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1.
World J Gastrointest Endosc ; 14(10): 636-641, 2022 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-36303813

RESUMO

BACKGROUND: Esophageal cancer is a common type of cancer and serious bleeding from esophageal tumors can occur in routine clinical practice. The arrest of bleeding from esophageal tumor is not a trivial task, which can sometimes require nonstandard solutions. We report a case of successful hemostasis of massive bleeding from esophageal tumor performed by a novel two-balloon catheter inserted endoscopically, with a local hemostatic treatment applied. CASE SUMMARY: A 36-years old male patient with advanced esophageal cancer developed bleeding from the tumor following endoscopic stenting with a self-expanding metal stent. Due to the ineffectiveness of standard approaches, after a medical conference, the patient was treated with a novel method based on the use of a two-balloon catheter creating an isolated area in esophagus and locally dispersing hemostatic polysaccharide powder inside the isolated interior. Hemostasis was successful and subsequent endoscopic examination revealed the presence of organized clot and localized defect, which was coagulated in a planned manner. CONCLUSION: The authors present a new catheter-based method of hemostasis of esophageal tumor bleeding.

2.
Biopreserv Biobank ; 19(1): 73-82, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33058731

RESUMO

The research biobanking field is developing rapidly in Russia. Over the course of the last decade, numerous biobanks were created or formed from existing collections of human and environmental biospecimens. The Russian National Association of Biobanks and Biobanking Specialists (NASBIO) was established in December 2018, aiming to: (1) unite professionals and research centers to create and develop a network of biobanks in Russia; (2) provide services and expertise in the field of biobanking; (3) execute various research projects utilizing biobanks' infrastructure; and (4) facilitate integration of Russian biomedical research centers into global research activities. The organizational structure, aims, and plans of this newly formed national association are reviewed in this article. The founders of NASBIO hope that the association will promote further development of biobanks and their networking in Russia, which is critically important for the success of national biomedical, pharmaceutical, and biotechnological research, and can facilitate international biobanking projects on a global scale.


Assuntos
Bancos de Espécimes Biológicos , Pesquisa Biomédica , Humanos , Federação Russa , Especialização
3.
Eur Child Adolesc Psychiatry ; 27(2): 241-252, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28822049

RESUMO

In view of the need for easily accessible biomarkers, we evaluated in ADHD children the epigenetic status of the 5'-untranslated region (UTR) in the SLC6A3 gene, coding for human dopamine transporter (DAT). We analysed buccal swabs and sera from 30 children who met DSM-IV-TR criteria for ADHD, assigned to treatment according to severity. Methylation levels at six-selected CpG sites (among which, a CGGCGGCGG and a CGCG motif), alone or in combination with serum titers in auto-antibodies against dopamine transporter (DAT aAbs), were analysed for correlation with CGAS scores (by clinicians) and Conners' scales (by parents), collected at recruitment and after 6 weeks. In addition, we characterized the DAT genotype, i.e., the variable number tandem repeat (VNTR) polymorphisms at the 3'-UTR of the gene. DAT methylation levels were greatly reduced in ADHD patients compared to control, healthy children. Within patients carrying at least one DAT 9 allele (DAT 9/x), methylation at positions CpG2 and/or CpG6 correlated with recovery, as evident from delta-CGAS scores as well as delta Conners' scales ('inattentive' and 'hyperactive' subscales). Moreover, hypermethylation at CpG1 position denoted severity, specifically for those patients carrying a DAT 10/10 genotype. Intriguingly, high serum DAT-aAbs titers appeared to corroborate indications from high CpG1 versus high CpG2/CpG6 levels, likewise denoting severity versus recovery in DAT 10/10 versus 9/x patients, respectively. These profiles suggest that DAT 5'UTR epigenetics plus serum aAbs can serve as suitable biomarkers, to confirm ADHD diagnosis and/or to predict the efficacy of treatment.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/genética , Polimorfismo Genético/genética , Adolescente , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Criança , Feminino , Genótipo , Humanos , Masculino
4.
J Neuroimmunol ; 278: 212-22, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25468771

