Nicotine and Cytisine Embryotoxicity in the Experimental Zebrafish Model.

Tobacco smoking is one of the most serious health problems. Potentially lethal effects of nicotine for adults can occur with as little as 30 to 60 mg, although severe symptoms can arise with lower doses. Furthermore, the route of administration also influences the toxicity. Cytisine is one of the most popular medications in nicotinism treatment. Like nicotine, cytisine is a plant alkaloid, signaling through nicotinic acetylcholine receptors. Our study evaluated the effects of cytisine in nicotine-induced embryotoxic effects using zebrafish larvae. We examined the teratogenicity of nicotine and cytisine alone or in combination. Nicotine increased mortality and delayed hatching of zebrafish larvae in a dose-dependent manner. Cytisine did not affect mortality in a wide range of concentrations, and hatching delay was observed only at the highest concentrations, above 2 mM. Administering compounds together partially reduced the adverse teratogenic effect induced by nicotine alone. The protective effect of cytisine against the nicotine effect, observed in zebrafish, will contribute to future studies or treatments related to nicotine addiction or prenatal nicotine exposure in humans.

Poly(levodopa)-Functionalized Polysaccharide Hydrogel Enriched in Fe3O4 Particles for Multiple-Purpose Biomedical Applications.

In recent years, there has been a significant increase in interest in the use of curdlan, a naturally derived polymer, for medical applications. However, it is relatively inactive, and additives increasing its biomedical potential are required; for example, antibacterial compounds, magnetic particles, or hemostatic agents. The stability of such complex constructs may be increased by additional functional networks, for instance, polycatecholamines. The article presents the production and characterization of functional hydrogels based on curdlan enriched with Fe3O4 nanoparticles (NPs) or Fe3O4-based heterostructures and poly(L-DOPA) (PLD). Some of the prepared modified hydrogels were nontoxic, relatively hemocompatible, and showed high antibacterial potential and the ability to convert energy with heat generation. Therefore, the proposed hydrogels may have potential applications in temperature-controlled regenerative processes as well as in oncology therapies as a matrix of increased functionality for multiple medical purposes. The presence of PLD in the curdlan hydrogel network reduced the release of the NPs but slightly increased the hydrogel's hemolytic properties. This should be taken into account during the selection of the final hydrogel application.

Xanthotoxin modulates oxidative stress, inflammation, and MAPK signaling in a rotenone-induced Parkinson's disease model.

AIMS: Parkinson's disease (PD) is characterized by motor disabilities precipitated by α-synuclein aggregation and dopaminergic neurodegeneration. The roles of oxidative stress, neuroinflammation, dysfunction of the mitogen-activated protein kinase (MAPK) pathway, and apoptosis in dopaminergic neurodegeneration have been established. We investigated the potential neuroprotective effect of xanthotoxin, a furanocoumarin extracted from family Apiaceae, in a rotenone-induced PD model in rats since it has not yet been elucidated. MAIN METHODS: For 21 days, rats received 11 rotenone injections (1.5 mg/kg, s.c.) on the corresponding days to induce a PD model and xanthotoxin (15 mg/kg, i.p.) daily. KEY FINDINGS: Xanthotoxin preserved dopaminergic neurons and restored tyrosine hydroxylase positive cells, with suppression of α-synuclein accumulation and restoration of striatal levels of dopamine and its metabolites resulting in amelioration of motor deficits. Furthermore, xanthotoxin impeded rotenone-stimulated neurodegeneration by reducing oxidative stress, which was confirmed by malondialdehyde suppression and glutathione antioxidant enzyme augmentation. It also suppressed neurotoxic inflammatory mediators including tumor necrosis factor-α, interleukin-1ß, and inducible nitric oxide synthase. Additionally, xanthotoxin attenuated the rotenone-mediated activation of MAPK kinases, C-Jun N-terminal kinase, p38 MAPK, and extracellular signal-regulated kinases 1/2, with consequent ablation of apoptotic mediators including Bax, cytochrome c, and caspase-3. SIGNIFICANCE: This study revealed the neuroprotective effect of xanthotoxin in a rotenone-induced PD model in rats, an action that could be attributed to its antioxidant, anti-inflammatory activities as well as to its ability to maintain the function of the MAPK signaling pathway and attenuate apoptosis. Therefore, it could be a valuable therapy for PD.

