Antagonistas adenosinérgicos revertem prejuízos cognitivos em modelo animal do transtorno de déficit de atenção
Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood psychiatric disorders, affecting between 2 and 12% of primary-school children. The spontaneously hypertensive rat (SHR) is considered a genetic model for the study of this disorder since it displays behavioral and neurochemical characteristics of ADHD. Recent studies demonstrated that administration of the non selective adenosine receptor antagonist caffeine improved memory impairments in SHR rats. Therefore the objective of this study was to investigate whether adult male and female SHR exhibit altered short-term object recognition abilities compared to Wistar rats (WIS). The acute effects of methylphenidate, caffeine, or selective adenosine receptor antagonists in the performance of adults WIS and SHR rats in the object recognition task and the effects of repeated administration of methylphenidate and caffeine in adult age and adolescence were also evaluated. The results show that WIS rats displayed discrimination ability for all the objects employed while, SHR only discriminated #distinct# pairs of objects, they were not able to discriminate pairs of objects with subtle structural differences. In addition, the acute intraperitoneal (i.p.) injection of methylphenidate (2 mg/kg), caffeine (1#10 mg/kg), the selective adenosine A1 receptor antagonist DPCPX (5 mg/kg), the selective adenosine A2A receptor antagonist ZM241385 (1.0 mg/kg) or association with low doses with DPCPX (3 m/kg) and ZM242385 (0,5 mg/kg), reversed the impairment of object recognition in SHR, without altering the locomotion or hypertensive state. The repeated treatment with methylphenidate (2 mg/kg) and caffeine (3 mg/kg) in the adult age or in adolescence improved the object recognition deficits in the SHR rats. However, in WIS rats these treatments during adolescence impaired the recognition task. Interestingly, no major differences in the immunoreactivity of adenosine A1 and A2A receptors were observed in brain areas of WIS and SHR rats. These findings suggest that the previously described inability of SHR in cognitive paradigm may not be associated with their capacity to store information for short-term periods but rather may reflect discriminative learning impairments associated with attentional deficits. The present work also shows that selective and non selective adenosine receptors antagonists improved the cognitive impairment in SHR rats. Moreover, the effects of repeated administration of these drugs were persistent after the end of treatment, suggesting the potential of adenosinergic drugs for the treatment of cognitive impairment associated to ADHD.
Advisor:Lisiane de Oliveira Porciúncula; Leandro José Bertoglio; Reinaldo Naoto Takahashi
School:Universidade Federal de Santa Catarina
Source Type:Master's Thesis
Keywords:farmacologia antagonistas e inibidores metilfenidato uso terapêutico avaliação cafeína sistema nervoso central
Date of Publication:02/15/2008