RESUMO

UNLABELLED: Interest is rising for auto-immune contribution in neuro-psychiatry. We evaluated the auto-antibodies against dopamine transporter (DAT aAbs) in 61 children (46 ADHD who met DSM-IV-TR criteria, 15 healthy controls). METHODS: ADHD patients were assigned, according to severity, either to a non-pharmacological therapy (NPT, N=32) or to a pharmacological treatment (PT, N=14) with methylphenidate (MPH). In ADHD children, blood samples were withdrawn twice, at recruitment (T0 basal) and after 6 weeks (T1); following 16 excluded subjects, DAT genotype was characterized (9-repeat or 10-repeat alleles; N=15 each). After 18 months of NPT or PT, some patients (carrying at least one 9-repeat allele) were blood sampled again (T2), for comparison with healthy controls (final n=8) RESULTS: Compared to NPT, basal DAT aAbs titers were higher within most severe patients (then assigned to PT), specifically if carrying a DAT 10/10 genotype. DAT aAbs levels of NPT group resulted highly correlated with distinct subscales of Conners' Parent/Teacher Scales (Rs>0.34), especially within DAT 10/10 genotype (Rs>0.53). While T1 titers were elevated over T0 baseline for NPT children, such an increase was not observed in PT patients carrying at least one 9-repeat allele, who also showed behavioral response to subchronic MPH. After 12-24 months of MPH exposure, DAT aAbs titers in PT subjects were comparable to those of healthy controls, while titers remained significantly elevated in NPT patients. Data warrant further research on serum DAT aAbs, which could be used to confirm ADHD diagnosis and/or to monitor therapeutic efficacy of MPH.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Autoanticorpos/sangue , Estimulantes do Sistema Nervoso Central/uso terapêutico , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Proteínas da Membrana Plasmática de Transporte de Dopamina/imunologia , Metilfenidato/uso terapêutico , Transtorno do Deficit de Atenção com Hiperatividade/sangue , Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Transtorno do Deficit de Atenção com Hiperatividade/genética , Criança , Análise Mutacional de DNA , Ensaio de Imunoadsorção Enzimática , Feminino , Seguimentos , Genótipo , Humanos , Masculino , Entrevista Psiquiátrica Padronizada , Repetições Minissatélites/genética
5.
Behav Brain Funct ; 8: 54, 2012 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-23192105

RESUMO

BACKGROUND: Possible interactions between nervous and immune systems in neuro-psychiatric disorders remain elusive. Levels of brain dopamine transporter (DAT) have been implicated in several impulse-control disorders, like attention deficit / hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Here, we assessed the interplay between DAT auto-immunity and behavioural / neurochemical phenotype. METHODS: Male CD-1 mice were immunized with DAT peptide fragments (DAT-i), or vehicle alone (VEH), to generate elevated circulating levels of DAT auto-antibodies (aAbs). Using an operant delay-of-reward task (20 min daily sessions; timeout 25 sec), mice had a choice between either an immediate small amount of food (SS), or a larger amount of food after a delay (LL), which increased progressively across sessions (from 0 to 150 sec). RESULTS: DAT-i mice exhibited spontaneous hyperactivity (2 h-longer wake-up peak; a wake-up attempt during rest). Two sub-populations differing in behavioural flexibility were identified in the VEH control group: they showed either a clear-cut decision to select LL or clear-cut shifting towards SS, as expected. Compared to VEH controls, choice-behaviour profile of DAT-i mice was markedly disturbed, together with long-lasting alterations of the striatal monoamines. Enhanced levels of DA metabolite HVA in DAT-i mice came along with slower acquisition of basal preferences and with impaired shifting; elevation also in DOPAC levels was associated with incapacity to change a rigid selection strategy. This scarce flexibility of performance is indicative of a poor adaptation to task contingencies. CONCLUSIONS: Hyperactivity and reduced cognitive flexibility are patterns of behaviour consistent with enduring functional impairment of striatal regions. It is yet unclear how anti-DAT antibodies could enter or otherwise affect these brain areas, and which alterations in DAT activity exactly occurred after immunization. Present neuro-behavioural alterations, coming along with an experimentally-induced rise of circulating DAT-directed aAbs, open the issue of a potential role for auto-immunity in vulnerability to impulse-control disorders.


