Altered striatal endocannabinoid signaling in a transgenic mouse model of spinocerebellar ataxia type-3

Decreased Peripheral Blood Lymphocytes in Spinocerebellar Ataxia Type 3 Correlate with Disease Severity

BACKGROUND

The immune system likely plays a role in the pathogenesis of spinocerebellar ataxia type 3 (SCA3). Peripheral blood leukocytes are indicative of the immune status in neurodegenerative diseases. However, alterations in the characteristics of peripheral blood leukocytes at different stages of SCA3 and their potential roles in disease progression remain unclear.

OBJECTIVES

The goal was to identify leukocyte profiles alterations at different stages of SCA3 and analyze their correlation with disease severity.

METHODS

This cross-sectional study included 150 total ATXN3 expansion carriers (20 pre-ataxic and 130 ataxic) and 113 healthy controls. Differences in leukocyte profiles were analyzed, and correlations with clinical characteristics were assessed using Spearman and partial correlation. Logistic regression and receiver operating characteristic curve identified independent factors associated with disease severity. Mediation analysis evaluated the effect of lymphocyte counts on the relationship between disease duration and SARA scores.

RESULTS

Alterations in neutrophil, lymphocyte, eosinophil, and basophil counts were observed across ATXN3 expansion carriers, including those in pre-ataxic and ataxic stages, compared with healthy controls. Lymphocyte counts negatively correlated with SARA and International Cooperative Ataxia Rating Scale scores, particularly in speech function. Leukocyte, monocyte, and basophil counts were also negatively associated with ataxia scales scores or sub-item scores. Lymphocyte counts distinguished disease severities, and partially mediated the effect of disease duration on ataxia scale scores in ataxic SCA3.

CONCLUSIONS

Leukocyte profiles alterations at different stages of SCA3 may be closely linked to disease progression and severity. Lymphocyte counts may serve as valuable indicators of disease severity. © 2025 International Parkinson and Movement Disorder Society.

Physiological Recordings of the Cerebellum in Movement Disorders

The cerebellum plays an important role in movement disorders, specifically in symptoms of ataxia, tremor, and dystonia. Understanding the physiological signals of the cerebellum contributes to insights into the pathophysiology of these movement disorders and holds promise in advancing therapeutic development. Non-invasive techniques such as electroencephalogram and magnetoencephalogram can record neural signals with high temporal resolution at the millisecond level, which is uniquely suitable to interrogate cerebellar physiology. These techniques have recently been implemented to study cerebellar physiology in healthy subjects as well as individuals with movement disorders. In the present review, we focus on the current understanding of cerebellar physiology using these techniques to study movement disorders.

Molecular Alterations of the Endocannabinoid System in Psychiatric Disorders

The therapeutic benefits of the current medications for patients with psychiatric disorders contrast with a great variety of adverse effects. The endocannabinoid system (ECS) components have gained high interest as potential new targets for treating psychiatry diseases because of their neuromodulator role, which is essential to understanding the regulation of many brain functions. This article reviewed the molecular alterations in ECS occurring in different psychiatric conditions. The methods used to identify alterations in the ECS were also described. We used a translational approach. The animal models reproducing some behavioral and/or neurochemical aspects of psychiatric disorders and the molecular alterations in clinical studies in post-mortem brain tissue or peripheral tissues were analyzed. This article reviewed the most relevant ECS changes in prevalent psychiatric diseases such as mood disorders, schizophrenia, autism, attentional deficit, eating disorders (ED), and addiction. The review concludes that clinical research studies are urgently needed for two different purposes: (1) To identify alterations of the ECS components potentially useful as new biomarkers relating to a specific disease or condition, and (2) to design new therapeutic targets based on the specific alterations found to improve the pharmacological treatment in psychiatry.

