A expressão de respostas de medo condicionadas e incondicionadas geradas por estímulos auditivos de natureza aversiva envolve a transmissão neural do colículo inferior (CI) para o núcleo geniculado medial do tálamo, principalmente através do seu núcleo central (CIc). Como outras drogas de abuso, o álcool atua em múltiplos alvos no cérebro produzindo uma variedade de efeitos, incluindo tanto efeitos recompensadores quanto aversivos. A ingestão crônica e a síndrome de abstinência ao álcool promovem alterações severas na regulação homeostática entre GABA e glutamato: os principais neurotransmissores inibitório e excitatório respectivamente, do sistema nervoso central, particularmente do CI. Esse estudo tem o objetivo de investigar os efeitos da interrupção crônica de álcool no processamento da informação acústica no CIc de ratos dependentes de álcool pelo uso da técnica dos potenciais evocados auditivos (PEA). Como uma medida adicional, os PEAs também foram registrados em ratos sob os efeitos do álcool. A influência da neurotransmissão de GABA e de glutamato na modulação das modificações induzidas pela abstinência ao álcool foi analisada por microinjeções locais no CI do agonista GABAA muscimol e do antagonista NMDA AP7. Nossos resultados mostraram que a ingestão crônica de álcool promove o seu bem conhecido efeito ansiolítico no processamento da informação auditiva no CIc, reduzindo a amplitude do PEA. Por outro lado, a abstinência ao álcool causa um aumento da sensibilidade dos neurônios do CIc a estímulos auditivos. Este efeito apareceu somente após 96 horas da retirada do álcool. Os resultados obtidos com a manipulação farmacológica mostraram que o muscimol e o AP7 promoveram efeitos bastante distintos com cursos de tempo diferentes. De fato, o muscimol foi eficaz na redução dos PEAs em ratos com 48 horas de abstinência. O antagonismo de receptores glutamatérgicos NMDA ocorreu somente após 96 horas da retirada do álcool. Esses resultados mostraram que as modificações induzidas pela abstinência ao álcool em neurônios do CIc de ratos dependentes de álcool são diferentemente modulados por mecanismos GABA e NMDA. / The expression of conditioned and unconditioned fear responses generated by auditory stimuli of aversive nature, involves neural transmission from the inferior colliculus (IC) to the medial geniculate nucleus of the thalamus and thence to the integrates acoustic information of aversive nature, mainly by its central nucleus (cIC). Like other drugs of abuse, alcohol acts on multiple targets in the brain to produce a complex array of effects, including both rewarding and aversive ones. Alcohol administration and alcohol withdrawal syndrome promote severe changes in the normal homeostatic regulation between GABA and glutamate; the major inhibitory and excitatory neurotransmitters in the IC, respectively. This study was aimed at investigating the alcohol chronic withdrawal effects on the processing of acoustic information in the cIC of alcohol-dependent rats through the use of the auditory evoked potentials (AEPs) technique. As an additional measure AEPs were also recorded in rats under alcohol effects. The influence of GABA and glutamate neurotransmission on the modulation of changes induced by alcohol withdrawal was analyzed by local IC microinjections of the GABAA agonist muscimol and the NMDA antagonist AP7. Our results showed that the chronic intake of alcohol promotes its well-known anxiolytic-like effects on the processing of auditory information in the cIC, reducing the amplitude of the AEPs. On the other hand, alcohol withdrawal causes increased sensitivity of the cIC neurons to auditory stimuli. This effect appeared only after 96 hours of alcohol withdrawal. The results obtained with the pharmacological manipulation showed that muscimol and AP7 promoted quite distinct effects with different time courses. In fact, muscimol was effective in reducing AEPs in 48 hours withdrawal-rats. The antagonism of glutamate NMDA receptors occurred only at 96 hours of alcohol withdrawal. These results showed that the changes induced by alcohol withdrawal on cIC neurons of alcohol-dependent rats are differently modulated by GABA and NMDA mechanisms.

