The impact of caffeine on gene expression in the brain and plasma corticosterone concentrations in rats with varying degrees of anxiety like behaviour.

Anxiety disorders are the most common psychiatric disorders worldwide and are associated withcomorbidity and morbidity. Although there are several therapeutic drugs for this mental condition,there is a need to develop alternative treatments as treatment response differ between patients.Meanwhile, many researchers suggest a link between mental diseases and adenosinergic signaltransduction regulation in the central nervous system (CNS). The adenosine receptor antagonist,caffeine, have been of interest in these studies as some hypotheses suggest its role in modulatinganxiety-like behaviour. The aim with this study was to measure the gene expression of A2aR, A1R,D2R and C-fos and corticosterone plasma levels in rats, after acute injection with caffeine (50 mg/kg)in three rat groups: low/intermediate/ high anxiety-like behaviour groups. We used qPCR and ELISAto conduct this study. In amygdala, a significant increase of A1R was observed in the low anxietygroup compared with the control group. The same group also showed a significant increase incorticosterone plasma levels. As a result of our findings, the adenosine receptor antagonist caffeinemay play a role in the regulation of certain genes and hormones involved in anxiety, further suggestinga role of the adenosine receptor system in anxiety disorders.