Baricitinib ameliorates behavioral deficits and NLRP3-related neuroinflammation in a ketamine rat model of schizophrenia: Role of JAK2/STAT3 and PI3K/AKT/mTOR signaling.

Abstract

Baricitinib, a selective JAK1/JAK2 inhibitor with established anti-inflammatory properties, has demonstrated therapeutic efficacy in several autoimmune and inflammatory diseases. This study aimed to investigate the neuroprotective potential of baricitinib in a ketamine-induced rat model of schizophrenia. Specifically, the study examined its effects on behavioral deficits, neurochemical alterations, and neuroinflammatory responses, while exploring the association of the JAK2/STAT3 and PI3K/AKT/mTOR signaling pathways with its neuroprotective effects. Schizophrenia-like symptoms were induced by intraperitoneal administration of ketamine (30 mg/kg) for five consecutive days, followed by oral treatment with baricitinib (5 or 20 mg/kg/day) for 14 days. Ketamine administration produced significant locomotor hyperactivity, social withdrawal, and cognitive impairment, accompanied by reduced dopamine D2 receptor (D2R), contrary to elevating fibroblast growth factor 9 (FGF9), NLRP3 expression, and pro-inflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor-α in both the hippocampus and prefrontal cortex. These changes were associated with marked hyperactivation of the JAK2/STAT3 and PI3K/AKT/mTOR pathways. Treatment with baricitinib, particularly at the higher dose (20 mg/kg), significantly attenuated behavioral deficits, restored D2R expression, suppressed FGF9 and NLRP3 levels, reduced pro-inflammatory cytokine production, and normalized aberrant signaling pathway activation. Histological analysis further confirmed preservation of neuronal integrity in both brain regions. These findings indicate that baricitinib exerts robust neuroprotective effects in a ketamine model of schizophrenia, accompanied by attenuation of neuroinflammation and modulation of the JAK/STAT and PI3K/AKT/mTOR pathways. The present results suggest that baricitinib may represent a promising therapeutic candidate for mitigating neuroimmune dysregulation associated with schizophrenia-like alterations.