Behavioral Sensitivity and Ethanol Potentiation of the N-Methyl-d-Aspartate Receptor Antagonist MK-801 in a Rat Line Selected for High Ethanol Sensitivity

The role of the N -methyl-d-aspartate (NMDA) receptors in differential ethanol sensitivity of the alcohol-insensitive [alcohol-tolerant (AT)] and alcohol-sensitive [alcohol-nontolerant (ANT)] rat lines selected for low and high sensitivity to ethanol-induced (2 g/kg) motor impairment was studied in behavioral and neurochemical experiments. A noncompetitive antagonist of the NMDA receptor, dirocilpine mal-eate (MK-801; 0.2 mg/kg), impaired motor function in ANT rats, but not in AT rats, in a tilting plane test. The impairment was further potentiated by a dose (0.75 glkg) of ethanol, which alone was inactive. This effect was apparently not associated with the locomotor stimulation produced by MK-801 (0.1 and 0.2 mg/kg), because stimulation did not differ between the rat lines. Locomotor stimulation was potentiated by the low ethanol dose in both rat lines. Ethanol treatment decreased the cerebellar and hippocampal cGMP concentrations both with and without MK-801 pretreatment in both rat lines. In situ hybridization using oligonucleotide probes specific for NMDA receptor subunit mRNAs NR1 and NR2A, B, C, and D revealed no clear differences in brain regional expression between ANT and AT rats. These results indicate that the alcohol-sensitive ANT rats are very sensitive to a low dose of ethanol in the presence of NMDA receptor antagonism, consistent with the hypothesis that this receptor system is involved in acute ethanol intoxication.     

Effects of Ethanol, Chlordiazepoxide, and MK-801 on Performance in the Elevated-Plus Maze and on Locomotor Activity

The effects of ethanol, chlordiazepoxide, and MK-801 on performance in the elevated-plus maze and on activity measured in a circular activity monitor were compared in Sprague-Dawley rats to determine whether these effects of ethanol could be explained by its action on either GABA_A or NMDA receptors. Both ethanol and chlordiarepoxide produced an increase in the time spent in the open arms of the elevated-plus maze and in the ratio of open arm to total arm entries, indicative of an anxiolytic action of these drugs. MK-801 did not alter either the time spent in the open arms or the ratio of open to total arm entries. Chlordiazepoxide and MK-801 produced an increase in total arm entries that suggested that these compounds were increasing locomotor activity. Ethanol also increased total arm entries, but the effect was not statistically reliable. Following habituation to an activity monitor, neither ethanol nor chlordiazepoxide increased activity in this task, whereas MK-801 produced a robust increase in locomotion. Additionally, neither ethanol nor chlordiazepoxide blocked the MK-801-induced locomotor stimulation. The latter finding suggests that the effects of ethanol on GABAA receptors was not Mocking an increased activity level produced by its antagonism of NMDA. Additionally, these results indicate that the anxiolytic and locomotor action of ethanol in rats parallel the effects of a benzodiazepine and not those of an NMDA antagonist. Finally, these results suggest that the consequence of ethanol's antagonism of NMDA receptor function is more restricted than that produced by MK-801.     

Neuronal Degeneration in Rat Cerebrocortical and Olfactory Regions During Subchronic "Binge" Intoxication with Ethanol: Possible Explanation for Olfactory Deficits in Alcoholics

