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Principal Investigator: Swati S More
Organization: UNIVERSITY OF MINNESOTA
Fiscal Year: 2024
Award: $571,020
Funding agency: National Institute on Drug Abuse
ABSTRACT
Angiotensin-converting enzyme (ACE) plays a well-established role in regulating blood pressure in the periphery.
ACE is also expressed in the brain, with high levels in the striatonigral pathway formed by medium spiny
projection neurons that express the Drd1 dopamine receptor (D1-MSNs). We have found that ACE degrades an
unconventional enkephalin heptapeptide, Met-enkephalin-Arg-Phe (MERF), in the nucleus accumbens of mice.
Captopril, a prototypical ACE inhibitor used to manage hypertension, enhances extracellular levels of MERF in
the nucleus accumbens. The resulting enhancement of mu opioid receptor activation by MERF causes a cell
type-specific long-term depression of glutamate release onto D1-MSNs. This mechanism of action has great
therapeutic potential, as our preliminary data indicate the decrease in excitatory drive to D1-MSNs can diminish
the rewarding effects of fentanyl. However, neither captopril nor modern ACE inhibitors routinely used in the
clinic have been optimized to regulate endogenous opioid signaling. For example, MERF may be specifically
degraded by the catalytic N-domain of ACE, whereas most clinically-approved ACE inhibitors have greater
selectivity for the catalytic C-domain of ACE. There is thus a need to identify optimal chemical entities that inhibit
MERF degradation by ACE in brain tissue. The goal of this project is to identify new compounds that inhibit ACE
and regulate endogenous opioid signaling in the nucleus accumbens. In AIM 1, we will screen a selected
library of ~2,000 small molecules for domain-selective inhibition of recombinant ACE protein. This will
include candidate molecules drawn from rationally selected libraries using a pharmacophore-based approach,
as well as molecules with diverse chemical scaffolds identified through a virtual screen. In AIM 2, we will
validate the domain selectivity and efficacy of lead compounds on MERF degradation in nucleus
accumbens tissue. This will include direct measurement of extracellular MERF using liquid chromatography-
tandem mass spectrometry, as well as whole-cell voltage-clamp recordings to measure functional effects on
excitatory input to D1-MSNs. These experiments will include knockout mice to test the necessity of each catalytic
domain of ACE in MERF degradation, as well as the involvement of mu opioid receptor signaling in physiological
changes. In AIM 3, we will evaluate the ability of lead compounds to attenuate fentanyl reward and
reinforcement. This will include measurement of fentanyl-conditioned place preference and intravenous self-
administration of fentanyl. At the conclusion of these experiments, we expect to identify chemical motifs that may
serve as leads to generate novel ACE inhibitors that block MERF degradation in the nucleus accumbens. We
may observe a double-dissociation between catalytic domains of ACE that degrade angiotensin (C-domain) and
MERF (N-domain), raising the exciting possibility of selectively manipulating endogenous opioid signaling in the
brain while avoiding cardiovascular side-effects in the periphery. Our results may also reveal that central ACE
inhibition can boost endogenous opioid signaling for clinical benefit, while mitigating risk of abuse/addiction.
