γ-Amino butyric acid analogs as novel potent GABA-AT inhibitors: molecular docking, synthesis, and biological evaluation

A new series, of γ-amino butyric acid analogs were designed and synthesized as novel potent GABA-AT inhibitors. A structure–activity relationship study was performed by correlating the effect of different substituents with GABA-AT inhibitory activity of the title compounds. The preliminary bioassays showed that acid hydrazones exhibited excellent inhibitory activities in micromolar (0.07–0.56 μM) range, while Schiff’s bases showed variable results. The most potent compound, 4-amino-N′-[(1Z)-1-(2-bromophenyl)ethylidene]butanehydrazide (AHG177) showed inhibitory potency (IC₅₀) of 0.073 μM. Aminobutyrate transaminase is a pyridoxal-P enzyme which follows a bi–bi ping pong mechanism and in pyridoxamine form can readily transaminate only with succinic semialdehyde and 2-oxoglutarate. The results strongly suggest that only the pyridoxal form of the enzyme is capable of reacting with the ligands. Our findings open up the possibility to extend this protocol to different databases in order to find new potential inhibitor for promising targets based on a rational drug design process.     

Why so impulsive? White matter alterations are associated with impulsivity in chronic marijuana smokers

Difficulty monitoring and inhibiting impulsive behaviors has been reported in marijuana (MJ) smokers; neuroimaging studies, which examined frontal systems in chronic MJ smokers, have reported alterations during inhibitory tasks. Diffusion tensor imaging (DTI) provides a quantitative estimate of white matter integrity at the microstructural level. We applied DTI, clinical ratings, and impulsivity measures to explore the hypotheses that chronic, heavy MJ smokers would demonstrate alterations in white matter microstructure and a different association between white matter measures and impulsivity relative to nonsmoking control subjects (NS). Fractional anisotropy (FA), a measure of directional coherence, and trace, a measure of overall diffusivity, were calculated for 6 locations including bilateral frontal regions in 15 chronic MJ smokers and 15 NS. Subjects completed clinical rating scales, including the Barratt Impulsivity Scale (BIS). Analyses revealed significant reductions in left frontal FA in MJ smokers relative to NS and significantly higher levels of trace in the right genu. MJ smokers also had significantly higher BIS total and motor subscale scores relative to NS, which were positively correlated with left frontal FA values. Finally, age of onset of MJ use was positively correlated with frontal FA values and inversely related to trace. These data represent the first report of significant alterations in frontal white matter tracts associated with measures of impulsivity in chronic MJ smokers. Early MJ use may result in reduced FA and increased diffusivity, which may be associated with increased impulsivity, and ultimately contribute to the initiation of MJ use or the inability to discontinue use.     

Altered regulation of glutamate release and decreased functional activity and expression of GLT1 and GLAST glutamate transporters in the hippocampus of adolescent rats perinatally exposed to Δ9-THC

The long-term effects of perinatal Δ⁹-tetrahydrocannabinol (Δ⁹-THC) exposure – from gestational day (GD) 15 to postnatal day (PND) 9 – on hippocampal glutamatergic neurotransmission were studied in slices from the 40-day-old offspring of Δ⁹-THC exposed (Δ⁹-THC-rats) and vehicle-exposed (control) dams. Basal and in K+-evoked endogenous hippocampal glutamate outflow were both significantly decreased in Δ⁹-THC-rats. The effect of short Δ⁹-THC exposure (0.1 μM) on K⁺-evoked glutamate release disclosed a loss of the stimulatory effect of Δ⁹-THC on hippocampal glutamate release in Δ⁹-THC-rats, but not in controls. In addition, l-[³H]-glutamate uptake was significantly lower in hippocampal slices from Δ⁹-THC-rats, where a significant decrease in glutamate transporter 1 (GLT1) and glutamate/aspartate transporter (GLAST) protein was also detected. Collectively, these data demonstrate that perinatal exposure to cannabinoids induces long-term impairment in hippocampal glutamatergic neurotransmission that persist into adolescence.     

Does exercise have an acute effect on desire to smoke,mood and withdrawal symptoms in abstaining adolescent smokers?