Collagen-Sealed Polyester Vascular Prostheses Functionalized by Polycatecholamine Coatings.

Collagen-sealed polyester (PET) prostheses are commonly used in reconstructive vascular surgery due to their self-sealing properties. To prevent post-surgical infection, different modification methods have been tested but so far none have showed long-term satisfactory efficiency. For this reason, in the present study, a commercial collagen-sealed PET prosthesis was coated by a highly adhesive poly (L-DOPA) layer maintaining the sealing protein without losing the original properties and functionality. This modified (as proven by SEM, FTIR, XPS and contact angle) graft exhibited comparable wettability and elasticity as pristine commercial graft, as well as reduced hemolysis-inducing effect, lowered toxicity against human endothelial cells and reduced toxicity in Danio rerio model. Poly (L-DOPA)-coated grafts were shown to bind six times more aminoglycoside antibiotic (gentamicin) than pristine graft. Poly (L-DOPA)-coated antibiotic-bound prostheses exhibited an improved antibacterial activity (bacterial growth inhibition and anti-adhesive capacity) in comparison with pristine antibiotic-bound graft. Overall, poly (L-DOPA)-coatings deposited on PET vascular grafts can effectively functionalize collagen-sealed prostheses without the loss of protein sealing layer and allow for antibiotics incorporation to provide higher safety in biomedical applications.

Polycatecholamine and gentamicin as modifiers for antibacterial and blood-biocompatible polyester vascular prostheses.

Polyester (PET) prostheses are commonly used in reconstructive vascular surgery. The most serious complication after implantation is early or late infection of the graft. Therefore, there is high demand to protect prosthesis against bacterial adhesion and biofilm development. For this reason, in this work PET prostheses were first coated by highly adhesive polycatecholamine layer. The grafts were then coupled with gentamicin and studied in relation to morphological and structural properties, biological safety (contact with blood, reaction of vascular endothelial cells (HUVEC), Danio rerio fish), drug release and antibacterial activity. Among two tested catecholamine monomers, L-DOPA was found to be more effective precursor in this process than dopamine. For L-DOPA, assistance of Cu2+, Mg2+ and Na+ ions seems to increase the amount of further immobilized drug. Coated prostheses exhibited greater human endothelial cell proliferation increase and lower cytotoxic effect than uncoated. The modification reduced the hemolysis observed for pristine commercial graft and limited the rate of abnormalities in D. rerio larvae, confirming the safety of the proposed modification. The coating allowed to double the amount of immobilized antibiotic in comparison with uncoated graft which resulted in increased antibacterial activity and reduced bacterial adhesion against 4 bacterial strains prevalent in biomaterials infections. Overall, poly(L-DOPA)-coatings deposited on PET vascular grafts can effectively functionalize these prostheses for higher safety in biomedical applications.

Tadalafil and bergapten mitigate streptozotocin-induced sporadic Alzheimer's disease in mice via modulating neuroinflammation, PI3K/Akt, Wnt/ß-catenin, AMPK/mTOR signaling pathways.

