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Background:The ventral tegmental area (VTA) is involved in regulating ethanol drinking, and the posterior VTA seems to be a neuroanatomical substrate that mediates the reinforcing effects of ethanol in ethanol‐naïve Wistar and ethanol‐naïve alcohol‐preferring (P) rats. The objective of this study was to test the hypothesis that chronic ethanol drinking increases the sensitivity of the posterior VTA to the reinforcing effects of ethanol.Methods:Two groups of female P rats (one given water as its sole source of fluid and the other given 24‐hr free‐choice access to 15% ethanol and water for at least 8 weeks) were stereotaxically implanted with guide cannulae aimed at the posterior VTA. One week after surgery, rats were placed in standard two‐lever (active and inactive) operant chambers and connected to the microinfusion system. Depression of the active lever produced the infusion of 100 nl of artificial cerebrospinal fluid (CSF) or ethanol. The ethanol‐naïve and chronic ethanol‐drinking groups were assigned to subgroups to receive artificial CSF or 25, 50, 75, or 125 mg/dl of ethanol (n= 6–9/dose/group) to self‐infuse (FR1 schedule) during the 4‐hr sessions given every other day.Results:Compared with the infusions of artificial CSF, the control group reliably (p < 0.05) self‐infused 75 and 125 mg/dl of ethanol but not the lower concentrations. The ethanol‐drinking group had significantly (p < 0.05) higher self‐infusions of 50, 75, and 125 mg/dl of ethanol than artificial CSF during the four acquisition sessions; the number of infusions of all three doses was higher in the ethanol‐drinking group than in the ethanol‐naive group. Both groups decreased responding on the active lever when artificial CSF was substituted for ethanol, and both groups demonstrated robust reinstatement of responding on the active lever when ethanol was restored.Conclusions:Chronic ethanol drinking by P rats increased the sensitivity of the posterior VTA to the reinforcing effects of ethanol.

Background:The ventral tegmental area (VTA) is involved in regulating ethanol drinking, and the posterior VTA seems to be a neuroanatomical substrate that mediates the reinforcing effects of ethanol in ethanol‐naïve Wistar and ethanol‐naïve alcohol‐preferring (P) rats. The objective of this study was to test the hypothesis that chronic ethanol drinking increases the sensitivity of the posterior VTA to the reinforcing effects of ethanol.Methods:Two groups of female P rats (one given water as its sole source of fluid and the other given 24‐hr free‐choice access to 15% ethanol and water for at least 8 weeks) were stereotaxically implanted with guide cannulae aimed at the posterior VTA. One week after surgery, rats were placed in standard two‐lever (active and inactive) operant chambers and connected to the microinfusion system. Depression of the active lever produced the infusion of 100 nl of artificial cerebrospinal fluid (CSF) or ethanol. The ethanol‐naïve and chronic ethanol‐drinking groups were assigned to subgroups to receive artificial CSF or 25, 50, 75, or 125 mg/dl of ethanol (n= 6–9/dose/group) to self‐infuse (FR1 schedule) during the 4‐hr sessions given every other day.Results:Compared with the infusions of artificial CSF, the control group reliably (p < 0.05) self‐infused 75 and 125 mg/dl of ethanol but not the lower concentrations. The ethanol‐drinking group had significantly (p < 0.05) higher self‐infusions of 50, 75, and 125 mg/dl of ethanol than artificial CSF during the four acquisition sessions; the number of infusions of all three doses was higher in the ethanol‐drinking group than in the ethanol‐naive group. Both groups decreased responding on the active lever when artificial CSF was substituted for ethanol, and both groups demonstrated robust reinstatement of responding on the active lever when ethanol was restored.Conclusions:Chronic ethanol drinking by P rats increased the sensitivity of the posterior VTA to the reinforcing effects of ethanol.

MRI examination revealed similar brain lesions in 5 alcoholic Korsakoff patients and 5 chronic alcoholics without cognitive impairment. Not only cerebral atrophy and demyelination, but also lesions thought to be specific for the Wernicke-Korsakoff syndrome were equally prominent in both groups. The morphological abnormalities thought to be typical of Wernicke-Korsakoff syndrome are probably common features of chronic alcoholism and malnutrition. Marked atrophy of the operculae was found in all Korsakoff patients and in 3 out of 5 chronic alcoholics. Alcohol amnestic disorder may not exclusively result from diencephalic lesions, but also from temporal lesions.

MRI examination revealed similar brain lesions in 5 alcoholic Korsakoff patients and 5 chronic alcoholics without cognitive impairment. Not only cerebral atrophy and demyelination, but also lesions thought to be specific for the Wernicke-Korsakoff syndrome were equally prominent in both groups. The morphological abnormalities thought to be typical of Wernicke-Korsakoff syndrome are probably common features of chronic alcoholism and malnutrition. Marked atrophy of the operculae was found in all Korsakoff patients and in 3 out of 5 chronic alcoholics. Alcohol amnestic disorder may not exclusively result from diencephalic lesions, but also from temporal lesions.

AbstractDiscrimination and reversal of the classically conditioned eyeblink response depends on cerebellar–brainstem interactions with the hippocampus. Neonatal “binge” exposure to alcohol at doses of 5 g/kg/day or more has been shown to impair single‐cue eyeblink conditioning in both weanling and adult rats. The present study exposed neonatal rats to acute alcohol intubations across different developmental periods (postnatal day [PND] 4‐9 or PND7‐9) and tested them from PND26‐31 on discriminative classical eyeblink conditioning and reversal. A high dose of alcohol (5 g/kg/day) dramatically impaired conditioning relative to controls when exposure occurred over PND4‐9, but produced mild or no impairments when delivered over PND7‐9. These findings support previous claims that developmental exposure period plays a critical role in determining the deleterious effects of alcohol on the developing brain. A lower dose of alcohol (4 g/kg/day) delivered from PND4‐9—lower than has previously been shown to affect single‐cue eyeblink conditioning—also produced deficits on the discrimination task, suggesting that discrimination learning and acquisition of responding to CS+ during reversal may be especially sensitive behavioral indicators of alcohol‐induced brain damage in this rat model. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 243–257, 2007.

AbstractDiscrimination and reversal of the classically conditioned eyeblink response depends on cerebellar–brainstem interactions with the hippocampus. Neonatal “binge” exposure to alcohol at doses of 5 g/kg/day or more has been shown to impair single‐cue eyeblink conditioning in both weanling and adult rats. The present study exposed neonatal rats to acute alcohol intubations across different developmental periods (postnatal day [PND] 4‐9 or PND7‐9) and tested them from PND26‐31 on discriminative classical eyeblink conditioning and reversal. A high dose of alcohol (5 g/kg/day) dramatically impaired conditioning relative to controls when exposure occurred over PND4‐9, but produced mild or no impairments when delivered over PND7‐9. These findings support previous claims that developmental exposure period plays a critical role in determining the deleterious effects of alcohol on the developing brain. A lower dose of alcohol (4 g/kg/day) delivered from PND4‐9—lower than has previously been shown to affect single‐cue eyeblink conditioning—also produced deficits on the discrimination task, suggesting that discrimination learning and acquisition of responding to CS+ during reversal may be especially sensitive behavioral indicators of alcohol‐induced brain damage in this rat model. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 243–257, 2007.

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.