Severe, repetitive (“binge”) ethanol intoxication in adult rats (intragastric delivery 3 times daily for 4 days in a modification of the Majchrowicz method) precipitates neuronal degeneration in selected cerebral cortical regions involved in memory and olfaction, confirming the results of Switzer and colleagues (Anat. Rec. 202 186a, 1982). Neuronal damage was visualized with the de Olmos cupric silver technique for degenerating neurons and processes (argyrophilia), and was quantitated by total counts and densities of argyrophilic cells/fields. The specificity of the degeneration provides a neuropathological basis for the olfactory memory deficits in chronic alcoholics. In highly intoxicated rats, argyrophilia was most extensive among hippocampal dentate gyrus granule cells, pyramidal neurons in layer 3 of the entorhinal cortex, and olfactory nerve terminals in the olfactory bulb. Degenerating pyramidal neurons were also consistently seen in the insular cortex and olfactory cortical regions, such as the piriform and perirhinal cortices. There were few argyrophilic neurons in the CA regions of the hippocampus and none in the cerebellum—regions generally shown to have cell loss in long-term ethanol feeding models—but degenerating mossy fibers in the CA2 region were observed. Degeneration was maximal before the peak period of abstinence symptoms in this model, because argyrophilic densities were no greater36 hr, compared with 8 hr after the last ethanol dose. High blood ethanol levels were required, because argyrophilia, absent from isocaloric controls, also was only evident in ethanol-intoxicated rats with mean blood ethanol levels for days 2 to 4 above 300 mg/dl; however, it increased substantially between 350 and 550 mg/dl. The resemblance of the argyrophilic distribution to the regional neuropathology that occurs in experimental seizures indicates that the ethanol-induced degeneration may have an excitotoxic basis. Progressive reductions in the seizure threshold (e.g., kindling phenomena that have been documented during binge ethanol intoxication) might be associated with excitotoxic hyperactivity during the repetitive nadirs between high blood and brain ethanol peaks. However, direct toxic actions of ethanol or its metabolites could also be involved. Overall, the model should be useful for studying mechanisms of ethanol-induced selective cortical and olfactory brain damage.     

Acamprosate,MK-801, and ifenprodil inhibit neurotoxicity and calcium entry induced by ethanol withdrawal in organotypic slice cultures from neonatal rat hippocampus

BACKGROUND: The antirelapse drug acamprosate has previously been reported to inhibit activating effects of polyamines on -methyl-D-aspartic acid receptor (NMDAR) function. Because increased synthesis of polyamines has been suggested as a mechanism for potentiation of NMDAR function during ethanol withdrawal, we evaluated the effects of acamprosate, MK-801, and ifenprodil in a cell culture model of ethanol withdrawal-induced neurotoxicity. METHODS: Organotypic hippocampal cultures from 8-day-old neonatal rats were maintained in vitro for 23 days before experimental use. The ethanol withdrawal model consisted of exposing cultures to ethanol (70-100 mM) for 4 days before being "withdrawn" into Calcium-Locke's buffer for 1 hr and then into minimal medium for 23 hr. Uptake of (45)CaCl(2) and propidium iodide by damaged cells was assessed 1 hr and 24 hr after the start of ethanol withdrawal, respectively. Additional studies examined effects of exposure to NMDA (50 microM) or spermidine (100 microM) on withdrawal-induced hippocampal damage. Last, these studies examined the ability of the sodium salt of acamprosate (Na-acamprosate, 200 microM), ifenprodil (50 microM), or MK-801 (30 microM) to inhibit neurotoxicity and (45)Ca(2+) entry produced by these insults. RESULTS: Ethanol withdrawal was associated with significantly greater toxicity and (45)Ca(2+) entry, relative to controls. Exposure to spermidine and NMDA during ethanol withdrawal further increased neurotoxicity and (45)Ca(2+) entry. Acamprosate, ifenprodil, and MK-801 almost completely prevented ethanol withdrawal-induced toxicity and (45)Ca(2+) entry. Acamprosate also reduced spermidine-induced neurotoxicity during ethanol withdrawal but was ineffective against NMDA-induced toxicity or (45)Ca(2+) entry at this time. CONCLUSIONS: The results support the contention that acamprosate, like ifenprodil, interacts with polyamines and that these compounds may be effective in reducing consequences of ethanol withdrawal. NMDAR activation is also strongly implicated in ethanol withdrawal neurotoxicity, but whether acamprosate causes any of these effects in this preparation directly via the NMDAR remains uncertain.     