Sporadic Alzheimer's disease (SAD) is a slowly progressive neurodegenerative disorder. This study aimed to investigate neuroprotective potential of tadalafil (TAD) and bergapten (BG) in SAD-induced cognitive impairment in mice. SAD was induced by single injection of streptozotocin (STZ; 3 mg/kg, ICV). STZ resulted in AD-like pathologies including Aß deposition, tau aggregation, impaired insulin and Wnt/ß-catenin signaling, as well as autophagic dysfunction and neuroinflammation. Administration of TAD or BG at doses of 20 and 25 mg/kg, respectively, for 21 consecutive days attenuated STZ-induced hippocampal insult, preserved neuronal integrity, and improved cognitive function in the Morris water maze and object recognition tests paralleled by reduction in Aß expression by 79 and 89% and tau hyperphosphorylation by 60 and 61%, respectively. TAD and BG also enhanced protein expression of pAkt, pGSK-3ß, beclin-1 and methylated protein phosphatase 2A (PP2A) and gene expression of cyclin D1, while raised BDNF immunoreactivity. Furthermore, TAD and BG boosted hippocampal levels of cGMP, PKG, Wnt3a, and AMPK and reduced expression of ß-catenin and mTOR by 74% and 51%, respectively. TAD and BG also halted neuroinflammation by reducing IL-23 and IL-27 levels, as well as protein expression of NF-κB by 62% & 61%, respectively. In conclusion, this study offers novel insights on the neuroprotective effects of TAD or BG in the management of SAD as evidenced by improved cognitive function and histological architecture. This could be attributed to modulation of the crosstalk among PI3K/Akt/GSK-3ß, PP2A, mTOR/autophagy, cGMP/PKG, and Wnt/ß-catenin signaling cascades and mitigation of neuroinflammation.

Mechanisms of the Procognitive Effects of Xanthotoxin and Umbelliferone on LPS-Induced Amnesia in Mice.

Neuroinflammation plays an essential role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease. Although coumarins have been shown to improve cognitive function in animal models and exert anti-inflammatory effects in cell cultures, the exact mechanism of their neuroprotective effects has not yet been fully elucidated. The present study aimed to investigate the neuroprotective effects of xanthotoxin (furanocoumarin) and umbelliferone (simple coumarin) in lipopolysaccharide-induced cognitive dysfunction in mice. For evaluation memory and learning processes, a passive avoidance test was used. Furthermore, acetylcholinesterase level and impact on the tumor necrosis factor α, interleukin 10 levels in the whole brain, and cyclooxygenase-II in hippocampus was established. Subchronic administration of both coumarins (15 mg/kg) enhanced the learning and memory function, but only the xanthotoxin improved cognitive processes impaired by lipopolysaccharide (0.8 mg/kg) administration. Behavioral results stay in line with acetylcholinesterase level in the brain. A statistically significant decrease in the level of tumor necrosis factor α and cyclooxygenase-II in lipopolysaccharide-treated rodents after coumarins' administration was observed. Together, our findings demonstrate that both coumarins improved cognitive functions, but only xanthotoxin significantly enhanced the learning and memory function and reduced the level of acetylcholinesterase in lipopolysaccharide-treated mice. This effect may suggest that only furanocoumarin-xanthotoxin attenuates neuroinflammation and enhances cholinergic neurotransmission, thus it can be a potential remedy with procognitive potential effective in treatment of neuroinflammatory disease.

Xanthotoxin and umbelliferone attenuate cognitive dysfunction in a streptozotocin-induced rat model of sporadic Alzheimer's disease: The role of JAK2/STAT3 and Nrf2/HO-1 signalling pathway modulation.