Assuntos
Comportamento Animal/fisiologia , Cognição/fisiologia , Corpo Estriado/fisiopatologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Hipercinese/fisiopatologia , Fragmentos de Peptídeos/farmacologia , Animais , Cognição/efeitos dos fármacos , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Comportamento Exploratório/fisiologia , Hipercinese/metabolismo , Imunização , Masculino , Camundongos , Fragmentos de Peptídeos/metabolismo , Recompensa
6.
Horm Behav ; 56(4): 391-8, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19632235

RESUMO

Early life experiences have been shown to adjust cognitive abilities, stress reactivity, fear responses and immune activity in adult mammals of many species. However, whereas severe stressors have been generally associated with the emergence of hypothalamic pituitary adreno-cortical (HPA)-mediated pathology, mild neonatal stressful experiences have been traditionally associated with 'positive' effects or resilience. External stressors stimulate the HPA axis to induce a corticosterone secretion in mouse dams, which, in turn is directly transmitted to the progeny through lactation. Such corticosteroid transfer may offer a unitary mechanism whereby early low corticosterone exposure may favor resilience in the offspring and high corticosterone increase vulnerability to pathology. In this study we further investigated this hypothesis by evaluating the long-term effects of a neonatal exposure to low (33 mg/l) and high (100 mg/l) doses of corticosterone during the first 10 days of life in outbred CD-1 mice through supplementation in the maternal drinking water. Offspring attentional set-shifting abilities, central neurotrophic regulation and levels of natural auto-antibodies (na-Abs) directed to serotonin (SERT) and dopamine (DAT) transporters were assessed in adulthood. While low levels of neonatal corticosterone improved adult cognitive abilities and increased na-Abs levels directed to SERT, high doses of neonatal corticosterone reduced hippocampal BDNF levels and na-Abs directed to DAT. These findings confirm and extend our previous findings, supporting the view that both adaptive plasticity and pathological outcomes in adulthood may depend on circulating neonatal corticosterone levels and that these effects follow a U-shaped profile.


Assuntos
Encéfalo/efeitos dos fármacos , Cognição/efeitos dos fármacos , Corticosterona/farmacologia , Estresse Psicológico/induzido quimicamente , Animais , Animais Recém-Nascidos , Autoanticorpos/sangue , Autoanticorpos/metabolismo , Encéfalo/crescimento & desenvolvimento , Encéfalo/fisiopatologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Cognição/fisiologia , Corticosterona/administração & dosagem , Corticosterona/sangue , Proteínas da Membrana Plasmática de Transporte de Dopamina/imunologia , Relação Dose-Resposta a Droga , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/crescimento & desenvolvimento , Hipocampo/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos , Testes Neuropsicológicos , Proteínas da Membrana Plasmática de Transporte de Serotonina/imunologia , Estresse Psicológico/fisiopatologia , Fatores de Tempo
7.
Psychopharmacology (Berl) ; 197(4): 535-48, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18265961

RESUMO

BACKGROUND: Possible interactions between nervous and immune systems during opioid addiction remain elusive. Recombinant mu-delta opioid receptors (MDOR) and the glutamate receptor 1 (GluR1) subunit of amino-3-hydroxy-5-methyl-4-isoxazole propionic acid glutamate receptors are involved in acute and chronic effects of morphine. Elevated levels of autoantibodies (aAbs) to these receptors were demonstrated in heroin human addicts and in animal models. This study characterized the role of aAbs to these receptors in behavioral modulations recruited during opioid tolerance and sensitization. METHODS AND FINDINGS: Male CD-1 mice, immunized with either MDOR or GluR1 peptide fragments (80 microg intraperitoneal (i.p.)), were examined for spontaneous behavior and response to morphine (5 mg/kg i.p.). Spontaneous home-cage activity, novelty-induced self-grooming and morphine-induced hyperactivity were higher in GluR1 mice compared to Vehicle subjects, whereas MDOR immunization was associated with an increased morphine-induced conditioned place preference. In response to escalating doses of morphine (from 10 to 60 mg/kg i.p., twice daily) and naloxone-precipitated withdrawal (1 mg/kg subcutaneous), GluR1 mice exhibited a more marked stereotyped sniffing behavior and less body tremors compared to Vehicle subjects, whereas less sniffing and teeth chattering were found in MDOR mice. The expected downregulation of mu receptor binding sites, induced by chronic morphine in vehicle subjects, was completely absent following MDOR immunization. CONCLUSIONS: These findings indicate an altered response to morphine-related reinforcing and aversive effects in MDOR mice and altered coping with the environment in GluR1 mice. Circulating aAbs to specific neuroreceptors may alter the response to opiates and play a role as determinants of vulnerability to opiate addiction.


