RESUMO
This study examined the effects of two chronic stress regimens upon depressive-like behavior, A(1) and A(2A) adenosine receptor binding and immunocontent. Male rats were subjected to unpredictable chronic mild stress (UCMS) or to chronic restraint stress (CRS) for 40 days. Subsequently, depressive-like behaviors (forced swimming and consumption of sucrose) were evaluated, and A(1) adenosine or A(2A) adenosine receptors were examined in the hippocampus or striatum, respectively. UCMS animals demonstrated depressive-related behaviors (decrease in sucrose consumption and increased immobility in the forced swimming test). This group also presented increased A(1) adenosine receptor binding and immunoreactivity in hippocampus, as well as increased striatal A(2A) adenosine receptor binding in the striatum, without alteration in immunoreactivity. Conversely, the chronic restraint stress group displayed only an increase in A(1) adenosine receptor binding and no alteration in the other parameters evaluated. We suggest that the alteration in adenosine receptors, particularly the upregulation of striatal A(2A) adenosine receptors following UCMS, could be associated with depressive-related behavior.
Assuntos
Depressão/etiologia , Depressão/patologia , Hipocampo/metabolismo , Receptor A1 de Adenosina/metabolismo , Receptor A2A de Adenosina/metabolismo , Estresse Psicológico/complicações , Adenosina Desaminase/farmacologia , Análise de Variância , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Hipocampo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Ligação Proteica/efeitos dos fármacos , Purinérgicos/farmacocinética , Ratos , Ratos Wistar , Sacarose/administração & dosagem , Edulcorantes/administração & dosagem , Natação/psicologia , Fatores de Tempo , Trítio/farmacocinética , Xantinas/farmacocinéticaRESUMO
In this study, we examined the effects of two chronic stress regimens upon anxiety-like behavior, Na(+), K(+)-ATPase activity and immunocontent, and oxidative stress parameters (antioxidant enzymes and reactive oxygen species production) in the amygdala. Male rats were subjected to chronic unpredictable and to chronic restraint stress for 40 days. Subsequently, anxiety-like behavior was examined. Both stressed groups presented increased anxiety-like behavior. Reduced amygdalal Na(+), K(+)-ATPase activity in the synaptic plasma membranes was also observed, without alterations in the amygdala immunocontent. In addition, when analyzing oxidative stress parameters, only superoxide dismutase activity was decreased in the amygdala of animals subjected to unpredictable stress. We conclude that both models of chronic stress lead to anxiety-like behavior and decreased amygdalal Na(+), K(+)-ATPase activity, which appears not to be related to oxidative imbalance. The relationship between this decreased activity and anxiety-like behavior remains to be studied.