The aim of the present study was to assess the neuroprotective effects of xanthotoxin and umbelliferone in streptozotocin (STZ)-induced cognitive dysfunction in rats. Animals were injected intracerebroventricularly (ICV) with STZ (3 mg/kg) once to induce a sporadic Alzheimer's disease (SAD)-like condition. Xanthotoxin or umbelliferone (15 mg/kg, i.p.) were administered 5 hr after ICV-STZ and daily for 20 consecutive days. Xanthotoxin or umbelliferone prevented cognitive deficits in the Morris water maze and object recognition tests. In parallel, xanthotoxin or umbelliferone reduced hippocampal acetylcholinestrase activity and malondialdehyde level. Moreover, xanthotoxin or umbelliferone increased glutathione content. These coumarins also modulated neuronal cell death by reducing the level of proinflammatory cytokines (tumour necrosis factor-alpha and interleukin-6), inhibiting the overexpression of inflammatory markers (nuclear factor κB [NF-κB] and cyclooxygenase II), and upregulating the expression of NF-κB inhibitor (IκB-α). Interestingly, xanthotoxin diminished phosphorylated JAK2 and phosphorylated STAT3 protein expression, while umbelliferone markedly replenished nuclear factor erythroid-derived 2-like 2 (Nrf2) and haem oxygenase-1 (HO-1) levels. The current study provides evidence for the protective effect of xanthotoxin and umbelliferone in STZ-induced cognitive dysfunction in rats. This effect may be attributed, at least in part, to inhibiting acetylcholinestrase and attenuating oxidative stress, neuroinflammation and neuronal loss.

Fishing for a deeper understanding of nicotine effects using zebrafish behavioural models.

Nicotine, the primary psychoactive component of tobacco, is the most widely used drug of abuse. Although the substance is well-known, there is still a lack of information concerning its long-term neurological and physiological effects and its mechanisms of action. In order to search for new, effective drugs in the therapy of nicotinism, as well as to design new drugs that exert positive nicotine-like effects, further experiments are needed, ideally also using new behavioural models and paradigms. A wide range of complex behaviours - including aggression, anxiety, long- and short-term memory, object discrimination and colour preference - have recently been comprehensively classified and characterized in the zebrafish model. Zebrafish offer an attractive experimental platform, based on a microscale in vivo bioassays, which can be used to investigate psychoactive drugs, their effects on the central nervous system and potential treatments of drug addictions. In this review, we present recent data revealing the potential of the zebrafish model to evaluate the effects and molecular mechanisms of nicotine by taking into consideration its impact on anxiety, learning and memory, addiction and social behaviours.

3-Furan-2-yl-N-p-tolyl-acrylamide, a highly selective positive allosteric modulator of α7 nicotinic receptors, produces anxiolytic-like activity in mice.

BACKGROUND: Several lines of investigations support the idea that nicotinic acetylcholine receptors modulate neuronal pathways involved in anxiety and depression. AIMS: The purpose of this study was to determine whether 3-furan-2-yl-N-p-tolyl-acrylamide, a highly selective positive allosteric modulator of α7 nicotinic acetylcholine receptors, influences anxiety-like behaviour in mice, and to determine the modulatory activity of 3-furan-2-yl-N-p-tolyl-acrylamide on mice pretreated with either nicotine or selective α7-agonists (i.e. PNU-282987 or (2.4)-dimethoxybenzylidene anabaseine dihydrochloride). METHODS: The elevated plus maze and novelty suppressed feeding tests were selected to evaluate 3-furan-2-yl-N-p-tolyl-acrylamide and other nicotinic ligands on anxiety-like behaviour in mice. RESULTS: The results indicated that: (a) 3-furan-2-yl-N-p-tolyl-acrylamide induces anxiolytic-like activity at 0.5 (elevated plus maze) and 1.0 (novelty suppressed feeding) mg/kg, respectively, after acute treatment, whereas its efficacy is increased after chronic treatments (i.e. active at 0.1 mg/kg; elevated plus maze). This is the first time showing anxiolytic-like activity elicited by 3-furan-2-yl-N-p-tolyl-acrylamide, contrary to the lack of activity for PNU-120596 (0.1 mg/kg); (b) the anxiolytic-like activity of 0.5 mg/kg 3-furan-2-yl-N-p-tolyl-acrylamide is inhibited by methyllycaconitine, a selective α7-antagonist, suggesting that α7 nicotinic acetylcholine receptors are involved in this process; (c) 0.5 mg/kg 3-furan-2-yl-N-p-tolyl-acrylamide reverses the anxiogenic effects induced by 0.1 mg/kg nicotine but not by 10.0 mg/kg PNU-282987; and (d) inactive doses of both 3-furan-2-yl-N-p-tolyl-acrylamide (0.1 mg/kg) and (2.4)-dimethoxybenzylidene anabaseine dihydrochloride (1.0 mg/kg) produce anxiolytic-like effects, suggesting drug interactions, probably synergistic. CONCLUSIONS: Our findings indicated that anxiolytic-like activity is mediated by α7 nicotinic acetylcholine receptors, supporting the concept that these receptors modulate anxiety processes. The results indicating that the chronic treatment with 3-furan-2-yl-N-p-tolyl-acrylamide is more efficient than the acute treatment in eliciting anxiolytic-like activity, and that 3-furan-2-yl-N-p-tolyl-acrylamide reverses the anxiogenic effects induced by nicotine, might be of therapeutic importance during smoking cessation.

