TAMI-24. INHIBITION OF GBM INVASION BY THE Α-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID (AMPA) GLUTAMATE RECEPTOR ANTAGONIST PERAMPANEL

BACKGROUND Extensive tumor cell invasion within the brain represents a major problem for effective treatment of glioblastomas (GBMs). The invasive processes can be divided into three types: Collective cell invasion, perivascular infiltration, and single-cell invasion into the brain parenchyma. GBM cells can form synapses with neural cells pointing at an extensive communication network between brain and GBM cells which can be mediated via the metabolites Glutamine and Glutamate both needed for GBM cell proliferation. In this context, it has been shown in preclinical models that Perampanel, an antiepileptic agent, functioning as non-competitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist, has an inhibitory effect on GBM growth. To delineate how Perampanel affects GBM invasion, we utilised a highly characterized 3D GBM-brain organoid invasion model where single-cell invasion was studied in real-time following Perampanel treatment. METHODS A brain coculture model, consisting of rat brain organoids expressing various markers of the human adult brain, where confronted with GFP-labelled tumor cells. By using time-lapse confocal microscopy, we quantified single-cell invasion patterns and speed of invasion using two glioma stem cell models (BG5 and BG7). RESULTS Perampanel treatment significantly reduces tumor cell invasion into the brain organoids with the strongest effect seen in the most invasive GBM (BG5). The single-tumor cell invasion ratio was reduced by 72 % compared to the control (p= 0.0033). In contrast, collective cell invasion was reduced by 19 % (p= 0.028). Statistical analysis was performed using an unpaired sample t-test. CONCLUSION The AMPA glutamate receptor antagonist Perampanel significantly inhibits GBM invasion, suggesting an important role of the glutamate-glutamine cycle between the GBM cells and neurons in the invasion process. Moreover, this communication and exchange of metabolites seem to be more prominent where single GBM cells invade into the brain parenchyma compared to areas where collective invasion take place.

OS06.6A Inhibition of GBM invasion by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist Perampanel

BACKGROUND Extensive tumor cell invasion within the brain represents a major problem for effective treatment of glioblastomas (GBMs). The invasive processes can be divided into three types: Collective cell invasion, perivascular infiltration and single-cell invasion into the brain parenchyma. It has recently been shown that GBM cells have the ability to form synapses with neural cells pointing at an extensive communication network between brain cells GBM cells. This communication network can be mediated via the metabolites glutamine and glutamate both needed for GBM cell proliferation. In this context, it has been shown in preclinical models that Perampanel, an antiepileptic agent, functioning as non-competitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonist, has an inhibitory effect on GBM growth. In order to delineate how Perampanel affects GBM invasion, we here utilised a highly characterized 3D GBM-brain organoid invasion model where single-cell invasion was studied in real-time following Perampanel treatment. MATERIAL AND METHODS A brain coculture model, consisting of rat brain organoids expressing various markers of the human adult brain, where confronted with GFP-labelled tumor cells. By using time-lapse confocal microscopy, we quantified single-cell invasion patterns and speed of invasion using two glioma stem cell models (GSCs; BG5 and BG7). RESULTS Perampanel treatment significantly reduces tumor cell invasion into the brain organoids with the strongest effect seen in the most invasive GBM (BG5). Here, the single-tumor cell invasion ratio was reduced by 72 % compared to the control group (p=0.0033). In contrast, collective cell invasion was reduced by 19 % (p=0.028). Statistical analysis was performed using an unpaired sample t-test. CONCLUSION The AMPA glutamate receptor antagonist Perampanel significantly inhibits GBM invasion, suggesting an important role of the glutamate-glutamine cycle between the GBM cells and neurons in the invasion process. Moreover, this communication and exchange of metabolites seems to be more prominent where single GBM cells invade into the brain parenchyma compared to areas where collective invasion take place.

The influence of N-Acetylcysteine on locomotor activity, brain oxidative damage, and demyelination in MK-801 model of schizophrenia

The purpose of this study is to investigate the effects of N-acetylcysteine (NAC) on potential cerebral demyelination, oxidative damage and schizophrenia-like behaviors caused by MK-801 which is an N-methyl-D-aspartate glutamate receptor antagonist. For this, 4 groups were formed by dividing 24 male BALB/c mice into groups of six. The control group was given a saline solution (10 ml/kg) intraperitoneally (i.p.). While MK-801 (1 mg/kg-i.p.) was given both alone and with NAC (100 mg/kg-i.p.), the last group was given only NAC (100 mg/kg-i.p.). The injections were made for 14 days. It was observed that, MK-801 caused behavioral problems. When the brain was examined, it was determined that it caused a reduction in the weight of the brain, glial cell infiltration, vacuolization in neurons and shrinking in the cell nuclei in the hippocampus. A reduction in myelin basic protein (MBP) secretion was also observed. In the mice given NAC as a protector, it was observed that behavioral problems covered, antioxidant levels increased, and other impairments were repaired. It was concluded that NAC may have a neuroprotective effect.

