Tolerance to effects of high doses of ethanol: 1. Lethal effects in mice

Evaluation of Pharmacokinetic Feasibility of Febuxostat/L-pyroglutamic Acid Cocrystals in Rats and Mice

Febuxostat (FBX), a selective xanthine oxidase inhibitor, belongs to BCS class II, showing low solubility and high permeability with a moderate F value (<49%). Recently, FBX/L-pyroglutamic acid cocrystal (FBX-PG) was developed with an improving 4-fold increase of FBX solubility. Nevertheless, the in vivo pharmacokinetic properties of FBX-PG have not been evaluated yet. Therefore, the pharmacokinetic feasibility of FBX in FBX- and FBX-PG-treated rats and mice was compared in this study. The results showed that the bioavailability (F) values of FBX were 210% and 159% in FBX-PG-treated rats and mice, respectively. The 2.10-fold greater total area under the plasma concentration-time curve from time zero to infinity (AUC0-inf) of FBX was due to the increased absorption [i.e., 2.60-fold higher the first peak plasma concentration (Cmax,1) at 15 min] and entero-hepatic circulation of FBX [i.e., 1.68-fold higher the second peak plasma concentration (Cmax,2) at 600 min] in FBX-PG-treated rats compared to the FBX-treated rats. The 1.59-fold greater AUC0-inf of FBX was due to a 1.65-fold higher Cmax,1 at 5 min, and a 1.15-fold higher Cmax,2 at 720 min of FBX in FBX-PG-treated mice compared to those in FBX-treated mice. FBX was highly distributed in the liver, stomach, small intestine, and lungs in both groups of mice, and the FBX distributions to the liver and lungs were increased in FBX-PG-treated mice compared to FBX-treated mice. The results suggest the FBX-PG has a suitable pharmacokinetic profile of FBX for improving its oral F value.

Effects of a novel toll-like receptor 4 antagonist IAXO-102 in a murine model of chemotherapy-induced gastrointestinal toxicity

INTRODUCTION

Gastrointestinal mucositis (GIM) is a side effect of high-dose irinotecan (CPT-11), causing debilitating symptoms that are often poorly managed. The role of TLR4 in the development of GIM has been clearly demonstrated. We, therefore, aimed to investigate the potential of the TLR4 antagonist, IAXO-102, to attenuate gastrointestinal inflammation as well as supress tumour activity in a colorectal-tumour-bearing mouse model of GIM induced by CPT-11.

METHODS

24 C57BL/6 mice received a vehicle, daily i.p. IAXO-102 (3 mg/kg), i.p. CPT-11 (270 mg/kg) or a combination of CPT-11 and IAXO-102. GIM was assessed using validated toxicity markers. At 72 h, colon and tumour tissue were collected and examined for histopathological changes and RT-PCR for genes of interest; TLR4, MD-2, CD-14, MyD88, IL-6, IL-6R, CXCL2, CXCR1, and CXCR2.

RESULTS

IAXO-102 prevented diarrhoea in mice treated with CPT-11. Tumour volume in IAXO-102-treated mice was lower compared to vehicle at 48 h (P < 0.05). There were no differences observed in colon and tumour weights between the treatment groups. Mice who received the combination treatment had improved tissue injury score (P < 0.05) in the colon but did not show any improvements in cell proliferation or apoptotic rate. Expression of all genes was similar across all treatment groups in the tumour (P > 0.05). In the colon, there was a difference in transcript expression in vehicle vs. IAXO-102 (P < 0.05) and CPT-11 vs. combination (P < 0.01) in MD-2 and IL-6R, respectively.

CONCLUSION

IAXO-102 was able to attenuate symptomatic parameters of GIM induced by CPT-11 as well as reduce tissue injury in the colon. However, there was no effect on cell proliferation and apoptosis. As such, TLR4 activation plays a partial role in GIM development but further research is required to understand the specific inflammatory signals underpinning tissue-level changes.

