Astrocyte Diversity and Alcohol-Related Gliovascular Alterations in the Human Dorsal Striatum Revealed by Combined Morphometric and Ultrastructural Analyses

Astrocytes are key regulators of neuronal, metabolic, and vascular homeostasis, yet their morphological diversity and involvement in alcohol-related brain pathology remain incompletely characterized. In this study, we investigated astrocytic morphology in the human striatum of control individuals and subjects with short- and long-term alcohol exposure using immunohistochemistry combined with Sholl-based morphometric analysis, and ultrastructural assessment. GFAP immunohistochemistry was used to identify astrocytes, assess their morphology, and manually quantify GFAP + cells in gray and white matter, followed by Sholl-based morphometric analysis to characterize astrocytic branching architecture and spatial organization. The number of GFAP + astrocytes differed between tissue compartments, with a significant increase in white matter in alcohol-exposed individuals and no detectable change in gray matter. Morphometric analysis revealed pronounced astrocytic heterogeneity across all study groups. Sholl-derived metrics supported the distinction of six recurrent astrocytic morphometric profiles in the human striatum, distinguished by soma size, branching complexity, process length, and cell territory size. These profiles were present across gray and white matter, indicating intrinsic astrocytic structural diversity. Ultrastructural analysis further revealed alcohol-associated alterations at the astrocyte-vascular interface, including swelling of perivascular astrocytic endfeet, accumulation of intermediate filaments, and focal reductions in vascular wall coverage. Together, these findings demonstrate substantial astrocytic structural diversity in the human striatum accompanied by alcohol-related gliovascular remodeling.