Prenatal immune activation potentiates endocannabinoid-related plasticity of inhibitory synapses in the hippocampus of adolescent rat offspring

Maternal Immune Activation and the Endocannabinoid System: Focus on Two-Hit Models of Schizophrenia

The devastating effects of the COVID-19 pandemic have underscored the significant threat that infectious diseases pose to our society. Pregnancy represents a period of heightened vulnerability to infections, which can compromise maternal health and increase the risk of neurodevelopmental disorders in offspring. Preclinical and clinical investigations suggest a potential association between maternal immune activation (MIA), which is triggered by viral or bacterial infections, and increased risk for neurodevelopmental disorders such as autism and schizophrenia. Genetic and environmental factors may contribute to the overall risk. Therefore, the two-hit hypothesis of schizophrenia suggests that MIA could act as a first trigger, with subsequent factors, such as stress or drug abuse, exacerbating latent abnormalities. A growing body of research is focused on the interaction between MIA and cannabis use during adolescence, considering the role of the endocannabinoid (eCB) system in neurodevelopment and in neurodevelopmental disorders. The eCB system, crucial for fetal brain development, may be disrupted by MIA, leading to adverse outcomes in adulthood. Recent research indicates the eCB system's significant role in the pathophysiology of neurodevelopmental disorders in preclinical models. However, findings on adolescent cannabinoid exposure in MIA-exposed animals have revealed unexpected complexities, with several studies failing to support the exacerbation of MIA-related abnormalities. In this review, we delve into the functional implications of the eCB system in MIA models, emphasizing the role of 2-AG (2-arachidonoylglycerol) signaling in synaptic plasticity and neuroinflammation and its relevance to the two-hit model of schizophrenia.

Synaptic proteome perturbations after maternal immune activation: Identification of embryonic and adult hippocampal changes

BACKGROUND

Maternal immune activation (MIA) triggers neurobiological changes in offspring, potentially reshaping the molecular synaptic landscape, with the hippocampus being particularly vulnerable. However, critical details regarding developmental timing of these changes and whether they differ between males and females remain unclear.

METHODS

We induced MIA in C57BL/6J mice on gestational day nine using the viral mimetic poly(I:C) and performed mass spectrometry-based proteomic analyses on hippocampal synaptoneurosomes of embryonic (E18) and adult (20 ± 1 weeks) MIA offspring.

RESULTS

In the embryonic synaptoneurosomes, MIA led to lipid, polysaccharide, and glycoprotein metabolism pathway disruptions. In the adult synaptic proteome, we observed a dynamic shift toward transmembrane trafficking, intracellular signalling cascades, including cell death and growth, and cytoskeletal organisation. In adults, many associated pathways overlapped between males and females. However, we found distinct sex-specific enrichment of dopaminergic and glutamatergic pathways. We identified 50 proteins altered by MIA in both embryonic and adult samples (28 with the same directionality), mainly involved in presynaptic structure and synaptic vesicle function. We probed human phenome-wide association study data in the cognitive and psychiatric domains, and 49 of the 50 genes encoding these proteins were significantly associated with the investigated phenotypes.

CONCLUSIONS

Our data emphasise the dynamic effects of viral-like MIA on developing and mature hippocampi and provide novel targets for study following prenatal immune challenges. The 22 proteins that changed directionality from the embryonic to adult hippocampus, suggestive of compensatory over-adaptions, are particularly attractive for future investigations.

Schizophrenia as metabolic disease. What are the causes?

Schizophrenia (SZ) is a devastating neurodevelopmental disease with an accelerated ageing feature. The criteria of metabolic disease firmly fit with those of schizophrenia. Disturbances in energy and mitochondria are at the core of complex pathology. Genetic and environmental interaction creates changes in redox, inflammation, and apoptosis. All the factors behind schizophrenia interact in a cycle where it is difficult to discriminate between the cause and the effect. New technology and advances in the multi-dispensary fields could break this cycle in the future.

