Comparative analysis of methamphetamine's metabolic effects on blood-brain barrier endothelial cells: an in vitro recreational versus addictive simulation.

Methamphetamine (Meth) neurotoxicity has traditionally been attributed to monoaminergic disruption, yet growing evidence implicates early injury at the blood-brain barrier (BBB). The brain microvascular endothelial cells (BMVECs), which are the core cell type of the BBB and form the cerebral capillaries, contain the highest mitochondrial density of any endothelial population. This high mitochondrial density is essential for maintaining the highly selectively permeable properties of the BBB, leaving the BMVECs and the BBB susceptible to metabolic stress. To model the two stereotypical types of Meth users, recreational and addictive, bEnd.5 cells were exposed to Meth at physiological (0.1, 1, 10, and 20 µM) and supraphysiological (100 µM) concentrations for 24 h only (acute exposure) or daily for 96 h (chronic exposure). Succinate dehydrogenase (SDH) activity, mitochondrial membrane potential (ΔΨm), intracellular reactive oxygen species (ROS) levels, and endothelial monolayer integrity were assessed. Acute Meth caused transient metabolic dysfunction in BMVECs, marked by reduced SDH activity, ΔΨm depolarization, and increased intracellular ROS production with subsequent metabolic recovery, however, endothelial monolayer integrity remained impaired long-term. Chronic Meth exposure, induced sustained ΔΨm depolarization, persistent ROS elevation, and prolonged decreased endothelial monolayer integrity. These findings demonstrate distinct responses to acute and chronic Meth exposure and implicate mitochondrial dysfunction as a central mechanism driving BBB endothelium disruption, potential neuroinflammation, and increased neurological vulnerability, shifting the focus beyond classical monoaminergic toxicity and highlight the BBB endothelium as the central contributor to Meth-induced neuropathology.