Effects of Prenatal and Early Postnatal Ethanol Exposure on [3H]MK-801 Binding in Rat Cortex and Hippocampus

The effects of prenatal and/or early postnatal exposure to ethanol at high concentrations on N-methyl-D-aspartate (NMDA) receptor number and functioning in the weanling rat were examined. The bingelike exposure protocol was used in an animal model of acute ethanol effects at two critical periods of development. [³H]MK-801 binding parameters for the internal channel phencyclidine site were assessed in the presence of 10 μM glutamate and 10 μ M glycine activation. Four treatment groups were included: (1) animals exposed to ethanol both prenatal and postnatal; (2) animals exposed only prenatal; (3) animals exposed early postnatal only; and (4) control animals with no exposure to ethanol. The results of the [³H]MK-801 binding experiments showed that both prenatal and postnatal exposure to ethanol resulted in a significant decrease in the density of NMDA receptors. In addition, data indicated an apparent increase in the percentage of high-affinity state (open channel state) relative to low-affinity state (close channel state) receptors in the ethanoltreated groups. These results show that both prenatal and postnatal ethanol exposure decrease NMDA receptor density in the cortex and hippocampus. The findings are consistent with previous observations by our laboratory and others that NMDA-mediated calcium influx is reduced in these regions, as well as in whole brain by prenatal ethanol exposure. It is suggested that after ethanol exposure, the remaining functional NMDA receptors might have altered sensitiviity to coagonist activation with an increased probability of channel opening.     

Effects of Ethanol, MK-801, and Chlordiazepoxide on Locomotor Activity in Different Rat Lines: Dissociation of Locomotor Stimulation from Ethanol Preference

Several lines of research have suggested a link between the reward value of a drug and its ability to stimulate locomotion. One goal of the present study was to determine whether ethanol preferentially stimulates locomotor activity in lines of rat that show a preference for ethanol. A secondary goal was to determine the extent to which the benzodiazepine-like and NMDA antagonistic action of ethanol accounted for its effect on locomotor activity. To meet these goals, the effects of varying doses of ethanol (0.125-1.0 g/kg), MK-801 (0.1-0.3 mg/kg), and chlordiazepoxide (0.3-3 mg/kg) on locomotor activity were studied in several lines of rats that had been habituated to the testing procedure. The effect of low doses of ethanol on motor activity in the Alcohol-Preferring (P) and Fawn-Hooded rats, which show a strong ethanol preference, were similar to those of the alcohol-nonpreferring (NP), Flinders Sensitive Line, and Flinders Resistant Line rats. Only the Flinder Resistant Line rats showed a small, but significant increase in locomotor activity after the administration of ethanol. The highest dose of ethanol (1.0 g/kg) produced locomotor depression in all lines except the P and NP lines, which were not tested at this dose. These findings do not support a link between locomotor stimulation by ethanol and ethanol preference. In contrast, all lines exhibited locomotor stimulation after moderate (0.1-0.3 mg/kg) doses of MK-801, but did not exhibit increases in activity following any dose of chlordiazepoxide. These data indicate that the profiles of activity after MK-801 and chlordiazepoxide were distinct from that of ethanol in the various rat lines. Therefore, the effects of ethanol on locomotor activity cannot be accounted for by reference solely to its antagonist-like action at NMDA receptors and/or its agonist-like action at GABA/benzodiazepine receptors.     

Changes in Blood Alcohol Levels as a Function of Alcohol Concentration and Repeated Alcohol Exposure in Adult Female Rats: Potential Risk Factors for Alcohol-Induced Fetal Brain Injury

Fetal alcohol syndrome and alcohol-related birth defects are the result of heavy maternal alcohol consumption during gestation. The magnitude of deficit manifested by the offspring is invariably a consequence of several risk factors that may result in high peak blood alcohol concentrations (BACs), such as the duration, timing, or pattern of alcohol consumption. In addition, the alcohol content of the consumed beverage may play a role in determining offspring developmental consequences. Because higher BACs are positively correlated with risk and severity of brain injury early in postnatal lie, initially it was important to determine how BAC is influenced by alcohol concentration and whether that influence is constant over repeated alcohol treatments. Groups of female Sprague-Dawley rats received daily intragastric intubations of 5 g/kg alcohol in one of several concentrations: 45% (v/v), 30% (v/v), 22.5% (v/v), or 15% (v/v) for a duration of 18 consecutive days. Blood samples were taken at various times postintubation on days 3,8,13, and 18 of treatment, and analyzed by headspace gas chromatography. Multivariate analyses of peak BAC, average BAC, and time to reach peak BAC revealed some noteworthy results. First, peak BAC and average BAC were significantly lower in the 45% group, compared with the other concentration groups, whereas this group also took a longer time to reach peak BAC than the other three groups. Second, peak BAC and averege BAC were higher on the last day of treatment than any of the other treatment days. These results suggest that alcohol concentration and repeated alcohol exposure can influence BAC and, as such, are important risk factors to be considered in the appraisal of alcohol-induced fetal brain injuries.     