Increased Excitatory Synaptic Transmission Associated with Adult Seizure Vulnerability Induced by Early-Life Inflammation in Mice

Early-life inflammatory stress increases seizure susceptibility later in life. However, possible sex- and age-specific differences and the associated mechanisms are largely unknown. C57BL/6 mice were bred in house, and female and male pups were injected with lipopolysaccharide (LPS; 100 μg/kg, i.p.) or vehicle control (saline solution) at postnatal day 14 (P14). Seizure threshold was assessed in response to pentylenetetrazol (1% solution, i.v.) in adolescence (∼P40) and adulthood (∼P60). We found that adult, but not adolescent, mice treated with LPS displayed ∼34% lower seizure threshold compared with controls. Females and males showed similar increased seizure susceptibility, suggesting that altered brain excitability was age dependent, but not sex dependent. Whole-cell recordings revealed no differences in excitatory synaptic activity onto CA1 pyramidal neurons from control or neonatally inflamed adolescent mice of either sex. However, adult mice of both sexes previously exposed to LPS displayed spontaneous EPSC frequency approximately twice that of controls, but amplitude was unchanged. Although these changes were not associated with alterations in dendritic spines or in the NMDA/AMPA receptor ratio, they were linked to an increased glutamate release probability from Schaffer collateral, but not temporoammonic pathway. This glutamate increase was associated with reduced activity of presynaptic GABA_B receptors and was independent of the endocannabinoid-mediated suppression of excitation. Our new findings demonstrate that early-life inflammation leads to long-term increased hippocampal excitability in adult female and male mice associated with changes in glutamatergic synaptic transmission. These alterations may contribute to enhanced vulnerability of the brain to subsequent pathologic challenges such as epileptic seizures.SIGNIFICANCE STATEMENT Adult physiology has been shown to be affected by early-life inflammation. Our data reveal that early-life inflammation increases excitatory synaptic transmission onto hippocampal CA1 pyramidal neurons in an age-dependent manner through disrupted presynaptic GABA_B receptor activity on Schaffer collaterals. This hyperexcitability was seen only in adult, and not in adolescent, animals of either sex. The data suggest a maturation process, independent of sex, in the priming action of early-life inflammation and highlight the importance of studying mature brains to reveal cellular changes associated with early-life interventions.

A synergistic effect between family intervention and rTMS improves cognitive and negative symptoms in schizophrenia: A randomized controlled trial

OBJECTIVE

The present study explored an efficient new therapy that combined repetitive transcranial magnetic stimulation (rTMS) and family intervention in addition to risperidone to improve schizophrenia.

METHODS

A randomized controlled trial (January 2016-September 2017) involving 200 patients, of which 188 patients completed the 12-week study, and 50 controls were conducted in the research. The patients were randomly assigned to 12 weeks of treatment with risperidone alone (risperidone group), rTMS and risperidone (rTMS group), family intervention and risperidone (family intervention group), rTMS and risperidone plus family intervention (combined group). MATRICS Consensus Cognitive Battery (MCCB) and the Positive and Negative Symptoms Scale (PANSS) were used to evaluate treatment efficacy. Repeated measures analysis of variance (RMANOVA) were performed to evaluate different treatment efficacy between four groups after 12 weeks of treatment.

RESULTS

(1) There were no significant differences in sex, age, education, cognitive function, or PANSS scores between the four groups at baseline (p's > 0.05). (2) There was a significant decrease in the PANSS scores and an increase in the MCCB scores after 12 weeks of treatment in all groups (time effect p's < 0.001). (3) The improvements in positive symptoms and negative symptoms were more obvious in the combined group than in other groups (p's < 0.05). (4) The combined group showed the superior effect in cognition function after 12 weeks. (5) And, interestingly, a remarkable synergistic effect between rTMS and family intervention therapy was observed.

CONCLUSION

There was a synergistic effect between rTMS and the family intervention as an effective combined therapy in improving schizophrenia. This study is registered with Chictr.org, number ChiCTR1900024422 (http://www.chictr.org.cn/edit.aspx?pid=34285&htm=4).