Synthesis and Photophysical Properties of Bipolar Compound: Triphenylamine/Diazafluorene-Carbazole.

Carbazole and triphenylamine, are two well-known hole transporting units that are attached to electron transporting unit 4,5-diazafluorene in a fascinating way to bring out non-planar configuration of a molecule. The synthesized compound exhibits good thermal stability (Td > 515 °C) and high glass transition temperature (Tg, 191 °C). Optical bandgap (Egopt) obtained from solid state absorption spectra was calculated to be 2.93 eV. Solid state photoluminescence spectra displays the emission maxima at 473 nm. The emission characteristics of the compound observed in solvents of different polarity confirms the existence of intramolecular charge transfer in their excited state. Density functional theory studies reveal that HOMO and HOMO-1 localized on triphenylamine is spatially separated from LUMO of 4,5-diazafluorene, which manifest its bipolar character. The realization of long lived charge separated state upon photo-excitation from time resolved photoluminescence studies ascertains the charge transfer from triphenylamine to 4,5-diazafluorene. The experimental and theoretical analysis of the compound proved it to be a promising candidate for the fabrication of OLED devices.

Principles of early human development and germ cell program from conserved model systems.

Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate during weeks 2-3 of early post-implantation development. Using in vitro models of hPGC induction, recent studies have suggested that there are marked mechanistic differences in the specification of human and mouse PGCs. This may be due in part to the divergence in their pluripotency networks and early post-implantation development. As early human embryos are not accessible for direct study, we considered alternatives including porcine embryos that, as in humans, develop as bilaminar embryonic discs. Here we show that porcine PGCs originate from the posterior pre-primitive-streak competent epiblast by sequential upregulation of SOX17 and BLIMP1 in response to WNT and BMP signalling. We use this model together with human and monkey in vitro models simulating peri-gastrulation development to show the conserved principles of epiblast development for competency for primordial germ cell fate. This process is followed by initiation of the epigenetic program and regulated by a balanced SOX17-BLIMP1 gene dosage. Our combinatorial approach using human, porcine and monkey in vivo and in vitro models provides synthetic insights into early human development.

Catalytic Selective Oxidation of ß-O-4 Bond in Phenethoxybenzene as a Lignin Model Using (TBA)5[PMo10V2O40] Nanocatalyst: Optimization of Operational Conditions.

The catalytic oxidation of phenethoxybenzene as a lignin model compound with a ß-O-4 bond was conducted using the Keggin-type polyoxometalate nanocatalyst (TBA)5[PMo10V2O40]. The optimization of the process's operational conditions was carried out using response surface methodology. The statistically significant variables in the process were determined using a fractional factorial design. Based on this selection, a central circumscribed composite experimental design was used to maximize the phenethoxybenzene conversion, varying temperature, reaction time, and catalyst load. The optimal conditions that maximized the phenethoxybenzene conversion were 137 °C, 3.5 h, and 200 mg of catalyst. In addition, under the optimized conditions, the Kraft lignin catalytic depolymerization was carried out to validate the effectiveness of the process. The depolymerization degree was assessed by gel permeation chromatography from which a significant decrease in the molar mass distribution Mw from 7.34 kDa to 1.97 kDa and a reduction in the polydispersity index PDI from 6 to 3 were observed. Furthermore, the successful cleavage of the ß-O-4 bond in the Kraft lignin was verified by gas chromatography-mass spectrometry analysis of the reaction products. These results offer a sustainable alternative to efficiently converting lignin into valuable products.

Prospects for increasing the utilization of cattle embryo transfer by small-scale milk and meat producers in tropical regions.

Small community cattle farmers in the tropics are facing challenges to deliver quality products whilst under pressure to increase milk and beef yields per cow. These challenges could be partially met by crossbreeding Bos taurus with Bos indicus (F1) cattle utilizing embryo transfer (ET) technology. The Bos taurus infusion would increase milk production, whilst the Bos indicus influence can improve resistance to the harsh environment of the tropics. Here, individuals from existing herds can be used to produce F1 embryos which benefit from hybrid vigour. Resultant female offspring would in turn receive an F1 embryo on reaching breeding maturity. This approach would help to provide a cost-effective, systematic approach to improve productivity in dairy and beef cattle in the tropics. However, full usage of ET, including in vitro applications, in the tropics will require improvements in procedures, resources and education.

Behavioural Fever Promotes an Inflammatory Reflex Circuit in Ectotherms.

