Nicotine physical dependence and tolerance in the mouse following chronic oral administration

RATIONALE

Although nicotine dependence and tolerance develop in rats, few studies have examined these processes in the mouse. Establishing such mouse models would eventually allow for an examination of the role of specific nicotinic receptor subtypes in mediating these processes (i.e. through the use of receptor knockouts).

OBJECTIVES

The goals of the present study were to establish mouse models of nicotine dependence and tolerance.

METHODS

Mice were chronically exposed to nicotine (0-200 mug/ml) in their drinking solution and assayed for plasma nicotine and cotinine levels, withdrawal signs following nicotine cessation (spontaneous withdrawal) or nicotinic antagonist administration (precipitated withdrawal), or nicotine tolerance. Dependence assays included somatic sign observations (paw tremors, backing and head shakes), tail-flick, plantar stimulation, elevated plus-maze and spontaneous activity. Tolerance was assayed using tail-flick, hot-plate and body temperature tests.

RESULTS

Plasma nicotine and cotinine levels were elevated during oral nicotine exposure (15.85 ng/ml and 538.00 ng/ml, respectively) and quickly declined following nicotine cessation (<1 ng/ml and <2 ng/ml, respectively), providing evidence that the oral route was pharmacologically relevant. Nicotine withdrawal increased numbers of somatic signs (spontaneous and mecamylamine-precipitated withdrawal) and/or hyperalgesia (spontaneous withdrawal only). Chronic nicotine exposure also produced tolerance, as indicated by reduced responsivity to acute nicotine in assays of analgesia and hypothermia.

CONCLUSIONS

These results indicate that chronic oral nicotine produces dependence and tolerance in the mouse. Further, nicotine dependence may be mediated by multiple nicotinic receptor subtypes, since specific nicotinic receptor antagonists failed to precipitate withdrawal.

Glaucoma and increased central corneal thickness in aphakic and pseudophakic patients after congenital cataract surgery

AIM

To compare the mean central corneal thickness (CCT) among aphakic and pseudophakic patients following congenital cataract surgery with age matched controls.

METHODS

This study included 43 eyes of 43 aphakic and pseudophakic patients following congenital cataract surgery. 44 healthy, age and sex matched volunteers were recruited for comparison with the patients. After a complete eye examination, corneal thickness and intraocular pressure were measured.

RESULTS

In the study group, 33 eyes were aphakic, and the remaining 10 eyes were pseudophakic. The median CCT was 556.0 microm (range 490-640 microm) in the control group and 626 microm (range 523-870 microm) in the study group (p<0.05). There was a significant difference in CCT between aphakic and pseudophakic eyes in which an intraocular lens (IOL) had been implanted at the time of congenital cataract surgery (p = 0.011). The same difference was not observed between aphakic and pseudophakic eyes in which an IOL had been implanted secondarily (p = 0.835). The median age of the patients at the time of lensectomy was 24 months (range 1 week to 120 months). There was a negative correlation between the age at lensectomy and CCT (r = -0.485, p = 0.001).

CONCLUSION

Aphakic and pseudophakic patients have significantly thicker corneas than age matched controls. This difference can have an important effect on interpreting intraocular pressures in these patients. It is also important to assess the effects of early surgery for congenital cataracts, as well as those of primary and secondary IOL implantation, on CCT.

Large-scale neurochemical metabolomics analysis identifies multiple compounds associated with methamphetamine exposure

