Distinct Adipocyte Responses to Δ⁹-Tetrahydrocannabinol (THC) Exposure Govern Hepatic Lipid Accumulation in an Obesogenic Setting

The effects of Δ⁹-tetrahydrocannabinol (THC) on adipocyte function under obesogenic, free-fatty-acid (FFA)-rich conditions remain poorly characterized, particularly regarding adipogenesis, FFA buffering, and downstream hepatocyte lipid handling. We investigated THC’s effect on adipogenic differentiation, temporal FFA buffering in mature adipocytes under lipid stress, and hepatocyte lipid accumulation driven by extracellular FFAs. The 3T3-L1 preadipocytes were differentiated in 0.5 mM oleate: palmitate (2:1) medium with vehicle (EtOH), THC (1 μM), or rosiglitazone (30 μM). Adipogenesis was assessed using BODIPY/NucSpot 650 staining followed by lipid droplet (LD) analysis. Adipocytes (days 10–18) were monitored for lipid accumulation, LD morphology, lipolysis, extracellular non-esterified fatty acids (NEFA), and lipid-handling gene expression. Conditioned media (CM) were applied to AML12 hepatocytes to assess lipid uptake. By day 6, THC enhanced adipogenesis, increasing lipid accumulation. In mature adipocytes, THC induced a biphasic buffering response: on day 10, NEFA levels were elevated despite unchanged lipid content, with increased isoproterenol-stimulated lipolysis. By day 18, buffering improved, with enhanced lipid storage, elevated stimulated lipolysis, smaller LDs, and altered gene expression. AML12 lipid accumulation corresponded with residual NEFA in CM, indicating that adipocyte FFA sequestration modulates hepatocyte lipid uptake. These findings reveal that under FFA-rich conditions, THC promotes late-stage adipogenesis and remodels adipocyte lipid handling, regulating extracellular FFA availability and hepatocyte lipid loading.