bluuebunny/crossref_metadata_2025_split huggingface dataset:
The BAI Sub‐Family of Adhesion GPCRs: New Insights into Regulation and Signaling
Authors: Purcell Ryan H. , Hall Randy A. 
Published: November 2023

The three members of the BAI sub‐family of adhesion GPCRs (BAI1‐3/ADGRB1‐3) have been implicated in dendritic spine morphogenesis, macrophagic and microglial phagocytosis, and skeletal myoblast fusion, suggesting an important role for these receptors in directing cytoskeletal dynamics. However, the activation mechanisms, downstream signaling pathways, and regulation of these orphan receptors remain poorly understood. Adhesion receptors can be autoproteolytically cleaved by their conserved N‐terminal GAIN domains into non‐covalently attached N‐terminal and seven‐transmembrane protomers. Cleavage and removal of the NT is thought to be a critical step in receptor activation by relieving an inhibitory constraint imposed by the NT on the 7TM. Several other aGPCRs have recently been shown to then be activated by their post‐cleavage stalks in a manner reminiscent of the protease‐activated receptor (PAR) family. Surprisingly, we found that BAI1/ADGRB1 (B1) exhibits no stalk‐dependent activity because a truncated receptor lacking the entire N‐terminus (including the stalk) signals at least as strongly as a truncated version of B1 that mimics the GAIN‐cleaved form of the receptor and thus still possesses the N‐terminal stalk. In addition, ongoing studies have revealed B1 and B2 interactions with several C‐terminus‐binding proteins, which are involved in both the regulation of G protein‐dependent signaling by B1 as well as the mediation of G protein‐independent aspects of receptor signaling. These studies have also led to insights into cross‐talk between heterotrimeric G protein and small GTPase signaling downstream of B1, which may significantly improve our understanding of the diverse functions of the BAI receptors.Support or Funding InformationSupported by NINDS R21NS094136
Modulation of the Facilitatory Effect of Dopamine at the Neuromuscular Junction by Adenosinergic and Purinergic Receptors
Authors: AlQot Hadir E. , Elnozahi Neveen A. , Mohy El‐Din Mahmoud M. , Bistawroos Azza E. , Abou Zeit‐Har Mohammed S. 
Published: November 2023

The objective of this study is to investigate the potential interactions between dopamine and the endogenous neuromodulators; adenosine triphosphate (ATP) and adenosine, at the neuromuscular junction.We have shown previously that dopamine, via the activation of dopamine D1‐like receptors, can enhance neuromuscular transmission. ATP and adenosine play a pivotal role in modulation of dopamine function in the central nervous system via purinergic and adenosinergic receptors, respectively. As such, we probed the potential existence of similar interactions in the periphery.We employed in‐vitro experiments using the isolated rat phrenic hemi‐diaphragm preparation which was stimulated indirectly through the stimulation of the phrenic nerve at low frequencies. The parameter used to assess neuromuscular transmission was the percentage change in the amplitude of nerve‐evoked muscle twitches relative to control.In presence of the selective adenosine A2A receptor antagonist (8‐(3‐Chlorostyryl) caffeine; CSC), the dopamine‐mediated facilitation of indirect muscle twitches was significantly reduced. This implies a positive interaction between dopamine and adenosine, via adenosine A2A receptors at the motor end‐plate.The enhancement of neuromuscular transmission by dopamine was, unexpectedly, depressed by 1,3‐Dipropyl‐8‐cyclopentylxanthine (DPCPX), a selective adenosine A1 receptor antagonist. Unlike what would be expected from an inhibitory receptor, the adenosine A1 receptor appears to contribute a positive effect towards the facilitation mediated by dopamine at the neuromuscular junction.On the other hand, a negative collaboration was established between dopamine and ATP as evidenced by the enhanced dopamine induced‐potentiation of indirect muscle twitches subsequent to the addition of suramin (purinergic antagonist). Hence suggesting that endogenous ATP, via purinergic P2 receptors, exerts an antagonistic influence on the dopamine effects.In conclusion, these results provide new insights into how dopamine effects can be modulated by co‐transmitters at the neuromuscular junction. Clinically this study highlights potential therapeutic targets for the treatment of disorders characterized by neuromuscular deficits based on the conceived interactions at the motor end‐plate.
Cannabinoid Receptor 2 stimulation enhances bactericidal activity of human neutrophils
Authors: Wiley Mark B , Nizet Victor , Insel Paul A , Corriden Ross 
Published: November 2023

