α and IL-6 levels to approximately 70 and 40%, respectively, when compared to the positive control, respectively. In vivo pharmacokinetic studies indicated that after intranasal administration, the AUC values of CUR in the plasma and brain of the CUR/HP-ß-CD inclusion complex group were 2.57-fold and 1.12-fold higher than those in the CUR-CS-PLGA-NP group at the same dose of 2 mg/kg, respectively. In conclusion, CUR/HP-ß-CD inclusion complexes displayed better properties than CUR-CS-PLGA-NPs as a carrier for intranasal delivery of CUR for application in AD.

Reverting Metabolic Dysfunction in Cortex and Cerebellum of APP/PS1 Mice, a Model for Alzheimer's Disease by Pioglitazone, a Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Agonist.

Identification of molecular mechanisms underlying early-stage Alzheimer's disease (AD) is important for the development of new therapies against and diagnosis of AD. In this study, gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolomics approach was employed to investigate the metabolic profiles in plasma and brain tissues harvested from 5-month-old APP/PS1 transgenic mice and their wildtype counterparts. Since different brain regions were expected to have their own distinct metabolic signals, four different brain regions, namely cortex, hippocampus, midbrain and cerebellum tissues, were dissected and had their metabolic profiles studied separately. Biochemical assays were also performed on plasma and brain cortex tissue of transgenic mice and wildtype mice, with a focus on mitochondrial health. Amyloid precursor protein and amyloid-ß levels in plasma, brain cortex tissue and mitochondria fractions isolated from brain cortex were measured to assess the amyloid pathology. Our findings include the observation of extensive metabolic alterations in cortex and cerebellum of APP/PS1 mice, but not in their hippocampus, midbrain and plasma. The major pathways affected in cortex and cerebellum of APP/PS1 mice were closely related to impaired energy metabolism and perturbation of amino acid metabolism in these mice. APP/PS1 mice also exhibited higher amyloid-ß40 and amyloid-ß42 in their cortex, accumulation of mitochondria APP in their cortex, and presented an altered oxidative state in their brain. Treatment with the peroxisome proliferator-activated receptor gamma (PPARγ) agonist pioglitazone (PIO) successfully restored the energy metabolism, lowered amyloid-ß levels and afforded the APP/PS1 mice a better antioxidative capacity in their cortex.

Role of serum albumin as a nanoparticulate carrier for nose-to-brain delivery of R-flurbiprofen: implications for the treatment of Alzheimer's disease.

OBJECTIVES: R-flurbiprofen (R-FP) was found to offer neuroprotective effects by inhibiting mitochondrial calcium overload induced by ß-amyloid peptide toxicity in Alzheimer's disease (AD). However, poor brain penetration after oral administration posed a challenge to its further development for AD treatment. In this study, we investigated the potential of serum albumin as nanoparticulate carriers for nose-to-brain delivery of R-FP to improve its brain accumulation. METHODS: Mice were subjected to three treatment groups: (1) intranasal R-FP solution, (2) oral R-FP solution and (3) intranasal R-FP albumin nanoparticles. We also investigated whether the in-vivo R-FP level achieved in the brain afforded by intranasal administration of R-FP nanoparticles had any effect on mitochondrial respiratory activity in an in-vitro AD model. KEY FINDINGS: Our in-vivo experiments demonstrate that the intranasal administration of serum albumin-based R-FP nanoparticles achieved higher brain-to-plasma ratio profile as compared to intranasal and oral administration of a simple R-FP solution. We observed significantly improved basal and maximal mitochondrial respiration in cells treated with R-FP albumin nanoparticles at in-vivo brain concentration. CONCLUSIONS: Serum albumin-based nanoparticles administered via the nasal route may be a viable approach in delivering therapeutic agents to the brain to alleviate mitochondrial dysfunction in AD.