Developmental alterations in olivary climbing fiber distribution following postnatal ethanol exposure in the rat.

Ethanol exposure during postnatal days (PN) 4-6 in rats alters cerebellar development resulting in significant loss of Purkinje cells. There is little knowledge, however, on what happens to the neurons that survive. In this study, rat pups were treated with a daily dose of ethanol (either 3.6 or 4.5 g/kg body weight) delivered by intragastric intubation on PN4, PN4-6, or PN7-9. Then the interactions between climbing fibers and Purkinje cells were examined on PN14 using confocal microscopy. Mid-vermal cerebellar sections were stained with antibodies to calbindin-D28k (to visualize Purkinje cells) and vesicular glutamate transporter 2 (VGluT2, to visualize climbing fibers). Confocal z-stack images were obtained from Lobule 1 and analyzed with Imaris software to quantify the staining of the two antibodies. The VGluT2 immunostaining was significantly reduced in the PN4 and PN4-6 ethanol groups for the 4.5 g/kg dose level, compared to controls, indicating that the cerebellar circuitry was significantly altered following developmental ethanol exposure. Not only were there fewer Purkinje cells following ethanol exposure, but the surviving neurons had significantly fewer VGluT2-labeled synapses. These alterations in the synaptic integrity were both dose dependent and temporally dependent.

Time course and manner of Purkinje neuron death following a single ethanol exposure on postnatal day 4 in the developing rat.

The present study was designed to evaluate the time course and manner of Purkinje cell death following a single ethanol dose delivered intragastrically on postnatal day (PN) 4 to rat pups. Analysis included immunolabeling of Purkinje cells with antibody specific for calbindin D28k and counting of Purkinje cells in each lobule of a mid-vermal slice. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis and immunodetection for cleaved (activated) caspase-3 enzyme was used to identify apoptosis, with calbindin D28k co-immunolabeling to identify apoptotic Purkinje cells. Finally, immunodetection for cytochrome c, again with co-labeling using calbindin D28k antibody, identified intracellular release of cytochrome c from the mitochondria into the cytoplasm of Purkinje cells. The data demonstrate that a single dose of ethanol results in a significant and extensive, lobular dependent loss of Purkinje cells within 24 h after administration. Extensive loss in the early developing lobules (I-III, VIII-X) and less to no loss in the later developing lobules (IV-VII) is consistent with prior literature reports on the ethanol-induced effects on Purkinje cells at this age. Clear and consistent evidence of apoptotic Purkinje cells was identified and the pattern was transient in nature. Finally, cytochrome c is released from the mitochondria of Purkinje cells in a time course consistent with the activation of the mitochondrial pathway of apoptosis. These data support the hypothesis that ethanol-induced loss of Purkinje cells involves apoptotic mechanisms. Furthermore, the initiation of apoptosis by ethanol is consistent with ethanol-induced interruptions of Purkinje cell neurotrophic support leading to activation of the mitochondrial pathway of apoptosis.

Purkinje cell vulnerability to developmental ethanol exposure in the rat cerebellum.

BACKGROUND: Ethanol exposure is a consistent and reliable producer of neuronal toxicity, especially during periods of enhanced neuronal vulnerability. For rat cerebellar Purkinje cells, the postnatal period during the time of the brain growth spurt exhibits the greatest vulnerability to ethanol. Analyses of studies completed over more than 20 years provides sufficient detail to allow for the determination of the specific vulnerable window for ethanol-induced loss of Purkinje cells. METHODS: Data reporting Purkinje cell counts after ethanol exposure were compiled from 18 studies published since 1975. We conducted linear regression analysis between peak blood ethanol concentration (BEC) and percent reduction in Purkinje cells for the following individual postnatal (PN) days: PN4, PN5. PN6, PN7, and PN8 or beyond (+). The slope of the regression and the coefficients of determination (r2) were the primary factors of interest. Analysis of variance of the regressions was conducted to identify whether the slopes were significantly different from zero, or from each other. RESULTS: Exposures involving the PN4-6 period demonstrated the greatest significance in the relationship between BEC and reduction of Purkinje cell number. No significant differences were identified between different ethanol exposure techniques or for different Purkinje cell counting techniques. In addition, the initial day of exposure and the duration of exposure were not identified as critical variables. CONCLUSIONS: The literature database, developed over the past 20 years is clear in its direction that studies designed to identify the ethanol-specific mechanisms of Purkinje cell death are best designed to involve ethanol exposure during the vulnerable window of postnatal days 4-6.

Drug-induced nightmares.

