Selection for pentobarbital withdrawal severity: correlated differences in withdrawal from other sedative drugs

Synthesis of novel 5-[3-(4-chlorophenyl)-substituted-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione derivatives as potential anti-diabetic and anticancer agents

In this work, we developed a series of novel 5-[3-(4-chlorophenyl)-substituted-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione derivatives 4(a-e) via a one-pot multicomponent reaction. The structures of the compounds were confirmed using analytical and spectroscopic techniques. Also, the synthesized compounds were screened for their anti-diabetic activity, cytotoxicity and in silico studies. The activity results suggested that the compound 4e exhibited least IC50 values of 0.055 ± 0.002 µM, 0.050 ± 0.002 µM and 0.009 ± 0.001 µM for α-amylase, α-glucosidase and cytotoxicity respectively. Further, in silico molecular docking results revealed that all the obtained compounds effectively interacted with exo-β-D-glucosaminidase and P38 MAP kinase proteins with good binding energies. In that, 4e compound established the least binding energy of -9.6 and -9.1 kcal/mol, respectively. Moreover, our synthesized compounds were subjected to ADME studies, which suggested that all the synthesized compounds obeyed all five rules with good bioavailability and were suitable as drug leads against anti-diabetic and anticancer treatment.

1,3-Dimethyl-3′,5-diphenyl-1,5-dihydro-2H,5′H-spiro[furo[2,3-d]pyrimidine-6,4′-isoxazole]-2,4,5′(3H)-trione

Michael addition–halogenation–intramolecular ring-closing (MHIRC) reactions are processes in which a halogen atom as a leaving group can attach to substrates or reactants during the reaction, which then undergoes intramolecular ring closure. In this communication the MHIRC transformation of 4-benzylidene-3-phenylisoxazol-5(4H)-one and 1,3-dimethylbarbituric acid in the presence of N-bromosuccinimide and sodium acetate in EtOH at room temperature was carefully investigated to give novel 1,3-dimethyl-3′,5-diphenyl-1,5-dihydro-2H,5′H-spiro[furo[2,3-d]pyrimi- dine-6,4′-isoxazole]-2,4,5′(3H)-trione in a good yield. The structure of the new compound was confirmed by the results of elemental analysis as well as mass, nuclear magnetic resonance, and infrared spectroscopy.

Antifibrotic Effects of a Barbituric Acid Derivative on Liver Fibrosis by Blocking the NF-κB Signaling Pathway in Hepatic Stellate Cells

Hepatic stellate cells (HSCs) are the major profibrogenic cells that promote the pathogenesis of liver fibrosis. The crosstalk between transforming growth factor-β1 (TGF-β1) signaling and lipopolysaccharide (LPS)-induced NF-κB signaling plays a critical role in accelerating liver fibrogenesis. Until now, there have been no FDA-approved drug treatments for liver fibrosis. Barbituric acid derivatives have been used as antiasthmatic drugs in the clinic; however, the effect of barbituric acid derivatives in treating liver fibrosis remains unknown. In this study, we synthesized a series of six barbituric acid (BA) derivatives, and one of the compounds, BA-5, exhibited the best ability to ameliorate TGF-β1-induced HSC activation without overt cytotoxic effects. Then, we treated HSCs and RAW264.7 macrophages with BA-5 to analyze the cross-talk of anti-fibrotic and anti-inflammatory effects. Carbon tetrachloride (CCl₄)-induced liver fibrosis mouse model was used to evaluate the therapeutic effects of BA-5. Treatment with BA-5 inhibited TGF-β1-induced α-SMA, collagen1a2, and phosphorylated smad2/3 expression in HSCs. Furthermore, BA-5 treatment reversed the LPS-induced reduction in BAMBI protein and decreased IκBα and NF-κB phosphorylation in HSCs. NF-κB nuclear translocation, MCP-1 secretion, and ICAM-1 expression were also inhibited in BA-5-treated HSCs. Conditioned medium collected from BA-5-treated HSCs showed a reduced ability to activate RAW264.7 macrophages by inhibiting the MAPK pathway. In the mouse model, BA-5 administration reduced CCl₄-induced liver damage, liver fibrosis, and F4/80 expression without any adverse effects. In conclusion, our study showed that the barbituric acid derivative BA-5 inhibits HSCs activation and liver fibrosis by blocking both the TGF-β1 and LPS-induced NF-κB signaling pathways and further inhibits macrophages recruitment and activation.

Recent applications of barbituric acid in multicomponent reactions

This review aims to show representative examples of multicomponent reactions utilizing barbituric acid in the synthesis of various heterocyclic structures.