BACKGROUND: The communication between the brain and the immune system is a cornerstone in animal physiology. This interaction is mediated by immune factors acting in both health and pathogenesis, but it is unclear how these systems molecularly and mechanistically communicate under changing environmental conditions. Behavioural fever is a well-conserved immune response that promotes dramatic changes in gene expression patterns during ectotherms' thermoregulatory adaptation, including those orchestrating inflammation. However, the molecular regulators activating the inflammatory reflex in ectotherms remain unidentified. METHODS: We revisited behavioural fever by providing groups of fish a thermal gradient environment during infection. Our novel experimental setup created temperature ranges in which fish freely moved between different thermal gradients: (1) wide thermoregulatory range; T° = 6.4 °C; and (2) restricted thermoregulatory range; T° = 1.4 °C. The fish behaviour was investigated during 5-days post-viral infection. Blood, spleen, and brain samples were collected to determine plasmatic pro- and anti-inflammatory cytokine levels. To characterize genes' functioning during behavioural fever, we performed a transcriptomic profiling of the fish spleen. We also measured the activity of neurotransmitters such as norepinephrine and acetylcholine in brain and peripheral tissues. RESULTS: We describe the first set of the neural components that control inflammatory modulation during behavioural fever. We identified a neuro-immune crosstalk as a potential mechanism promoting the fine regulation of inflammation. The development of behavioural fever upon viral infection triggers a robust inflammatory response in vivo, establishing an activation threshold after infection in several organs, including the brain. Thus, temperature shifts strongly impact on neural tissue, specifically on the inflammatory reflex network activation. At the molecular level, behavioural fever causes a significant increase in cholinergic neurotransmitters and their receptors' activity and key anti-inflammatory factors such as cytokine Il10 and Tgfß in target tissues. CONCLUSION: These results reveal a cholinergic neuronal-based mechanism underlying anti-inflammatory responses under induced fever. We performed the first molecular characterization of the behavioural fever response and inflammatory reflex activation in mobile ectotherms, identifying the role of key regulators of these processes. These findings provide genetic entry points for functional studies of the neural-immune adaptation to infection and its protective relevance in ectotherm organisms.

Impact of oenological antioxidant substances on the formation of 1-hydroxyethyl radical and phenolic composition in SO2 free red wines.

BACKGROUND: Different natural substances, chitosan, inactive dry yeasts and freeze-dried aqueous extracts from two wine industry by-products (stems and shoots) were used in red winemaking as possible alternatives to SO2 . The resistance to oxidation of wines was evaluated by electron paramagnetic resonance. The phenolic composition of wines was analyzed by high-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry, antioxidant activity was determined by DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and ABTS [2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation] assays and spectrophotometric measurements of color were compared. RESULTS: The wines elaborated with chitosan and inactive dry yeast presented greater capacity to inhibit the formation of the 1-hydroxyethyl radical compared to the wines elaborated with stem or shoot extracts. The total content of anthocyanins was higher in the wines elaborated with SO2 ; however, the concentration of flavan-3-ols was higher in the wines with chitosan. In addition, the wines with chitosan and inactive dry yeast presented the highest % polymerization. Wines elaborated with stem extract had a lower concentration of flavonols and stilbenes. CONCLUSION: Chitosan and inactive dry yeast, which are used as an alternative to SO2 in winemaking, allow the control of the formation of 1-HER in red wines. Wines with stem and shoot extracts showed a lower resistance to oxidation. © 2020 Society of Chemical Industry.

Multivariate approach to hydrogenated TiO2 photocatalytic activity under visible light.

The photocatalytic activity of hydrogenated TiO2 was evaluated in the photooxidation of methyl orange (MO). The hydrogenation of TiO2 was carried out by calcination of a mixture of TiO2 P-25 and NaBH4 , at 300 and 350°C for blue TiO2 and black TiO2 , respectively. An experimental design was made for the determination of the best reaction conditions for the oxidation of MO. The influence of catalyst dosage and pH on photocatalytic efficiency was optimized, and the degradation percentage of MO was the response factor. The photocatalytic reaction was performed using a Xenon lamp that simulates the solar light spectrum for the activation of the catalyst. It was determined that both blue and black TiO2 show the greatest activity at pH = 2 and 0.8 g/L of catalyst. Additionally, the positive influence of hydrogen peroxide in the photocatalytic activity of both hydrogenated catalysts was determined. In parallel, COD and TOC were also studied. PRACTITIONER POINTS: The extent of titania reduction by hydrogenation is dependent on the reaction time with sodium borohydride. The extent of titania reduction affects the photocatalytic activity in the oxidation of methyl orange. An excess of catalyst reduction inhibits the oxidation of the dye because of the increase of recombination points. The best reaction conditions were determined by multivariate optimization as pH 2 and 0.8 g L-1 of hydrogenated catalyst. The addition of hydrogen peroxide into the reaction system improves the oxidation yield attributed to their electron accepting capacity.

