Restorative properties of chronic lurasidone treatment on emotional dysfunction in rats exposed to chronic unavoidable stress: A role for medial prefrontal cortex - nucleus accumbens network

Anhedonia, a transdiagnostic symptom prevalent in depressive and psychotic disorders, poses a significant challenge for pharmacological intervention due to its association with impaired motivation. Understanding how psychotropic drugs can modulate this pathological domain and elucidating the molecular mechanisms underlying such effects are crucial endeavors in psychiatric research. In this study, we aimed to investigate the pro-motivational properties of lurasidone in a rat (Sprague Dawley males) model of anhedonia and to unravel the interplay between lurasidone and the brain regions critical for reward processing. Exposure to unpredictable chronic stress (UCS) led to a marked reduction in motivation, a deficit that was restored by lurasidone treatment at 3 mg/kg, but not at 10 mg/kg. Interestingly, the stress-induced decrease in reactivity to negative stimuli was reversed by both doses of lurasidone. At the molecular level, stressed animals exhibited reduced expression of neuroplastic markers, that was increased following lurasidone administration. Furthermore, UCS exposure impaired the activation of the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) in response to hedonic stimuli, an effect amended by lurasidone treatment. Additionally, lurasidone restored the impaired phosphorylation of DARPP-32, a key regulator of dopamine signaling, in mPFC and NAc of UCS rats exposed to a hedonic stimulus. These findings underscore the potential of lurasidone in improving various psychopathological domains, like impaired motivation and emotional reactivity, core elements contributing to the disability associated with mental disorders. These effects highlight the therapeutic potential of lurasidone in addressing the intricate behavioral and neurochemical alterations associated with anhedonia and related mood disorders.