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Acute oral administration of ethanol (3.2g/kg) to rats increased (DOPAC) levels in the caudate nucleus, but had no effect on DOPAC levels in the substantia nigra and frontal cortex and failed to modify dopamine content in any of the above areas. On the other hand, the administration of the same dose of ethanol to rats which had been chronically treated with ethanol (3.2g/kg daily for 60 days), produced a decrease of DA content and a parallel increase of DOPAC levels in all areas studied. In chronically treated rats, 24 hrs after last ethanol administration dopamine levels in the frontal cortex were 60% higher than in controls. The results suggest that ethanol administration causes dopamine release in different brain areas.

Acute oral administration of ethanol (3.2g/kg) to rats increased (DOPAC) levels in the caudate nucleus, but had no effect on DOPAC levels in the substantia nigra and frontal cortex and failed to modify dopamine content in any of the above areas. On the other hand, the administration of the same dose of ethanol to rats which had been chronically treated with ethanol (3.2g/kg daily for 60 days), produced a decrease of DA content and a parallel increase of DOPAC levels in all areas studied. In chronically treated rats, 24 hrs after last ethanol administration dopamine levels in the frontal cortex were 60% higher than in controls. The results suggest that ethanol administration causes dopamine release in different brain areas.

AbstractNon‐adaptive activation of dopamine transmission in the nucleus accumbens shell by drugs of abuse has been attributed a fundamental role in the mechanism of drug addiction. In order to test this hypothesis, we compared in the same subject the effect of an addictive drug (ethanol) and of taste stimuli, including ethanol's own taste, on dialysate dopamine in the nucleus accumbens shell as an estimate of dopamine transmission and on taste reactivity as an expression of motivational valence. Ethanol was also monitored in the dialysates. In naive rats, intraoral infusion of a 20% sucrose + chocolate solution elicited a monophasic increase of dialysate dopamine immediately after the intraoral infusion. In contrast, intraoral infusion of 10% ethanol, 10% ethanol + 20% sucrose or 10% ethanol + 20% sucrose + chocolate solutions elicited a biphasic increase of nucleus accumbens dopamine with an early taste‐related rise and a late rise related to dialysate ethanol. Pre‐exposure to the ethanol solutions 24 h before resulted in the absence of the early dopamine rise and permanence of the late dopamine rise. This late dopamine rise was actually increased as compared with that of the nonpre‐exposed group when sucrose‐containing ethanol solutions were tested. The results indicate that single trial pre‐exposure to the ethanol solutions differentially affects the responsiveness of nucleus accumbens shell dopamine to the direct intracerebral action of ethanol and to the effect of its taste with potentiation, or no change of the first and abolition of the second. These observations point to the existence of major differences in the adaptive regulation of nucleus accumbens dopamine transmission in the shell after drug as compared with taste reward. These differences, in turn, are consistent with a role of nucleus accumbens shell dopamine in the mechanism of the behavioural effects of addictive drugs.

AbstractNon‐adaptive activation of dopamine transmission in the nucleus accumbens shell by drugs of abuse has been attributed a fundamental role in the mechanism of drug addiction. In order to test this hypothesis, we compared in the same subject the effect of an addictive drug (ethanol) and of taste stimuli, including ethanol's own taste, on dialysate dopamine in the nucleus accumbens shell as an estimate of dopamine transmission and on taste reactivity as an expression of motivational valence. Ethanol was also monitored in the dialysates. In naive rats, intraoral infusion of a 20% sucrose + chocolate solution elicited a monophasic increase of dialysate dopamine immediately after the intraoral infusion. In contrast, intraoral infusion of 10% ethanol, 10% ethanol + 20% sucrose or 10% ethanol + 20% sucrose + chocolate solutions elicited a biphasic increase of nucleus accumbens dopamine with an early taste‐related rise and a late rise related to dialysate ethanol. Pre‐exposure to the ethanol solutions 24 h before resulted in the absence of the early dopamine rise and permanence of the late dopamine rise. This late dopamine rise was actually increased as compared with that of the nonpre‐exposed group when sucrose‐containing ethanol solutions were tested. The results indicate that single trial pre‐exposure to the ethanol solutions differentially affects the responsiveness of nucleus accumbens shell dopamine to the direct intracerebral action of ethanol and to the effect of its taste with potentiation, or no change of the first and abolition of the second. These observations point to the existence of major differences in the adaptive regulation of nucleus accumbens dopamine transmission in the shell after drug as compared with taste reward. These differences, in turn, are consistent with a role of nucleus accumbens shell dopamine in the mechanism of the behavioural effects of addictive drugs.

Platelet aggregation, secretion of serotonin, and formation of thromboxane B2 induced by platelet-activating factor (1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) were studied in plasma containing physiological concentrations of ionized calcium in eight alcoholics after cessation of heavy drinking. Responses of platelets of four nonalcoholic volunteers, matched with a subgroup of the alcoholics by age and sex, were also investigated. Aggregation of platelets from alcoholics was significantly less throughout the 6-day detoxification period compared with controls. Secretion of serotonin (5-hydroxy-tryptamine) was negligible and the production of thromboxane B2 was not detectable. Decreased platelet aggregability in response to aggregating agents, including platelet-activating factor, may be important in the development of hemorrhagic complications in alcoholics.

Platelet aggregation, secretion of serotonin, and formation of thromboxane B2 induced by platelet-activating factor (1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine) were studied in plasma containing physiological concentrations of ionized calcium in eight alcoholics after cessation of heavy drinking. Responses of platelets of four nonalcoholic volunteers, matched with a subgroup of the alcoholics by age and sex, were also investigated. Aggregation of platelets from alcoholics was significantly less throughout the 6-day detoxification period compared with controls. Secretion of serotonin (5-hydroxy-tryptamine) was negligible and the production of thromboxane B2 was not detectable. Decreased platelet aggregability in response to aggregating agents, including platelet-activating factor, may be important in the development of hemorrhagic complications in alcoholics.

AbstractEthanol induces severe alterations in membrane trafficking in hepatocytes and astrocytes, the molecular basis of which is unclear. One of the main candidates is the cytoskeleton and the molecular components that regulate its organization and dynamics. Here, we examine the effect of chronic exposure to ethanol on the organization and dynamics of actin and microtubule cytoskeletons and glucose uptake in rat astrocytes. Ethanol‐treated cells cultured in either the presence or absence of fetal calf serum showed a significant increase in 2‐deoxyglucose uptake. Ethanol also caused alterations in actin organization, consisting of the dissolution of stress fibres and the appearance of circular filaments beneath the plasma membrane. When lysophosphatidic acid (LPA), which is a normal constituent of serum and a potent intercellular lipid mediator with growth factor and actin rearrangement activities, was added to ethanol‐treated astrocytes cultured without fetal calf serum, it induced the re‐appearance of actin stress fibres and the normalization of 2‐deoxyglucose uptake. Furthermore, ethanol also perturbed the microtubule dynamics, which delayed the recovery of the normal microtubule organization following removal of the microtubule‐disrupting agent nocodazole. Again, pre‐treatment with LPA prevented this alteration. Ethanol‐treated rodent fibroblast NIH3T3 cells that constitutively express an activated Rho mutant protein (GTP‐bound form) were insensitive to ethanol, as they showed no alteration either in actin stress‐fibre organization or in 2‐deoxyglucose uptake. We discuss the putative signalling targets by which ethanol could alter the cytoskeleton and hexose uptake and the cytoprotective effect of LPA against ethanol‐induced damages. The latter opens the possibility that LPA or a similar non‐hydrolysable lipid derivative could be used as a cytoprotective agent against the noxious effects of ethanol.