Optimization of Cyclohexanol and Cyclohexanone Yield in the Photocatalytic Oxofunctionalization of Cyclohexane over Degussa P-25 under Visible Light.

The sustainable transformation of basic chemicals into organic compounds of industrial interest using mild oxidation processes has proved to be challenging. The production of cyclohexanol and cyclohexanone from cyclohexane is of interest to the nylon manufacturing industry. However, the industrial oxidation of cyclohexane is inefficient. Heterogeneous photocatalysis represents an alternative way to synthesize these products, but the optimization of this process is difficult. In this work, the yields of photocatalytic cyclohexane conversion using Degussa P-25 under visible light were optimized. To improve cyclohexanol production, acetonitrile was used as an inert photocatalytic solvent. Experiments showed that the use of the optimized conditions under solar light radiation did not affect the cyclohexanol/cyclohexanone ratio. In addition, the main radical intermediary produced in the reaction was detected by the electronic paramagnetic resonance technique.

Bosutinib Inhibits EGFR Activation in Head and Neck Cancer.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and although new therapeutic approaches have been recently evaluated, overall patient survival is still poor. Thus, new effective and selective clinical treatments are urgently needed. An analysis of data from large-scale, high-throughput drug screening cell line projects identified Bosutinib, a Src/Abl inhibitor that is currently used for the treatment of chronic myelogenous leukemia, as a candidate drug to treat HNSCC. Using a panel of HNSCC-derived cell lines, we found that treatment with Bosutinib reduced cell proliferation and induced apoptosis of sensitive cell lines. The drug rapidly inhibited Src and EGFR (epidermal growth factor receptor) phosphorylation, and sensitivity to Bosutinib was correlated with the activation status of EGFR. Similar findings were observed in in vivo xenograft assays using HNSCC derived cells. Moreover, in the presence of mutations in PIK3CA, the combination of Bosutinib with the PI3Kα inhibitor Alpelisib showed a synergistic effect. These results suggest that Bosutinib could be a new effective drug for the treatment of HNSCC, particularly in tumors with high EGFR activity. Its combination with Alpelisib could especially benefit patients bearing activating mutations of PIK3CA.

The Reactivity and Reaction Pathway of Fenton Reactions Driven by Substituted 1,2-Dihydroxybenzenes.

Fenton systems are interesting alternatives to advanced oxidation processes (AOPs) applied in soil or water remediation. 1,2-Dihydroxybenzenes (1,2-DHBs) are able to amplify the reactivity of Fenton systems and have been extensively studied in biological systems and for AOP applications. To develop efficient AOPs based on Fenton systems driven by 1,2-DHBs, the change in reactivity mediated by different 1,2-DHBs must be understood. For this, a systematic study of the reactivity of Fenton-like systems driven by 1,2-DHBs with different substituents at position 4 was performed. The substituent effect was analyzed using the Hammett constant (σ), which has positive values for electron-withdrawing groups (EWGs) and negative values for electron-donating groups (EDGs). The reactivity of each system was determined from the degradation of a recalcitrant azo dye and hydroxyl radical (HO·) production. The relationship between these reactivities and the ability of each 1,2-DHB to reduce Fe(III) was determined. From these results, we propose two pathways for HO· production. The pathway for Fenton-like systems driven by 1,2-DHBs with EDGs depends only on the Fe(III) reduction mediated by 1,2-DHB. In Fenton-like reactions driven by 1,2-DHBs with EWGs, the Fe(III) reduction is not primarily responsible for increasing the HO· production by this system in the early stages.

Reversal of the Hartmann's procedure: A comparative study of laparoscopic versus open surgery.