Rutin as Neuroprotective Agent: From Bench to Bedside.

Flavonoids are major dietary constituents of plant-based food found ubiquitously in plant kingdom where they are usually present in substantial amounts. Rutin is a flavonol-type polyphenol which consists of the flavonol quercetin and the disaccharide rutinose. Rutin has been reported to exert diverse biological effects such as antitumor and antimicrobial mainly associated to its antioxidant and anti-inflammatory activities. Mental, neurological, and behavioural disorders are an important and growing cause of morbidity. Most of these disorders combine a high prevalence, early onset, progressive clinical course, and impairment of critical brain functions making them a major contributor to the global disease burden. In the present work, the biological in vitro and in vivo effects and the potential therapeutic applications of rutin in neurodegenerative processes are reviewed, as well as their bioavailability and pharmacokinetics, which are essential for a better understanding of its biological effectiveness. Moreover, the present review also provides an overview of the molecular mechanisms through which rutin is proposed to exert its neuroprotective effects.

Perspectives and New Aspects of Metalloproteinases' Inhibitors in the Therapy of CNS Disorders: From Chemistry to Medicine.

Matrix metalloproteinases (MMPs) play a key role in remodeling of the extracellular matrix (ECM) and, at the same time, influence cell differentiation, migration, proliferation, and survival. Their importance in a variety of human diseases including cancer, rheumatoid arthritis, pulmonary emphysema and fibrotic disorders has been known for many years but special attention should be paid on the role of MMPs in the central nervous system (CNS) disorders. Till now, there are not many well documented physiological MMP target proteins in the brain but only some pathological ones. Numerous neurodegenerative diseases are a consequence of or result in disturbed remodeling of brain ECM, therefore proper action of MMPs as well as control of their activity may play crucial roles in the development of these diseases. In the present review, we discuss the role of metalloproteinase inhibitors, from the wellknown natural endogenous tissue inhibitors of metalloproteinases (TIMPs) to the exogenous synthetic ones like (4-phenoxyphenylsulfonyl)methylthiirane (SB-3CT), tetracyclines, batimastat (BB-94) and FN-439. As the MMP-TIMP system has been well described in physiological development as well as in pathological conditions mainly in neoplastic diseases, the knowledge about the enzymatic system in mammalian brain tissue still remains poorly understood in this context. Therefore, we focus on MMPs inhibition in the context of the physiological function of the adult brain as well as pathological conditions including neurodegenerative diseases, brain injuries, and others.

Impacts of cannabinoid receptor ligands on nicotine- and chronic mild stress-induced cognitive and depression-like effects in mice.