Tetracycline derivatives reduce binge alcohol consumption in High Drinking in the Dark mice

Alcohol use disorders (AUDs) are prevalent, and are characterized by binge-like drinking, defined by patterns of focused drinking where dosages ingested in 2-4 ​h reach intoxicating blood alcohol levels (BALs). Current medications are few and compliance with the relatively rare prescribed usage is low. Hence, novel and more effective medications are needed. We developed a mouse model of genetic risk for binge drinking (HDID: High Drinking in the Dark mice) by selectively breeding for high BALs after binge drinking. A transcriptional analysis of HDID brain tissue with RNA-Seq implicated neuroinflammatory mechanisms, and, more specifically extracellular matrix genes, including those encoding matrix metalloproteinases (MMPs). Prior experiments from other groups have shown that the tetracycline derivatives doxycycline, minocycline, and tigecycline, reduce binge drinking in inbred C57BL/6J mice. We tested these three compounds in female and male HDID mice and found that all three reduced DID and BAL. They had drug-specific effects on intake of water or saccharin in the DID assay. Thus, our results show that the effectiveness of synthetic tetracycline derivatives as potential therapeutic agents for AUDs is not limited to the single C57BL/6J genotype previously targeted, but extends to a mouse model of a population at high risk for AUDs.

Striatal morphological and functional alterations induced by prenatal alcohol exposure

Prenatal alcohol exposure (PAE) is an insidious yet preventable cause of developmental disability. The prenatal stage is a critical period for brain development with the concurrence of high vulnerability to the acute and prolonged effects of PAE. There is substantial evidence from both human observations and laboratory experiments that PAE is a common risk factor that predisposes to an array of postnatal mental disorders, including emotional, cognitive, and motor deficits. Although it is well accepted that PAE causes substantial morbidity, available treatments are limited. One reason is the lack of sufficient understanding about the neuroalterations induced by PAE, and how these changes contribute to PAE-induced mental disorders. Among a number of brain structures that have been explored extensively in PAE, the striatum has attracted great attention in the last 20 years in the field of PAE neurobiology. Interestingly, in animal models, the striatum has been considered as a pivotal switch of brain dysfunction induced by PAE, such as addiction, anxiety, depression, and neurodegeneration. In this review, we focus on recent advances in the understanding of morphological and functional changes in brain regions related to alterations after PAE, in particular the striatum. Because this region is central for behavior, emotion and cognition, there is an urgent need for more studies to uncover the PAE-induced alterations at the circuit, neuronal, synaptic and molecular levels, which will not only improve our understanding of the neuroplasticity induced by PAE, but also provide novel biological targets to treat PAE-related mental disorders with translational significance.

Serotonin transporter gene variation is associated with alcohol sensitivity in rhesus macaques exposed to early-life stress

BACKGROUND

Decreased sensitivity to alcohol has been demonstrated to be a predictor of alcoholism in humans, and variation in the gene-linked polymorphic region of the serotonin transporter (5-HTTLPR) is associated with the response to the motor-impairing effects of alcohol. In a nonhuman primate model of excessive alcohol intake, we have shown that decreased serotonin turnover is associated with both lower initial sensitivity to alcohol and higher prospective alcohol consumption using rhesus macaques. In addition, we have demonstrated that macaques separated from their mothers and reared in peer-only groups are more likely to consume alcohol as adults.

METHOD

To examine the relationship between serotonin transporter genotype, early rearing experience, and initial sensitivity to alcohol, peer- and mother-reared, adolescent, alcohol-naive rhesus macaques (n = 123) were rated for intoxication after intravenous administration of ethanol (2.2 g/kg and 2.0 g/kg for males and females, respectively) during two testing periods. Serotonin transporter (rh5-HTTLPR) genotype was determined using polymerase chain reaction followed by gel electrophoresis, and data were analyzed using ANOVA and the Mann-Whitney U test.

RESULTS

Our analyses demonstrate an effect of serotonin transporter gene variation on ethanol sensitivity, such that animals homozygous for the l allele exhibited decreased sensitivity to the ataxic and sedating effects of alcohol. This effect remained after correction for blood ethanol concentrations and birth cohort. When animals were segregated according to rearing condition, serotonin transporter gene variation predicted intoxication scores among peer-reared animals.

CONCLUSIONS

As in some human reports, this study demonstrates a diminution in the response to alcohol in animals homozygous for the l rh5-HTTLPR allele. The phenotypic expression of this genotype in l/s animals, however, is environmentally dependent.