Polymorphonuclear neutrophils (PMNs), the most abundant white blood cell in circulation, play an essential role in host defense against pathogenic bacteria. Central to this activity is the ability of PMNs to sense and rapidly respond to extracellular stimuli. Although GPCRs are the largest membrane receptor family in the human genome, only a limited number of GPCRs have been evaluated as regulators of PMN function. Here, we investigate the role of Cannabinoid Receptor 2 (CB2), typically expressed by immune cells in the periphery, in the regulation of PMN function. We find that activation of neutrophil CB2 receptors using the cannabinoid receptor agonist CB‐13 enhances killing by PMNs of methicillin‐resistant Staphylococcus aureus (MRSA) in an in vitro assay of bactericidal activity. However, CB‐13 does not affect PMN migration in a chemoattractant gradient (measured using a transwell assay), production of reactive oxygen species (ROS; determined using the fluorescent ROS scavenger DCF‐AM) or neutrophil extracellular trap (NET) formation (assayed via fluorescence‐based DNA quantification). Experiments using fluorescently‐labeled, pH‐sensitive S. aureus bioparticles suggest that enhancement of PMN killing by CB‐13 results from an increase in phagocytosis. Together these results lead us to conclude that CB2 activation may “prime” PMNs to detect and kill bacteria and thus, that CB2 may represent a novel therapeutic target for pharmacological modulation of neutrophil antimicrobial activity. As such, CB2 appears to be a previously unappreciated PMN‐expressed GPCR that enhances innate immunity and microbial surveillance.Support or Funding InformationResearch was supported by NIH grants HD071600, AI057153 and AI052453.
Experimentally‐ induced chronic kidney disease in rats, and the influence of curcumin thereon
Authors: Ali Badreldin H. , Al‐Salam Suhail , Al Za'abi Mohamed H. , Al Suleminai Yousif , Nemmar Abderrahim 
Published: November 2023

Curcumin (a natural phenolic yellow pigment isolated from turmeric) has several pharmacological properties that include antioxidant, anti‐inflammatory and antiapoptotic activities. Here, we investigated some effects of three graded oral doses of curcumin (37.5, 75 and 150 mg/kg) for 35 days on kidney structure and function in rats with chronic kidney disease (CKD) induced by adenine (0.25% w/w in feed for 35 days), which is known to involve inflammation, oxidative stress and apoptosis. Using several indices in plasma, urine and kidney homogenates, adenine was found to lower creatinine clearance and increase plasma concentrations of creatinine, urea, neutrophil gelatinase‐associated lipocalin and N‐Acetyl‐beta‐D‐glucosaminidase activity. Furthermore, it raised plasma concentrations of the uremic toxin indoxyl sulfate, some inflammatory cytokines and urinary albumin concentration. Renal morphology was severely damaged and histopathological markers of inflammation and fibrosis were especially increased. In renal homogenates, antioxidant indices, including superoxide dismutase and catalase activities, total antioxidant capacity and reduced glutathione were all adversely affected. Most of these adenine ‐ induced actions were moderately and dose ‐dependently mitigated by curcumin, especially at the highest dose. Curcumin did not cause any overt adverse effect on the treated rats. The results suggest that different doses of curcumin produce variable salutary effects against adenine‐induced CKD in rats, and that, pending further pharmacological and toxicological studies, its usability as a possible ameliorative agent in human CKD should be considered.Support or Funding InformationThis work was funded by the Research Council, Oman (RC/MED/PHAR/13/01)
Development of a New Practical Approach to Perform Single‐Mouse Pharmacokinetic Study
Authors: Jilek Joseph Lionel , Tian Ye , Yu Ai‐Ming 
Published: November 2023