OBJECTIVE: To compile and assess the English-language literature on drug-induced nightmares, excluding nightmares secondary to drug withdrawal or drug-associated night terrors. DATA SOURCES: Published articles, letters, case reports, and abstracts in English were identified by MEDLINE (1966-May 1998) searches using the search term nightmares, chemically induced. Additional articles were obtained from bibliographies of retrieved articles. DATA EXTRACTION: All case reports of drug-induced nightmares were evaluated using the Naranjo algorithm for causality. Clinical studies of drugs that reported nightmares as an adverse effect were assessed for frequency of occurrence. DATA SYNTHESIS: Nightmares, defined as nocturnal episodes of intense anxiety and fear associated with a vivid, emotionally charged dream experience, are generally classified as a parasomnia. Possible pharmacologic mechanisms for drug-induced nightmares, such as REM suppression and dopamine receptor stimulation, are reviewed. However, the vast majority of therapeutic agents implicated in causing nightmares have no obvious pharmacologic mechanism. CONCLUSIONS: Assessing causality with an event such as a nightmare is difficult because of the high incidence of nightmares in the healthy population. Using qualitative, quantitative, and possible pharmacologic mechanism criteria, it appears that sedative/hypnotics, beta-blockers, and amphetamines are the therapeutic modalities most frequently associated with nightmares. These drug classes have a plausible pharmacologic mechanism to explain this effect. Dopamine agonists also have evidence of causality, with dopamine receptor stimulation as a possible pharmacologic mechanism.

Intragastric intubation: important aspects of the model for administration of ethanol to rat pups during the postnatal period.

One technique for the controlled delivery of ethanol to neonatal rat pups is intragastric intubation. Often, the vehicle used for delivery of ethanol is composed of a nutrient mixture to compensate for decreased suckling or other possible nutritional compromise. This study analyzed the selection of nutrient vehicle, the combination of experimental treatment groups within a litter, and the overall litter size on the growth rate of ethanol-intubated and intubated-control pups, compared with mother-raised control pups. Sprague-Dawley rat pups were raised in litters of 8 or 10, and administered ethanol by intragastric intubation with 20% (v/v) Sustacal or 80% (v/v) Intralipid-II nutrient vehicle. Pups were treated between postnatal days 2 and 10, and body weight was analyzed on day 10. Pups were assigned to a treatment group as either intubated ethanol, intubated control, or nonintubated mother-raised controls. Experimental comparison by statistical analyses was performed to identify the optimal treatment design (mixed treatment groups in a single litter or a single treatment group per litter), the optimal vehicle (Sustacal or Intralipid-II), and the optimal number of pups per litter (8 vs. 10). The analyses demonstrate that the mixing of intubated control, intubated ethanol, and nonintubated mother-raised control treatment groups within a single litter introduced an uncontrolled variable that confounded measurement of ethanol-specific alterations. The sensitivity of treatment groups to inclusion in mixed litters was dependent on the nutrient vehicle and thus nutritional adequacy. Our results suggest that an optimal design was achieved with eight pups per litter. Furthermore, ethanol intubated and intubated control pups grow at a rate identical to parallel litters of eight mother-raised control pups when Intralipid-II is used as nutrient vehicle, and a single treatment group is present in a litter. Optimization of these experimental parameters has provided an excellent neonatal rat model for analysis of specific ethanol effects on brain development during the third trimester.

Nutritional factors modify the inhibition of CNS development by combined exposure to methadone and ethanol in neonatal rats.

The consequences resulting from the combined exposure to methadone and ethanol during a time period equivalent to the third trimester brain growth spurt was the purpose of this study. Rat pups were treated on postnatal days 6-10 and sacrificed on postnatal day 11. Body weight along with the heart, liver, kidneys, whole brain, cerebrum, cerebellum, and brain stem weights were measured. The impact of nutritional factors were identified by delivery of the drug solutions in one of two intubation vehicles differing in both caloric density and composition. Ethanol and methadone in combination result in significantly increased detrimental effects compared to methadone alone only when possible nutritional compromise was present. The combined effect of both drugs significantly inhibited body growth and the development of all brain regions studied. Neither drug alone, nor in combination, produced significant inhibition of growth in the liver, heart, or kidney. The nutritional status of the pup, as represented by vehicle composition, was able to modify the specific drug effects and suggests that nutritional status can mask or enhance the determination of specific drug effects.

Microencephaly and selective decreases in cerebellar Purkinje cell numbers following combined exposure to ethanol and methadone during rat brain development.