Role of gamma-aminobutyric acid type A (GABAA) receptor subtypes in acute benzodiazepine physical dependence-like effects: evidence from squirrel monkeys responding under a schedule of food presentation

RATIONALE

Assays of schedule-controlled responding can be used to characterize the pharmacology of benzodiazepines and other GABAA receptor modulators, and are sensitive to changes in drug effects that are related to physical dependence.

OBJECTIVE

The present study used this approach to investigate the role of GABAA receptor subtypes in mediating dependence-like effects following benzodiazepine administration.

METHODS

Squirrel monkeys (n = 6) were trained on a fixed-ratio schedule of food reinforcement. Initially, the response rate-decreasing effects of chlordiazepoxide (0.1-10 mg/kg; nonselective GABAA receptor agonist), zolpidem (0.032-1.0 mg/kg; α1 subunit-containing GABAA subtype-preferring agonist), and HZ-166 (0.1-10 mg/kg; functionally selective α2 and α3 subunit-containing GABAA receptor agonist) were assessed. Next, acute dependence-like effects following single injections of chlordiazepoxide, zolpidem, and HZ-166 were assessed with flumazenil (0.1-3.2 mg/kg; nonselective GABAA receptor antagonist). Finally, acute dependence-like effects following zolpidem administration were assessed with βCCt and 3-PBC (0.1-3.2 mg/kg and 0.32-10 mg/kg, respectively; α1 subunit-containing GABAA receptor antagonists).

RESULTS

Chlordiazepoxide, zolpidem, and HZ-166 produced dose- and time-dependent decreases in response rates, whereas flumazenil, βCCT, and 3-PBC were ineffective. After the drug effects waned, flumazenil produced dose-dependent decreases in response rates following administration of 10 mg/kg chlordiazepoxide and 1.0 mg/kg zolpidem, but not following any dose of HZ-166. Further, both βCCT and 3-PBC produced dose-dependent decreases in response rates when administered after 1.0 mg/kg zolpidem.

CONCLUSIONS

These data raise the possibility that α1 subunit-containing GABAA receptors play a major role in physical dependence-related behaviors following a single injection of a benzodiazepine.

Substantia nigra pars reticulata is crucially involved in barbiturate and ethanol withdrawal in mice

Sedative-hypnotic CNS depressant drugs are widely prescribed to treat a variety of disorders, and are abused for their sedative and euphoric effects. Physiological dependence and associated withdrawal episodes are thought to constitute a motivational force that sustains their use/abuse and may contribute to relapse in dependent individuals. Although no animal model duplicates depressant dependence, models for specific factors, like withdrawal, are useful for identifying potential neural determinants of liability in humans. Recent analyses implicate the caudolateral substantia nigra pars reticulata (clSNr) in withdrawal following acute and repeated ethanol exposures in mice, but did not assess its impact on withdrawal from other sedative-hypnotics or whether intrinsic neurons or fibers of passage are involved. Here, we demonstrate that bilateral chemical (ibotenic acid) lesions of the clSNr attenuate barbiturate (pentobarbital) and ethanol withdrawal. Chemical lesions did not affect convulsions in response to pentylenetetrazole, which blocks GABA(A) receptor-mediated transmission. Our results demonstrate that the clSNr nucleus itself rather than fibers of passage is crucial to its effects on barbiturate and ethanol withdrawal. These findings support suggest that clSNr could be one of the shared neural substrates mediating withdrawal from sedative-hypnotic drugs.

Mapping a barbiturate withdrawal locus to a 0.44 Mb interval and analysis of a novel null mutant identify a role for Kcnj9 (GIRK3) in withdrawal from pentobarbital, zolpidem, and ethanol

Here, we map a quantitative trait locus (QTL) with a large effect on predisposition to barbiturate (pentobarbital) withdrawal to a 0.44 Mb interval of mouse chromosome 1 syntenic with human 1q23.2. We report a detailed analysis of the genes within this interval and show that it contains 15 known and predicted genes, 12 of which demonstrate validated genotype-dependent transcript expression and/or nonsynonymous coding sequence variation that may underlie the influence of the QTL on withdrawal. These candidates are involved in diverse cellular functions including intracellular trafficking, potassium conductance and spatial buffering, and multimolecular complex dynamics, and indicate both established and novel aspects of neurobiological response to sedative-hypnotics. This work represents a substantial advancement toward identification of the gene(s) that underlie the phenotypic effects of the QTL. We identify Kcnj9 as a particularly promising candidate and report the development of a Kcnj9-null mutant model that exhibits significantly less severe withdrawal from pentobarbital as well as other sedative-hypnotics (zolpidem and ethanol) versus wild-type littermates. Reduced expression of Kcnj9, which encodes GIRK3 (Kir3.3), is associated with less severe sedative-hypnotic withdrawal. A multitude of QTLs for a variety of complex traits, including diverse responses to sedative-hypnotics, have been detected on distal chromosome 1 in mice, and as many as four QTLs on human chromosome 1q have been implicated in human studies of alcohol dependence. Thus, our results will be primary to additional efforts to identify genes involved in a wide variety of behavioral responses to sedative-hypnotics and may directly facilitate progress in human genetics.