A expressão de respostas de medo condicionadas e incondicionadas geradas por estímulos auditivos de natureza aversiva envolve a transmissão neural do colículo inferior (CI) para o núcleo geniculado medial do tálamo, principalmente através do seu núcleo central (CIc). Como outras drogas de abuso, o álcool atua em múltiplos alvos no cérebro produzindo uma variedade de efeitos, incluindo tanto efeitos recompensadores quanto aversivos. A ingestão crônica e a síndrome de abstinência ao álcool promovem alterações severas na regulação homeostática entre GABA e glutamato: os principais neurotransmissores inibitório e excitatório respectivamente, do sistema nervoso central, particularmente do CI. Esse estudo tem o objetivo de investigar os efeitos da interrupção crônica de álcool no processamento da informação acústica no CIc de ratos dependentes de álcool pelo uso da técnica dos potenciais evocados auditivos (PEA). Como uma medida adicional, os PEAs também foram registrados em ratos sob os efeitos do álcool. A influência da neurotransmissão de GABA e de glutamato na modulação das modificações induzidas pela abstinência ao álcool foi analisada por microinjeções locais no CI do agonista GABAA muscimol e do antagonista NMDA AP7. Nossos resultados mostraram que a ingestão crônica de álcool promove o seu bem conhecido efeito ansiolítico no processamento da informação auditiva no CIc, reduzindo a amplitude do PEA. Por outro lado, a abstinência ao álcool causa um aumento da sensibilidade dos neurônios do CIc a estímulos auditivos. Este efeito apareceu somente após 96 horas da retirada do álcool. Os resultados obtidos com a manipulação farmacológica mostraram que o muscimol e o AP7 promoveram efeitos bastante distintos com cursos de tempo diferentes. De fato, o muscimol foi eficaz na redução dos PEAs em ratos com 48 horas de abstinência. O antagonismo de receptores glutamatérgicos NMDA ocorreu somente após 96 horas da retirada do álcool. Esses resultados mostraram que as modificações induzidas pela abstinência ao álcool em neurônios do CIc de ratos dependentes de álcool são diferentemente modulados por mecanismos GABA e NMDA. / The expression of conditioned and unconditioned fear responses generated by auditory stimuli of aversive nature, involves neural transmission from the inferior colliculus (IC) to the medial geniculate nucleus of the thalamus and thence to the integrates acoustic information of aversive nature, mainly by its central nucleus (cIC). Like other drugs of abuse, alcohol acts on multiple targets in the brain to produce a complex array of effects, including both rewarding and aversive ones. Alcohol administration and alcohol withdrawal syndrome promote severe changes in the normal homeostatic regulation between GABA and glutamate; the major inhibitory and excitatory neurotransmitters in the IC, respectively. This study was aimed at investigating the alcohol chronic withdrawal effects on the processing of acoustic information in the cIC of alcohol-dependent rats through the use of the auditory evoked potentials (AEPs) technique. As an additional measure AEPs were also recorded in rats under alcohol effects. The influence of GABA and glutamate neurotransmission on the modulation of changes induced by alcohol withdrawal was analyzed by local IC microinjections of the GABAA agonist muscimol and the NMDA antagonist AP7. Our results showed that the chronic intake of alcohol promotes its well-known anxiolytic-like effects on the processing of auditory information in the cIC, reducing the amplitude of the AEPs. On the other hand, alcohol withdrawal causes increased sensitivity of the cIC neurons to auditory stimuli. This effect appeared only after 96 hours of alcohol withdrawal. The results obtained with the pharmacological manipulation showed that muscimol and AP7 promoted quite distinct effects with different time courses. In fact, muscimol was effective in reducing AEPs in 48 hours withdrawal-rats. The antagonism of glutamate NMDA receptors occurred only at 96 hours of alcohol withdrawal. These results showed that the changes induced by alcohol withdrawal on cIC neurons of alcohol-dependent rats are differently modulated by GABA and NMDA mechanisms.

