• NEURONAL CYTOSKELETON AND SYNAPTIC DENSITIES ARE ALTERED AFTER A CHRONIC TREATMENT WITH THE CANNABINOID RECEPTOR AGONIST WIN 55,212-2.

TAGLIAFERRO, AP; RAMOS, AJ; ONAIVE, ES; EVRARD, SG; DUHALDE VEGA, M; BRUSCO, A

San Diego, USA

Congreso; SFN 34th Annual Meeting; 2004

The cannabinoid receptor is one of the most abundant G-protein-coupled receptors in the brain and its presynaptic location suggests a role for cannabinoids in modulating the release of neurotransmitters from axon terminals. In the present work we analysed the morphological changes induced by a chronic treatment with the synthetic cannabinoid receptor agonist, WIN55,212-2 in four brain regions where the receptor is present in high density: the CA1 hippocampal area, corpus striatum, cerebellum and frontal cortex. After a twice-daily treatment for fourteen days with WIN55,212-2 (4 mg/kg, each dose) in young male Wistar rats (150-170g), the expression of neurofilaments (Nf-160 and Nf-200), MAP-2, synaptophysin (Syn) and glial fibrillary acidic protein (GFAP, the main astroglial cytoskeletal protein) was studied by immunohistochemistry and digital image analysis. Ultrastructural study of the synaptic connections was done using electron microscopy. After the treatment, an important increase in the expression of neuronal cytoskeletal proteins was observed but we did not find changes in the astroglial one. Increases in the Syn expression as well as changes in the ultrastructure of the synapses were observed mainly in cerebellum and hippocampus. These structural and ultrastructural changes might represent morphological evidences of neuronal plasticity phenomena in which the cannabinoid receptor is involved.