The endocannabinoid system (eCS) is widely distributed in mammalian tissues and it is classically formed by cannabinoid receptors, endogenous bioactive lipids and its synthesis and degradation enzymes. Due to the modulatory role of eCS in synaptic activity in the Central Nervous System (CNS), phytocannabinoids have been increasingly used for the treatment of neurological disorders, even though little is known in terms of the long-term effect of these treatments on CNS development, mainly in the timeframe that comprises childhood and adolescence. Furthermore, an increased number of clinical trials using full-spectrum Cannabis extracts has been seen, rather than the isolated form of phytocannabinoids, when exploring the therapeutical benefits of the Cannabis plant. Thus, this study aims to evaluate the effect of cannabidiol (CBD)-enriched Cannabis extract on synaptic components in the hippocampus of rats from adolescence to early adulthood (postnatal day 45 to 60). Oral treatment of healthy male Wistar rats with a CBD-enriched Cannabis extract (3 mg/kg/day CBD) during 15 days did not affect food intake and water balance. There was also no negative impact on locomotor behaviour and cognitive performance. However, the hippocampal protein levels of GluA1 and GFAP were reduced in animals treated with the extract, whilst PSD95 levels were increased, which suggests rearrangement of glutamatergic synapses and modulation of astrocytic features. Microglial complexity was reduced in CA1 and CA3 regions, but no alterations in their phagocytic activity have been identified by Iba-1 and LAMP2 co-localization. Collectively, our data suggest that CBD-enriched Cannabis treatment may be safe and well-tolerated in healthy subjects, besides acting as a neuroprotective agent against hippocampal alterations related to the pathogenesis of excitatory and astrogliosis-mediated disorders in CNS.

Dravet syndrome (DS) is a rare and severe childhood‐onset developmental epileptic encephalopathy caused primarily by mutations in the sodium channel gene SCN1A. Animal models have undeniably advanced our understanding of DS, but they still do not fully capture its clinical heterogeneity, highlighting the need for complementary human in vitro systems. Here, we generated induced pluripotent stem cells (iPSCs) from urine epithelial cells of three DS patients carrying distinct SCN1A variants and differentiated them into neural stem cells (NSCs) and early‐stage neurospheres. Clinical severity was assessed using the DANCE checklist, and molecular phenotypes were characterized through isobaric quantitative proteomics. Comparative analyses identified differences in protein abundance across patient‐derived lines, with distinct molecular patterns associated with clinical severity measures. The patient‐derived lines exhibited variability in protein groups related to synaptic organization, mitochondrial processes, and RNA processing, reflecting interindividual molecular differences within the cohort. These findings establish patient‐derived neurospheres as a scalable human model for investigating molecular variability in DS. This approach provides a framework to explore disease heterogeneity and provides a foundation for future studies linking molecular profiles to clinical variability in DS. image

Peripheral nervous system myelination requires tightly coordinated structural and calcium-dependent communication between sensory axons and Schwann cells, processes that are profoundly influenced by extracellular matrix architecture. Here we describe a neonatal mouse dorsal root ganglia explant co-culture grown on laminin-1 pre-polymerized in acidic acetate buffer at pH 4 (polylaminin). This optimized substrate induced spontaneous formation of MBP-positive myelin sheaths, accompanied by enhanced alignment of Schwann cells with neurite bundles. Polylaminin also promoted robust clustering of the neuregulin receptor ErbB2 and a substantial increase in Connexin-43 gap-junction clusters along Schwann cell processes compared with laminin assembled in neutral phosphate buffer at pH 7 or with Poly-l-lysine. Fura-2 calcium imaging demonstrated that cultures on polylaminin exhibited faster, larger, and more sustained Ca²⁺ transients after KCl depolarization and ATP stimulation, indicating superior neuron-glia coupling and excitability. In contrast, laminin at pH 7 preferentially supported neurite outgrowth and Schwann cell migration, whereas Poly-l-lysine showed limited organization and responsiveness. The study establishes a simple and reproducible in vitro platform in which laminin supramolecular organization directs DRG cells toward neuritogenic or myelinating phenotypes through integrin/FAK/AKT signaling. By reducing the complexity of myelin induction while preserving functional communication, this model offers a valuable tool to investigate early events of peripheral demyelination, Cx43-dependent dysfunction, and degenerative responses characteristic of neuropathies that often precede CNS involvement.

Oral administration of drugs in laboratory rodents such as rats is conventionally performed using the gavage technique. Despite effectiveness, gavage can induce distress associated with restraint, especially following repeated animal handling. To mitigate these adverse effects and reduce morbidity associated with traditional methods, we explored oromucosal/buccal administration of cannabidiol (CBD)-enriched Cannabis extract. In this method, male rats were treated daily for 15 days with medium-chain triglycerides (TCM) derived from coconut oil or CBD-enriched Cannabis extract. Each treatment was administered individually while animals were gently immobilized using an affectionate touch technique. The administration involved the use of a micropipette to apply the oily formulation directly into the oral mucosa. The dosage was calculated based on the CBD concentration in the Cannabis extract, standardized at 3 mg/kg/day. To ensure accuracy, animals were weighed daily, allowing for dose adjustments in accordance with weight changes over the treatment period. This method offers non-invasive and stress-reducing treatment, potentially improving animal welfare in experimental settings. The treatment with CBD-enriched Cannabis extract was safe, and the analysis of the hippocampus of these animals' showed alterations in the expression levels of GluA1 and GFAP proteins, which are directly associated with glutamatergic receptor functionality and neuroinflammation, respectively. This suggests that Cannabis extract could be applied in pathological conditions where glutamatergic excitotoxicity and astrogliosis are observed.

Neuropsychiatric disorders represent a significant global health burden. Despite decades of research, current treatments typically provide only symptomatic relief, rather than addressing the underlying mechanisms of these conditions. Historically, research focused on the dopaminergic and serotonergic systems, which are deeply involved in the pathophysiology of many mental health disorders, including depression, schizophrenia, anxiety, autism spectrum disorder (ASD), and different substance use disorders, including alcohol use disorder (AUD). However, therapies targeting these systems have limitations, often only producing partial symptom relief plus compliance‐limiting side effects. This highlights the need for improved treatments that may emerge from a broader understanding of the neurobiological bases of these conditions, especially neurochemical systems beyond dopamine and serotonin. Additional monoamines (e.g., histamine, acetylcholine, norepinephrine), neurolipid systems (e.g., endocannabinoids), and diverse signaling molecules such as neuropeptides, trace amines, and cytokines are increasingly recognized as key players in the dysfunction of neural circuits. In this review, which originated from the International Society for Neurochemistry (ISN)/Journal of Neurochemistry 5th Flagship School in October 2024 held in Naxos, Greece, we describe the importance of these neuromodulatory systems in the pathophysiology of select neuropsychiatric disorders, discuss their potential as targets for therapeutic intervention, exploring how they may offer more effective, mechanism‐based treatments. We also highlight recent clinical trials, underscoring the progress in advancing towards clinical application, as well as sex‐specific neurobiological differences, a historically overlooked, yet fundamental determinant of the pathophysiology of neuropsychiatric disorders. We propose that expanding our focus beyond traditional monoamines offers a promising avenue for the development of new, disease‐modifying treatments that can more effectively address the underlying causes of neuropsychiatric disorders. By targeting these pathways, we believe it may be possible to develop therapies that restore balance to dysregulated brain circuits and improve long‐term outcomes for patients. image