Kynurenine/Aryl Hydrocarbon Receptor Modulates Mitochondria-Mediated Oxidative Stress and Neuronal Apoptosis in Experimental Intracerebral Hemorrhage

Aims: Oxidative stress and neuronal apoptosis play crucial roles in the pathological processes of secondary injury after intracerebral hemorrhage (ICH). Aryl hydrocarbon receptor (AHR), together with its endogenous ligand kynurenine, is known to mediate free radical accumulation and neuronal excitotoxicity in central nervous systems. Herein, we investigate the pathological roles of kynurenine/AHR after ICH. Results: Endogenous AHR knockout alleviated reactive oxygen species accumulation and neuronal apoptosis in ipsilateral hemisphere at 48 h after ICH in mice. The ICH insult resulted in an increase of total and nucleus AHR protein levels and AHR transcriptional activity. Inhibition of AHR provided both short- and long- term neurological benefits by attenuating mitochondria-mediated oxidative stress and neuronal apoptosis after ICH in mice. RhoA-Bax signaling activated mitochondrial death pathway and participated in deleterious actions of AHR. Finally, we reported that exogenous kynurenine aggravated AHR activation and mediated the brain mentioned earlier. Male animals were used in the experiments. Innovation: We show for the first time that kynurenine/AHR mediates mitochondria death and free radical accumulation, at least partially via the RhoA/Bax signaling pathway. Pharmacological antagonists of AHR and kynurenine may ameliorate neurobehavioral function and improve the prognosis of patients with ICH. Conclusion: Kynurenine/AHR may serve as a potential therapeutic target to attenuate mitochondria-mediated oxidative stress and neuronal cells impairment in patients with ICH. Antioxid. Redox Signal. 37, 1111–1129.