Biology subjects

Buchler, I. P.

Publications and source records attributed to Buchler, I. P..

4 recordsLinked to original sources

bioRxiv2025

Development of a Novel Benzodiazepine to Delineate Peripheral GABA-A Signaling Mechanisms in Visceral Pain Syndromes

Background and AimsVisceral pain is a cardinal symptom of many disorders affecting the gut. Modulators of gamma-aminobutyric acid (GABA) such as benzodiazepines may attenuate colonic pain but the specific contribution of peripheral GABAA receptors remains unclear as these agents have prominent central effects. MethodsUsing medicinal chemistry optimization of the benzodiazepine scaffold, we developed a novel and potent benzodiazepine-based positive allosteric modulator (PAM) of GABAA receptors, Li633, with no significant central nervous system (CNS) penetration. ResultsThe locomotor activity of rats placed in an open field was unchanged with Li633 at doses up to 30 mg/kg, confirming its lack of a CNS effect. LI-633 produced robust potentiation of GABA-induced inward current, with EC50 values ranging from 8 nM (5{beta}2{gamma}2) to 128 nM (3{beta}2{gamma}2). In vitro electrophysiological studies confirmed its ability to reduce excitability of human dorsal root ganglion (DRG) neurons. LI-633 potentiated muscimol-induced GABAergic currents in rat DRG neurons in a dose-dependent manner, with an EC50 of 70.4 nM. In vivo, LI-633 significantly attenuated visceral hypersensitivity and pain behavior in a rat model of irritable bowel syndrome (IBS) and functional dyspepsia (FD). In the IBS model, administration of the drug also resulted in decreased excitability of colon-specific DRG neurons and significantly reduced the colonic afferent response to balloon distention as measured by recordings of neural activity in dorsal ganglia rootlets. ConclusionsThese findings highlight the potential of targeting peripheral GABAA receptors for pain management in IBS and other disorders associated with visceral hypersensitivity.

neuroscience↗

bioRxiv2022

Clemastine fumarate enhances myelination and promotes functional recovery in a syndromic ASD mouse model of Pitt-Hopkins Syndrome

Pitt-Hopkins syndrome (PTHS) is an autism spectrum disorder (ASD) caused by autosomal dominant mutations in the Transcription Factor 4 gene (TCF4). One pathobiological process caused by Tcf4 mutation is a cell autonomous reduction in oligodendrocytes (OLs) and myelination. In this study, we show that clemastine is effective at restoring myelination defects in a PTHS mouse model. In vitro, clemastine treatment reduced excess oligodendrocyte precursor cells (OPCs) and normalized OL density. In vivo, two-week intraperitoneal administration of clemastine also normalized OPC and OL density in the cortex of Tcf4 mutant mice and appeared to increase the number of axons undergoing myelination, as EM imaging of the corpus callosum showed a significant increase in uncompacted myelin. Importantly, this treatment paradigm resulted in functional rescue by improving electrophysiology and behavior. Together, these results provide preclinical evidence that remyelination therapies may be beneficial in PTHS and potentially other neurodevelopmental disorders characterized by demyelination.

neuroscience↗

bioRxiv2019

Development of a PC12 cell-based assay for in vitro screening of catechol-O-methyltransferase inhibitors

The male rat adrenal pheochromocytoma cell-originated PC12 cell line can synthesize and release catecholamine neurotransmitters, and it has been widely used as a model system in cell biology and toxicology research. Catechol-O-methyltransferase (COMT) is involved in the inactivation of the catecholamine neurotransmitters, and it is particularly important for theregulation of dopamine. In this study, we explored the feasibility of using PC12 cells as an in vitro drug screening platform to compare the activity of multiple COMT inhibitors. Incubation of PC12 cells with tolcapone, a highly potent and selective COMT inhibitor, increased the concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) while reducing the metabolites 3-methoxytyramine (3-MT) and homovanillic acid (HVA) in the cell culture medium. LIBD-3, a novel, non-nitrocatechol COMT inhibitor produced similar effects compared to tolcapone. LIBD-4, a less potent inhibitor, exhibited the expected right-shift in functional inhibition in the assay. These results match the known in vivo effects of COMT inhibition in rodents. Together, these data support the continued use of PC12 cells as an in vitro screen that bridges cell-free enzyme assays and more costly in vivo assays.

neuroscience↗

bioRxiv2019

Novel, non-nitrocatechol COMT inhibitors modulate dopamine neurotransmission in the frontal cortex and improve cognitive flexibility

Cognitive impairment is a primary feature of many neuropsychiatric disorders and there is a need for new therapeutic options. Catechol-O-methyltransferase (COMT) inhibitors modulate cortical dopaminergic function and have been proposed as potential cognitive enhancers. Unfortunately, currently available COMT inhibitors are not good candidates due to either poor blood-brain barrier penetration or severe toxicity. To address the need for safe, brain-penetrant COMT inhibitors, we tested multiple novel COMT inhibitors in a set of preclinical in vivo efficacy assays to determine their viability as potential clinical candidates. We found that multiple COMT inhibitors, exemplified by LIBD-1 and LIBD-3, significantly modulated dopaminergic function measured as decreases in homovanillic acid (HVA) and increases in 3,4-Dihydroxyphenylacetic acid (DOPAC), two dopamine metabolites, in cerebrospinal fluid (CSF) and the frontal cortex. Additionally, we found the LIBD-1 significantly improved cognitive flexibility in a rat attentional set-shifting assay (ASST), an effect previously seen with the COMT inhibitor tolcapone. These results demonstrate that LIBD-1 is a novel COMT inhibitor with promising in vivo activity and the potential to serve as a new therapy for cognitive impairment.

neuroscience↗