Single‐animal pharmacokinetic (PK) study has largely been limited to rats and larger animals. However, given the increasingly large body of research using transgenic and immunocompromised mouse models, and an economical advantage, a single‐mouse PK model is highly warranted. Given a high sensitivity of LC‐MS/MS in quantification of drugs and metabolites, we have established a practical and standard protocol for series blood samplings from single mouse via tail vein at multiple time points towards a complete PK profile. CD‐1 Mice were given a cocktail of cytochrome P450 (CYP) isoform‐specific probe substrates per os, consisting of midazolam (MDZ), dextromethorphan (DXM), phenacetin (PHE), diclofenac (DIC), and chlorzoxazone (CHL). CYP inhibitors, ketoconazole (KTZ) and α‐napthoflavone (α‐NF), were administered by intraperitoneal injection 1 hour prior to dosing; CYP inducers, pregnenolone 16α‐carbonitrile (PCN) and 3‐methyl cholanthrene (3‐Me), were administered 3 days prior to dosing. Blood (10–20 μl per time point) was collected by tail vein puncture at 7–10 different time points over 3 hours and plasma was prepared for LC‐MS/MS quantification of MDZ, DXM, PHE, DIC, and CHL, and CYP isoform‐specific metabolites 1′‐OH‐MDZ, DXO, ACE, 4′‐OH‐DIC, and 6′‐OH‐CHL, respectively.A small volume (3 μl) of plasma at each time point was found to be sufficient to produce a complete PK profile in a single mouse. Visual inspection and non‐compartmental PK modeling showed that formation of 1′‐OH‐MDZ and ACE was sharply and significantly reduced in mice pre‐treated with KTZ and α‐NF, respectively, suggesting that these compounds preferentially inhibit MDZ 1′‐hydroxylase and PHE O‐deethylase, respectively, in mice in vivo. Additionally, plasma MDZ concentrations and all PK parameters (Cmax, AUC, t1/2) were significantly altered in mice administered PCN. Interestingly, this was not reflected by an increase of 1′‐OH‐MDZ levels, yet by a decrease in plasma 1′‐OH‐MDZ and Cmax and AUC values, suggesting that formation of other metabolites may be induced. Furthermore, plasma PHE and all PK parameters were significantly reduced to near negligible concentrations in mice administered 3‐Me, but plasma ACE, Cmax, and AUC were also slightly attenuated relative to control, suggesting that other metabolic pathways may be induced. Lastly and surprisingly, plasma MDZ concentrations were also reduced in mice administered 3‐Me, but to a much lesser extent, suggesting that 3‐Me is a promiscuous inhibitor to MDZ 1′‐hydroxylation in mice.This approach provides a useful and practical means to conduct single mouse PK research and may prove useful for studying drug metabolism in widely‐used laboratorial mouse models. Additionally, our data suggest alternative roles for classical human CYP inhibitors and inducers in a mouse model.Support or Funding InformationJ.L.J., Y.T., and A.‐M. Y. were supported by a National Institutes of Health National Cancer Institute grant [U01CA175315].
Absence of Age‐Related Differences in Internal Dosimetry of Deltamethrin (DLM) at Low Exposure Levels
Authors: Chen Chen 
Published: November 2023

Most people are exposed to low levels of pyrethroids, the most widely‐used insecticides in the U.S. and Europe. Immature rats are more susceptible than adult animals to high doses of the pyrethroid DLM. This is attributed to the less efficient metabolic detoxification of the neurotoxic parent compound. Experiments were conducted to test the hypothesis that age differences in DLM internal dosimetry disappear when doses are low enough to be adequately metabolized. Postnatal day (PND) 15, 21 and 90 rats were gavaged with 100, 250 or 500 μg DLM/kg. Serial plasma, brain and liver samples were taken for 48 h post dosing and analyzed for their DLM content by GC‐MS. Age‐dependent differences in biological sample DLM content generally diminished with decrease in dose. PND 15 plasma AUC∞° values, for example, were 4.6‐, 2.4‐, and 1.5‐fold higher than corresponding adult values for DLM doses of 500, 250 and 100 μg/kg. Liver and brain Cmax values exhibited similar patterns. The 100 μg/kg dose is similar to EPA upper bound estimates of DLM environmental exposure levels. Our findings suggest that children and adults will experience comparable internal doses and, in turn, risks from current pyrethroid exposures.Support or Funding InformationCouncil for the Advancement of Pyrethroid Human Health Risk Assessment (CAPHRA)
Use of Age‐dependent Carboxylesterase 1 Protein Expression to Predict in vitro Elimination and in vivo Pharmacokinetics of Oseltamivir in Infants
Authors: Boberg Mikael , Mehrotra Aanchal , Vrana Marc , Prasad Bhagwat 
Published: November 2023