OBJECTIVE: Previous studies have shown that exercise acutely reduces desire to smoke and withdrawal symptoms among adult smokers; however, no study has examined these effects in younger smokers. This study investigated the impact of a short bout of moderate intensity exercise on desire to smoke, withdrawal symptoms and exercise-induced affect in temporarily abstinent adolescent smokers. METHODS: Thirty-seven low-active male and female smokers aged 16-19 years, abstained from smoking overnight and were assigned to either (i) 10 min of moderate intensity cycle ergometry (n=18) or (ii) a placebo control condition that involved very light intensity cycle ergometry (n=19). Measures of desire to smoke, the Mood and Physical Symptoms Scale (MPSS) and Subjective Exercise Experience Scale (SEES) were administered at baseline, 5 min during, 5 min after and 30 min after both conditions. RESULTS AND CONCLUSION: A significant interaction effect for group by time was recorded for psychological distress scores, when the baseline value was covaried. Follow-up tests indicated that the exercise group reported significantly higher PD scores than the placebo control during exercise, but not at any other time point. No other significant effects were found for any other variables. Unlike research involving adult populations, a short bout of moderate intensity exercise did not alter desire to smoke among abstaining adolescent smokers and may negatively impact affective responses during exercise.     

Do thyroid abnormalities detected in patients treated for HCV-related chronic hepatitis persist?

One hundred and twenty-one patients with HCV-related chronic hepatitis and normal baseline thyroid function were studied. Forty-six patients received IFN alpha-2b, while 75 patients had Peg-IFN alpha-2b with ribavirin more recently. Thirty patients (ten belonging to the standard IFN group) were re-treated. The pre-treatment prevalence of thyroid antibodies was 3.3%. At the end of the first antiviral treatment, the prevalence of laboratory alterations (presence of antibodies and abnormal hormonal levels) of thyroid was assessed to be 20.7% (25 patients), being quite similar for standard-interferon- and pegylated-interferon-treated patients (P = 0.63). TSH level alteration was seen in eleven patients (9.1% of the overall population and 44% of the antibodies positive patients), of whom ten were females. The anti-microsomal, anti-thyroperoxidase and anti-thyroglobulin antibodies, in combined or isolated presence, were detected in all 25 patients. During the re-treatment we noticed worsening only of previous thyroid abnormalities. No patient changed the antiviral schedule after the emerging of thyroid alterations. All eleven patients remained thyroid dysfunctional at the end of the follow-up (ten with Hashimoto's thyroiditis and one with Graves disease), meanwhile the near totality of patients with presence of antibodies remained positive. Interestingly, eight out the 14 patients who showed mood disorders after antiviral therapy, belonged to the aforementioned cohort.     

Interleukin 1β-induced inhibition of gastric acid secretion involves glutamate,NO and cGMP synthesis in the brain

This study examines the role of a central pathway involving glutamate receptors, nitric oxide (NO) and cGMP in the acute inhibitory effects of central interleukin 1beta on pentagastrin-stimulated acid production.The acid-inhibitory effect of central interleukin 1beta was prevented by intracisternal (i.c.) microinjections of interleukin 1beta together with the NMDA receptor antagonist, dizocilpine maleate (MK-801). Intracisternal co-administration of the nitric oxide synthase inhibitor, N(G)-nitro- L-arginine methyl esther ( L-NAME) or 1H-[1,2,4]oxazodiolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase (sGC) blocker, both reversed the hyposecretory effect of central interleukin 1beta. Peripheral administration of endotoxin significantly reduced pentagastrin-stimulated gastric acid secretion. I.c. pre-treatment with the interleukin 1 receptor antagonist, IL-1ra, failed to restore acid secretory responses in these rats. In addition, endotoxin did not modify the levels of endogenous mRNA for IL-1beta in the brainstem.We conclude that central glutamate receptors are involved in the acid inhibitory effect of centrally administered interleukin 1beta. This central pathway involves synthesis of NO, which acts on the enzyme sGC. However, endogenous interleukin 1beta does not seem to be involved in the inhibition of gastric acid secretion elicited by peripheral endotoxin.     