Taking into account the rather frequent concomitance of nicotine abuse and stress, we aimed to research memory- and depression-related effects of nicotine administration in combination with chronic mild unpredictable stress (CMUS) in mice and an involvement of the endocannabinoid system through CB1 and CB2 receptors. Mice were submitted to the CMUS for 4 weeks. Effects on depression-like behaviors and cognition, exerted by a combined administration of CB1, i.e., Oleamide (2.5, 5.0 mg/kg), AM 251 (0.1, 0.25 mg/kg) and CB2, i.e., JWH 133 (0.5, 2.0 mg/kg), AM 630 (0.25, 2.0 mg/kg) receptor ligands and nicotine (0.05, 0.1, 0.2 and 0.5 mg/kg), were then studied in stressed and unstressed mice by the forced swimming test and the passive avoidance paradigm, respectively. The results revealed that the CMUS-exposed mice exhibited depression-like behaviors and memory disturbances, while both effects were alleviated by nicotine. CB1 receptor ligands decreased antidepressive and cognitive (the latter for CB1 receptor antagonist only) effects of subchronic nicotine administration in stressed mice. CB1 and CB2 receptor antagonists exerted themselves some procognitive effects in those mice. Regarding the unstressed mice, CB1 and CB2 receptor ligands reversed the antidepressive effects of subchronic nicotine administration, while nicotine, in an ineffective dose, co-administered with CB2 receptor ligands, improved cognition. We confirmed the role of the two main subtypes of cannabinoid receptors, termed CB1 and CB2, on stress- and nicotine-related behavioral changes in mice. Our study has contributed to the understanding of the mechanisms involved in stress- and nicotine-induced disorders, such as anhedonia and memory disturbances.

Tanshinones and mental diseases: from chemistry to medicine.

The prevalence of mental diseases, especially neurodegenerative disorders, is ever-increasing, while treatment options for such disorders are limited and insufficient. In this scarcity of available medication, it is a feasible strategy to search for potential drugs among natural compounds, such as those found in plants. One such plant source is the root of Chinese sage, Salvia miltiorrhiza Bunge (Labiatae), which contains several compounds reported to possess neuroprotective activities. The most important of these compounds are tanshinones, which have been reported to possess ameliorative activity against a myriad of mental diseases such as Alzheimer's disease, cerebral ischemia/reperfusion injury, and glioma, along with promoting neuronal differentiation and manifesting antinociceptive and anticonvulsant outcomes. This review offers a critical evaluation of the utility of tanshinones to treat mental illnesses, and sheds light on the underlying mechanisms through which these naturally occurring compounds confer neuroprotection.

In vivo modulation of the behavioral effects of nicotine by the coumarins xanthotoxin, bergapten, and umbelliferone.

RATIONALE: Nicotine, a dominant alkaloid found in tobacco, is responsible for physical dependence, as well as addiction to cigarette smoking; consequently, smoking cessation is a very difficult process. Hepatic cytochrome P-450 2A6 (CYP2A6) is involved in the 70-80 % of the initial metabolism of nicotine and its co-metabolites. As this metabolism is slowed by inhibitors of CYP2A6, this kind of enzymatic inhibition has been proposed as a novel target for smoking cessation. OBJECTIVES: Nicotine administered alone improved memory acquisition and consolidation as well as exerted antidepressive activity in animal models. These effects persist for 24 h. However, they are completely extinguished 48 h after administration. METHODS: To investigate if the coumarins prolong the behavioral effects of nicotine, the forced swimming test (FST)-animal models of depression, and passive avoidance (PA) test-memory and learning paradigm were used. RESULTS: This study revealed that three CYP2A6 inhibitors: two furanocoumarins, xanthotoxin (15 mg/kg) and bergapten (25 mg/kg), and the simple coumarin umbelliferone (25 mg/kg), prolonged the antidepressive and procognitive effects of nicotine. CONCLUSIONS: These natural products may offer a new approach to the treatment of nicotinism as antidepressant and memory improvement actions are one of the main factors of nicotine dependence.

The positive allosteric modulator of α7 nicotinic acetylcholine receptors, 3-furan-2-yl-N-p-tolyl-acrylamide, enhances memory processes and stimulates ERK1/2 phosphorylation in mice.

