Avaliação dos efeitos do consumo em longo prazo e da retirada de álcool sobre células serotonérgicas no núcleo dorsal da rafe em ratas

Abstract

Long-term alcohol abuse may cause neuroadaptations impairing the normal functioning of the central nervous system. Among the altered neurotransmission pathways, there is serotonergic system that plays a fundamental role in the mediation of emotions. It is known that this system is dysfunctional during long-term use e withdrawal of alcohol, with deregulation of the serotonin level and this metabolites and even the level of this receptors. Such changes may favour affective and behavioural disorders observed in dependent individuals. Women constitute a risk group for emotional disorders; so, this study evaluated whether long-term consumption and withdrawal of alcohol promoted changes in serotonergic cell density in the dorsal (DDR) and caudal (DCR) subdivisions of the dorsal raphe nucleus of female Wistar rats. The dorsal nucleus of the raphe contains a large number of serotonergic neurons and the DDR e DCR subdivisions project into areas involved with emotional responses, such as amygdala, bed nucleus of the terminal stria, paraventricular hypothalamus, and ventral hippocampus. The animals were submitted to increasing concentrations of alcohol (2%, 4% and 6%) as the unique source of liquid diet for 21 days or water (control group). Both groups had free access to the feed. After this treatment period, the alcohol was replaced with water and the animals were submitted to transcardiac perfusion and brain removal 72 hours after replacement by water (short term withdrawal group) or 21 days after replacement by water (long term withdrawal group). Immunohistochemical analysis was performed the detection of immunoreactive cells for serotonin (5-HT) in the DDR and DCR. It was observed that long-term withdrawal produced an increase in the density of 5-HT immunolabelled cells in the middle region of DDR and in DCR. Taken together, it may be suggested that this increased in density of 5-HT immunolabelled cells is related to the dysregulation of emotional and behavioural responses observed in the period of long-term alcohol withdrawal.