Effects of glutamate and α2-noradrenergic receptor antagonists on the development of neurotoxicity produced by chronic rotenone in rats

Systemic inhibition of complex I by rotenone in rats represents a model of Parkinson's disease (PD). The aim of this study was to elucidate whether neramexane (NMDA, nicotinic α9/α10 and 5-HT₃ receptor antagonist), idazoxan (α₂-adrenoceptor antagonist) or 2-methyl-6-(phenyl-ethyl)-pyrimidine (MPEP, metabotropic glutamate receptor 5 antagonist) prevents rotenone-induced parkinsonian-like behaviours and neurochemical changes in rats. Rotenone (2.5 mg/kg i.p. daily) was administered over 60 days together with saline, neramexane (5 mg/kg i.p., b.i.d.), idazoxan (2.5 mg/kg i.p., b.i.d.) or MPEP (2.5 mg/kg i.p., b.i.d.). The same doses of neramexane, idazoxan and MPEP were administered to rats treated with vehicle instead of rotenone. Treatment-related effects on parkinsonian-like behaviours, such as hypokinesia/rigidity and locomotor activity, were evaluated. Moreover, concentrations of dopamine, serotonin and their metabolites were measured in rats from each experimental group. Over the 60-day treatment period, the rotenone + saline treated animals developed hypokinesia, expressed as an increase in the bar and grid descent latencies in the catalepsy test, and a decrease in locomotor activity. Neramexane and idazoxan partially prevented the development of catalepsy in rotenone-treated rats. Co-administration of MPEP with rotenone resulted only in a decrease in descent latency in the grid test on day 60. Chronic rotenone treatment reduced concentrations of dopamine and serotonin in the anterior striatum, which was blocked by co-treatment with neramexane or idazoxan but not with MPEP. Only neramexane treatment blocked the rotenone-induced decrease in dopamine levels in the substantia nigra pars compacta. In conclusion, neramexane and idazoxan counteracted to some extent the development of parkinsonian symptoms and neurochemical alterations in the rotenone model of Parkinson's disease.     

Differential behavioural and neurochemical outcomes from chronic paroxetine treatment in adolescent and adult rats: a model of adverse antidepressant effects in human adolescents?

Selective serotonin reuptake inhibitor use is associated with increased risk of suicidal ideation in adolescent humans, yet the neuropharmacological basis of this phenomenon is unknown. Consequently, we examined the behavioural and neurochemical effects of chronic paroxetine (PRX) treatment in adult and adolescent rats. Rats received PRX in their drinking water (target dose 10 mg/kg) for 22 d, during which time they were assessed for depression- and anxiety-like behaviours. Subsequent ex-vivo analyses examined serum PRX concentrations, striatal neurotransmitter content, and regional serotonin and dopamine transporter (SERT, DAT) binding density. After 11-12 d treatment, PRX-treated adolescent rats showed a significant inhibition of social interaction while adults were unaffected. After 19-20 d treatment, adolescents failed to show an antidepressant-like effect of PRX treatment on the forced swim test (FST), while PRX-treated adults showed a typical decrease in immobility and increase in swimming. Two PRX-treated adolescents died unexpectedly after the FST suggesting a compromised response to physical stress. Despite their greater apparent adverse reaction to the drug, adolescents had significantly lower plasma PRX than adults at day 22 of treatment. Chronic PRX treatment had similar effects in adults and adolescents on striatal 5-HT (unchanged relative to controls) and 5-HIAA levels (decreased), while markers of dopaminergic function (DOPAC, HVA, DA turnover) were increased in adults only. SERT density was up-regulated in the amygdala in PRX-treated adolescents only while DAT density in the nucleus accumbens was down-regulated only in PRX-treated adults. These data suggest that the immature rat brain responds differently to PRX and that this might be of use in modelling the atypical response of human adolescents to antidepressants. The age-specific PRX-induced changes in dopaminergic markers and SERT and DAT binding provide clues as to the neural mechanisms underlying adverse PRX effects in adolescent humans.     

Cannabidiol potentiates ��9-tetrahydrocannabinol (THC) behavioural effects and alters THC pharmacokinetics during acute and chronic treatment in adolescent rats

Rationale

The interactions between ??⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD) during chronic treatment, and at equivalent doses, are not well characterised in animal models.

