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Abstract: The effects of pharmacologically relevant concentrations of ethanol on the release of endogenous adenosine from rat cerebellar synaptosomes were investigated. Release was conducted for 5, 10, 30, or 60 s after which time the incubation medium (containing the released adenosine) was rapidly separated from the synaptosomal membranes by vacuum filtration. The adenosine content of the filtrate was measured by HPLC–fluorescence detection. Both basal and KCl‐stimulated adenosine release consisted of an initial rapid phase, for the first 10 s, that was followed by a relatively slower phase. Basal endogenous adenosine release was estimated as 199 ± 14 pmol/mg protein/5 s. Potassium (chloride) increased adenosine release from the basal level to 433 ± 83 pmol/mg protein/5 s. Ethanol caused a dose‐dependent increase of adenosine release. The interaction between dilazep and ethanol indicates that ethanol‐stimulated release does not involve the dilazep‐sensitive transport system. The results support previous findings that indicate that cerebellar adenosine is involved in the mediation of ethanol‐induced motor disturbances in the rat.

Abstract: The effects of pharmacologically relevant concentrations of ethanol on the release of endogenous adenosine from rat cerebellar synaptosomes were investigated. Release was conducted for 5, 10, 30, or 60 s after which time the incubation medium (containing the released adenosine) was rapidly separated from the synaptosomal membranes by vacuum filtration. The adenosine content of the filtrate was measured by HPLC–fluorescence detection. Both basal and KCl‐stimulated adenosine release consisted of an initial rapid phase, for the first 10 s, that was followed by a relatively slower phase. Basal endogenous adenosine release was estimated as 199 ± 14 pmol/mg protein/5 s. Potassium (chloride) increased adenosine release from the basal level to 433 ± 83 pmol/mg protein/5 s. Ethanol caused a dose‐dependent increase of adenosine release. The interaction between dilazep and ethanol indicates that ethanol‐stimulated release does not involve the dilazep‐sensitive transport system. The results support previous findings that indicate that cerebellar adenosine is involved in the mediation of ethanol‐induced motor disturbances in the rat.

In the present study, we have investigated the effect of intraperitoneal injection of ethanol (3.5 g/kg) on tyrosine phosphorylation in rat brain. Immunoblot analysis using an antiphosphotyrosine antibody revealed that a 130‐kDa protein band was detected in the brain extract in response to ethanol administration. This ethanol‐stimulated tyrosine phosphorylation of the 130‐kDa protein was found in the brain but not in the heart, liver or thymus. The 130‐kDa phosphotyrosine‐containing protein was identified by immunoprecipitation to be Cas, a crk‐associated src substrate. This ethanol‐stimulated tyrosine phosphorylation of Cas was observed most prominently in the cerebellum and the cerebral cortex. We further examined the possible involvement of Fyn kinase in ethanol‐stimulated Cas tyrosine phosphorylation. Immunecomplex kinase assay showed that Fyn was activated in the cerebellum and cerebral cortex of ethanol‐administered rats. Immunoprecipitation experiments also showed that Fyn was co‐immunoprecipitated with an anti‐Cas antibody in these regions from ethanol‐administered rats. Furthermore, exogenous Fyn was shown to phosphorylate Cas from cerebellum and cerebral cortex in vitro. These findings indicate that ethanol stimulates tyrosine phosphorylation of Cas in rat cerebellum and cerebral cortex, and that Fyn may be involved in the process.

In the present study, we have investigated the effect of intraperitoneal injection of ethanol (3.5 g/kg) on tyrosine phosphorylation in rat brain. Immunoblot analysis using an antiphosphotyrosine antibody revealed that a 130‐kDa protein band was detected in the brain extract in response to ethanol administration. This ethanol‐stimulated tyrosine phosphorylation of the 130‐kDa protein was found in the brain but not in the heart, liver or thymus. The 130‐kDa phosphotyrosine‐containing protein was identified by immunoprecipitation to be Cas, a crk‐associated src substrate. This ethanol‐stimulated tyrosine phosphorylation of Cas was observed most prominently in the cerebellum and the cerebral cortex. We further examined the possible involvement of Fyn kinase in ethanol‐stimulated Cas tyrosine phosphorylation. Immunecomplex kinase assay showed that Fyn was activated in the cerebellum and cerebral cortex of ethanol‐administered rats. Immunoprecipitation experiments also showed that Fyn was co‐immunoprecipitated with an anti‐Cas antibody in these regions from ethanol‐administered rats. Furthermore, exogenous Fyn was shown to phosphorylate Cas from cerebellum and cerebral cortex in vitro. These findings indicate that ethanol stimulates tyrosine phosphorylation of Cas in rat cerebellum and cerebral cortex, and that Fyn may be involved in the process.