Assuntos
Autoanticorpos/sangue , Dependência de Morfina/imunologia , Motivação , Receptores de AMPA/imunologia , Receptores Opioides delta/imunologia , Receptores Opioides mu/imunologia , Recompensa , Animais , Nível de Alerta/efeitos dos fármacos , Aprendizagem da Esquiva/efeitos dos fármacos , Encéfalo/imunologia , Condicionamento Operante/efeitos dos fármacos , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Asseio Animal/efeitos dos fármacos , Imunização , Masculino , Camundongos , Morfina/farmacologia , Atividade Motora/efeitos dos fármacos , Naloxona/farmacologia , Fragmentos de Peptídeos/imunologia , Meio Social , Comportamento Estereotipado/efeitos dos fármacos , Síndrome de Abstinência a Substâncias/imunologia
8.
Brain Res ; 1131(1): 173-80, 2007 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-17174287

RESUMO

Reelin is an extracellular matrix protein, secreted by GABAergic interneurons, that provides a signal for neural plasticity. A downregulation of reelin may be a factor to be considered in the study of major psychiatric disorders. The heterozygous reeler mouse model, thus, may be important to reveal those alterations in behavioral phenotype produced by reduced neural plasticity. Heterozygous (HZ) and wild-type (WT) mice were tested for anxiety-related behavior, motor impulsivity, and morphine-induced analgesia. Heterozygous mice showed significantly lower levels of anxiety- and risk-assessment-related behaviors in the elevated plus-maze during adolescence, in the absence of basal changes in general locomotion. Adult mice were assessed for profiles of impulsive behavior in operant chambers, and HZ mice exhibited elevated levels of motor impulsivity. When mice were assessed in nociception tests, a genotype difference in morphine-induced analgesia was found, and these results were confirmed by measurement of mu-receptors in the midbrain. The basal behavioral profile of the HZ genotype reveals important differences, consistent with decreased behavioral inhibition and emotionality, which can be revealed as early as in adolescence, together with slight increment of impulsive behavior and altered pain threshold and at the adult age. The HZ genotype can thus represent a useful animal model for the study of behavioral disorders consequent to reduced neural plasticity.


Assuntos
Transtornos de Ansiedade/genética , Química Encefálica/genética , Moléculas de Adesão Celular Neuronais/genética , Proteínas da Matriz Extracelular/genética , Comportamento Impulsivo/genética , Proteínas do Tecido Nervoso/genética , Limiar da Dor/fisiologia , Dor/genética , Serina Endopeptidases/genética , Analgésicos Opioides/farmacologia , Animais , Transtornos de Ansiedade/metabolismo , Transtornos de Ansiedade/fisiopatologia , Modelos Animais de Doenças , Resistência a Medicamentos/efeitos dos fármacos , Resistência a Medicamentos/genética , Tolerância a Medicamentos/genética , Emoções/fisiologia , Feminino , Predisposição Genética para Doença/genética , Heterozigoto , Comportamento Impulsivo/metabolismo , Comportamento Impulsivo/fisiopatologia , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Mesencéfalo/efeitos dos fármacos , Mesencéfalo/metabolismo , Camundongos , Camundongos Mutantes Neurológicos , Morfina/farmacologia , Atividade Motora/efeitos dos fármacos , Atividade Motora/genética , Plasticidade Neuronal/genética , Dor/tratamento farmacológico , Dor/metabolismo , Limiar da Dor/efeitos dos fármacos , Receptores Opioides mu/efeitos dos fármacos , Receptores Opioides mu/metabolismo , Proteína Reelina
9.
Eur J Pharmacol ; 557(1): 37-43, 2007 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-17174300

