Molecular changes underlying decay of sensory responses and enhanced seizure propensity in peritumoral neurons

BACKGROUND

Glioblastoma growth impacts on the structure and physiology of peritumoral neuronal networks, altering the activity of pyramidal neurons which drives further tumor progression. It is therefore of paramount importance to identify glioma-induced changes in pyramidal neurons, since they represent a key therapeutic target.

METHODS

We longitudinal monitored visual evoked potentials after the orthotopic implant of murine glioma cells into the mouse occipital cortex. With laser microdissection we analysed layer II-III pyramidal neurons molecular profile and with Local Field Potentials (LFP) recordings we evaluated the propensity to seizures in glioma-bearing animals with respect to control mice.

RESULTS

We determine the time course of neuronal dysfunction of glioma-bearing mice and we identify a symptomatic stage, based on the decay of visual response. At that time point, we microdissect layer II-III pyramidal neurons and evaluate the expression of a panel of genes involved in synaptic transmission and neuronal excitability. Compared to the control group, peritumoral neurons show a decrease in the expression of the SNARE complex gene SNAP-25 and the alpha1 subunit of the GABA-A receptor. No significant changes are detected in glutamatergic (i.e., AMPA or NMDA receptor subunit) markers. Further reduction of GABA-A signalling by delivery of a benzodiazepine inverse agonist, DMCM (methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate) precipitates seizures in two mouse models of tumor-bearing mice.

CONCLUSIONS

These studies reveal novel molecular changes that occur in the principal cells of the tumor-adjacent zone. These modifications may be therapeutically targeted to ameliorate patients' quality of life.

Old Stars and New Players in the Brain Tumor Microenvironment

In recent years, the direct interaction between cancer cells and tumor microenvironment (TME) has emerged as a crucial regulator of tumor growth and a promising therapeutic target. The TME, including the surrounding peritumoral regions, is dynamically modified during tumor progression and in response to therapies. However, the mechanisms regulating the crosstalk between malignant and non-malignant cells are still poorly understood, especially in the case of glioma, an aggressive form of brain tumor. The presence of unique brain-resident cell types, namely neurons and glial cells, and an exceptionally immunosuppressive microenvironment pose additional important challenges to the development of effective treatments targeting the TME. In this review, we provide an overview on the direct and indirect interplay between glioma and neuronal and glial cells, introducing new players and mechanisms that still deserve further investigation. We will focus on the effects of neural activity and glial response in controlling glioma cell behavior and discuss the potential of exploiting these cellular interactions to develop new therapeutic approaches with the aim to preserve proper brain functionality.

Impact of the take ACTION Train-the-Trainer model of opioid overdose education with naloxone distribution- who benefits?

BACKGROUND

Overdose education with naloxone distribution (OEND) is a key national strategy to reduce morbidity and mortality related to opioid overdoses. Train-the-trainer model has been one method to increase the pool of trainers to facilitate greater dissemination of OEND. This exploratory study seeks to (1) evaluate participant's change in knowledge and confidence, (2) examine if pre- and post-training test outcomes differed by occupation and level of experience, and (3) determine if train-the-trainer participants trained others 6 months later. Methods: Fifteen train-the-trainer sessions were delivered to staff from community organizations who served high-risk clients in four counties whose overdose death rates ranged from 11.2 to 32.8 per 100,000. Participants were administered pre- and post-training tests from September 2017 to December 2018. A follow-up survey was conducted 6 months post-training to evaluate outcomes. Final paired pre-and post-training surveys of 109 participants were used for analysis. Paired sample t-tests were used to evaluate changes in the knowledge and confidence in teaching others. One-way ANOVA compared the change scores across groups with different demographic or experiential characteristics. Kruskal-Wallis Test was used for Likert scales. Results: The one and one-half hour train-the-trainer curriculum increased participants' knowledge and confidence to teach others (p < .001). This was particularly true for participants who had no prior experience compared to those who had some experience with naloxone (p = .0003). Changes in confidence to teach others significantly improved among demographic subgroups of participants. At 6 months after completing the train-the-trainer curriculum, 14 participants had trained 243 new trainees. Conclusions: Implementing a train-the-trainer model for OEND increases knowledge and participants' confidence to teach others. This demonstrates the important potential of the train-the-trainer model to respond to the growing opioid overdose epidemic.