COCAINE AS AN EMERGING ENVIRONMENTAL CONTAMINANT: CB1 AND BARRIER FUNCTION ALTERATIONS IN INTESTINAL HUMAN CELLS

Cocaine (COC) is among the most widely used substances of abuse worldwide, with a global production estimated at approximately 1,982 tons in 2020 (UNODC). Its extensive consumption has led to its detection in both drinking and non-drinking water, suggesting risks of unintentional exposure and confirming its emerging role as an environmental contaminant. The impact of COC on public health is therefore significant, as it acts on the central nervous system (CNS) by inhibiting the dopamine transporter (DAT) and increasing extracellular dopamine levels, generating potent psychostimulant effects. Recent evidence also indicates that the endocannabinoid (eCB) system modulates many behavioral and physiological responses induced by cocaine. In particular, the type-1 cannabinoid receptor (CB1), predominantly expressed in the CNS but also present in several peripheral districts, plays a crucial role. However, while the interaction between COC and CB1 in the CNS is well documented, the peripheral regulation of this receptor remains poorly understood. The gastrointestinal (GI) tract, where CB1 is involved in motility, secretion, and modulation of inflammation, represents a potential gut–brain axis node relevant to cocaine responses. In light of this, the present study investigated whether COC influences CB1 expression in human colorectal adenocarcinoma cells (Caco-2). Exposure to COC concentrations consistent with environmental levels (0–330 nM) revealed a non-monotonic response: 1 nM increased cellular metabolic activity, measured via MTT assay. Western blot analysis further showed that 24 hours of treatment reduced CB1 expression and altered the regulation of junctional proteins (E-cadherin and Claudin-5), results confirmed by immunofluorescence. These preliminary data suggest that COC may modulate both CB1 and metabolic and junctional parameters in Caco-2 cells, indicating a potential contribution to increased intestinal permeability (“leaky gut”), a phenomenon associated with various gastrointestinal disorders.