Alkoholkonsum beginnt häufig bereits im Jugendalter. Allerdings fehlen bisher Erkenntnisse darüber, ob, wie häufig und aufgrund welcher Merkmale Jugendlichen und junge Erwachsene auch bereits klinisch definierte Mißbrauchs- und Abhängigkeitsdiagnosen entwickeln. In der vorliegenden Arbeit werden Ergebnisse einer repräsentativen Untersuchung an 3021 Jugendlichen im Alter von 14-24 Jahren vorgestellt. Neben der Prävalenz von Alkoholmißbrauch und -abhängigkeit nach DSM-IV werden Daten zur Häufigkeit und Menge des Alkoholkonsums berichtet sowie erste Symptome beschrieben. 9,7% der befragten Jugendlichen erhielten aufgrund von DSM-IV-Kriterien eine Mißbrauchsdiagnose, 6,2% eine Abhängigkeitsdiagnose. Bei männlichen Jugendlichen war die Prävalenz wesentlich höher als bei weiblichen. Die Prävalenz war in den älteren Geburtskohorten höher. Als erstes Missbrauchssymptom trat am häufigsten "Gebrauch mit körperlicher Gefährdung" (91,9%), als erstes Abhängigkeitssymptom "Toleranzentwicklung" (34,3%) auf. Erste diagnostische Kriterien einer Alkoholstörung traten zumeist deutlich vor dem 18. Lebensjahr auf. Diese Daten unterstreichen, daß Alkoholmißbrauch und -abhängigkeit bereits im Jugend- und frühen Erwachsenenalter häufig sind. / Alcohol use frequently begins in adolescence. However, only few studies have reported the prevalence of alcohol abuse disorders in adolescents. This paper reports results from a representative study in a sample of 3021 adolescents, aged 14-24 years. The Prevalence of alcohol abuse and dependence according to DSM-IV criteria, as well as the prevalence, frequency and quantity of alcohol abuse and a description of the first occuring symptoms, are presented here. Alcohol abuse was reported by 9.7% of respondents and alcohol dependence by 6.2%. Males were more likely to report an alcohol disorder than females, and the prevalence also increased in the older age cohorts. The most frequent initial symptoms were "hazardous use" (91.9%) for abuse and "tolerance" (34.3%) for dependence. First symptoms have been shown to occur long before the age of 18. These results show that even in adolescents and young adults alcohol abuse and dependence are frequent disorders.

Alkoholkonsum beginnt häufig bereits im Jugendalter. Allerdings fehlen bisher Erkenntnisse darüber, ob, wie häufig und aufgrund welcher Merkmale Jugendlichen und junge Erwachsene auch bereits klinisch definierte Mißbrauchs- und Abhängigkeitsdiagnosen entwickeln. In der vorliegenden Arbeit werden Ergebnisse einer repräsentativen Untersuchung an 3021 Jugendlichen im Alter von 14-24 Jahren vorgestellt. Neben der Prävalenz von Alkoholmißbrauch und -abhängigkeit nach DSM-IV werden Daten zur Häufigkeit und Menge des Alkoholkonsums berichtet sowie erste Symptome beschrieben. 9,7% der befragten Jugendlichen erhielten aufgrund von DSM-IV-Kriterien eine Mißbrauchsdiagnose, 6,2% eine Abhängigkeitsdiagnose. Bei männlichen Jugendlichen war die Prävalenz wesentlich höher als bei weiblichen. Die Prävalenz war in den älteren Geburtskohorten höher. Als erstes Missbrauchssymptom trat am häufigsten "Gebrauch mit körperlicher Gefährdung" (91,9%), als erstes Abhängigkeitssymptom "Toleranzentwicklung" (34,3%) auf. Erste diagnostische Kriterien einer Alkoholstörung traten zumeist deutlich vor dem 18. Lebensjahr auf. Diese Daten unterstreichen, daß Alkoholmißbrauch und -abhängigkeit bereits im Jugend- und frühen Erwachsenenalter häufig sind. / Alcohol use frequently begins in adolescence. However, only few studies have reported the prevalence of alcohol abuse disorders in adolescents. This paper reports results from a representative study in a sample of 3021 adolescents, aged 14-24 years. The Prevalence of alcohol abuse and dependence according to DSM-IV criteria, as well as the prevalence, frequency and quantity of alcohol abuse and a description of the first occuring symptoms, are presented here. Alcohol abuse was reported by 9.7% of respondents and alcohol dependence by 6.2%. Males were more likely to report an alcohol disorder than females, and the prevalence also increased in the older age cohorts. The most frequent initial symptoms were "hazardous use" (91.9%) for abuse and "tolerance" (34.3%) for dependence. First symptoms have been shown to occur long before the age of 18. These results show that even in adolescents and young adults alcohol abuse and dependence are frequent disorders.