Objective:This study aims to investigate the behavioral changes, gut microbiota alterations, and short-chain fatty acid levels in mice with chronic dizocilpine (MK-801) administration and to evaluate the correlation between gut microbiota and its metabolites with schizophrenia-like behaviors.Methods:This study was conducted from March to September 2024, involving 24 male C57BL/6 mice aged 6 to 8 weeks, purchased from the Guangdong Provincial Medical Laboratory Animal Center. The mice were randomly divided into a control group and a model group using a random number table method. The model group mice were intraperitoneally injected with MK-801 (0.6 mg/kg) for 14 days, while the control group mice were intraperitoneally injected with an equal amount of normal saline for 14 days. After modeling, behavioral performance was assessed using the open field test (OFT), novel object recognition test (NOR), forced swimming test (FST), tail suspension test (TST), elevated plus maze test (EPM), and prepulse inhibition test (PPI). Additionally, mouse feces were collected for 16S rRNA sequencing to analyze the composition of gut microbiota. The gas chromatography-tandem mass spectrometry (GC-MS/MS) was applied to detect the levels of short-chain fatty acids quantitatively. Between-group comparisons of behavioral data were performed using an independent samples t-test or repeated measures ANOVA with adjusted Bonferroni or corrected Greenhouse-Geisser. Between-group comparisons of gut microbiota composition were conducted using an independent samples t-test or the Mann-Whitney U test. Between-group comparisons of short-chain fatty acids were performed using an independent samples t-test. The correlations among behavioral indicators, gut microbiota composition, and short-chain fatty acids were analyzed using Spearman′s rank correlation. Results:(1) Behavioral experiments showed that the model group mice exhibited significantly prolonged immobility times in the FST and TST ( t=-4.84, -2.54; P<0.05), significantly reduced exploration frequency and time in the open arms of the EPM ( t=3.31, 2.48; P<0.05), significantly lower PPI at 76 dB, 79 dB, and 85 dB ( F=23.28, 10.65, 17.82; P<0.05), and a significantly reduced NOR index ( t=2.90, P<0.05) compared to the control group, indicating successful modeling. (2)16S rRNA sequencing revealed that, compared with the control group, the model group exhibited significantly lower relative abundances of Actinobacteriota, Coriobacteriia, Coriobacteriales, and Ileibacterium( Z=-3.10--2.04, all P<0.05). Conversely, the relative abundances of Tannerellaceae, Rikenellaceae, Alistipes, Bacteroides, Intestinimonas, Parabacteroides, Unclassified_f_Prevotellaceae, and unclassified_f_Erysipelotrichaceae significantly increased ( Z=-3.78--2.04; all P<0.05). (3)GC-MS/MS analysis showed that the concentrations of acetic acid and butyric acid in the feces of the model group were significantly lower compared to the control group ( t=2.66, 2.10; P<0.05). (4)Spearman correlation analysis with FDR correction (Benjamini-Hochberg method) revealed that Actinobacteriota significantly positively correlated with the open-arm exploration frequency in the EPM ( r=0.69, Q<0.05), whereas unclassified_f_Erysipelotrichaceae significantly negatively correlated with this measure ( r=-0.66, Q<0.05). Additionally, Bacteroides and Intestinimonas were significantly negatively correlated with PPI at 85 dB ( r=-0.71, -0.63; Q<0.05).Conversely, Ileibacterium demonstrated a significant positive correlation with PPI at 85 dB ( r=0.64, Q<0.05). Conclusion:Alterations in gut microbiota and SCAFs may be associated with MK-801-induced schizophrenia-like behaviors.

Objective:This study aims to investigate the behavioral changes, gut microbiota alterations, and short-chain fatty acid levels in mice with chronic dizocilpine (MK-801) administration and to evaluate the correlation between gut microbiota and its metabolites with schizophrenia-like behaviors.Methods:This study was conducted from March to September 2024, involving 24 male C57BL/6 mice aged 6 to 8 weeks, purchased from the Guangdong Provincial Medical Laboratory Animal Center. The mice were randomly divided into a control group and a model group using a random number table method. The model group mice were intraperitoneally injected with MK-801 (0.6 mg/kg) for 14 days, while the control group mice were intraperitoneally injected with an equal amount of normal saline for 14 days. After modeling, behavioral performance was assessed using the open field test (OFT), novel object recognition test (NOR), forced swimming test (FST), tail suspension test (TST), elevated plus maze test (EPM), and prepulse inhibition test (PPI). Additionally, mouse feces were collected for 16S rRNA sequencing to analyze the composition of gut microbiota. The gas chromatography-tandem mass spectrometry (GC-MS/MS) was applied to detect the levels of short-chain fatty acids quantitatively. Between-group comparisons of behavioral data were performed using an independent samples t-test or repeated measures ANOVA with adjusted Bonferroni or corrected Greenhouse-Geisser. Between-group comparisons of gut microbiota composition were conducted using an independent samples t-test or the Mann-Whitney U test. Between-group comparisons of short-chain fatty acids were performed using an independent samples t-test. The correlations among behavioral indicators, gut microbiota composition, and short-chain fatty acids were analyzed using Spearman′s rank correlation. Results:(1) Behavioral experiments showed that the model group mice exhibited significantly prolonged immobility times in the FST and TST ( t=-4.84, -2.54; P<0.05), significantly reduced exploration frequency and time in the open arms of the EPM ( t=3.31, 2.48; P<0.05), significantly lower PPI at 76 dB, 79 dB, and 85 dB ( F=23.28, 10.65, 17.82; P<0.05), and a significantly reduced NOR index ( t=2.90, P<0.05) compared to the control group, indicating successful modeling. (2)16S rRNA sequencing revealed that, compared with the control group, the model group exhibited significantly lower relative abundances of Actinobacteriota, Coriobacteriia, Coriobacteriales, and Ileibacterium( Z=-3.10--2.04, all P<0.05). Conversely, the relative abundances of Tannerellaceae, Rikenellaceae, Alistipes, Bacteroides, Intestinimonas, Parabacteroides, Unclassified_f_Prevotellaceae, and unclassified_f_Erysipelotrichaceae significantly increased ( Z=-3.78--2.04; all P<0.05). (3)GC-MS/MS analysis showed that the concentrations of acetic acid and butyric acid in the feces of the model group were significantly lower compared to the control group ( t=2.66, 2.10; P<0.05). (4)Spearman correlation analysis with FDR correction (Benjamini-Hochberg method) revealed that Actinobacteriota significantly positively correlated with the open-arm exploration frequency in the EPM ( r=0.69, Q<0.05), whereas unclassified_f_Erysipelotrichaceae significantly negatively correlated with this measure ( r=-0.66, Q<0.05). Additionally, Bacteroides and Intestinimonas were significantly negatively correlated with PPI at 85 dB ( r=-0.71, -0.63; Q<0.05).Conversely, Ileibacterium demonstrated a significant positive correlation with PPI at 85 dB ( r=0.64, Q<0.05). Conclusion:Alterations in gut microbiota and SCAFs may be associated with MK-801-induced schizophrenia-like behaviors.