Methamphetamine (MA) is an illegal stimulant drug of abuse with serious negative health consequences. The neurochemical effects of MA have been partially characterized, with a traditional focus on classical neurotransmitter systems. However, these directions have not yet led to novel drug treatments for MA abuse or toxicity. As an alternative approach, we describe here the first application of metabolomics to investigate the neurochemical consequences of MA exposure in the rodent brain. We examined single exposures at 3 mg/kg and repeated exposures at 3 mg/kg over 5 days in eight common inbred mouse strains. Brain tissue samples were assayed using high-throughput gas and liquid chromatography mass spectrometry, yielding quantitative data on >300 unique metabolites. Association testing and false discovery rate control yielded several metabolome-wide significant associations with acute MA exposure, including compounds such as lactate (p = 4.4 × 10^-5, q = 0.013), tryptophan (p = 7.0 × 10^-4, q = 0.035) and 2-hydroxyglutarate (p = 1.1 × 10^-4, q = 0.022). Secondary analyses of MA-induced increase in locomotor activity showed associations with energy metabolites such as succinate (p = 3.8 × 10^-7). Associations specific to repeated (5 day) MA exposure included phosphocholine (p = 4.0 × 10^-4, q = 0.087) and ergothioneine (p = 3.0 × 10^-4, q = 0.087). Our data appear to confirm and extend existing models of MA action in the brain, whereby an initial increase in energy metabolism, coupled with an increase in behavioral locomotion, gives way to disruption of mitochondria and phospholipid pathways and increased endogenous antioxidant response. Our study demonstrates the power of comprehensive MS-based metabolomics to identify drug-induced changes to brain metabolism and to develop neurochemical models of drug effects.

Attenuation of nicotine's discriminative stimulus effects in rats and its locomotor activity effects in mice by serotonergic 5-HT2A/2C receptor agonists

RATIONALE

Reports have indicated that administration of nicotine inhibits, while withdrawal of chronically administered nicotine augments effects of serotonergic 5HT2A/2C agonists.

OBJECTIVE

It was our objective to determine whether 5HT2A/2C agonists can modulate the discriminative stimulus effects of nicotine in rats or its locomotor activity effects in mice.

METHODS

Adult male Sprague-Dawley rats were trained to discriminate 0.3 mg/kg nicotine base from saline in a two-lever, fixed-ratio (FR10), food-reinforced, operant-conditioning task during daily (Monday-Friday) 15-min experimental sessions. After characterizing a dose-response curve for nicotine, we tested the ability of the 5HT(2A/2C) agonists (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCL (DOI; 0.18-1.0 mg/kg) and 1-(4-bromo-2, 5-dimethoxyphenyl)-2-aminopropane (DOB; 0.1-1.0 mg/kg), the 5HT2C agonist 6-chloro-2-(1-piperazinyl)pyrazine hydrochloride (MK 212; 0.1 mg/kg-1.0 mg/kg), and the 5HT1A agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT; 0.01 mg/kg-1.0 mg/kg) to modulate nicotine's discriminative stimulus effects. After finding that DOI was able to attenuate the percentage nicotine lever responding (%NLR), we tested for it to also reverse nicotine's effects on locomotor activity in mice.

RESULTS

The 5HT2A/2C agonists-in particular DOI-dose dependently attenuated %NLR. The effects of DOI were reversed by the 5HT2A/2C antagonist ketanserin. MK 212 and 8-OH-DPAT had irregular effects among rats and only reduced %NLR to below 50% levels at doses markedly suppressing responding. DOI also dose dependently blocked nicotine's acute rate-lowering locomotor activity effects.

CONCLUSIONS

These results indicate that activation of serotonin 5HT2A/2C receptors can blunt the discriminative stimulus and locomotor activity effects of nicotine and presents the possibility that activation of these receptors might also be able to attenuate other effects of nicotine.

The Comparison of Eyelash Lengthening Effect of Latanoprost Therapy in Adults and Children

PURPOSE

To compare the eyelash lengthening effect of latanoprost in adults and children with glaucoma.

METHODS

Twenty eyes of 13 men and 7 women (mean age: 54.9, range 42-69 years) with primary open-angle glaucoma and 20 eyes of 9 boys and 11 girls (mean age: 10.7, range 6-16 years) with glaucoma were included in this prospective study. In 19 children, juvenile glaucoma and in one, pseudophakic glaucoma had been detected. A single eyelash was pulled from the center of the upper eyelid before latanoprost therapy and at the sixth month of therapy, and measured.

RESULTS

In adult cases, the mean eyelash length was 5.79+/-0.18 mm (5.5-6.1 mm) at baseline and 6.45+/-0.21 mm (6.2-6.8 mm) at the sixth month. In children, the mean length was 5.66+/-0.22 mm (5.3-6.0 mm) at baseline and 6.39+/-0.37 mm (5.9-6.9 mm) at the sixth month. The mean difference in eyelash lengths at baseline and the sixth month was 0.67+/-0.09 mm (0.5-0.7 mm) in adults and 0.75+/-0.25 mm (0.4-1.2 mm) in children.