Objectives

The aim of this study is to examine whether the behavioural effects of THC, and blood and brain THC levels are affected by pre-treatment with equivalent CBD doses.

Methods

Adolescent rats were treated with ascending daily THC doses over 21?days (1 then 3 then 10?mg/kg). Some rats were given equivalent CBD doses 20?min prior to each THC injection to allow examination of possible antagonistic effects of CBD. During dosing, rats were assessed for THC and CBD/THC effects on anxiety-like behaviour, social interaction and place conditioning. At the end of dosing, blood and brain levels of THC, and CB₁ and 5-HT_1A receptor binding were assessed.

Results

CBD potentiated an inhibition of body weight gain caused by chronic THC, and mildly augmented the anxiogenic effects, locomotor suppressant effects and decreased social interaction seen with THC. A trend towards place preference was observed in adolescent rats given CBD/THC but not those given THC alone. With both acute and chronic administration, CBD pre-treatment potentiated blood and brain THC levels, and lowered levels of THC metabolites (THC-COOH and 11-OH-THC). CBD co-administration did not alter the THC-induced decreases in CB₁ receptor binding and no drug effects on 5-HT_1A receptor binding were observed.

Conclusions

CBD can potentiate the psychoactive and physiological effects of THC in rats, most likely by delaying the metabolism and elimination of THC through an action on the CYP450 enzymes that metabolise both drugs.     

Psychomotor performance, subjective and physiological effects and whole blood Δ⁹-tetrahydrocannabinol concentrations in heavy, chronic cannabis smokers following acute smoked cannabis

Δ?-Tetrahydrocannabinol (THC) is the illicit drug most frequently observed in accident and driving under the influence of drugs investigations. Whole blood is often the only available specimen collected during such investigations, yet few studies have examined relationships between cannabis effects and whole blood concentrations following cannabis smoking. Nine male and one female heavy, chronic cannabis smokers resided on a closed research unit and smoked ad libitum one 6.8% THC cannabis cigarette. THC, 11-hydroxy-THC and 11-nor-9-carboxy-THC were quantified in whole blood and plasma. Assessments were performed before and up to 6 h after smoking, including subjective [visual analog scales (VAS) and Likert scales], physiological (heart rate, blood pressure and respirations) and psychomotor (critical-tracking and divided-attention tasks) measures. THC significantly increased VAS responses and heart rate, with concentration-effect curves demonstrating counter-clockwise hysteresis. No significant differences were observed for critical-tracking or divided-attention task performance in this cohort of heavy, chronic cannabis smokers. The cannabis influence factor was not suitable for quantifying psychomotor impairment following cannabis consumption and was not precise enough to determine recent cannabis use with accuracy. These data inform our understanding of impairment and subjective effects following acute smoked cannabis and interpretation of whole blood cannabinoid concentrations in forensic investigations.     

Women’s perception of adolescent marijuana use in a hispanic seasonal farm worker community: A qualitative study

We examined the perception of adolescent children’s marijuana use and its consequences in the Hispanic seasonal farmworking community of South Florida via three focus groups with Hispanic adult female seasonal workers (n?=?29). The women described how adolescents’ marijuana use increased over the past five years. Social networks for marijuana use were reported near schools and bus stations. Although participants expressed concern over adolescent marijuana use and involvement in selling marijuana, they reported that their job demands preclude their ability to supervise their children. Participants do not report unlawful marijuana use due to fear of deportation.     

Reinforcing effects of oral Δ<Superscript>9</Superscript>-THC in male marijuana smokers in a laboratory choice procedure