Multivariate analyses reveal common and drug-specific genetic influences on responses to four drugs of abuse

Vulnerability to abused drugs is influenced by multiple genes unique to each drug and to risk genes for polydrug abuse. If several inbred mouse strains respond to different drugs similarly, this implies the action of a common group of genes. Simultaneous analysis of multiple responses to multiple drugs has been attempted infrequently. We performed multivariate analyses of published strain responses to four drugs. Genetic similarity in responses did not simply track pharmacological class. Withdrawal severity and preference for ethanol and diazepam were affected by many genes in common, although inversely. We focused on behavioral responses, but there is a growing archival database of physiological, pharmacological and biochemical strain traits. The genomics community is increasingly focusing on single-nucleotide polymorphism and haplotype-based gene mapping approaches, for which inbred strain data are also useful. Thus, similar analyses should be applicable to other laboratories, traits and genotypes.

Use of a novel mouse genotype to model acute benzodiazepine withdrawal

Withdrawal from benzodiazepines in physically dependent rodents often requires that the drug be dislodged from its receptor with a competitive antagonist. Withdrawal Seizure-Prone (WSP) mice were selectively bred for their susceptibility to handling-induced withdrawal convulsions following chronic treatment with ethanol. Reflecting pleiotropic genetic influences, they also experience more severe withdrawal from other sedative-hypnotics including the benzodiazepine, diazepam. We used this susceptible genotype to test whether other benzodiazepine receptor (BZR) agonists also produce physical dependence following acute administration, comparing studies of spontaneous withdrawal with those where convulsions were precipitated by a BZR antagonist (flumazenil). Separate groups of mice were tested following a single injection of one of eight BZR agonists. Several doses of each drug were tested for spontaneous withdrawal, and a single dose of each drug was tested for precipitated withdrawal. Withdrawal convulsions were seen after all of the drugs by at least one method, suggesting that BZR agonists as a class elicit acute physical dependence in this susceptible genotype.

Alcohol withdrawal severity in inbred mouse (Mus musculus) strains

Male mice (Mus musculus) from 15 standard inbred strains were exposed to a nearly constant concentration of ethanol (EtOH) vapor for 72 hr, averaging 1.59 +/- 0.03 mg EtOH/mL blood at withdrawal. EtOH- and air-exposed groups were tested hourly for handling-induced convulsions for 10 hr and at Hours 24 and 25. Strains differed markedly in the severity of withdrawal (after subtraction of control values), and by design these differences were independent of strain differences in EtOH metabolism. Correlation of strain mean withdrawal severity with other responses to EtOH supported previously reported genetic relationships of high EtOH withdrawal with low drinking, high conditioned taste aversion, low tolerance to EtOH-induced hypothermia, and high stimulated activity after low-dose EtOH. Also supported were the positive genetic correlations among EtOH, barbiturate, and benzodiazepine withdrawal. Sensitivity of naive mice to several chemical convulsant-induced seizures was also correlated with EtOH withdrawal.

Fine mapping of a sedative-hypnotic drug withdrawal locus on mouse chromosome 11

We have established that there is a considerable amount of common genetic influence on physiological dependence and associated withdrawal from sedative-hypnotic drugs including alcohol, benzodiazepines, barbiturates and inhalants. We previously mapped two loci responsible for 12 and 9% of the genetic variance in acute alcohol and pentobarbital withdrawal convulsion liability in mice, respectively, to an approximately 28-cM interval of proximal chromosome 11. Here, we narrow the position of these two loci to a 3-cM interval (8.8 Mb, containing 34 known and predicted genes) using haplotype analysis. These include genes encoding four subunits of the GABA(A) receptor, which is implicated as a pivotal component in sedative-hypnotic dependence and withdrawal. We report that the DBA/2J mouse strain, which exhibits severe withdrawal from sedative-hypnotic drugs, encodes a unique GABA(A) receptor gamma2 subunit variant compared with other standard inbred strains including the genetically similar DBA/1J strain. We also demonstrate that withdrawal from zolpidem, a benzodiazepine receptor agonist selective for alpha1 subunit containing GABA(A) receptors, is influenced by a chromosome 11 locus, suggesting that the same locus (gene) influences risk of alcohol, benzodiazepine and barbiturate withdrawal. Our results, together with recent knockout studies, point to the GABA(A) receptor gamma2 subunit gene (Gabrg2) as a promising candidate gene to underlie phenotypic differences in sedative-hypnotic physiological dependence and associated withdrawal episodes.