To determine whether 3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2), a positive allosteric modulator of α7 nicotinic acetylcholine receptors (nAChRs), improves memory processes, passive avoidance tests were conducted in male mice after acute and chronic treatments. To determine the neuronal mechanisms underlying the promnesic activity elicited by PAM-2, the effect of this ligand on α7 nAChR up-regulation and ERK1/2 phosphorylation was assessed in the hippocampus and prefrontal cortex. The results indicate that: (1) PAM-2 improves memory acquisition/consolidation after acute treatment (Day 2) and memory consolidation after chronic treatment (Day 22). Although no effect was observed on α7 nAChR up-regulation, the chronic, but not acute, PAM-2 treatment increases ERK1/2 kinase phosphorylation, (2) the promnesic activity of PAM-2 was inhibited by methyllycaconitine, a selective α7-antagonist, confirming the role of α7 nAChRs, (3) a synergistic (acute) effect was observed between inactive doses of PAM-2 (0.1 mg/kg) and DMXBA (0.3 mg/kg), a selective α7-agonist, and (4) PAM-2 reversed the memory impairment elicited by scopolamine, a muscarinic antagonist. The results demonstrate that PAM-2 presents promnesic activity mediated by α7 nAChRs, and is able to trigger ERK1/2 phosphorylation only after chronic treatment.

Mephedrone and nicotine: oxidative stress and behavioral interactions in animal models.

The purpose of our experiment was to examine the influence of co-administration of nicotine and mephedrone on anxiety-like behaviors, cognitive processes and the nicotine-induced behavioral sensitization as well as processes connected with induction of oxidative stress in the brain of male Swiss mice. The results revealed that co-administration of subthreshold doses of mephedrone and nicotine (0.05 mg/kg each) exerted marked anxiogenic profile in the elevated plus maze and displayed pro-cognitive action in the passive avoidance paradigm (nicotine 0.05 mg/kg and mephedrone 2.5 mg/kg). Furthermore, one of the main findings of the present study was that mephedrone, administered alone at the dose not affecting locomotor activity of mice (1 mg/kg), enhanced the expression of nicotine-induced locomotor sensitization. Moreover, mephedrone administered with nicotine decreased general antioxidant status and catalase activity as well as antioxidant enzymes activity in the hippocampus and prefrontal cortex and increased concentration of malondialdehyde, an indicator of lipid peroxidation processes. Considering the likelihood that mephedrone is taken as a part of polydrug combination with nicotine, the effects of this combination on mammalian organisms have been confirmed in our study. Understanding the consequences of co-administration of psychoactive substances on the central nervous system and oxidative processes in the brain provide the important toxicological significance, and may be useful in polydrug intoxication treatment.

Influence of calcium channel antagonists on nonsomatic signs of nicotine and D-amphetamine withdrawal in mice.

BACKGROUND: Nonsomatic signs of psychostimulant withdrawal, difficult to demonstrate in animal paradigms, may appear to promote drug seeking and drug relapse in humans; thus, it is important to understand the mechanisms that mediate this kind of behaviors. The present study was undertaken to examine the calcium-dependent mechanism of negative nonsomatic and anhedonia-related symptoms of acute and protracted withdrawal of nicotine and D-amphetamine. METHODS: Mice were chronically treated with nicotine (seven days, three times daily, 3.35 mg/kg, sc) or D-amphetamine (14 days, once daily, 2.5mg/kg, ip). Then, at the first, seventh or 14th day of withdrawal, anxiety- or depression-related effects, as well as cognition or nociception were studied. RESULTS: Our results demonstrated that, at the seventh or 14th day of D-amphetamine or nicotine withdrawal, respectively, mice exhibited increased anxiety and depression-like effects, memory impairment and hyperalgesia. Further, major findings showed that calcium channel antagonists, i.e., nimodipine, verapamil and flunarizine (10 and 20mg/kg, ip), injected before the test, attenuated above-mentioned signs of drug withdrawal. CONCLUSIONS: As an outcome, these findings support the hypothesis that similar calcium-dependent mechanisms are involved in an aversive nonsomatic component, associated with nicotine or d-amphetamine withdrawal. We can suggest that calcium channel blockers have potential to alleviate drug withdrawal and may thus be beneficial as pharmacotherapy of drug cessation and relapse.