BACKGROUND: The Hartmann's operation, although less frequently performed today, is still used when initial colonic anastomosis is too risky in the short term. However, the subsequent procedure to restore gastrointestinal continuity is associated with significant morbidity and mortality. PATIENTS AND METHODS: The review of an institutional review board (IRB)-approved prospectively maintained database provided data on the Hartmann's reversal procedure performed by either laparoscopic or open technique at our institution. The data collected included: demographic data, operative approach, conversion for laparoscopic cases and perioperative morbidity and mortality. RESULTS: Over a 14-year period from January 1997 to August 2011, 74 Hartmann's reversal procedures were performed (laparoscopic surgery-49, open surgery-25). The average age was 55 years for the laparoscopic and 57 years for the open surgery group, respectively. Male patients represent 61% of both groups. There was no significant difference in operative time between the two groups (149 min vs 151 min; P = 0.95), and there was a tendency to lower morbidity (3/49-7.3% vs 4/25-16%; P = 0.24) in the laparoscopic surgery group. In the laparoscopic group, eight patients (16.3%) were converted to open surgery, mostly due to severe adhesions. The length of hospital stay was significantly shorter for the laparoscopic group (5 days vs 7 days; P = 0.44). CONCLUSIONS: The Hartmann's reversal procedure can be safely performed in the majority of the cases using a laparoscopic approach with a low morbidity rate and achieving a shorter hospital stay.

Homogeneous and heterogeneous degradation of caffeic acid using photocatalysis driven by UVA and solar light.

Waste water from the wine industry is characterized by a high concentration of dissolved organic matter and the presence of natural phenolic compounds with low biodegradability. High concentrations of phenolic compounds may cause environmental pollution and risks to human health. In this article caffeic acid (CA) was used as a model compound of wine effluent because it is refractory to the conventional wastewater treatments. The oxidation of caffeic acid in water solution (0.01 g L(-1)) by heterogeneous photocatalysis and photo-Fenton reaction was studied using UVA. The optimal conditions for each treatment were performed by multivariate experimental design. The optimal conditions for heterogeneous photocatalysis were pH 5.3 and 0.9 g L(-1) TiO2. In the case of photo-Fenton treatment, optimized variable were 82.4 µmol L(-1) of Fe(2+) and 558.6 µmol L(-1) of H2O2. The degradation profiles of CA were monitored by UV-Vis, HPLC, TOC and COD. To reach 90% of CA removal, 40 and 2 min of reaction, respectively, were required by heterogeneous and photo-Fenton processes, respectively. For comparison purposes, the reactions were also performed under solar light. The use of solar light does not change the efficiency of the photo-Fenton reaction, yet the performance of the heterogeneous process was significantly improved, reaching 90% of degradation in 15 min.

Optimized photocatalytic degradation of caffeic acid by sol-gel TiO2.

TiO2anatase powder was prepared by means of the sol-gel method with titanium(IV) butoxide as precursor. The formation of a tetragonal crystal structure of TiO2anatase at 500 °C was confirmed by X-ray powder diffraction. The characterization of the samples synthesized was complemented by scanning electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, nitrogen adsorption-desorption isotherms (Brunauer-Emmett-Teller) and diffuse reflectance spectroscopy. The photocatalytic activity of the TiO2anatase powder was evaluated in the degradation of caffeic acid in aqueous solution under ultraviolet radiation. A central composite circumscribed design was used to assess the weight of the experimental variables, pH and amount of catalyst in the percentage of caffeic acid degraded and the optimal conditions. The optimized conditions were found to be pH = 5.2 and a load of TiO2of 1.1 g L⁻¹. Under these conditions more than 90% of caffeic acid degradation was achieved after 30 min of lamp irradiation. At this time the mineralization reached was almost 60%.

Oxidative degradation of sulfathiazole by Fenton and photo-Fenton reactions.

This article presents experimental results on 47 µmol L(-1) sulfathiazole (STZ) degradation by Fenton and photo-Fenton reactions using multivariate analysis. The optimal experimental conditions for reactions were obtained by Response Surface Methodology (RSM). In the case of the Fenton reactions there were 192 µmol L(-1) ferrous ions (Fe(II)) and 1856 µmol L(-1) hydrogen peroxide (H2O2), as compared with 157 µmol L(-1) (Fe(II)) and 1219 µmol L(-1) (H2O2) for photo-Fenton reactions. Under these conditions, around 90% of STZ degradation were achieved after 8 minutes treatment by Fenton and photo-Fenton reactions, respectively. Moreover, a marked difference was observed in the total organic carbon (TOC) removal after 60-min treatment, achieving 30% and 75% for the Fenton and photo-Fenton reactions, respectively. Acetic, maleic, succinic and oxamic acids could be identified as main Fenton oxidation intermediates. A similar pattern was found in the case of photo-Fenton reaction, including the presence of oxalic acid and ammonia at short periods of irradiation with UV-A. The calculated values of Average Oxidation State (AOS) corroborate the formation of oxidized products from the initial steps of the reaction.

