Amyloid-β (1-42) (Aβ42) is a neurotoxic 42-amino acid protein fragment found in amyloid plaques in postmortem cerebral cortex from patients with Alzheimer's disease.1,2,3Aggregation of Aβ42 results in the formation of neurotoxic fibrils or globular oligomers.1Aβ42 accumulates in the brain of many transgenic mouse models of Alzheimer's disease and, in many models, the onset of amyloid deposition positively correlates with deficits in spatial learning and memory.4 1.Wolfe, M.S.Therapeutic strategies for Alzheimer's diseaseNat. Rev. Drug Discov.1(11)859-866(2002) 2.Iwatsubo, T., Odaka, A., Suzuki, N., et al.Visualization of Aβ42(43) and Aβ40 in senile plaques with end-specific Aβ monoclonals: Evidence that an initially deposited species is Aβ42(43)Neuron13(1)45-53(1994) 3.Hardy, J.A., and Higgins, G.A.Alzheimer's disease: The amyloid cascade hypothesisScience256(5054)184-185(1992) 4.Jankowsky, J.L., and Zheng, H.Practical considerations for choosing a mouse model of Alzheimer's diseaseMol. Neurodegener.12(1)89(2017)
Amyloid-β (25-35) (Aβ (25-35)) is an 11-residue fragment of the Aβ protein that retains the physical and biological characteristics of the full length peptide. It forms fibrils that react to thioflavin T and Congo red and are organized in a cross-β arrangement of β-strands similar to Aβ (1-40) and Aβ (1-42) fibrils. Aggregated Aβ (25-35) decreases the viability of rat adrenal PC12 cells. It also decreases the viability of primary rat cortical neurons at concentrations ranging from 1 nM to 30 μM. In vivo, intracerebral injection of Aβ (25-35) (20 nmol) in rats induces lesions of neuronal and tissue loss. Aggregated Aβ (25-35) administered intracerebroventricularly to rats induces learning and memory impairments in the Y-maze, novel object recognition, and contextual fear conditioning tests.
Uridine-3'-monophosphate is a nucleoside used in the biochemical synthesis of ribothymidine-3'-phosphate. It has been used as a bioavailable source of uridine in research studies designed to enhance learning and memory.
PF-04449613 is a phosphodiesterase 9A (PDE9A) inhibitor (IC50= 22 nM).1It is selective for PDE9A over PDE1C (IC50= >1,000 nM), as well as over a variety of other PDEs, inhibiting PDE2-8, -10, and -11 activity by less than 30% in a panel of enzymes, ion channels, and transporters at 1 μM but does inhibit the human dopamine transporter (DAT; Ki= 293 nM). PF-04449613 (0.1-100 mg kg, s.c.) increases cerebrospinal fluid (CSF) levels of cyclic GMP (cGMP) in rats. Subcutaneous administration of PF-04449613 (10 mg kg) increases the rate of dendritic spine formation and elimination in mouse primary motor cortex pyramidal neuronsin vivo.2It increases the average running speed of mice in an accelerating rotarod task, indicating improved motor learning, at the same dose. 1.Claffey, M.M., Helal, C.J., Verhoest, P.R., et al.Application of structure-based drug design and parallel chemistry to identify selective, brain penetrant, in vivo active phosphodiesterase 9A inhibitorsJ. Med. Chem.55(21)9055-9068(2012) 2.Lai, B., Li, M., Hu, A., et al.The phosphodiesterase 9 inhibitor PF-04449613 promotes dendritic spine formation and performance improvement after motor learningDev. Neurobiol.78(9)859-872(2018)