The Adrenocortical Response to Brain Injury: Correlation with the Severity of Neurologic Dysfunction, Effects of Intoxication, and Patient Outcome

To test the hypothesis that cortisol levels reflect the extent of neurologic dysfunction and predict patient outcome, neurologic function and cortisol levels were determined in 120 traumatically brain injured patients who never received glucocorticoid treatment. Their mean age was 29 years and 78% were men. The impact of intoxication was examined in 59 patients who had ethanol levels measured. Ethanol was detectable in 40 patients and greater than or equal to 100 mg/dl in 31. There were significant correlations between the extent of neurologic dysfunction, determined by the Glasgow Coma Score and plasma cortisol concentrations 1 and 4 days postaccident. Cortisol levels were universally elevated on admission and approached normal 7 days later. Multiple linear regression analysis revealed significant effects of circulating ethanol levels on the association between cortisol concentrations and progressively worsening neurologic function, i.e., ethanol reduced the magnitude of the cortisol elevations in a dose dependent manner, abolishing this relationship at levels above 100 mg/dl. Analysis of the relationships between circulating cortisol levels and patient outcome provided a second method for ascertaining the association between injury severity and the magnitude of adrenocortical activation. Admission and day 1 cortisol concentrations were 25 to 40% lower in patients having good recoveries or moderate disabilities than those who remained severely disabled, persistently vegetative or died; serum cortisol values of less than 20 micrograms/dl one day after the accident were more likely to be associated with a good outcome than a poor one (55 vs. 25%, p less than 0.001). The worsening prognosis of patients having higher cortisol values is further reflected in the duration of acute hospitalization of these individuals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sex Differences and the Effects of Alcohol on Immune Response in Male and Female Rats

Although it is clear that both alcohol and sex hormones impact immune function, very little information is available on the effects of alcohol on immune response in males versus females. We decided to determine if the alterations in immune response resulting from alcohol feeding might be expressed differently in males and females. To accomplish this we utilized pair-fed male and female Sprague-Dawley rats. Animals were fed a liquid diet for 60 days containing 30% of their calories as ethanol, and after 1 week this concentration was increased to 45% ethanol. Controls received liquid control diet of the same caloric and nutritional composition, and immune status was monitored with in vivo and in vitro techniques. Ethanol feeding significantly reduced the phytohemagglutinin skin response in males ( p = 0.020) and females ( p = 0.012). The concanavalin A blastogenic response of spleen cells prepared from female rats fed ethanol was significantly depressed with respect to spleen cells prepared from female rats fed the control diet ( p = 0.0071). Alcohol also appeared to depress spleen cell blastogenic response in males, but this trend did not quite reach significance ( p = 0.071). Spleen cells from groups of ethanol and control male and female rats were labeled with fluorescent monoclonal antibodies and run on a Fluorescent-Activated Cell Sorter. Ethanol significantly increased the percentage population of CD4 (T-helper cell) in males ( p = 0.017), but not in females, and promoted an apparent, although nonsignificant, increase in the CD4/CD8 ratio in both sexes. An ELISA was used to measure IgM and IgG antibody elaborated by pokeweed mitogen-stimulated spleen cells in cultures. Ethanol feeding increased both IgM secretion ( p = 0.0001) and IgG secretion ( p = 0.034) in cells from females but not males, and female cells secreted significantly more immunoglobins than did male cells.     