CONCLUSIONS

The differences in mean eyelash lengths at baseline and at the sixth month of latanoprost therapy were statistically significant in both adults and children (p=0.000). The mean of the difference of the eyelash length in children was higher than in adults but the result was not statistically significant (p=0.678).

Glycogen synthase kinase 3 beta regulates ethanol consumption and is a risk factor for alcohol dependence

Understanding how ethanol actions on brain signal transduction and gene expression lead to excessive consumption and addiction could identify new treatments for alcohol dependence. We previously identified glycogen synthase kinase 3-beta (Gsk3b) as a member of a highly ethanol-responsive gene network in mouse medial prefrontal cortex (mPFC). Gsk3b has been implicated in dendritic function, synaptic plasticity and behavioral responses to other drugs of abuse. Here, we investigate Gsk3b in rodent models of ethanol consumption and as a risk factor for human alcohol dependence. Stereotactic viral vector gene delivery overexpression of Gsk3b in mouse mPFC increased 2-bottle choice ethanol consumption, which was blocked by lithium, a known GSK3B inhibitor. Further, Gsk3b overexpression increased anxiety-like behavior following abstinence from ethanol. Protein or mRNA expression studies following Gsk3b over-expression identified synaptojanin 2, brain-derived neurotrophic factor and the neuropeptide Y Y5 receptor as potential downstream factors altering ethanol behaviors. Rat operant studies showed that selective pharmacologic inhibition of GSK3B with TDZD-8 dose-dependently decreased motivation to self-administer ethanol and sucrose and selectively blocked ethanol relapse-like behavior. In set-based and gene-wise genetic association analysis, a GSK3b-centric gene expression network had significant genetic associations, at a gene and network level, with risk for alcohol dependence in humans. These mutually reinforcing cross-species findings implicate GSK3B in neurobiological mechanisms controlling ethanol consumption, and as both a potential risk factor and therapeutic target for alcohol dependence.

Neurochemical Metabolomics Reveals Disruption to Sphingolipid Metabolism Following Chronic Haloperidol Administration

Haloperidol is an effective antipsychotic drug for treatment of schizophrenia, but prolonged use can lead to debilitating side effects. To better understand the effects of long-term administration, we measured global metabolic changes in mouse brain following 3 mg/kg/day haloperidol for 28 days. These conditions lead to movement-related side effects in mice akin to those observed in patients after prolonged use. Brain tissue was collected following microwave tissue fixation to arrest metabolism and extracted metabolites were assessed using both liquid and gas chromatography mass spectrometry (MS). Over 300 unique compounds were identified across MS platforms. Haloperidol was found to be present in all test samples and not in controls, indicating experimental validity. Twenty-one compounds differed significantly between test and control groups at the p < 0.05 level. Top compounds were robust to analytical method, also being identified via partial least squares discriminant analysis. Four compounds (sphinganine, N-acetylornithine, leucine and adenosine diphosphate) survived correction for multiple testing in a non-parametric analysis using false discovery rate threshold < 0.1. Pathway analysis of nominally significant compounds (p < 0.05) revealed significant findings for sphingolipid metabolism (p = 0.015) and protein biosynthesis (p = 0.024). Altered sphingolipid metabolism is suggestive of disruptions to myelin. This interpretation is supported by our observation of elevated N-acetyl-aspartyl-glutamate in the haloperidol-treated mice (p = 0.004), a marker previously associated with demyelination. This study further demonstrates the utility of murine neurochemical metabolomics as a method to advance understanding of CNS drug effects.

