Application of the cannabinoid agonist ACEA and the antagonist AM251 influences neuronal survival and CB 1 receptor expression in cultured hippocampi.

CALTANA LAURA; HEIMRICH BERND; BRUSCO ALICIA

Washington

Conferencia; NIDA - Mini Convention; 2011

National Institute of Drug Abuse

Ischemic insult of the brain is known to lead to neuronal cell death. Excessive glutamate release, intracellular Ca2+ rise, recruitment of pro-inflammatory cells and increase in reactive oxygen species preceed this fatal outcome. Therapeutic strategies counteracting these deleterious events may exert neuroprotective effects and therefore they could be beneficial for the injured nervous tissue. Potentially neuroprotective actions of endocannabinoid receptor agonists (THC, 2-AG, ACEA, WIN55, 212-2) have already been demonstrated in the CNS. Agonist treatment blocks glutamatergic transmission, can reduce calcium inflow and is able to enhance the expression of neurotrophins and transcription factors. By the use of a mouse model of focal brain ischemia (MCAo) we could clearly show that treatment with cannabinoid agonists improves recovery after ischemic injury by decreasing neuronal death, astroglial reaction and inflammatory response. Here we introduced an organotypic slices culture of mouse hippocampus as an in vitro assay for evaluation of neuroprotective impact of endocannabinoid agonists and antagonists. Various concentrations of the CB1 agonist ACEA and its antagonist AM251 were administered and effects on neurons and glial cells were analyzed at different time points. We showed that incubation of hippocampal slices with a low concentration (0,5 µM) of ACEA did not seem to affect neither cellular organization and neuronal morphology neither glial response. In contrast, at a higher concentration (5µM) of ACEA many neurons exhibit strong caspase-3 immunoreactivity. After treatment with AM251 we observed an increase in caspase-3 immunoreactivity and a downregulation of CB1 receptor expression. Our preliminary data show that long term hippocampal slice cultures respond to both cannabinoid receptor activation and inactivation by changing neuronal protein expression patterns. In addition, behavioural experiments will be performed to analyze ameliorating effects of CB1 activation after MCA occlusion.