Reproducibility of olfactory fMRI activations in the OB and PC after MK801 injection.

<p>The data from all NHPs after MK801 injection were averaged to map the activations (p < 0.05, cluster size = 4) to define the ROIs of OB and PC. Within the OB and PC ROIs, color-encoded percentage fMRI signal changes were calculated from the averaged data over odd measurements (<b>A</b>) and from the averaged data over even measurements (<b>B</b>). The percentage change of fMRI signals for each voxel within the OB and PC for the two subsets are plotted against each other in (<b>C</b>) and (<b>D</b>). As shown in these figures, data points predominantly lie along their diagonal lines (slope = 1), indicating the fMRI signal changes from odd subsets are quantitatively similar to signal changes from even subsets. For the activations in OB (C), the cross correlation value is 0.91 (<i>p</i> = 1.41e^-42). For the activations in PC (D), the cross correlation value is 0.70 (<i>p</i> = 9.65e^-7). OB: olfactory bulb. PC: piriform cortex.</p

Olfactory fMRI activations before and after MK801 injection.

<p>The data from all NHPs were averaged to map the activations (p < 0.05, cluster size = 4). (<b>A</b>) Olfactory fMRI Activations <i>before</i> MK801 injection. Color-encoded activations (red/yellow) were observed in the consecutive 3 slices where olfactory bulb is located. <b>(B)</b> Olfactory fMRI activations <i>after</i> MK801 injection. Color-encoded activations were observed in the consecutive 3 slices where olfactory bulb and piriform cortex are located. Green arrows: activations in the piriform cortex. OB: olfactory bulb.</p

Definition of the 2 ROIs and the olfactory fMRI responses in these ROIs before and after MK801 injection.

<p>(<b>A</b>) The color-encoded ROIs were superimposed on the 3 consecutive axial gradient-echo EPI images. Purple: olfactory bulb (OB); red: piriform cortex (PC). (<b>B & C</b>) Olfactory response in the OB and PC in the different 1-h periods of 4-h experiment session (mean ± SD, n = 4). Red bars: 1-min odor stimulation. In the OB (<b>B</b>), robust olfactory fMRI response was observed before MK801 injection, and MK801 increased the response. In the PC (<b>C</b>), no robust olfactory response was observed before MK801 injection. After MK801 injection, robust and repeatable olfactory responses were observed. (<b>D & E</b>) Strengths of the olfactory responses during the 4-h experimental session (mean ± SD, n = 4). MK801 increased the response amplitudes in the OB and PC. The asterisks ‘*’ indicate that the strengths of response were significantly larger than the strengths during the first hour before MK801 delivery (paired <i>t</i>-test, all p<0.04).</p

The impact of respiration rate on the olfactory responses in naïve NHPs.

<p>Data are from seven NHPs that did not receive any pharmacological agents. The 7 NHPs were separated into two groups based on their respiration rates. (<b>A & C</b>) Olfactory responses in the OB and PC from 4 NHPs with lower respiration rates of 19–25 breaths/min. (<b>B & D</b>) Olfactory responses in the OB and PC from 3 NHPs with higher respiration rates of 29–35 breaths/min. The difference in respiration rate from these 2 groups of NHPs has no effect on the olfactory responses in the OB and PC.</p

Early intervention of tau pathology prevents behavioral changes in the rTg4510 mouse model of tauopathy