Behavioral metabolomics analysis identifies novel neurochemical signatures in methamphetamine sensitization

Behavioral sensitization has been widely studied in animal models and is theorized to reflect neural modifications associated with human psychostimulant addiction. While the mesolimbic dopaminergic pathway is known to play a role, the neurochemical mechanisms underlying behavioral sensitization remain incompletely understood. In this study, we conducted the first metabolomics analysis to globally characterize neurochemical differences associated with behavioral sensitization. Methamphetamine (MA)-induced sensitization measures were generated by statistically modeling longitudinal activity data for eight inbred strains of mice. Subsequent to behavioral testing, nontargeted liquid and gas chromatography-mass spectrometry profiling was performed on 48 brain samples, yielding 301 metabolite levels per sample after quality control. Association testing between metabolite levels and three primary dimensions of behavioral sensitization (total distance, stereotypy and margin time) showed four robust, significant associations at a stringent metabolome-wide significance threshold (false discovery rate, FDR <0.05). Results implicated homocarnosine, a dipeptide of GABA and histidine, in total distance sensitization, GABA metabolite 4-guanidinobutanoate and pantothenate in stereotypy sensitization, and myo-inositol in margin time sensitization. Secondary analyses indicated that these associations were independent of concurrent MA levels and, with the exception of the myo-inositol association, suggest a mechanism whereby strain-based genetic variation produces specific baseline neurochemical differences that substantially influence the magnitude of MA-induced sensitization. These findings demonstrate the utility of mouse metabolomics for identifying novel biomarkers, and developing more comprehensive neurochemical models, of psychostimulant sensitization.

Synthesis and biological characterization of (3R,4R)-4-(2-(benzhydryloxy)ethyl)-1-((R)-2-hydroxy-2-phenylethyl)-piperidin-3-ol and its stereoisomers for activity toward monoamine transporters

A novel series of optically active molecules based on a 4-(2-(benzhydryloxy)ethyl)-1-((R)-2-hydroxy-2-phenylethyl)-piperidin-3-ol template were developed. Depending on stereochemistry, the compounds exhibit various degrees of affinity for three dopamine, serotonin, and norepinephrine transporters. These molecules have the potential for treating several neurological disorders such as drug abuse, depression, and attention deficit hyperactivity disorder.Herein we describe the synthesis and biological evaluation of a series of asymmetric 4-(2-(benzhydryloxy)ethyl)-1-((R)-2-hydroxy-2-phenylethyl)-piperidin-3-ol-based dihydroxy compounds in which the hydroxy groups are located on both the piperidine ring and the N-phenylethyl side chain. In vitro uptake inhibition data of these molecules indicate high affinity for the dopamine transporter (DAT) in addition to moderate to high affinity for the norepinephrine transporter (NET). Interestingly, compounds 9 b and 9 d exhibit affinities for all three monoamine transporters, with highest potency at DAT and NET, and moderate potency at the serotonin transporter (SERT) (K(i): 2.29, 78.4, and 155 nM for 9 b and 1.55, 14.1, and 259 nM for 9 d, respectively). Selected compounds 9 a, 9 d, and 9 d' were tested for their locomotor activity effects in mice and for their ability to occasion the cocaine-discriminative stimulus in rats. These test compounds generally exhibit a much longer duration of action than cocaine for elevating locomotor activity, and completely generalize the cocaine-discriminative stimulus in a dose-dependent manner.

Nd:YAG laser iridotomy in the management of secondary glaucoma associated with Behçet's disease

PURPOSE

To report the outcome of Nd:YAG laser iridotomy in the management of secondary glaucoma associated with Behçet's disease (BD).

METHODS

In this prospective study, Nd:YAG laser iridotomy was performed on eyes with secondary angle-closure and pupillary block glaucoma associated with BD. The pretreatment and post-treatment intraocular pressures (IOP) and the number of antiglaucoma medications were compared by Mann-Whitney U test.

RESULTS

The study consisted of 16 eyes of 11 patients (2 female, 9 male, mean age 39.2+/-8.9 years). Post-treatment follow-up ranged from 6 to 36 months (mean 13.8+/-8.9). The mean IOP was 21.6+/-2.5 mmHg on 2.5+/-0.6 medications before iridotomy. IOP reduced to 17.7+/-2.5 mmHg on 1+/-0.6 medications at the first month and 17.1+/-3.2 mmHg on 1.7+/-0.9 medications at the sixth month of treatment. The differences between IOP and number of antiglaucoma medications at baseline and at the sixth month of the treatment was statistically significant (p<0.00001). For four eyes trabeculectomy with mitomycin C and for one eye Ahmed valve implantation were performed in the follow-up period.

