Effect of blueberry extract on energetic metabolism, levels of brain-derived neurotrophic factor, and Ca2+-ATPase activity in the hippocampus and cerebral cortex of rats submitted to ketamine-induced mania-like behavior

Proteomic Characteristics of the Prefrontal Cortex and Hippocampus in Mice with Chronic Ketamine-Induced Anxiety and Cognitive Impairment

Schizophrenia, a complex psychiatric disorder with diverse symptoms, has been linked to ketamine, known for its N-methyl-D-aspartate (NMDA) receptor antagonistic properties. Understanding the distinct roles and mechanisms of ketamine is crucial, especially regarding its induction of schizophrenia-like symptoms. Recent research highlights the impact of ketamine on key brain regions associated with schizophrenia, specifically the prefrontal cortex (PFC) and hippocampus (Hip). This study focused on these regions to explore proteomic changes related to anxiety and cognitive impairment in a chronic ketamine-induced mouse model of schizophrenia. After twelve consecutive days of ketamine administration, brain tissues from these regions were dissected and analyzed. Using tandem mass tag (TMT) labeling quantitative proteomics techniques, 34,797 and 46,740 peptides were identified in PFC and Hip, corresponding to 5,668 and 6,463 proteins, respectively. In the PFC, a total of 113 proteins showed differential expression, primarily associated with the immuno-inflammatory process, calmodulin, postsynaptic density protein, and mitochondrial function. In the Hip, 129 differentially expressed proteins were screened, mainly related to synaptic plasticity proteins and mitochondrial respiratory chain complex-associated proteins. Additionally, we investigated key proteins within the glutamatergic synapse pathway and observed decreased expression levels of phosphorylated CaMKII and CREB. Overall, the study unveiled a significant proteomic signature in the chronic ketamine-induced schizophrenia mouse model, characterized by anxiety and cognitive impairment in both the PFC and Hip, and this comprehensive proteomic dataset may not only enhance our understanding of the molecular mechanisms underlying ketamine-related mental disorders but also offer valuable insights for future disease treatments.

Blueberry Extract Modulates Brain Enzymes Activities and Reduces Neuroinflammation: Promising Effect on Lipopolysaccharide-Induced Depressive-Like Behavior

Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders with high rates of prevalence and mortality. MDD is pathophysiologically complex, and treatment options are limited. Blueberries are rich in polyphenols and have neuroprotective potential. The aim of this study was to investigate the effects of blueberry extract on neuroinflammatory and neuroplasticity parameters, as well as Na⁺/K⁺-ATPase, monoamine oxidase-A (MAO-A), and acetylcholinesterase (AChE) activities in the cerebral cortex and hippocampus of mice subject to lipopolysaccharide (LPS)-induced depressive-like behavior. We also analyzed the interaction between anthocyanins and indoleamine 2 3-dioxygenase (IDO). Male Swiss mice (60-day-old) received vehicle, fluoxetine (20 mg/kg), or blueberry extract (100 or 200 mg/kg) intragastrically for 7 days before intraperitoneal LPS (0.83 mg/kg) injection. Twenty-four hours after LPS administration, the mice were subjected to behavioral tests. Both fluoxetine and blueberry extract (200 mg/kg) decreased the immobility time in the forced swim test, without affecting locomotor activity. Fluoxetine attenuated the decrease of Na⁺/K⁺-ATPase in the cerebral cortex, while blueberry extract promoted this same effect in the hippocampus. Additionally, fluoxetine and blueberry extract attenuated the decrease in the activity of MAO-A in the hippocampus. Blueberry extract (200 mg/kg) also prevented LPS-induced increase in AChE activity in the hippocampus as well as LPS upregulation of relative mRNA expression of tumor necrosis factor alpha, interleukin (IL)-1β, and IL-10 in the cerebral cortex. Molecular docking analysis revealed binding sites for malvidin 3-galactoside (- 7.8 kcal/mol) and malvidin 3-glucoside (- 7.9 kcal/mol) residues with IDO. Taken together, these results indicate that blueberry extract improved depression-like behavior and attenuated the neurochemical and molecular changes in the brains of mice challenged with LPS.

Chronic lithium treatment ameliorates ketamine-induced mania-like behavior via the PI3K-AKT signaling pathway

Ketamine, a rapid-acting antidepressant drug, has been used to treat major depressive disorder and bipolar disorder (BD). Recent studies have shown that ketamine may increase the potential risk of treatment-induced mania in patients. Ketamine has also been applied to establish animal models of mania. At present, however, the underlying mechanism is still unclear. In the current study, we found that chronic lithium exposure attenuated ketamine-induced mania-like behavior and c-Fos expression in the medial prefrontal cortex (mPFC) of adult male mice. Transcriptome sequencing was performed to determine the effect of lithium administration on the transcriptome of the PFC in ketamine-treated mice, showing inactivation of the phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway. Pharmacological inhibition of AKT signaling by MK2206 (40 mg/kg), a selective AKT inhibitor, reversed ketamine-induced mania. Furthermore, selective knockdown of AKT via AAV-AKT-shRNA-EGFP in the mPFC also reversed ketamine-induced mania-like behavior. Importantly, pharmacological activation of AKT signaling by SC79 (40 mg/kg), an AKT activator, contributed to mania in low-dose ketamine-treated mice. Inhibition of PI3K signaling by LY294002 (25 mg/kg), a specific PI3K inhibitor, reversed the mania-like behavior in ketamine-treated mice. However, pharmacological inhibition of mammalian target of rapamycin (mTOR) signaling with rapamycin (10 mg/kg), a specific mTOR inhibitor, had no effect on ketamine-induced mania-like behavior. These results suggest that chronic lithium treatment ameliorates ketamine-induced mania-like behavior via the PI3K-AKT signaling pathway, which may be a novel target for the development of BD treatment.

The Na+/K+ pump dominates control of glycolysis in hippocampal dentate granule cells

Cellular ATP that is consumed to perform energetically expensive tasks must be replenished by new ATP through the activation of metabolism. Neuronal stimulation, an energetically demanding process, transiently activates aerobic glycolysis, but the precise mechanism underlying this glycolysis activation has not been determined. We previously showed that neuronal glycolysis is correlated with Ca2+ influx, but is not activated by feedforward Ca2+ signaling (Díaz-García et al., 2021a). Since ATP-powered Na+ and Ca2+ pumping activities are increased following stimulation to restore ion gradients and are estimated to consume most neuronal ATP, we aimed to determine if they are coupled to neuronal glycolysis activation. By using two-photon imaging of fluorescent biosensors and dyes in dentate granule cell somas of acute mouse hippocampal slices, we observed that production of cytoplasmic NADH, a byproduct of glycolysis, is strongly coupled to changes in intracellular Na+, while intracellular Ca2+ could only increase NADH production if both forward Na+/Ca2+ exchange and Na+/K+ pump activity were intact. Additionally, antidromic stimulation-induced intracellular [Na+] increases were reduced >50% by blocking Ca2+ entry. These results indicate that neuronal glycolysis activation is predominantly a response to an increase in activity of the Na+/K+ pump, which is strongly potentiated by Na+ influx through the Na+/Ca2+ exchanger during extrusion of Ca2+ following stimulation.