Partial inhibition of mitochondrial complex I ameliorates Alzheimer's disease pathology and cognition in APP/PS1 female mice.

Alzheimer's Disease (AD) is a devastating neurodegenerative disorder without a cure. Here we show that mitochondrial respiratory chain complex I is an important small molecule druggable target in AD. Partial inhibition of complex I triggers the AMP-activated protein kinase-dependent signaling network leading to neuroprotection in symptomatic APP/PS1 female mice, a translational model of AD. Treatment of symptomatic APP/PS1 mice with complex I inhibitor improved energy homeostasis, synaptic activity, long-term potentiation, dendritic spine maturation, cognitive function and proteostasis, and reduced oxidative stress and inflammation in brain and periphery, ultimately blocking the ongoing neurodegeneration. Therapeutic efficacy in vivo was monitored using translational biomarkers FDG-PET, 31P NMR, and metabolomics. Cross-validation of the mouse and the human transcriptomic data from the NIH Accelerating Medicines Partnership-AD database demonstrated that pathways improved by the treatment in APP/PS1 mice, including the immune system response and neurotransmission, represent mechanisms essential for therapeutic efficacy in AD patients.

Magnetization transfer and adiabatic R 1ρ MRI in the brainstem of Parkinson's disease.

BACKGROUND: In addition to classic midbrain pathology, Parkinson's disease (PD) is accompanied by changes in pontine and medullary brainstem structures. These additional abnormalities may underlie non-motor features as well as play a role in motor disability. METHODS: Using novel magnetic resonance imaging (MRI) methods based on rotating frame adiabatic R(1ρ) (i.e., measurements of longitudinal relaxation during adiabatic full passage pulses) and modified magnetization transfer (MT) MRI mapping, we sought to identify brainstem alterations in nine individuals with mild-moderate PD (off medication) and ten age-matched controls at 4 T. RESULTS: We discovered significant differences in MRI parameters between midbrain and medullary brainstem structures in control subjects as compared to PD patients. CONCLUSIONS: These findings support the presence of underlying functional/structural brainstem changes in mild-moderate PD.

Assessing subjective and psychomotor effects of the herbal medication valerian in healthy volunteers.

Valerian is the common name given to the genus Valeriana, an odiferous, herbaceous perennial plant widely distributed in the temperate regions of Asia, Europe, and North America. It is among the most widely used herbal medicines in the world. Numerous clinical studies have demonstrated valerian's ability to improve sleep; however, to the best of our knowledge, no study has systematically assessed subjective and psychomotor/cognitive effects of valerian in young healthy adults across a range of doses. In the present study, we sought to determine whether valerian extract (Valeriana officinalis) altered mood and/or impaired psychomotor/cognitive performance in young healthy volunteers. We examined the effects of valerian extract (600, 1200, and 1800 mg) and 10 mg diazepam (positive control) compared to placebo in 10 young healthy volunteers. Dependent measures included subjective and psychomotor variables. The valerian extract had no significant effects on any of the dependent measures. Diazepam, though, produced subjective effects as measured by four different rating scales, and impaired psychomotor/cognitive performance. The data suggest that acute administration of valerian does not have mood-altering or psychomotor/cognitive effects in young healthy volunteers.

The gamma-aminobutyric acidergic effects of valerian and valerenic acid on rat brainstem neuronal activity.

UNLABELLED: Valerian is a medicinal herb that produces anxiolytic and sedative effects. It was suggested that valerian acts via gamma-aminobutyric acid (GABA)ergic mechanisms. Previous studies showed binding of valerian extract to GABA receptors, but the functional effect of the binding has not been demonstrated. In this study we evaluated the GABAergic effect of valerian extract and one of its major constituents, valerenic acid, on brainstem neuronal activity in an in vitro neonatal rat brainstem preparation. We first observed that muscimol, a GABA(A) receptor agonist, decreased the firing rate in most brainstem neurons in a concentration-related fashion; 30 micro M produced a 38.9% +/- 3.0% (mean +/- SE) inhibition compared with control values (P < 0.01; 50% inhibitory concentration [IC(50)], 2.0 +/- 0.1 microM). This effect was antagonized by bicuculline (10 microM), a GABA(A) antagonist. Then we showed that valerian extract 3 mg/mL induced a 29.6% +/- 5.1% inhibition with an IC(50) of 240 +/- 18.7 microg/mL, whereas 100 microM valerenic acid induced a 22.2% +/- 3.4% inhibition with an IC(50) of 23 +/- 2.6 microM (both P < 0.01). Bicuculline antagonized the inhibitory effects of both the valerian extract and valerenic acid. In addition, pretreatment with valerian extract or valerenic acid decreased the brainstem inhibitory effects produced by muscimol (both P < 0.05), suggesting that these compounds play an important role in the regulation of GABAergic activity. Data from this study suggest that the pharmacological effects of valerian extract and valerenic acid are mediated through modulation of GABA(A) receptor function. Thus, valerian may potentiate the sedative effects of anesthetics and other medications that act on GABA receptors, and presurgical valerian use may cause a valerian-anesthetic interaction. IMPLICATIONS: Valerian is an herb used in treating anxiety and insomnia. We observed that the valerian effects are mediated through brain gamma-aminobutyric acid (GABA) receptors in a rat brainstem preparation. Thus, valerian may potentiate the effects of anesthetics that act on GABA receptors, and presurgical valerian use may cause a valerian-anesthetic interaction.

Kavalactones and dihydrokavain modulate GABAergic activity in a rat gastric-brainstem preparation.

Using an in vitro neonatal rat gastric-brainstem preparation, the activity of majority neurons recorded in the nucleus tractus solitarius (NTS) of the brainstem were significantly inhibited by GABA A receptor agonist, muscimol (30 microM), and this inhibition was reversed by selective GABA A receptor antagonist, bicuculline (10 microM). Application of kavalactones (300 microg/ml) and dihydrokavain (300 microM) into the brainstem compartment of the preparation also significantly reduced the discharge rate of these NTS neurons (39 % and 32 %, respectively, compared to the control level), and this reduction was partially reversed by bicuculline (10 microM). Kavalactones or dihydrokavain induced inhibitory effects were not reduced after co-application of saclofen (10 microM; a selective GABA B receptor antagonist) or naloxone (100 nM; an opioid receptor antagonist). Pretreatment with kavalactones (300 microg/ml) or dihydrokavain (300 microM) significantly decreased the NTS inhibitory effects induced by muscimol (30 microM), approximately from 51 % to 36 %. Our results demonstrated modulation of brainstem GABAergic mechanism by kavalactones and dihydrokavain, and suggested that these compounds may play an important role in regulation of GABAergic neurotransmission.