Case Report: Treatment of Kratom Use Disorder With a Classical Tricyclic Antidepressant

Kratom or Mitragyna speciosa (Korth.) is an evergreen tree of the coffee family native to South-East Asia and Australasia. It is used by locals recreationally to induce stimulant and sedative effects and medically to soothe pain and opiate withdrawal. Its leaves are smoked, chewed, or infused, or ground to yield powders or extracts for use as liquids. It contains more than 40 alkaloids; among these, mitragynine and 7-hydroxymitragynine are endowed with variable mu, delta, and kappa opioid stimulating properties (with 7-hydroxymitragynine having a more balanced affinity), rhynchophylline, which is a non-competitive NMDA glutamate receptor antagonist, but is present in negligible quantities, and raubasine, which inhibits α1-adrenceptors preferentially over α2-adrenceptors, while the latter are bound by 7-hydroxymitragynine, while mitragynine counters 5-HT2A receptors. This complexity of neurochemical mechanisms may account for kratom's sedative-analgesic and stimulant effects. It is commonly held that kratom at low doses is stimulant and at higher doses sedative, but no cut-off has been possible to define. Long-term use of kratom may produce physical and psychological effects that are very similar to its withdrawal syndrome, that is, anxiety, irritability, mood, eating, and sleep disorders, other than physical symptoms resembling opiate withdrawal. Kratom's regulatory status varies across countries; in Italy, both mitragynine and the entire tree and its parts are included among regulated substances. We describe the case of a patient who developed anxiety and dysphoric mood and insomnia while using kratom, with these symptoms persisting after withdrawal. He did not respond to a variety of antidepressant combinations and tramadol for various months, and responded after 1 month of clomipramine. Well-being persisted after discontinuing tramadol.

NMDA receptors in the insular cortex modulate cardiovascular and autonomic but not neuroendocrine responses to restraint stress in rats

Background and Purpose: The insular cortex (IC) is a brain structure involved in the modulation of autonomic, cardiovascular and neuroendocrine adjustments during stress situations. However, the local neurochemical mechanisms involved in the control of these responses by the IC are poorly understood. Glutamate is a prominent excitatory neurotransmitter in the brain. Thus, the current study aimed to investigate the involvement of glutamatergic neurotransmission within the IC in cardiovascular, autonomic and neuroendocrine responses to acute restraint stress. Experimental Approach: The selective NMDA glutamate receptor antagonist LY235959 (1 nmol/100 nL) and the selective non-NMDA glutamate receptor antagonist NBQX (1 nmol/100 nL) were microinjected into the IC 10 min before the onset of restraint stress. Key Results: The antagonism of NMDA receptors within the IC potentiated the restraint-evoked increases in both arterial pressure and heart rate, while non-NMDA blockade had no effect on these parameters. Spontaneous baroreflex analysis demonstrated that microinjection of LY235959 into the IC decreased baroreflex activity during restraint stress. The decrease in tail skin temperature during restraint stress was shifted to an increase in animals treated with the NMDA receptor antagonist. Moreover, the blockade of IC glutamate receptors did not affect the increase in circulating corticosterone levels during restraint stress. Conclusion and Implications: Overall, our findings provide evidence that IC glutamatergic signalling, acting via NMDA receptors, plays a prominent role in the control of autonomic and cardiovascular responses to restraint stress but does not affect neuroendocrine adjustments.

Prolonged unconsciousness in perampanel overdose

Clinical experience of perampanel overdoses is markedly limited and the relevant literature is sparse. Perampanel is a novel antiepileptic drug (an amino-3-hydroxy-5-methyl-4-isoxazlepropionic acid glutamate receptor antagonist) with a long half-life, which is used for the adjunctive treatment of epilepsy. The literature available identifies a potential for prolonged unconsciousness in overdose. We report a case of prolonged unconsciousness for 14 days following a perampanel overdose of 3.5 times the maximum daily dose, requiring protracted intubation and ventilation on intensive care, with eventual complete neurological recovery. This represents the longest known period of unconsciousness with full recovery and the first reported in a perampanel naïve patient. This case helps to inform decision-making in critical care, particularly the early consideration of admission and intubation. It highlights that while perampanel overdose may not initially cause systemic effects such as cardiac toxicity, it can cause protracted altered consciousness with secondary compromise requiring prolonged intensive care management.