90% of drugs prescribed for neonates and infants are off‐label or unlicensed. Therefore it is imperative to develop alternate approaches to predict drug disposition in this special population. In this direction, the aim of this study is to test whether age‐dependent protein expression data of carboxylesterase 1 (CES1) can predict in vitro elimination and in vivo pharmacokinetics (PK) of oseltamivir in infants using physiologically based PK (PBPK) modeling.CES1 protein expression data determined by LC‐MS/MS in pediatric (n=44, including infants (0 – 1 yr, n=14)) and adult (n=7) human liver microsome (HLM) samples, were used to compare relative hepatic metabolic clearance of oseltamivir in vitro and in vivo. CES1 mediated metabolic clearance of oseltamivir was quantified by incubating 100 nM of oseltamivir in 100 μg/ml of pediatric and adult HLM samples in phosphate buffer (pH 7.4) at 37ºC. For in vivo simulation study, the adult PBPK model was developed for oseltamivir by incorporating various reported observed and predicted drug‐ and system‐dependent parameters in Simcyp (Version 14, Sheffield, UK). The model was then fitted with the observed in vivo data [1, 2] for adult subjects and key PK parameters were compared.An age‐dependent variability in oseltamivir metabolic stability and CES1 expression was observed. A significant correlation was observed between CES1 protein expression and oseltamivir metabolism in representative HLM samples (p<0.05). The CES1 activity measured as metabolic rate constant (k, min−1) was higher by 2.4‐fold (p<0.05) in the adults compared to the pediatric group. The k (min−1) for the active metabolite oseltamivir carboxylate (OC) formation was correlated with depletion of oseltamivir (p<0.001) suggesting that OC is the only metabolite formed. Significantly, the CES1 expression was found to be 3.7‐fold (p<0.001) higher in adults as compared to the infants. Oseltamivir PK in adult was predicted accurately with mean parameters (predicted vs. observed [2]) as AUC 314 vs. 297 ng/ml.h, Cmax 89 vs. 99 ng/ml and Tmax 1.04 vs. 0.95 h, respectively. All the observed in vivo data points for the adults were within the predicted 5th and 95th percentiles.Once the data are available from our large number of pediatric and adult samples, we will incorporate the expression data into the already developed adult PBPK model. The adult model optimized in this study and difference in the protein expression will be applied to predict drug disposition in infants. The predicted oseltamivir concentration‐time profile will be compared to the reported infant in vivo data[3]. If successful, the neonatal/infant PBPK model of CES1 metabolism will be important in predicting efficacy of ester prodrugs, safety of ester drugs and toxicity of environmental toxins such as phthalates, benzoates and carbamates.Support or Funding InformationFunded by NIH/NICHD1R01HD081299‐01A1
Toxicokinetics of Domoic Acid in Cynomolgus Monkeys
Authors: Jing Jing , Petroff Rebekah , Crouthamel Brenda , Grant Kimberly , Burbacher Thomas , Isoherranen Nina 
Published: November 2023

ObjectivesDomoic acid (DA), a potent neurotoxin, is produced by various marine algae and diatoms. DA acts as an analog of the neurotransmitter glutamate and is excitotoxic in the central nervous system and other glutamate receptor‐rich organs. Multiple DA intoxication cases have been reported worldwide in both marine animals and humans due to the increase of DA producing algal blooms. However, the toxicokinetics of DA has not yet been characterized in humans and it is unclear how well different animal models reproduce DA disposition in humans. In addition, due to the low assay sensitivity of DA, no toxicokinetic studies have been conducted at doses close to the tolerable daily intake (TDI) of DA in humans (0.075 ppm). The aim of this study was to determine the bioavailability and distribution and elimination kinetics of DA at doses close to the TDI in the cynomolgus monkey, a non‐human primate model for toxicokinetic studies.MethodsThree healthy female adult cynomolgus monkeys (5.1±1.9 kg) were included in this study. DA was administered in a crossover design as an IV bolus of 0.005 mg/kg or as an oral solution in sugary water (0.075 mg/kg and 0.15 mg/kg, the TDI and 2* TDI in humans) with and without concomitant food. Plasma samples were collected before dosing and up to 48 hr post‐dosing. A novel LC‐MS/MS method was developed to measure DA concentrations in plasma.ResultsThe elimination of DA from plasma after IV dosing was biphasic with alpha half‐life of 6.0 ± 4.3 min and beta half‐life of 59.6 ± 2.7 min. The clearance of DA was 2.7 ± 0.7 ml/min/kg. The clearance of DA is similar to the reported glomerular filtration rate in cynomolgus monkeys (3.1 ± 0.5 ml/min/kg) suggesting that the renal clearance of DA is primarily through filtration. The mean absolute bioavailability of DA was 13.7 % and food had no effect on DA absorption kinetics. After oral administration, the absorption of DA was slow with Tmax of 5.0 ± 4.3 hr and Cmax of 5.6 ± 1.1 ng /ml. The disposition of DA after oral dosing was characterized by flip‐flop kinetics with absorption half‐life of 16.7 ± 5.2 hr and elimination half‐life of 53.7 ± 17.4 min.ConclusionsFor the first time, our study fully characterized the toxicokinetics of DA in non‐human primates. The obtained toxicokinetic parameters could be further used to predict DA disposition in human and evaluate human exposure to DA.Support or Funding InformationThis research was funded by NIH grants P51OD010425 and 1R01ES023043‐01A1.
Distribution, metabolism and elimination of opicapone in the rats and non‐human primates
Authors: Loureiro Ana , Fernandes‐Lopes Carlos , Soares‐da‐Silva Patrício 
Published: November 2023