Sublethal neurotoxicity of saxitoxin in early zebrafish development: Impact on sensorimotor function and neurotransmission systems.

Saxitoxin (STX) represents a marine toxin of significant concern due to its deleterious implications for aquatic ecosystems and public food safety. As a potent paralytic agent, the role of STX in obstructing voltage-gated sodium channels (VGSCs) is well-characterized. Yet, the mechanistic details underlying its low-dose toxicity remain largely enigmatic. In the current study, zebrafish embryos and larvae were subjected to subchronic exposure of graded STX concentrations (0, 1, 10, and 100 µg/L) until the 7th day post-fertilization. A tactile stimulus-based assay was employed to evaluate potential behavioral perturbations resulting from STX exposure. Both behavioral and transcription level analyses unveiled a compromised tactile response, which was found to be associated with a notable upregulation in the mRNA of two distinct VGSC isoforms, specifically the scn8aa/ab and scn1Laa/ab transcripts, even at the minimal STX dose. Notably, exposure to this lowest STX concentration also resulted in alterations in the transcriptional patterns of pivotal genes for cholinergic and GABAergic pathways, including ache and gabra1. Furthermore, STX induced a marked decrease in the levels of the neurotransmitter GABA. Our findings underscore that prolonged low-dose STX exposure during early development can significantly compromise the tactile response behavior in zebrafish. This study reveals that chronic low-dose STX exposure of developing zebrafish alters neurotransmission pathways that converge on altered tactile behavior.

Phenylmercury degradation by heterogeneous photocatalysis assisted by UV-A light.

Photocatalytic degradation of phenylmercury was studied using TiO2 in aqueous suspension assisted by UV-A irradiation. Reaction conditions, such as pH and amount of TiO2 were set using a factorial design of experiments resulting in a greater influence of pH on phenylmercury degradation. Hg (II) reduction and simultaneous oxidation of aromatic group was observed. Optimum reaction conditions were obtained under nitrogen atmosphere at pH 10 and 0.35 g/L(-1) TiO2. Under these conditions almost 100% reduction of mercury was reached after 30 min UV irradiation. Total mercury reduction was achieved after 40 min reaction under saturated oxygen. Furthermore, phenol and diphenylmercury were identified as intermediate products of oxidation. It was observed that a major fraction of the reduced mercury was removed as metallic vapor by gas stripping, whereas a minor fraction was adsorbed on the catalyst surface, probably as Hg(OH)2. Under optimal conditions obtained by multivariable analysis, total mineralization of organic matter was achieved after about 60-min irradiation.

Stress, Sport Anxiety, Neuroticism, and Coping in Student-Athletes: Implications for Patient Mental Health.

CONTEXT: Patients' mental health has been recognized as important in providing patient-centered care in athletic training. OBJECTIVE: To evaluate stress, sport anxiety, neuroticism, and coping in student-athletes. DESIGN: Cross-sectional study. SETTING: University athletics. PATIENTS OR OTHER PARTICIPANTS: The sample comprised 86 student-athletes competing in National Collegiate Athletic Association (NCAA) Division III. MAIN OUTCOME MEASURE(S): The Perceived Stress Scale, Sport Anxiety Scale-2, neuroticism scale of the Big Five Inventory, and Brief COPE were used to measure stress, sport anxiety, neuroticism, and coping, respectively. RESULTS: Sport anxiety was positively related to stress (r = 0.446, P < .001) and neuroticism (r = 0.311, P < .01) and not related to emotion-focused coping (r = 0.270, P = .804). Neuroticism was a negative predictor of emotion-focused coping (b = -0.373, P < .001), and sport anxiety and stress were predictors of dysfunctional coping (b = 0.120, P < .05; b = 0.037, P < .05). Stress, sport anxiety, and neuroticism were not predictors of problem-focused coping. CONCLUSIONS: Support was evident for the relationship among stress, sport anxiety, neuroticism, and coping in NCAA Division III student-athletes. Such results warrant future exploration to inform behavioral interventions targeting student-athlete psychosocial factors to promote improved performance, reduce injury risk factors (eg, stress, personality, coping), and enhance student-athlete mental health and well-being.