RESUMO

There is evidence for the existence of functional interactions between nicotine and cannabinoids and opioid compounds in adult experimental animals. However, there is scarce information about these relationships in young animals. In the present study we evaluated short and long-term effects of a subchronic nicotine treatment [0.4 mg/kg daily i.p. injections from postnatal day (PND) 34 to PND 43], upon hippocampal and striatal cannabinoid-CB(1) and mu-opioid receptors in Wistar rats of both genders. Rats were sacrificed 2 h after the last nicotine injection (short-term effects, PND 43) or one month later (long-term effects, PND 75). Hippocampal and striatal cannabinoid CB(1) and mu-opioid receptors were quantified by Western blotting. The subchronic nicotine treatment induced a region-dependent long-lasting effect in cannabinoid CB(1) receptor: a significant increase in hippocampal cannabinoid CB(1) receptors and a significant decrease in striatal cannabinoid CB(1) receptors, with these effects being similar in males and females. With respect to mu-opioid receptors, subchronic nicotine induced a significant down-regulation in hippocampal and striatal mu-opioid receptors in the long-term, and within the striatum the effects were more marked in adult males than in females. The present results indicate that juvenile nicotine taking may have implications for the endocannabinoid and endogenous opioid function and for the behaviors served by those systems, this includes possible modification of the response of adults to different psychotropic drugs, i.e. cannabis and morphine/heroin when taken later in life.


Assuntos
Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Receptor CB1 de Canabinoide/metabolismo , Receptores Opioides mu/metabolismo , Animais , Gânglios da Base/efeitos dos fármacos , Gânglios da Base/metabolismo , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
10.
Neurosci Lett ; 403(1-2): 1-5, 2006 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-16687214

RESUMO

Several groups of brain receptors are involved in the mechanisms underlying the development of opiate addiction, but the interactions occurring between these neuroreceptors and the immune system, including potential autoimmune responses, remain poorly understood. We studied in rats the effects of repeated administration of different psychotropic drugs on serum levels of autoantibodies (aAbs) to the mu delta-opiate receptor (MDOR), as well as to the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) GluR1 and to the N-methyl-D-aspartate (NMDA) NR2 subunits of the glutamate receptor, as analyzed by ELISA. We found that repeated administration of morphine significantly elevated aAbs levels to MDOR and to the AMPA GluR1 subunit, but not to the NMDA NR2 subunit. In contrast, a similar regimen of a psychostimulant drug, such as D-amphetamine, or a commonly abused substance, such as nicotine, had no effect on these aAbs levels. A nonspecific elevating effect on aAbs to the brain structural protein S100B was observed for all drugs tested versus controls. These observations support the hypothesis that, following opiate administration, specific interactions between nervous and immune systems occur. Therefore, together with further investigations on their potential functional consequences, we propose a thorough exploration of aAbs to MDOR and to AMPA GluR1 subunit as early biomarkers signaling opiate addiction.


Assuntos
Autoanticorpos/sangue , Ácido Glutâmico/imunologia , Morfina/farmacologia , Psicotrópicos/farmacologia , Receptores Opioides delta/imunologia , Receptores Opioides mu/imunologia , Animais , Astrócitos/metabolismo , Biomarcadores/sangue , Dextroanfetamina/farmacologia , Ensaio de Imunoadsorção Enzimática , Masculino , Fatores de Crescimento Neural/imunologia , Nicotina/farmacologia , Subunidades Proteicas/imunologia , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/imunologia , Receptores de N-Metil-D-Aspartato/imunologia , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/imunologia
11.
Neuropsychopharmacology ; 29(5): 869-78, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-14666123