ObjectivesPharmacokinetic evaluation of opicapone in Cynomolgus monkey and Wistar rat.MethodsOpicapone disposition was evaluated in the Cynomolgus monkey and Wistar rat after intravenous (1 mg/kg) and oral administration (10 mg/kg) of [14C]‐opicapone.ResultsFive to seven days after administration of [14C]‐opicapone, more than 89.0% and more than 68% of opicapone related radioactivity has been excreted in rats and in monkeys, respectively. The radioactivity peaked in plasma at 4 and 0.25 h post‐dosing in rats and monkeys, respectively, followed by a quick decline and a very slow terminal phase. Opicapone related radioactivity were mainly recovered via the biliary route with a very low levels (less than 10%) excreted in urine in both species, rat and monkey. Whole body autoradiography studies in rat following single oral administration of [14C]‐opicapone (10 mg/kg), indicate that radioactivity was rapidly absorbed and distributed throughout the body. The high tissue to blood ratio of total radioactivity observed in liver and kidney at 48h post‐dosing suggests a slower elimination of opicapone related radioactivity from this tissues. Following oral administration of 1000 mg/kg opicapone, opicapone 3‐O‐sulfate, glucuronidation 3‐O‐glucuronide and the N‐oxide reduced form of opicapone were quantified in rat and monkey. With exception of N‐oxide reduced form for which the AUC0‐t was 13‐fold higher in monkeys, the exposure to opicapone and quantified metabolites were higher in rat.ConclusionsOpicapone was found to be rapidly absorbed and primarily excreted via feaces in the Cynomolgus monkey and the Wistar rat. Differences in opicapone and metabolites exposure were noticed between species.
Cholic acid feeding increases CYP2D6 expression in CYP2D6‐humanized mice
Authors: Kent Rebecca , Pan Xian , Jeong Hyunyoung 
Published: November 2023

Cytochrome P450 (CYP) 2D6 is a major drug‐metabolizing enzyme in the liver, but factors involved in the regulation of CYP2D6 expression remain poorly defined. Recent studies have shown that CYP2D6 expression is repressed by small heterodimer partner (SHP), a transcriptional repressor that is upregulated in cholestasis (1,2). The objective of this study was to determine whether cholestasis modulates CYP2D6 expression by upregulating SHP. To this end, CYP2D6‐humanized transgenic mice were fed normal chow (control) or chow supplemented with 1% (w/w) cholic acid (CA) for 2 weeks (n=4/group), and hepatic SHP and CYP2D6 expression was measured. SHP mRNA expression did not differ between the groups while SHP protein expression decreased by 2‐fold. CYP2D6 mRNA and protein expression levels were increased in the CA group by 1.5‐fold. To determine the mechanism for the disconnect between the changes in SHP mRNA and protein levels in CA‐fed mice, an in situ analysis of 3′‐untranslated region of SHP was performed, and a putative binding site for a microRNA, miR142‐3p, was identified. miR142‐3p expression was found to be increased by 5‐fold in the liver of CA‐fed mice. Promoter reporter assays using a luciferase vector harboring the 3′‐untranslated region of SHP revealed that miR142‐3p represses SHP expression by 2‐fold in HEK293T cells. Overall, these results indicate that CA feeding in mice leads to decreased SHP protein levels and increased CYP2D6 expression.Support or Funding InformationThis study was supported by NIH (GM112746 and HD065532).