CONCLUSIONS

Nd:YAG laser iridotomy can provide reduction of IOP and the number of antiglaucoma medications in selected cases with secondary glaucoma associated with Behcet's disease.

A new technique for endoscopic treatment of gastric phytobezoars: fragmentation using guidewire

BACKGROUND AND STUDY AIMS

Bezoars result from accumulation of indigestible materials in the gastrointestinal tract and often occur in the stomach. In this study, we evaluated the use of guidewires in patients with gastric phytobezoars (PBs) as a new method for PB removal and examined the safety of the procedure.

PATIENTS AND METHODS

Between February 2009 and January 2013, we analyzed data from 11 patients with gastric PBs. We fitted a transparent cap to a standard endoscope (EG450WR5, Fujinon), and a 0.025 inch guidewire was passed through the standart endoscope. PBs were surrounded by a loop in the guidewire and destroyed. After 2 weeks of treatment, patients were re-evaluated for effectiveness.

RESULTS

PB fragmentation time was 5-11 minutes. In five patients with a history of gastric surgery, we needed an additional 16-28 minutes for removal of the fragments. In six patients additionally treated with enzymatic degradation after the breaking procedure, PBs completely disappeared within 2 weeks. There were no complications during the procedure.

CONCLUSIONS

The guidewire and fragmentation procedure for PBs is an efficient and reliable method. When combined with enzymatic degradation, PBs can be managed quickly and effectively.

Serum ghrelin levels: Is there any association with malnutrition and depression in peritoneal dialysis patients?

BACKGROUND

Ghrelin is a physiologic regulatory hormone of appetite and body weight, and its concentrations increase in chronic kidney disease. This study aimed to analyze the effects of malnutrition and depression on the plasma ghrelin levels in peritoneal dialysis (PD) patients.

METHODS/PATIENTS

The relationship between fasting serum ghrelin concentration, type of dialysate solution, malnutrition-inflammation score (MIS), and depressive symptoms of 87 PD patients were analyzed. Depressive symptoms were evaluated using the Beck Depression Inventory.

RESULTS

No significant relationship between ghrelin concentration and body mass index (BMI), MIS or depression scores was detected. The mean serum ghrelin concentration in patients using amino acid-based solutions was higher than in non-users (p <0.001). The mean serum ghrelin concentration of the patients using icodextrin-based solutions was found to be significantly higher than non-users (8.69 ± 5.04 vs 6.61 ± 2.8 ng/ml respectively, p =0.02). There was no significant difference in MIS between the patients in terms of amino-acid and/or icodextrin usage.

CONCLUSIONS

There is no association between BMI, MIS, and depression with ghrelin concentrations in PD patients. Icodextrin and/or amino acid-based solutions usage may increase the serum ghrelin concentration without a significant effect on BMI and measures of malnutrition. HIPPOKRATIA 2018, 22(1): 43-48.

Translating Alcohol Research: Opportunities and Challenges

Alcohol use disorder (AUD) and its sequelae impose a major burden on the public health of the United States, and adequate long-term control of this disorder has not been achieved. Molecular and behavioral basic science research findings are providing the groundwork for understanding the mechanisms underlying AUD and have identified multiple candidate targets for ongoing clinical trials. However, the translation of basic research or clinical findings into improved therapeutic approaches for AUD must become more efficient. Translational research is a multistage process of stream-lining the movement of basic biomedical research findings into clinical research and then to the clinical target populations. This process demands efficient bidirectional communication across basic, applied, and clinical science as well as with clinical practitioners. Ongoing work suggests rapid progress is being made with an evolving translational framework within the alcohol research field. This is helped by multiple interdisciplinary collaborative research structures that have been developed to advance translational work on AUD. Moreover, the integration of systems biology approaches with collaborative clinical studies may yield novel insights for future translational success. Finally, appreciation of genetic variation in pharmacological or behavioral treatment responses and optimal communication from bench to bedside and back may strengthen the success of translational research applications to AUD.