Alteration of [3H]MK-801 Binding Associated with the JV-Methyl-d-Aspartate Receptor Complex by Acute Ethanol in Rat Cortex and Hippocampus In Vitro

We investigated the effect of ethanol on specific binding of [³H]MK-801 to the intrachannel phencyclidine (PCP) receptor site, as an index of change in the functional response of the N-methyl-d -Aspartate (NMDA)-associated ion channel. Saturation binding experiments were performed on synaptic membrane homogenates from adult rat cortex and hippocampus. [³H]MK-801 binding assays were conducted under conditions of basal, 10 μm glutamate, or 10 μm glutamate + 30 μm d -serine, with and without 50 or 100 mm ethanol. Association experiments of [³H]MK-801 binding (5 nm) were conducted under conditions of 0 or 10 μm glutamate, with varying concentrations of glycine (0.01, 0.10, and 10 μm) with and without 100 mm ethanol. Ethanol (50 and 100 mm ) significantly decreased the percentage of high-affinity (open-channel state) MK-801 receptors with a concomitant increase in percentage of low-affinity receptors, but did not change high- and low-affinity constants of the two binding states. An ethanol-induced increase in the closed-channel receptor density in basal and activated conditions was suggested by the saturation experiments. Association experiments further explained this finding, in that ethanol (100 mm ) significantly decreased fast component (open-channel) [³H]MK-801 binding in conditions of glycine (0.01–10 μm ) only and activated conditions of glutamate + glycine (0.01–0.10 μm ). However, the observed fast and slow kinetic rate constants of [³H]MK-801 binding, as well as total specific binding (fast + slow components), were not altered. Thus, ethanol seems to act as a noncompetitive antagonist upon the gating mechanism of, and ligand access to, the NMDA-coupled ion channel. These findings support previous observations of ethanol selectively reducing NMDA-activated calcium influx, and reducing the frequency and duration of ion channel opening in electrophysiological studies. Similar to previous reports on NMDA-stimulated calcium influx and [³H]MK-801 binding, glycine (at the maximal concentration of 10 μm ), in the presence of 10 μm glutamate, was found to reverse ethanol inhibition of fast component binding.     

Effects of Abstinence on the Brain: Quantitative Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging in Chronic Alcohol Abuse

Background: Structural brain damage, especially to white matter, is well documented in chronic alcohol abuse. There is also evidence for brain metabolic abnormalities in this condition. It is unknown, however, to what extent these structural and metabolic changes are present in treated alcohol abusers who achieve long-term abstinence versus treatment-naïve, heavily drinking individuals. Methods: This study compared 12 recovering alcoholics with 8 actively heavily drinking subjects. Participants underwent magnetic resonance (MR) imaging and proton MR spectroscopic imaging of the brain. Semiautomated image segmentation techniques yielded volumes for gray matter, white matter, white matter lesions, and cerebral spinal fluid in multiple brain regions defined by Talairach stereotaxic coordinates. Automated spectral processing methods yielded gray and white matter concentrations of the metabolites N-acetylaspartate, creatine, and choline for the same regions. Results: Recovering alcoholics had greater volumes of frontal white matter, but the opposite was true for white matter in a “remainder” region encompassing the basal frontal and temporal lobes, the cerebellum, and the brainstem. Recovering alcoholics also had smaller volumes of white matter lesions in whole brain, in occipital and mesial parietal regions, and in the remainder region. Recovering alcoholics had greater gray matter volumes in the orbital frontal pole and postcentral gyrus, but smaller gray matter volumes in the anterior cingulate. Whole-brain and regional metabolite concentrations did not differ significantly between the two groups. Conclusions: White and gray matter volumes in different regions of the brain were greater or smaller in recovering, treated alcoholics. The findings suggest region-specific structural recovery from chronic alcohol–induced brain injury, but also region-specific long-term structural damage in abstinent alcoholics. White matter lesions were widespread in active drinkers and may partly resolve during long-term abstinence. Proton MR spectroscopic measures, as applied in this cross-sectional study, were largely ineffective in revealing metabolic effects of abstinence on the alcohol-damaged brain.     