Rationale Oral Delta-9-tetrahydrocannabinol (Δ⁹-THC; Marinol) is medically available for the treatment of nausea associated with cancer chemotherapy and for wasting syndromes related to HIV/AIDS. Little is known about its reinforcing effects. Objective This study was conducted to characterize the reinforcing effects of oral Δ⁹-THC in experienced marijuana smokers under controlled laboratory conditions. Methods Ten healthy male marijuana users completed this 17-day residential study. On days 2, 6, 10, and 14, at 0900 h, participants received a “sample” oral dose of Δ⁹-THC (0, 10, 20 mg) and an alternative reinforcer, a $2 voucher (redeemable for cash at study’s end). Over the next 3 days, they had 11 opportunities to self-administer either the sampled dose of Δ⁹-THC or to receive a $2 voucher. Results Participants chose active Δ⁹-THC (10 and 20 mg) more often than placebo (<two selections vs ∼four selections, respectively). However, they chose active Δ⁹-THC on less than 50% of choice opportunities. Both active Δ⁹-THC doses produced significant increases in “positive” subjective effects, impaired psychomotor performance, and increased heart rate, relative to the placebo conditions. Conclusion These data indicate that oral Δ⁹-THC may have modest abuse liability in experienced marijuana smokers.     

Cortical glutamate–dopamine interaction and ketamine-induced psychotic symptoms in man

Rationale The noncompetitive glutamate N-methyl-d-aspartate receptor antagonist ketamine induces transient psychotic symptoms in man. Involvement of dopaminergic mechanisms in these effects has been suggested. Objectives The purpose of this article is to study the effects of ketamine on extrastriatal dopamine receptor availability in healthy subjects and extracellular dopamine levels in rat cortex. Materials and methods The effect of computer-driven subanesthetic ketamine infusion on cortical dopamine release was studied in healthy male subjects using a controlled study design. Dopamine D2/D3 receptor availability was quantified using positron emission tomography (PET) and [¹¹C]FLB 457. A conventional region of interest-based analysis and voxel-based analysis was applied to the PET data. The ketamine-induced cortical dopamine release in rats was studied using in vivo microdialysis. Results Ketamine infusion reduced significantly the [¹¹C]FLB 457 binding potential (BP) in the posterior cingulate/retrosplenial cortices, suggestive of increased dopamine release. This brain imaging finding was further supported by a microdialysis experiment in rats showing that ketamine increased the extracellular dopamine concentration by up to 200% in the retrosplenial cortex. Ketamine-induced psychotic symptoms were associated with changes in the [¹¹C]FLB 457 BP in the dorsolateral prefrontal and anterior cingulate cortices. Conclusions Our results suggest that cortical dopaminergic mechanisms have a role in the emergence of ketamine-induced psychosis-like symptoms in man. The glutamate–dopamine interaction in the posterior cingulate during ketamine infusion is well in line with the recent functional and structural imaging studies suggesting involvement of this cortical area in the development of schizophrenic psychosis.     

Plasma paraoxonase and arylesterase activities in smokers and smokeless tobacco users as Maraş powder

Abstract

Context: Mara? powder (MP), a different type of smokeless tobacco (ST) prepared from a tobacco called Nicotiana rustica Linn, is widely used in the Southern Turkey. Smoking and ST cause oxidative stress (OS) in the human body. Paraoxonase (PON) and arylesterase (ARE) are antioxidant enzymes.

Objective: To investigate the effects of MP on activities of PON, ARE, and malondialdehyde (MDA) levels in plasma and to compare these parameters in smokers and MP users (MPU).

Materials and methods: The study consisted of smokers, MPU, and control group (CG) neither smoking nor using MP healthy subjects. PON and ARE activities were measured spectrophotometrically using paraoxon and phenylacetate substrates, respectively.

Results: PON and ARE activities were decreased whereas MDA levels were increased in tobacco groups compared to the CG. The differences of ARE and MDA values between the tobacco groups and CG were found statistically significant (p?<?0.01). But no significant differences were detected between the groups in the activity of PON (p?>?0.05). However, the lowest activities of the enzymes were obtained in MPU.

Conclusion: Our results can help to evaluate harmful effects of cigarette and ST as MP. These effects can be attributed to increased OS. Increased plasma MDA levels and decreased ARE activities may be important in assessing oxidant/antioxidant imbalance in MPU as well as smokers. Also, using of MP has harmful effects at least cigarette smoking.     

