Effect of rolipram, a phosphodiesterase enzyme type– 4 inhibitor, on γ-amino butyric acid content of the frontal cortex in mice exposed to chronic mild stress

Objectives: To investigate the alterations in GABA levels by rolipram in the model of depression. Materials and Methods: The alteration of GABA content by rolipram as a phosphodiesterase enzyme type-4 inhibitor in the frontal cortex (FCx; as a brain region crucial for the control of emotion and cognition) obtained from male mice exposed to chronic mild stress (CMS)-induced anhedonia (the loss of pleasure or lack of sensitivity to pleasure stimuli) was recorded. Results: The results demonstrated the reversal of CMS-induced anhedonia after 3 weeks per os of rolipram in a dose of 0.1 mg/kg/day dissolved in distilled water. Furthermore, rolipram showed a significant reduction in duration of immobility in long-term behavioral changes recorded by the FST. Additionally, there was a significant increase in the GABA content of the FCx of rolipram-treated mice exposed to CMS-induced anhedonia. Conclusions: The present study suggested that GABA levels may be decreased in an animal model of depression and its reversal together with the behaviour improvement by rolipram could support the hypothesis that modification in GABAergic activity has a role in mood disorders. These effects may complement the antidepressant effect of rolipram that is originally mediated via inhibition of phosphodiesterase enzyme type-4 [PDE4] that increases cyclic adenosine monophosphate signalling the pharmacotherapy of depression.