Alcohol-Related Aggression in Males and Females: Effects of Blood Alcohol Concentration, Subjective Intoxication, Personality, and Provocation

This study tested the combined predictive ability of blood alcohol concentration (BAC), subjective intoxication, and aggressive personality traits on physical aggression in males and females in Highland Low-provocation conditions. Sixty intoxicated White social drinkers (30 males and 30 females) competed against a fictitious opponent on a modified version of the Taylor aggression paradigm in which subjects both received and delivered electric shocks to their opponents in provoking and nonprovoking conditions. Provocation conditions (High and Low) were defined by the intensity of the shocks the subjects received. Aggression was operationalized as the intensity of the shocks selected by the subjects. Results indicated that, for males in the High-provocation condition, aggressive personality traits, subjective intoxication, and BAC were effective predictors of physical aggression. However, in the Low-provocation condition, only aggressive personality traits and BAC predicted aggression. None of the variables were effective predictors of aggression for intoxicated females.     

Increase in Alcohol Intake,Reduced Flexibility of Alcohol Drinking,and Evidence of Signs of Alcohol Intoxication in Sardinian Alcohol‐Preferring Rats Exposed to Intermittent Access to 20% Alcohol

Background: This study assessed in Sardinian alcohol‐preferring (sP) rats a procedure known to promote alcohol drinking and based on the intermittent (once every other day) access to 2 bottles containing alcohol (20%, v/v) and water, respectively (Wise, 1973). Methods: To this end, sP rats were exposed – under the 2‐bottle choice regimen – to: (i) 10% (v/v) alcohol with continuous access (CA10%; i.e., the procedure under which sP rats had been selectively bred); (ii) 10% (v/v) alcohol with intermittent access (IA10%); (iii) 20% (v/v) alcohol with continuous access (CA20%); (iv) 20% (v/v) alcohol with intermittent access (IA20%; the “Wise” condition) (Experiment 1). Additional experiments assessed the influence of (i) adulteration with quinine of the alcohol solution (Experiment 2) and (ii) concurrent presentation of a saccharin solution (Experiment 3) on alcohol drinking under the CA10% and IA20% conditions. Finally, it was assessed whether alcohol drinking under the CA10% and IA20% conditions resulted in motor incoordination at the Rota‐Rod task, as a possible sign of alcohol intoxication (Experiment 4). Results: Daily alcohol intake markedly escalated in rats exposed to the IA20% condition, averaging 9.0 g/kg (in comparison with the average intake of 6.5 g/kg in the CA10% rat group). CA20% and IA10% rats displayed intermediate values of daily alcohol intake between those of CA10% and IA20% rats. Alcohol intake was virtually abolished by addition of quinine or by concurrent presentation of the saccharin solution in CA10% rats; conversely, alcohol intake in IA20% rats was only partially affected by gustatory aversion or concurrent presentation of an alternative reinforcer. Finally, alcohol intake in IA20%, but not in CA10%, rats resulted in clear motor‐incoordinating effects. Conclusions: These data suggest that the “Wise” procedure is effective in inducing marked increases in alcohol intake in sP rats. These increases are associated with a reduced flexibility of alcohol drinking (suggesting the development of “behavioral” dependence) and produce signs of alcohol intoxication that are not detected when sP rats are exposed to the more conventional CA10% condition.     

Female Rats Release More Corticosterone Than Males in Response to Alcohol: Influence of Circulating Sex Steroids and Possible Consequences for Blood Alcohol Levels