Reversal by 3,3′,5-triido-l-thyronine of the working memory deficit,and the decrease in acetylcholine,glutamate and γ-aminobutyric acid induced by ethylcholine aziridinium ion in mice

Summary The effect of 3,3,5-triiodo-l-thyronine (T₃) on working memory in ethylcholine aziridinium ion (AF64A)-treated mice was studied in a delayed nonmatching to sample task using a T-maze. After behavioural testing was completed, mice were killed by microwave irradiation and regional brain levels of acetylcholine, aspartate, glutamate, glutamine, glycine, taurine, and -aminobutyric acid (GABA) were measured by high-performance liquid chromatography with electrochemical detection. Treatment with AF64A (7 nmol, i. c. v.) produced a deficit in working memory performance in the non-matching to sample task at 30 s delay, and decreased acetylcholine, glutamate, and GABA levels in the hippocampus, but not in the septum and cerebral cortex. Administration of T₃ (0.3 mg/kg, p.o., once daily for 6 days) to AF64A-treated animals improved the deficit in working memory performance and reversed the decrease in acetylcholine, glutamate, and GABA levels in the hippocampus. These results indicate that the deficit in performance induced by AF64A can be improved by T₃ administration. Correspondence to: E. Abe at the above address     

Pulmonary hypertension and vascular oxidative damage in cigarette smoke exposed eNOS−/− mice and human smokers

Context: Cigarette smoke is known to be associated with pulmonary hypertension in humans and in animal models. Although the etiology of pulmonary hypertension in smokers is not understood, recent work has suggested a role for inducible nitric oxide synthase (iNOS) in inducing oxidative stress.

Objective and Methods: To further evaluate this question, we assessed eNOS-/- mice exposed to air or cigarette smoke for the presence of pulmonary hypertension and examined vascular remodeling and expression of nitrotyrosine, a marker of reactive nitrogen species-induced oxidative damage, using immunohistochemistry. To ascertain whether oxidants may play a role in humans, we also examined lung tissue from nonsmokers, and patients with chronic obstructive pulmonary disease (COPD) with and without pulmonary hypertension.

Results: We found that eNOS^?/? mice developed increased pulmonary arterial pressure after six months cigarette smoke exposure, and this was associated with vascular remodeling and increased vascular nitrotyrosine staining. iNOS gene expression was decreased in the pulmonary arteries of the smoke exposed animals, and no protein was detectable by immunohistochemistry. In humans, vascular nitrotyrosine staining intensity was increased in smokers with COPD compared to nonsmokers, and further increased in smokers with combined COPD and pulmonary hypertension.

Conclusions: We conclude that cigarette smoke-induced pulmonary hypertension is associated with evidence of oxidative vascular damage by reactive nitrogen species, but that iNOS does not appear to be the major contributor to such damage. Most likely the source of reactive nitrogen species is the cigarette smoke itself.     

Effect of stearic acid on neuroprotection against oxygen/glucose deprivation, H2O2 and glutamate insults in rat hippocampal cells

AIM： To observe the neuroprotective effect of stearic acid （SA） （1 -30μmol/L） on rat hippocampal cells insulted by oxygen-glucose depriveation （OGD）, H2O2 and glutamate in vitro. METHODS： Primarily cultured fetus rat hippocampal cells were partitioned into three groups at random as follows： control group, injury group, and pretreatment group. Injury models of hippocampal cells were induced by oxygen-glucose deprivation, H2O2 and glutamate.     

Uptake of ω-Amino Acids by Rat Small Intestine and Kidney Cortex in vitro

Abstract

1. The mode of uptake of some ω-amino acids was studied in vitro using everted sacs prepared from rat small intestine.

2. The therapeutic, antifibrinolytic compounds, ?-aminocaproic acid (Epsicapron) and trans-4-aminomethylcyclohexanecarboxylic acid (Cyclocapron) were not actively transported against the concentration gradient.

3. β-Alanine, DL-β-aminoisobutyric acid, γ-aminobutyric acid, δ-aminovaleric acid and ω-aminocaprylic acid failed to show active transport with small intestine in vitro.

4. DL-β-Aminoisobutyric acid, Epsicapron, Cyclocapron and ω-amino-caprylic acid transferred from the intestine by diffusion down the concentration gradient.

5. Epsicapron, Cyclocapron and β-alanine were accumulated to a small extent by kidney-cortex slices.