Terms: <5-Methionine Enkephalin><ACE Inhibitors><ACE2><Actiq><Acute><Affect><Aminopeptidase><Angiotensin Converting Enzyme><Angiotensin I-Converting Enzyme><Angiotensin I-Converting Enzyme Inhibitors><Angiotensin-Converting Enzyme Antagonists><Angiotensin-Converting Enzyme Inhibitors><Angiotensins><Assay><Attenuated><Axon Terminals><BP homeostasis><BP regulation><Behavior><Behavior assessment><Bioassay><Biochemical Reaction><Biological Assay><Blood - brain barrier anatomy><Blood-Brain Barrier><Body Tissues><Brain><Brain Nervous System><CD143 Antigens><Captopril><Carboxycathepsin><Cardiovascular><Cardiovascular Body System><Cardiovascular Organ System><Cardiovascular Physiology><Cardiovascular system><Catalytic Core><Catalytic Domain><Catalytic Region><Catalytic Site><Catalytic Subunit><Cell Body><Cell Communication and Signaling><Cell Signaling><Cells><Chemicals><Clinic><Clinical><Data><Dependence><Dipeptidyl Peptidase A><Dissociation><Dopamine Receptor><Dose><Drug Exposure><Drug Kinetics><Duragesic><Encephalon><Enkephalins><Enzymatic Reaction><Enzyme Inhibition><Excretory function><FDA approved><Fentanest><Fentanyl><Fentyl><Food><Genetic><Genetic Alteration><Genetic Change><Genetic defect><Glutamates><Goals><Heart Vascular><Hemato-Encephalic Barrier><High Throughput Assay><Hydrolysis><Hypertension><Impairment><In Vitro><Intermediary Metabolism><Intracellular Communication and Signaling><Intravenous><KO mice><Kininase A><Kininase II><Kininase II Antagonists><Kininase II Inhibitors><Knock-out Mice><Knockout Mice><L-Glutamate><Lead><Libraries><Liquid Chromatography><Long-Term Depression><Long-Term Synaptic Depression><Measurement><Measures><Met(5)-Enkephalin><Met-Enkephalin><Metabolic Processes><Metabolism><Methionine Enkephalin><Mice><Mice Mammals><Modernization><Molecular Fingerprinting><Molecular Profiling><Motor><Murine><Mus><Mutation><N Domain><Nerve Cells><Nerve Unit><Neural Cell><Neurocyte><Neurons><Nucleus Accumbens><Null Mouse><Opiates><Opioid><Pathway interactions><Pb element><Peptidyl-Dipeptidase A><Peripheral><Pharmacokinetics><Phentanyl><Physiologic><Physiological><Play><Presynaptic Nerve Endings><Presynaptic Terminals><Property><Proteins><Psychological reinforcement><Receptor Activation><Receptor Signaling><Recombinants><Reinforcement><Research><Rewards><Role><Self Administered><Self Administration><Signal Transduction><Signal Transduction Systems><Signaling><Slice><Synaptic Boutons><Synaptic Terminals><Testing><Therapeutic><Time><Tissues><Toxic effect><Toxicities><Transgenic Mice><Validation><Vascular Hypertensive Disease><Vascular Hypertensive Disorder><absorption><addiction><addictive disorder><angiotensin converting enzyme 2><angiotensin converting enzyme II><attenuate><attenuates><behavioral assessment><biological signal transduction><blood pressure homeostasis><blood pressure regulation><bloodbrain barrier><brain tissue><cardiovascular effects><cardiovascular function><cell type><chemical library><circulatory system><conditioned place preference><drug development><endogenous opiate><endogenous opioids><excretion><experiment><experimental research><experimental study><experiments><extracellular><fentanyl self-administration><genome mutation><glutamatergic><heavy metal Pb><heavy metal lead><high blood pressure><high throughput screening><hyperpiesia><hyperpiesis><hypertension control><hypertension management><hypertensive disease><hypertensive disorder><improved><in vivo><inhibitor><interest><longterm depression><longterm synaptic depression><molecular profile><molecular signature><mu opioid receptors><neuronal><new drug treatments><new drugs><new pharmacological therapeutic><new therapeutics><new therapy><next generation therapeutics><novel><novel drug treatments><novel drugs><novel pharmaco-therapeutic><novel pharmacological therapeutic><novel therapeutics><novel therapy><opiate use disorder><opioid growth factor><opioid use disorder><patch clamp><pathway><pharmacologic><pharmacophore><place conditioning><presynaptic><prevent><preventing><regulate BP><regulate blood pressure><response><risk mitigation><scaffold><scaffolding><side effect><small molecule><small molecule libraries><social role><tandem mass spectrometry><therapeutic target><validations><virtual><voltage clamp><μ opioid receptors><μ-OR><μOR>