Maternal immune activation induces neurodevelopmental impairments of adult offspring through alterations in tryptophane-kynurenine pathway in the placenta.

Maternal immune activation (MIA) is recognized as one of the significant environmental risk factors for neuropsychiatric disorders such as schizophrenia in adult offspring. However, the pathophysiological mechanisms remain unknown. The tryptophan (TRP)-kynurenine (KYN) pathway, influenced by inflammation, may be implicated in the pathophysiology of neuropsychiatric disorders.

Deficiency of kynurenine 3-monooxygenase exacerbates impairment of prepulse inhibition induced by phencyclidine.

Phencyclidine (PCP) causes mental symptoms that closely resemble schizophrenia through the inhibition of the glutamatergic system. The kynurenine (KYN) pathway (KP) generates metabolites that modulate glutamatergic systems such as kynurenic acid (KA), quinolinic acid (QA), and xanthurenic acid (XA). Kynurenine 3-monooxygenase (KMO) metabolizes KYN to 3-hydroxykynurenine (3-HK), an upstream metabolite of QA and XA.

Kynurenine 3-monooxygenase deficiency induces depression-like behavior via enhanced antagonism of α7 nicotinic acetylcholine receptors by kynurenic acid.

Tryptophan (TRP) is metabolized via the kynurenine (KYN) pathway, which is related to the pathogenesis of major depressive disorder (MDD). Kynurenine 3-monooxygenase (KMO) is a pivotal enzyme in the metabolism of KYN to 3-hydroxykynurenine. In rodents, KMO deficiency induces a depression-like behavior and increases the levels of kynurenic acid (KA), a KYN metabolite formed by kynurenine aminotransferases (KATs).