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Chronic intake of high-energy diets alters the physiological response to food and favors overconsumption. Feeding, especially of palatable food, leads to dopamine (DA) release in the Nucleus Accumbens (NAc, in the ventral striatum), prefrontal cortex (PFC) and dorsal striatum. The mesocortical (ventral tegmental area (VTA) projecting to NAc) DA system has been implicated in motivational drive and food seeking while the nigrostriatal DA (projections from the substantia nigra (SN) to the dorsal striatum) pathway plays a role in both food anticipatory behavior and reinforcement. In humans, hypersensitivity to food-associated reward may predispose to weight gain, however as obesity progresses deficit in reward signaling emerges. Individuals with obesity have reduced DRD2 availability in prefrontal brain regions compared to lean counterparts. 

Jiyoung S. Kim, Kevin C. Williams, Rebecca A. Kirkland, Ruth Schade, ... Claire B. de La Serre

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Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

Okka Scholz, Elena Huß, Silke Otter, Diran Herebian, ... Eckhard Lammert

Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

Objective

Dextromethorphan (DXM) is a commonly used antitussive medication with positive effects in people with type 2 diabetes mellitus, since it increases glucose tolerance and protects pancreatic islets from cell death. However, its use as an antidiabetic medication is limited due to its central nervous side effects and potential use as a recreational drug. Therefore, we recently modified DXM chemically to reduce its blood–brain barrier (BBB) penetration and central side effects. However, our best compound interacted with the cardiac potassium channel hERG (human ether-à-go-go-related gene product) and the μ-opioid receptor (MOR). Thus, the goal of this study was to reduce the interaction of our compound with these targets, while maintaining its beneficial properties.

Methods

Receptor and channel binding assays were conducted to evaluate the drug safety of our DXM derivative. Pancreatic islets were used to investigate the effect of the compound on insulin secretion and islet cell survival. Via liquor collection from the brain and a behavioral assay, we analyzed the BBB permeability. By performing intraperitoneal and oral glucose tolerance tests as well as pharmacokinetic analyses, the antidiabetic potential and elimination half-life were investigated, respectively. To analyze the islet cell-protective effect, we used fluorescence microscopy as well as flow cytometric analyses.

Results

Here, we report the design and synthesis of an optimized, orally available BBB-impermeable DXM derivative with lesser binding to hERG and MOR than previous ones. We also show that the new compound substantially enhances glucose-stimulated insulin secretion (GSIS) from mouse and human islets and glucose tolerance in mice as well as protects pancreatic islets from cell death induced by reactive oxygen species and that it amplifies the effects of tirzepatide on GSIS and islet cell viability.

Conclusions

We succeeded to design and synthesize a novel morphinan derivative that is BBB-impermeable, glucose-lowering and islet cell-protective and has good drug safety despite its morphinan and imidazole structures.

Articles in Press

Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

Okka Scholz, Elena Huß, Silke Otter, Diran Herebian, ... Eckhard Lammert

Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

Objective

Dextromethorphan (DXM) is a commonly used antitussive medication with positive effects in people with type 2 diabetes mellitus, since it increases glucose tolerance and protects pancreatic islets from cell death. However, its use as an antidiabetic medication is limited due to its central nervous side effects and potential use as a recreational drug. Therefore, we recently modified DXM chemically to reduce its blood–brain barrier (BBB) penetration and central side effects. However, our best compound interacted with the cardiac potassium channel hERG (human ether-à-go-go-related gene product) and the μ-opioid receptor (MOR). Thus, the goal of this study was to reduce the interaction of our compound with these targets, while maintaining its beneficial properties.

Methods

Receptor and channel binding assays were conducted to evaluate the drug safety of our DXM derivative. Pancreatic islets were used to investigate the effect of the compound on insulin secretion and islet cell survival. Via liquor collection from the brain and a behavioral assay, we analyzed the BBB permeability. By performing intraperitoneal and oral glucose tolerance tests as well as pharmacokinetic analyses, the antidiabetic potential and elimination half-life were investigated, respectively. To analyze the islet cell-protective effect, we used fluorescence microscopy as well as flow cytometric analyses.

Results

Here, we report the design and synthesis of an optimized, orally available BBB-impermeable DXM derivative with lesser binding to hERG and MOR than previous ones. We also show that the new compound substantially enhances glucose-stimulated insulin secretion (GSIS) from mouse and human islets and glucose tolerance in mice as well as protects pancreatic islets from cell death induced by reactive oxygen species and that it amplifies the effects of tirzepatide on GSIS and islet cell viability.

Conclusions

We succeeded to design and synthesize a novel morphinan derivative that is BBB-impermeable, glucose-lowering and islet cell-protective and has good drug safety despite its morphinan and imidazole structures.

2021 impact factor: 8.568

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