Correlation between desynchrony of hippocampal neural activity and hyperlocomotion in the model mice of schizophrenia and therapeutic effects of aripiprazole.

AIMS: The hippocampus has been reported to be morphologically and neurochemically altered in schizophrenia (SZ). Hyperlocomotion is a characteristic SZ-associated behavioral phenotype, which is associated with dysregulated dopamine system function induced by hippocampal hyperactivity. However, the neural mechanism of hippocampus underlying hyperlocomotion remains largely unclear. METHODS: Mouse pups were injected with N-methyl-D-aspartate receptor antagonist (MK-801) or vehicle twice daily on postnatal days (PND) 7-11. In the adulthood phase, one cohort of mice underwent electrode implantation in field CA1 of the hippocampus for the recording local field potentials and spike activity. A separate cohort of mice underwent surgery to allow for calcium imaging of the hippocampus while monitoring the locomotion. Lastly, the effects of atypical antipsychotic (aripiprazole, ARI) were evaluated on hippocampal neural activity. RESULTS: We found that the hippocampal theta oscillations were enhanced in MK-801-treated mice, but the correlation coefficient between the hippocampal spiking activity and theta oscillation was reduced. Consistently, although the rate and amplitude of calcium transients of hippocampal neurons were increased, their synchrony and correlation to locomotion speed were disrupted. ARI ameliorated perturbations produced by the postnatal MK-801 treatment. CONCLUSIONS: These results suggest that the disruption of neural coordination may underly the neuropathological mechanism for hyperlocomotion of SZ.

Maternal sevoflurane exposure affects neural stem cell differentiation in offspring rats through NRF2 signaling.

Studies have shown that sevoflurane, a halogenated inhalational anesthetic, interferes with neurogenesis in the developing rodent brain. However, the mechanisms by which sevoflurane affects neural stem cells (NSCs) differentiation require further elucidation. Pregnant rats (gestational day 14) were anesthetized with 3.5% sevoflurane for 2 h, with or without ML385 pretreatment. ML385 is a specific nuclear factor erythroid 2-related factor 2 (NRF2) inhibitor. NRF2 expression and the downstream Sonic Hedgehog (SHH)/glioma-associated oncogene homolog 1 (GLI1) signaling cascade were determined by western blotting in the fetal brain at 24 h and 72 h after maternal sevoflurane exposure. Immunofluorescence and western blotting were performed to evaluate NSC neuronal and astrocytic differentiation in fetal brain tissues at 24 h and 72 h post-anesthesia as well as in the hippocampus on postnatal day (P) 28. Nissl staining was performed to measure the neuronal density on P28. Morris Water Maze tests were used to evaluate learning and memory function on P28-33. Neuronal and astrocytic differentiation of NSCs was markedly promoted in the fetal brain at 24 h and 72 h after maternal sevoflurane exposure, accompanied by upregulated NRF2. However, neuronal reduction and astrocyte proliferation were observed in the rat hippocampus at P28. Pretreatment with ML385 reversed sevoflurane-induced premature differentiation of NSCs, accompanied by suppression of SHH/GLI1 signaling. Furthermore, ML385 rescued sevoflurane-induced decreased neuronal density and impaired learning and memory function in the offspring. Prenatal sevoflurane exposure promotes neuronal and astrocytic differentiation of NSCs in the fetal rat brain, leading to long-term neuron reduction but astrocyte proliferation in the postnatal rat hippocampus. Prenatal sevoflurane exposure modulates NSC differentiation through NRF2/SHH/GLI1.

Dexmedetomidine and Ketamine Attenuated Neuropathic Pain Related Behaviors via STING Pathway to Induce ER-Phagy.

Our previous work indicated that ER-phagy level had altered in spinal nerve ligation (SNL) rats. In this study, we investigated whether dexmedetomidine or ketamine exhibits anti-anxiety or anti-nociceptive effects via modulation of the spinal STING/TBK pathway to alter ER-phagy in SNL rats. We evaluated the analgesic and anti-anxiety effects of ketamine and dexmedetomidine in SNL rats. 2'3'-cGAMP (a STING pathway agonist) was administrated to investigate whether enhanced spinal STING pathway activation could inhibit dexmedetomidine or ketamine treatment effects in SNL rats. Analgesic effects were assessed with the mechanical withdrawal threshold (MWT) and anti-anxiety effects were measured via an open field test (OFT). Protein expression levels were evaluated by immunoblotting. Distribution and cellular localization of Grp78 (ER stress marker) were evaluated by confocal immunofluorescence. SNL induced mechanical hypersensitivity and anxiety in rats; dexmedetomidine and ketamine both provided analgesia and anti-anxiety effects in SNL rats. Furthermore, the STING pathway was involved in the modulation of ER stress and ER-phagy in SNL rats and dexmedetomidine and ketamine alleviated ER stress by inhibiting STING pathway to enhance ER-phagy. Thus, both ketamine and dexmedetomidine provided anti-anxiety and anti-nociceptive effects by alleviating ER stress through the inhibition of the STING/TBK pathway to modulate spinal ER-phagy in SNL rats.