Sarah K. Leonard

Bio: Sarah K. Leonard is an academic researcher from Princeton University. The author has contributed to research in topics: Agonist & Liver X receptor. The author has an hindex of 3, co-authored 3 publications receiving 490 citations.

Pharmacology of neuropeptide S in mice: therapeutic relevance to anxiety disorders.

Abstract: Neuropeptide S (NPS) and its receptor (NPSR) comprise a recently deorphaned G protein-coupled receptor system. Recent reports implicate NPS in the mediation of anxiolytic-like activity in rodents. To extend the characterization of NPS, the present studies examined the in vitro pharmacology of mouse NPSR and the in vivo pharmacology of NPS in three preclinical mouse models predictive of anxiolytic action: the four-plate test (FPT), elevated zero maze (EZM), and stress-induced hyperthermia (SIH). The ability of NPS to produce antidepressant-like effects in the tail suspension test (TST) was also investigated. In vitro, mouse NPS1–20 (mNPS1–20) and the C-terminal glutamine-truncated mouse NPS1–19 bound mNPSR with high affinity (K i = 0.203 ± 0.060, 0.635 ± 0.141 nM, respectively) and potently activated intracellular calcium release (EC50 = 3.73 ± 1.08, 4.10 ± 1.25 nM). NPS produced effects in vivo consistent with anxiolytic-like activity. In FPT, NPS increased punished crossings (minimal effective dose [MED]: mNPS1–20 = 0.2 μg, mNPS1–19 = 0.02 μg), similar to the reference anxiolytic, alprazolam (MED 0.5 μg). NPS increased the percentage of time spent in the open quadrants of EZM (MED: mNPS1–20 = 0.1 μg, mNPS1–19 = 1.0 μg), like the reference anxiolytic, chlordiazepoxide (MED 56 μg). In SIH, NPS attenuated stress-induced increases in body temperature similar to alprazolam but with a large potency difference between the NPS peptides (MED: mNPS1–20 = 2.0 μg, mNPS1–19 = 0.0002 μg) and mNPS1–20 increased baseline temperature. Unlike fluoxetine, NPS did not effect immobility time in TST, indicating a lack of antidepressant-like activity. These data provide an important confirmation and expansion of the anxiolytic-like effects of NPS and implicate the NPS system as a novel target for anxiolytic drug discovery.

Apolipoprotein E and Alzheimer disease: risk, mechanisms and therapy

Abstract: Apolipoprotein E (Apo-E) is a major cholesterol carrier that supports lipid transport and injury repair in the brain. APOE polymorphic alleles are the main genetic determinants of Alzheimer disease (AD) risk: individuals carrying the e4 allele are at increased risk of AD compared with those carrying the more common e3 allele, whereas the e2 allele decreases risk. Presence of the APOE e4 allele is also associated with increased risk of cerebral amyloid angiopathy and age-related cognitive decline during normal ageing. Apo-E-lipoproteins bind to several cell-surface receptors to deliver lipids, and also to hydrophobic amyloid-β (Aβ) peptide, which is thought to initiate toxic events that lead to synaptic dysfunction and neurodegeneration in AD. Apo-E isoforms differentially regulate Aβ aggregation and clearance in the brain, and have distinct functions in regulating brain lipid transport, glucose metabolism, neuronal signalling, neuroinflammation, and mitochondrial function. In this Review, we describe current knowledge on Apo-E in the CNS, with a particular emphasis on the clinical and pathological features associated with carriers of different Apo-E isoforms. We also discuss Aβ-dependent and Aβ-independent mechanisms that link Apo-E4 status with AD risk, and consider how to design effective strategies for AD therapy by targeting Apo-E.

Apolipoprotein E and its receptors in Alzheimer's disease: pathways, pathogenesis and therapy

Abstract: The vast majority of Alzheimer's disease (AD) cases are late-onset and their development is probably influenced by both genetic and environmental risk factors. A strong genetic risk factor for late-onset AD is the presence of the e4 allele of the apolipoprotein E (APOE) gene, which encodes a protein with crucial roles in cholesterol metabolism. There is mounting evidence that APOE4 contributes to AD pathogenesis by modulating the metabolism and aggregation of amyloid-β peptide and by directly regulating brain lipid metabolism and synaptic functions through APOE receptors. Emerging knowledge of the contribution of APOE to the pathophysiology of AD presents new opportunities for AD therapy.

Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease

Abstract: Sleep and circadian rhythm disruption are frequently observed in patients with psychiatric disorders and neurodegenerative disease. The abnormal sleep that is experienced by these patients is largely assumed to be the product of medication or some other influence that is not well defined. However, normal brain function and the generation of sleep are linked by common neurotransmitter systems and regulatory pathways. Disruption of sleep alters sleep-wake timing, destabilizes physiology and promotes a range of pathologies (from cognitive to metabolic defects) that are rarely considered to be associated with abnormal sleep. We propose that brain disorders and abnormal sleep have a common mechanistic origin and that many co-morbid pathologies that are found in brain disease arise from a destabilization of sleep mechanisms. The stabilization of sleep may be a means by which to reduce the symptoms of--and permit early intervention of--psychiatric and neurodegenerative disease.