Toxic cocaine- and convulsant-induced modification of forced swimming behaviors and their interaction with ethanol: comparison with immobilization stress

BACKGROUND

Swimming behaviors in the forced swimming test have been reported to be depressed by stressors. Since toxic convulsion-inducing drugs related to dopamine [cocaine (COC)], benzodiazepine [methyl 6,7-dimethoxy-4-ethyl-beta-carboline-carboxylate (DMCM)], gamma-aminobutyric acid (GABA) [bicuculline (BIC)], and glutamate [N-methyl-D-aspartate (NMDA)] receptors can function as stressors, the present study compared their effects on the forced swimming behaviors with the effects of immobilization stress (IM) in rats. Their interactions with ethanol (EtOH), the most frequently coabused drug with COC which also induces convulsions as withdrawal symptoms but interferes with the convulsions caused by other drugs, were also investigated.

RESULTS

Similar to the IM (10 min) group, depressed swimming behaviors (attenuated time until immobility and activity counts) were observed in the BIC (5 mg/kg IP) and DMCM (10 mg/kg IP) groups at the 5 h time point, after which no toxic behavioral symptoms were observed. However, they were normalized to the control levels at the 12 h point, with or without EtOH (1.5 g/kg IP). In the COC (60 mg/kg IP) and NMDA (200 mg/kg IP) groups, the depression occurred late (12 h point), and was normalized by the EtOH cotreatment. At the 5 h point, the COC treatment enhanced the swimming behaviors above the control level.

CONCLUSIONS

Although the physiological stress (IM), BIC, and DMCM also depressed the swimming behaviors, a delayed occurrence and EtOH-induced recovery of depressed swimming were observed only in the COC and NMDA groups. This might be correlated with the previously-reported delayed responses of DA and NMDA neurons rather than direct effects of the drugs, which could be suppressed by EtOH. Furthermore, the characteristic psychostimulant effects of COC seemed to be correlated with an early enhancement of swimming behaviors.

Premorbid behaviors produced by cocaine, ethanol and cocaethylene in the mouse

1. The premorbid behaviors produced by the administration of cocaine, ethanol, their combination, as well as a metabolite produced by their co-administration, viz. cocaethylene, were defined, determined and quantified in the HS strain of mice. 2. The LD50 for ethanol was 9.71 g/kg in males and 9.45 g/kg in females, whereas the LD50 values in male and female mice for cocaine were 101.55 and 90.00 mg/kg, respectively. 3. The data indicate that clonic-tonic seizures continued into status epilepticus after cocaine administration and prior to cocaine-induced lethality. In contrast, administration of the cocaine-ethanol metabolite cocaethylene produced status epilepticus without producing clonic-tonic seizures yet still resulted in lethality. 4. Thus, both cocaine and cocaethylene may produce their lethal effects in mice through neuro-regulatory mechanisms mediating protracted seizure induction.

Role of environmental cues as Pavlovian-conditioned stimuli in enhancement of tolerance to ethanol effects: 1. Lethal effects in mice and rats

Twice daily for 4 days, Swiss Webster or BALB/c mice were injected with 3.5 g/kg ethanol (20% w/v, IP) immediately after moving their home cages from the colony room to the experimental room. On day 5, half the mice were moved to the same room and the other half to a novel room with different lighting, acoustic, and olfactory stimuli. All mice were injected with ethanol overdoses ranging from 4.5-10.0 g/kg. LD50 for ethanol increased following ethanol preexposure as compared to control ethanol-naive mice tested in the same experimental room. However, LD50 was lower in both Swiss Webster and BALB/c mice tested in a novel environment than in the familiar environment. Novelty increased sensitivity to the effect of low and moderate but not the highest lethal doses of ethanol. This effect of novelty occurred only in ethanol-experienced, but not ethanol-naive mice. In the following experiments, using a balanced design, Swiss Webster mice and Wistar rats were exposed to ethanol and saline alternatively in two distinct experimental rooms. On the final day, we found that there was no difference between animals tested in the room previously associated with administration of ethanol and animals tested in a saline-associated room in terms of LD50 for ethanol. These results suggest that: a) Environmental stimuli do not play a role as Pavlovian conditioning stimuli in the development of tolerance to ethanol-induced lethality; and b) novelty acts as an unconditioned stimulus that increases ethanol's lethal effects by unspecific disruption of conditioned compensatory responses to internal conditioned stimuli, such as irritation of peritoneal cavity, smell, and taste of ethanol.