The hypothalamic-pituitary-adrenal (HPA) axis of female rats is more responsive to a variety of stimuli than that of males. Proestrous females are also reported to release more ACTH and corticosterone in response to restraint stress than females at other stages of the estrous cycle. Finally, blood alcohol levels (BALs) reached in response to a standard dose of alcohol also indicate the presence of a gender specificity, with females exhibiting higher BALs than males. The aim of this study was therefore 2-fold: first, we investigated the influence of gender on the ability of alcohol to increase plasma ACTH and corticosterone secretion in the rat. Second, we tested the hypothesis that corticosterone alters alcohol metabolism and asked whether this might represent a mechanism underlying the sex difference in BALs. We observed that compared with intact males, intact females taken at random stages of the estrous cycle secreted significantly (p < 0.01) more ACTH and corticosterone in response to alcohol (0.2-1.8 g/kg). Within females, the intraperitoneal administration of alcohol was followed by higher plasma ACTH and corticosteroids levels during proestrus and estrus, compared with diestrus. Removal of circulating sex steroids abolished the gender difference in terms of ACTH secretion, but ovariectomized females still released more corticosterone than castrated males in response to 0.6 and 1.8 g alcohol/kg. This difference could not be explained by a sex-related component of pituitary responsiveness to corticotropin-releasing factor. These results demonstrate the existence of a sex-specific activation of the HPA axis in response to alcohol, and suggest that sex steroids exert an activational influence on ACTH and corticosterone release in response to ethanol. The possible influence of corticosteroids on the pharmacokinetics of alcohol was investigated in intact males, intact females, and adrenalectomized (ADX) males bearing 15 mg (low dose) or 150 mg (high dose) corticosterone pellets. Following the intraperitoneal injection of a standard dose of ethanol (1.5 g/kg), ADX animals with low corticosterone therapy had higher BALs than either intact rats, or ADX animals with high corticosterone replacement. Intact females exhibited the highest corticosterone levels of all groups of animals, but showed BALs that were intermediate between those of intact males and ADX rats with the low dose corticosterone pellets. Thus, although we cannot exclude an influence of body water content in ADX rats replaced with various regimens of corticosteroids, our results indicate that corticosteroids may modulate alcohol metabolism in the rat. In summary, we have shown that, in the rat, alcohol induces a gender-specific pattern of ACTH and corticosterone secretion that appears to be at least in part dependent on circulating sex steroids. Our results also suggest that although corticosteroids may play a role in regulating the rate of alcohol metabolism, this effect cannot account for the higher BALs measured in female rats.     

Permanent Neuronal Cell Loss in the Inferior Olive of Adult Rats Exposed to Alcohol during the Brain Growth Spurt: A Stereological Investigation

The purpose of this study was to examine whether exposure of rat pups to alcohol postnatally over a period of brain development similar to that of the human 3rd trimester results in a permanent loss of cells in the inferior olivary nucleus. It was hypothesized that a deficit of neurons in the inferior olive, the sole source of climbing fibers, may contribute to the cerebellar dysfunction observed following exposure to alcohol during development.
Sprague-Dawley rat pups were artificially reared and administered alcohol over postnatal days 4–9. One artificially reared group received a daily alcohol dose of 4.5 g/kg, administered as a 10.2% solution in 2 of 12 daily feedings (10.2% group). This pattern of alcohol administration resulted in high peak blood alcohol concentrations with near total clearance. The other artificially reared group was fed a diet made isocaloric to the alcohol-containing diet (gastrostomy control group). Pups were allowed to grow to adulthood and killed on postnatal day 115. The total number of neurons in the inferior olivary nucleus was estimated using unbiased stereological methods.
Exposure to alcohol resulted in a significant deficit in the number of neurons in the inferior olive at 115 days of age. The total number of neurons in the alcohol-exposed group was 40.12 ± 8.7 ± 10³, compared with 53.37 ± 3.7 ± 10³ in the artificially reared controls.
These results indicate that there is a permanent deficit of neurons in the inferior olive after postnatal exposure to alcohol. This supports the hypothesis that cerebellar dysfunction after exposure to alcohol during the brain growth spurt may be the result of more extensive neuronal deficits than previously thought.     

糖尿病大鼠血、睾丸和脑组织内皮素水平的初步研究

目的　探讨糖尿病大鼠以及用银杏叶提取物 (EGb)治疗后血浆、睾丸和脑组织中内皮素的变化及意义。方法　将SD大鼠分为正常对照组、糖尿病模型组、EGb治疗组三组 ,在EGb治疗 5周后 ,用放射免疫法同时测定各组大鼠血浆、睾丸和脑组织中内皮素 (ET)的含量。结果　脑组织及血浆中ET含量正常对照组与糖尿病组比较无显著性差异 (P >0 0 5 ) ,睾丸组织中ET含量糖尿病组明显高于正常对照组 ,两者有显著性差异 (P <0 0 5 ) ;糖尿病组与EGb治疗组比较各种组织ET含量有下降倾向 ,但无显著性差异 (P >0 0 5 )。结论　糖尿病大鼠睾丸组织中ET含量增高 ,可能造成睾丸组织损害 ;EGb治疗可能有利于降低大鼠血液、睾丸和脑组织中的ET含量 ,但需进一步试验证实。     