The ferryl generation by fenton reaction driven by catechol.

The Fenton and Fenton-like reactions are based on the decomposition of hydrogen peroxide catalyzed by Fe(II), primarily producing highly oxidizing hydroxyl radicals (HO∙). While HO∙ is the main oxidizing species in these reactions, Fe(IV) (FeO2+) generation has been reported as one of the primary oxidants. FeO2+ has a longer lifetime than HO∙ and can remove two electrons from a substrate, making it a critical oxidant that may be more efficient than HO∙. It is widely accepted that the preferential generation of HO∙ or FeO2+ in the Fenton reaction depends on factors such as pH and Fe: H2O2 ratio. Reaction mechanisms have been proposed to generate FeO2+, which mainly depend on the radicals generated in the coordination sphere and the HO∙ radicals that diffuse out of the coordination sphere and react with Fe(III). As a result, some mechanisms are dependent on prior HO∙ radical production. Catechol-type ligands can induce and amplify the Fenton reaction by increasing the generation of oxidizing species. Previous studies have focused on the generation of HO∙ radicals in these systems, whereas this study investigates the generation of FeO2+ (using xylidine as a selective substrate). The findings revealed that FeO2+ production is increased compared to the classical Fenton reaction and that FeO2+ generation is mainly due to the reactivity of Fe(III) with HO∙ from outside the coordination sphere. It is proposed that the inhibition of FeO2+ generation via HO∙ generated from inside the coordination sphere is caused by the preferential reaction of HO∙ with semiquinone in the coordination sphere, favoring the formation of quinone and Fe(III) and inhibiting the generation of FeO2+ through this pathway.

Berberis microphylla G. Forst Intake Reduces the Cardiovascular Disease Plasmatic Markers Associated with a High-Fat Diet in a Mice Model.

Polyphenols are bioactive substances that participate in the prevention of chronic illnesses. High content has been described in Berberis microphylla G. Forst (calafate), a wild berry extensively distributed in Chilean-Argentine Patagonia. We evaluated its beneficial effect through the study of mouse plasma metabolome changes after chronic consumption of this fruit. Characterized calafate extract was administered in water, for four months, to a group of mice fed with a high-fat diet and compared with a control diet. Metabolome changes were studied using UHPLC-DAD-QTOF-based untargeted metabolomics. The study was complemented by the analysis of protein biomarkers determined using Luminex technology, and quantification of OH radicals by electron paramagnetic resonance spectroscopy. Thirteen features were identified with a maximum annotation level-A, revealing an increase in succinic acid, activation of tricarboxylic acid and reduction of carnitine accumulation. Changes in plasma biomarkers were related to inflammation and cardiovascular disease, with changes in thrombomodulin (-24%), adiponectin (+68%), sE-selectin (-34%), sICAM-1 (-24%) and proMMP-9 (-31%) levels. The production of OH radicals in plasma was reduced after calafate intake (-17%), especially for the group fed with a high-fat diet. These changes could be associated with protection against atherosclerosis due to calafate consumption, which is discussed from a holistic and integrative point of view.

Post-weaning social isolation increases the incentive value of nicotine-related contexts and decreases the accumulation of ΔFosB in nucleus accumbens in adolescent rats.

Adolescent social conditions profoundly affect vulnerability to drug abuse. Preclinical studies have shown that preventing social interactions during adolescence increases the rewarding effects of drugs like alcohol, cocaine, or amphetamines, however, little data exist regarding the impact of social isolation on nicotine effects. The current study evaluated the effects of differential rearing conditions during adolescence (isolation or group rearing) on (1) conditioned place preference induced by low nicotine doses (0.1 or 0.3 mg/kg) and (2) sensitization to the locomotor effects of nicotine after sub-chronic administration (3) and accumulation of ΔFosB in nucleus accumbens (NAc). Results showed that nicotine induced place preference in isolated and grouped rats, but the effect was more persistent for the rats reared in isolation. Isolated reared rats also exhibited lower levels of ΔFosB accumulation in NAc. No differences were found in the behavioral sensitization to nicotine effects between rearing conditions. The results suggest that isolation engenders a more robust incentive value of nicotine-related contexts. This effect could be related to the basal expression of ΔFosB: lower levels of this transcription factor seem to impair the motivation of isolated reared rats and increase their vulnerability to the effects of drugs like nicotine.