Effect of acute physical exercise on motor sequence memory

Acute physical exercise improves memory functions by increasing neural plasticity in the hippocampus. In animals, a single session of physical exercise has been shown to boost anandamide (AEA), an endocannabinoid known to promote hippocampal plasticity. Hippocampal neuronal networks encode episodic memory representations, including the temporal organization of elements, and can thus benefit motor sequence learning. While previous work established that acute physical exercise has positive effects on declarative memory linked to hippocampal plasticity mechanisms, its influence on memory for motor sequences, and especially on neural mechanisms underlying possible effects, has been less investigated. Here we studied the impact of acute physical exercise on motor sequence learning, and its underlying neurophysiological mechanisms in humans, using a cross-over randomized within-subjects design. We measured behavior, fMRI activity, and circulating AEA levels in fifteen healthy participants while they performed a serial reaction time task before and after a short period of exercise (moderate or high intensity) or rest. We show that exercise enhanced motor sequence memory, significantly for high intensity exercise and tending towards significance for moderate intensity exercise. This enhancement correlated with AEA increase, and dovetailed with local increases in caudate nucleus and hippocampus activity. These findings demonstrate that acute physical exercise promotes sequence learning, thus attesting the overarching benefit of exercise to hippocampus-related memory functions.

The Endocannabinoid System May Modulate Sleep Disorders in Aging

Aging is an inevitable process that involves changes across life in multiple neurochemical, neuroanatomical, hormonal systems, and many others. In addition, these biological modifications lead to an increase in age-related sickness such as cardiovascular diseases, osteoporosis, neurodegenerative disorders, and sleep disturbances, among others that affect activities of daily life. Demographic projections have demonstrated that aging will increase its worldwide rate in the coming years. The research on chronic diseases of the elderly is important to gain insights into this growing global burden. Novel therapeutic approaches aimed for treatment of age-related pathologies have included the endocannabinoid system as an effective tool since this biological system shows beneficial effects in preclinical models. However, and despite these advances, little has been addressed in the arena of the endocannabinoid system as an option for treating sleep disorders in aging since experimental evidence suggests that some elements of the endocannabinoid system modulate the sleep-wake cycle. This article addresses this less-studied field, focusing on the likely perspective of the implication of the endocannabinoid system in the regulation of sleep problems reported in the aged. We conclude that beneficial effects regarding the putative efficacy of the endocannabinoid system as therapeutic tools in aging is either inconclusive or still missing.

Endocannabinoid System in Spinocerebellar Ataxia Type-3 and Other Autosomal-Dominant Cerebellar Ataxias: Potential Role in Pathogenesis and Expected Relevance as Neuroprotective Targets

Spinocerebellar ataxias (SCAs) are a group of hereditary and progressive neurological disorders characterized by a loss of balance and motor coordination typically associated with cerebellar atrophy. The most prevalent SCA types are all polyQ disorders like Huntington’s disease, sharing the most relevant events in pathogenesis with this basal ganglia disorder, but with most of the damage concentrated in cerebellar neurons, and in their afferent and efferent connections (e.g., brainstem nuclei). SCAs have no cure and effective symptom-alleviating and disease-modifying therapies are not currently available. However, based on results obtained in studies conducted in murine models and information derived from analyses in post-mortem tissue samples from patients, which show notably higher levels of CB₁ receptors found in different cerebellar neuronal subpopulations, the blockade of these receptors has been proposed for acutely modulating motor incoordination in cerebellar ataxias, whereas their chronic activation has been proposed for preserving specific neuronal losses. Additional studies in post-mortem tissues from SCA patients have also demonstrated elevated levels of CB₂ receptors in Purkinje neurons as well as in glial elements in the granular layer and in the cerebellar white matter, with a similar profile found for endocannabinoid hydrolyzing enzymes, then suggesting that activating CB₂ receptors and/or inhibiting these enzymes may also serve to develop cannabinoid-based neuroprotective therapies. The present review will address both aspects. On one hand, the endocannabinoid system becomes dysregulated in the cerebellum and also in other CNS structures (e.g., brainstem, basal ganglia) in SCAs, which may contribute to the progression of pathogenic events in these diseases. On the other hand, these endocannabinoid alterations may be pharmacologically corrected or enhanced, and this may have therapeutic consequences, either alleviating specific symptoms or eliciting neuroprotective effects, an objective presently under investigation.