<div><p>Although tau pathology, behavioral deficits, and neuronal loss are observed in patients with tauopathies, the relationship between these endpoints has not been clearly established. Here we found that rTg4510 mice, which overexpress human mutant tau in the forebrain, develop progressive age-dependent increases in locomotor activity (LMA), which correlates with neurofibrillary tangle (NFT) pathology, hyperphosphorylated tau levels, and brain atrophy. To further clarify the relationship between these endpoints, we treated the rTg4510 mice with either doxycycline to reduce mutant tau expression or an O-GlcNAcase inhibitor Thiamet G, which has been shown to ameliorate tau pathology in animal models. We found that both doxycycline and Thiamet G treatments starting at 2 months of age prevented the progression of hyperactivity, slowed brain atrophy, and reduced brain hyperphosphorylated tau. In contrast, initiating doxycycline treatment at 4 months reduced neither brain hyperphosphorylated tau nor hyperactivity, further confirming the relationship between these measures. Collectively, our results demonstrate a unique behavioral phenotype in the rTg4510 mouse model of tauopathy that strongly correlates with disease progression, and that early interventions which reduce tau pathology ameliorate the progression of the locomotor dysfunction. These findings suggest that better understanding the relationship between locomotor deficits and tau pathology in the rTg4510 model may improve our understanding of the mechanisms underlying behavioral disturbances in patients with tauopathies.</p></div

Discovery and Optimization of a Series of Pyrimidine-Based Phosphodiesterase 10A (PDE10A) Inhibitors through Fragment Screening, Structure-Based Design, and Parallel Synthesis

Screening of a fragment library for PDE10A inhibitors identified a low molecular weight pyrimidine hit with PDE10A <i>K</i>_i of 8700 nM and LE of 0.59. Initial optimization by catalog followed by iterative parallel synthesis guided by X-ray cocrystal structures resulted in rapid potency improvements with minimal loss of ligand efficiency. Compound <b>15h</b>, with PDE10A <i>K</i>_i of 8.2 pM, LE of 0.49, and >5000-fold selectivity over other PDEs, fully attenuates MK-801-induced hyperlocomotor activity after ip dosing

LMA in 5-month-old rTg4510 mice correlates with brain atrophy and NFT pathology.

<p>(A), Negative correlation between LMA and forebrain weight (r = -0.52, p<0.01, n = 27). (B), Positive correlation between LMA and NFT pathology in entorhinal cortex (r = 0.58, p<0.01, n = 27). (C–D), Representative images of NFT pathology in entorhinal cortex of rTg4510 mice with LMA distance > 2000 cm (C) and < 2000 cm (D). Insets, higher magnification images of NFT bearing neurons in entorhinal cortex (Scale bar, 800 μm; 20 μm in inset).</p

Effects of OGA inhibitor Thiamet G treatment on rTg4510 disease progression.

<p>(A) LMA was measured at the baseline (2 months of age) and monthly after the onset of treatment (n = 20–21/group; **p < 0.01, ***p < 0.001, Two-way ANOVA followed by Bonferroni's test compared to baseline groups at 2 months of age). (B–D) Thiamet G significantly reduced brain hyperphosphorylated tau levels detected by PHF6 AlphaLISA (B), prevented brain atrophy (C), and reduced CSF total tau levels (D) in rTg4510 mice (n = 21/group; *p < 0.05, **p < 0.01, ***p < 0.001, one-way ANOVA followed by Dunnett’s test compared to vehicle group).</p

Effects of doxycycline treatment on rTg4510 disease progression.

<p>(A) Brain hyperphosphorylated tau levels were revealed by PHF6 AlphaLISA in rTg4510 mice (n = 22–24 mice/group; ***p < 0.001, t-test). (B) Effects of doxycycline treatment on forebrain weight was measured in both WT and rTg4510 mice (n = 8 WT and 22–24 rTg4510 mice per group, *p < 0.05, **p < 0.01, t-test).</p

Effects of doxycycline treatment on progression of hyperactivity in rTg4510 mice are age-dependent.

<p>WT and rTg4510 mice were dosed with either normal mouse chow (Veh) or normal mouse chow containing doxycycline at 1g/kg (Dox) for 4 months starting at either 2 months of age (A) or 4 months of age (B). LMA was tested monthly after the onset of treatment to monitor the progression of hyperactivity. (n = 8 WT and 22–24 rTg4510 mice per group; ***p<0.001, Two-way ANOVA followed by Bonferroni's test compared to baseline groups).</p