Urolithin A alleviates schizophrenic-like behaviors and cognitive impairment in rats through modulation of neuroinflammation, neurogenesis, and synaptic plasticity

Cognitive impairment in schizophrenia occurs in the early stages of the disease and is closely associated with prognosis. Alleviation of cognitive impairment in schizophrenia faces major challenges owing to the lack of preventive and therapeutic drugs that are novel and effective. Urolithin A (UA) is a gut microbial metabolite of ellagic acid that has demonstrated neuroprotective effects in multiple neurological disease models. Nonetheless, the neuromodulatory role of UA in schizophrenia is yet to be elucidated. Wistar rat pups were separated from their mothers for 24 h on postnatal days (PNDs) 9-10 to establish an early-life stress model. The pups were pretreated with UA at different administration times (2, 4, and 6 weeks) and doses (50, 100, and 150 mg/kg) from adolescence (PND29). Behavioral tests were performed after the end of the administration. Subsequently, hippocampal samples were collected for histopathological and molecular evaluations. Male offspring rats subjected to maternal separation exhibited increased sensitivity to prepulse inhibition and cognitive impairment, accompanied by severe neuroinflammation and impaired neurogenesis. However, UA attenuated maternal separation-induced prepulse inhibition deficits and cognitive impairments and restored hippocampal neurogenesis in a dose-dependent manner. Furthermore, UA pretreatment preserved dendritic spine density, synapses, and presynaptic vesicles. In addition, it exerted anti-inflammatory effects by inhibiting microglial activation and expression of the proinflammatory cytokines tumor necrosis factor-α, interleukin-6, and interleukin-1β. Potential mechanisms included upregulation of brain-derived neurotrophic factor protein expression and activation of the extracellular signal-regulated kinase signaling pathway. This study is the first preclinical evaluation of the effects of UA on cognitive impairment in schizophrenia. The findings suggest that changes in cognitive function linked to schizophrenia are driven by the interaction among neuroinflammation, neurogenesis, and synaptic plasticity and that UA has the potential to reverse these processes. These observations provide evidence for future clinical trials of UA as a dietary supplement for preventing schizophrenia.