Effects of Ethyl Alcohol Administration to THA Rat Dams During Their Gestation Period on Learning Behavior and on Levels of Monoamines and Metabolites in the Brain of Pups after Birth

Children born from chronic alcoholic mothers have shown behavioral teratogenic effects more frequently than morphological malformations. To investigate the possible mechanisms and evaluate maternal alcohol dosage levels to induce behavioral dysfunctions, we gave pregnant Tokai High Avoider (THA) rats 0, 5,10, and 20% ethanol (EtOH) as drinking water during the gestation period. We evaluated the brain function of pups born of alcohol-administered dams. Sidman avoidance behavior test and the levels of monoamines (nor-adrenalin, dopamine, and serotonin) and metabolites (3,4-dihydroxy-phenyl acetic acid, homovanillic acid, and 5-hydroxyindole acetic acid) in whole brain were examined for neurobehavioral and neurochemical effects. EtOH-exposed THA offsprings showed high pre-and postnatal mortality, growth deficits, and brain weight reductions. Compared with the results of the same conditioning experiment using Wistar rats, the THA rat may have higher susceptibility to the effects of in utero EtOH exposure than Wistar rats. EtOH-exposed THA pups exhibited deficits in avoidance operant learning that were not shown in Wistar rats. We also observed the increased levels of all monoamines that were assumed to be related with the deficit of learning, the decreased levels of 3,4-dihydroxyphenyl acetic acid and homovanillic acid, and the unchanged levels of 5-hydroxyindole acetic acid in pups from dams administered 10 and 20% EtOH. However, contrary alteration of monoamines and their metabolites were shown in pups from 5% EtOH-administered dams.     

Optical Spectroscopy and Cerebral Vascular Effects of Alcohol in the Intact Brain: Effects on Tissue Deoxyhemoglobin, Blood Content, and Reduced Cytochrome Oxidase

Dose-response effects of acute ethanol infusions were studied, noninvasively, in the unopened brain to examine the hypothesis that ethanol can induce stroke-like events as a consequence of cerebral vasospasm and tissue ischemia. By using a single sending and receiving fiber, an optical backscatter measurement (500–800 nm) was used to monitor the levels of deoxyhemoglobin (DH), reduced cytochrome oxidase (rCO), and relative tissue blood content in a closed cranium preparation. Anesthetized rats were prepared by cannulating a branch of the internal carotid artery and subjected to either bolus infusions (1.25 or 2.5 μm ethanol in Ringers/g tissue) or to constant infusions of 5 or 10% ethanol at various rates (0.30–2.92 μm /g/min). To facilitate optical penetration, a portion of the left parietal cranium was shaved to a translucent appearance. Results showed that low, bolus doses of ethanol typically produced a slight increase (5–10%) in the oxyhemoglobin signal, indicating that vasodilation had probably occurred. Higher doses, however, produced a prompt and significant reduction in the hemoglobin signal, increased levels of DH, and a rise in rCO suggesting a vasoconstrictor response leading to ischemia had occurred, followed by recovery within 3–5 min. Constant infusions of ethanol produced a similar cerebral vascular response, in a dose-related manner, but of a more sustained nature. At levels of 50–60% of the maximum bolus dose, the effect was more pronounced, accompanied by an increase in the levels of rCO (by 50–90%). Control experiments using identical volumes/flow rates of Ringers solution produced no significant alterations in the optical spectrum. Overall, these data indicate that, depending on dose: (a) ethanol can induce vasodilatory or vasoconstrictor effects in the intact brain; (b) the more pronounced effects involve vasospasm in the cortical microcirculation leading to global ischemia; and (c) optical measurements permit direct noninvasive assessment of the cerebral vascular effects of alcohol and, potentially, other substances of abuse