Cannabinoids reduce tremor associated with motor disorders induced by injuries and neurodegenerative disease. Here we show that this effect is mediated by cannabinoid receptors on astrocytes in the ventral horn of the spinal cord, where alternating limb movements are initiated. We first demonstrate that tremor is reduced in a mouse model of essential tremor after intrathecal injection of the cannabinoid analog WIN55,212-2. We investigate the underlying mechanism using electrophysiological recordings in spinal cord slices and show that endocannabinoids released from depolarized interneurons activate astrocytic cannabinoid receptors, causing an increase in intracellular Ca²⁺, subsequent release of purines and inhibition of excitatory neurotransmission. Finally, we show that the anti-tremor action of WIN55,212-2 in the spinal cords of mice is suppressed after knocking out CB₁ receptors in astrocytes. Our data suggest that cannabinoids reduce tremor via their action on spinal astrocytes.

Glioblastoma (GBM), a highly malignant brain tumor, arises within a complex microenvironment that plays a critical role in facilitating tumor progression, ensuring survival, and enabling immune evasion, ultimately contributing to therapeutic resistance. Cancer-associated fibrosis is increasingly recognized as a key factor in the tumor pathophysiology, particularly in extracranial cancers, and reported therapeutic strategies in several cancers consist of the current use of the standard-of-care treatment combined with anti-fibrotic drugs. However, it remains unclear how the fibrotic changes associated with the GBM microenvironment contribute to the transformation of GBM from a chemosensitive state to a chemoresistant one. Here, we developed an in vitro model that mimics a fibrosis-like mechanism using the U-87MG GBM cell line. To achieve this, we identified the optimal experimental conditions (i.e., U-87MG cultured in serum-deprivation medium in the presence of recombinant TGF-B1 at 5 ng/mL for 72 h) that effectively induced fibrosis, as suggested by the counter-regulated expression of E- and N-cadherin and sustained levels of α-SMA and collagen I. As expected, U-87MG fibrotic cells were demonstrated to be more resistant to TMZ (predicted EC₅₀ = 35 µM) as compared to the non-fibrotic counterpart (EC₅₀ not achieved here; predicted EC₅₀ = 351 µM). Accordingly, the anti-fibrotic uPAcyclin—a new derivative cyclic compound inspired as a A6 decapeptide drug—showed a significant cytotoxic effect, sensitizing resistant U-87MG fibrotic cells to TMZ. This highlights that targeting fibrosis may help to overcome TMZ resistance in GBM.