A comparison of mecamylamine and bupropion effects on memory-related responses induced by nicotine and scopolamine in the novel object recognition test in mice.

BACKGROUND: The aim of the present study was to evaluate the involvement of the cholinergic receptors ligands in the memory-related responses in mice, using the novel object recognition (NOR) test. METHODS: The NOR test is based on natural, exploratory abilities of animals exposed to a new environment. In the first session, two copies of the same object were presented. In the next sessions (30min and 24h after), one of the familiar object and a new object were presented. RESULTS: The mice injected with nicotine (0.035 and 0.175mg/kg, free base, sc) before the first session spent more time exploring the new object than the familiar one at the second and third session, indicating that nicotine improved cognition. In turn, the mice injected with scopolamine (0.3 and 1mg/kg, ip) before the first session spent less time exploring the new object than the familiar one at the second and third trial, indicating that scopolamine impaired the memory performance. Additionally, the acute injection of drugs used in smoking cessation in humans: mecamylamine (0.5 and 1mg/kg) and bupropion (5 and 10mg/kg), prior to injections of nicotine (0.035mg/kg) or scopolamine (1mg/kg), significantly prevented nicotine-induced memory improvement or scopolamine-induced memory impairment, at the second and third session. CONCLUSIONS: The results of our studies unveiling neuronal mechanisms for cholinergic system of memory processes, via both nicotinic and muscarinic cholinergic receptors, will be useful for development of more effective pharmacotherapies for memory impairment-like treatment of human disorders in which cholinergic pathways have been implicated.

Effects of imperatorin on nicotine-induced anxiety- and memory-related responses and oxidative stress in mice.

The purpose of the reported experiments was to examine the effects of imperatorin [9-[(3-methylbut-2-en-1-yl)oxy]-7H-furo[3,2-g]chromen-7-one] on anxiety and memory-related responses induced by nicotine in mice and their relation to the level of nicotine-induced oxidative stress in brain as well as in the hippocampus and the prefrontal cortex. Male Swiss mice were tested for anxiety in the elevated plus maze test (EPM), and for cognition using passive avoidance (PA) procedures. Imperatorin, purified by high-speed counter-current chromatography from methanol extract of fruits of Angelica officinalis, acutely administered at the doses of 10 and 20mg/kg impaired the anxiogenic effect of nicotine (0.1mg/kg, s.c.). Furthermore, acute injections of subthreshold dose of imperatorin (1mg/kg, i.p.) improved processes of memory acquisition when co-administered with nicotine used at non-active dose of 0.05 mg/kg, s.c. Additionally, repeated administration of imperatorin (1mg/kg, i.p., twice daily, for 6 days) improved different stages of memory processes (both acquisition and consolidation) when injected in combination with non-active dose of nicotine (0.05 mg/kg, s.c.) in the PA task. Oxidative stress was assessed by determination of antioxidant enzymes (glutathione peroxidases (GPx), superoxide dismutase (SOD), glutathione reductase (GR)) activities as well as of malondialdehyde (MDA) concentration in the whole brain, the hippocampus and the prefrontal cortex after repeated administration of imperatorin (1mg/kg, 6 days) and single nicotine injection (0.05 mg/kgs.c.) on the seventh day. The results of our research suggest strong behavioural interaction between imperatorin and nicotine at the level of anxiety- and cognitive-like processes. Furthermore, imperatorin inhibited nicotine-induced changes in examined indicators of oxidative stress, especially in the hippocampus and the cortex.