RESUMO

People are very likely to start psychoactive drug use during adolescence, an earlier onset being associated with a higher risk of developing addiction later in life. In experiment I, Pre- (postnatal day (pnd) 23-35), Mid- (pnd 36-48), or Post- (pnd 49-61) adolescent mice underwent a restricted-drinking period (2 h/day for 12 days), one bottle containing water and the other containing nicotine (10 mg/l) or water. After this period, Mid-adolescents showed prominent exploration and reduced anxiety in the plus-maze. This ontogenetic profile was dampened by nicotine consumption. After 2 months, these mice were tested in a novel environment (30 min/day for 3 days). Locomotor-habituation profiles were specifically disrupted by nicotine consumption during Mid-adolescence, suggesting this age as a critical period. In experiment II, Mid-adolescent (pnd 35-44) and adult (pnd > 70) mice were pretreated with nicotine (0, 0.03, 0.10, 0.30 mg/kg/day for 10 days). Acute nicotine administration had opposite effects on anxiety in adolescents and adults. At 2 months after pretreatment, we measured levels of AMPA GluR2/3 subunits, thought to be involved in the control of addictive behaviors. Nicotine exposure during Mid-adolescence dose-dependently downregulated these subunits in the striatum and hippocampus, but comparable exposure during adulthood had either opposite or no effects. NMDA NR2A/B subunits were affected by nicotine, but without age-related differences. The present data identified a nicotine-vulnerable age window, characterized by long-term disruption of locomotor habituation and downregulation of AMPA receptors. These findings support neurobiological vulnerability to drugs in adolescent humans.


Assuntos
Comportamento Animal/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Envelhecimento/fisiologia , Animais , Western Blotting , Peso Corporal/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Comportamento de Ingestão de Líquido/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Nicotina/administração & dosagem , Agonistas Nicotínicos/administração & dosagem , Receptores de AMPA/efeitos dos fármacos , Receptores de Glutamato/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
12.
Neurosci Biobehav Rev ; 27(7): 639-51, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14624808

RESUMO

Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric syndrome, affecting human infants and adolescents. Two main behavioural features are reported: (1). impaired attention and (2). an impulsive-hyperactive behavioural trait. The latter has been studied in a series of experiments, using the spontaneously hypertensive-rat (SHR) strain (which is regarded as a validated animal model for ADHD) in operant tasks. Food-restricted SHRs and their Wistar-Kyoto (WKY) controls were tested during adolescence (i.e. post-natal days 30-45), in operant chambers provided with two nose-poking holes. Nose-poking in one hole (H1) resulted in the immediate delivery of a small amount of food, whereas nose-poking in the other hole (H5) delivered a larger amount of food after a delay, which was increased progressively each day (0-100 s). As expected, all animals showed a shift in preference from the large (H5) to the immediate (H1) reinforcer as the delay length increased. Impulsivity can be measured by the steepness of this preference-delay curve. The two strains differed in home-cage circadian activity, SHRs being more active than WKYs at several time-points. During the test for impulsivity, inter-individual differences were completely absent in the WKY strain, whereas a huge inter-individual variability was evident for SHRs. On the basis of the median value of average hole-preference, we found an 'impulsive' SHR subgroup, with a very quick shift towards the H1 hole, and a flat-slope ('non-impulsive') SHR subgroup, with little or no shift. The impulsive subpopulation also presented reduced noradrenaline levels in both cingulated and medial-frontal cortex, as well as reduced serotonin turnover in the latter. Also, cannabinoid CB1 receptor density resulted significantly lower in the prefrontal cortex of impulsive SHRs, when compared to both the non-impulsive subgroup and control WKYs. Interestingly, acute administration of a cannabinoid agonist (WIN 55,212, 2 mg/kg s.c.) normalized the impulsive behavioural profile, without any effect on WKY rats. Thus, two distinct subpopulations, differing for impulsive behaviour and specific neurochemical parameters, were evidenced within adolescent SHRs. These results support the notion that a reduced cortical density of cannabinoid CB1 receptors is associated with enhanced impulsivity. This behavioural trait can be positively modulated by administration of a cannabinoid agonist. Present results confirm and extend previous literature, indicating that adolescent SHRs represent a suitable animal model for the preclinical investigation of the early-onset ADHD syndrome.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Modelos Animais de Doenças , Comportamento Impulsivo/fisiopatologia , Córtex Pré-Frontal/fisiologia , Receptor CB1 de Canabinoide/fisiologia , Animais , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Condicionamento Operante/fisiologia , Comportamento Impulsivo/psicologia , Ratos , Ratos Endogâmicos SHR , Ratos Wistar
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