This study evaluated the neuroanatomical effects of combined ethanol and methadone exposure on cerebellar development. Ethanol, methadone or a combination of both drugs was delivered twice daily to rat pups using intra-gastric intubation from postnatal day 6 (PN6) to PN10 inclusive. The intubated control group (IK) received equal volumes of isocaloric vehicle. Purkinje cell numbers in cerebellar lobules I-X were quantified from midsagittal sections of the cerebellar vermis at PN11. Deficits of 15-23% in body, total brain, cerebrum, cerebellum and brainstem weights were exhibited for the ethanol/methadone-treated (IEM) group compared to IK. Purkinje cell deficits resulting from IEM treatment were found in lobules VI through X compared to IK with significant decreases of 31 and 23%, respectively, for lobules VIII and X. In contrast, neither ethanol nor methadone exposures under these treatment conditions caused cerebellar deficits.

Local analgesia with opioid drugs.

These data suggest the presence of peripheral opioid receptors that are involved in the clinical perception of pain. This is a radical change in our traditional thinking of opioid pharmacology and pain management. Most clinicians have been taught that opioids work through the central nervous system. These new data depart from this traditionally held view of an exclusively central site of action. Further data, specifically, additional dose-response data with varying amounts of morphine, additional studies in pain syndromes other than knee arthroscopy, and the development and pharmacology of orally active opioid compounds that do not cross the central nervous system, are necessary to confirm and expand the present findings. The possibility of providing opioid pain relief free of central nervous system adverse effects is an exciting prospect. Additional studies of topical opioid preparations also would be of interest.

Intragastric intubation of alcohol during postnatal development of rats results in selective cell loss in the cerebellum.

Postnatal alcohol exposure produces reductions in the number of Purkinje cells in the rat cerebellum. The goal of this study was to determine if the method of postnatal alcohol exposure would influence the degree of vulnerability of the Purkinje cells. Previously reported studies from other laboratories have demonstrated cerebellar Purkinje cell count reductions following postnatal alcohol exposure via artificial rearing and vapor inhalation techniques. This study used gastric intubation to administer alcohol (3.6 g ethanol/kg body weight, bid) to male rat pups from postnatal days 4-10. Peak blood alcohol levels were 203 +/- 12.7 mg/dl on postnatal day 6. On postnatal day 10, the animals were perfused, and brain weights were obtained. Body weight was not significantly altered by the postnatal alcohol exposure, yet the wet weights of the cerebral cortex and whole brain were significantly reduced. Although the cerebellar weight was not significantly reduced, the overall number of Purkinje cells measured in the cerebellar vermis was significantly reduced by 24% compared with the isocaloric and normal control groups. The pattern of vulnerability for the individual cerebellar lobules was similar to the previously reported studies, indicating that alcohol's teratogenicity transcends experimental paradigm and is remarkably consistent, when relatively similar blood alcohol profiles are established.

Differential neuronal loss following early postnatal alcohol exposure.

Neonatal rats were exposed to 6.6 g/kg of alcohol each day between postnatal days 4 and 10 while artificial-rearing procedures were used, in a manner which produced high peak and low trough blood alcohol concentrations each day. Gastrostomy controls were reared artificially with maltose/dextrin isocalorically substituted for alcohol in the milk formula, and suckle controls were reared normally by dams. The pups were sacrificed on day 10 and tissue sections (2 microns thick) were obtained in the sagittal plane through the cerebellum and in the horizontal plane through the hippocampal formation. Overall area measures were obtained for the hippocampus proper, area dentata, and cerebellum, along with areas of the cell layers of these regions. In the hippocampal formation, cell counts were made of the pyramidal cells of the hippocampus proper, the multiple cell types of the hilus, and the granule cells of the area dentata. In the cerebellum, cell counts of Purkinje cells, granule cells of the granular layer, granule cells of the external granular layer, and mitotic cells of the external granular layer were obtained from lobules I, V, VII, VIII, and IX. Alcohol selectively reduced areas and neuronal numbers in the cerebellum but had no significant effects on neuronal numbers in the hippocampal formation. Purkinje cells exhibited the greatest percent reductions, and cerebellar granule cells were significantly reduced in the granular layer but not in the external granular layer. All lobules showed these effects, but lobule I was significantly more affected than the other four lobules that were analyzed. The results demonstrate the differential vulnerability of selected neuronal populations to the developmental toxicity of alcohol exposure during the brain growth spurt.

Manipulating peak blood alcohol concentrations in neonatal rats: review of an animal model for alcohol-related developmental effects.

Fetal alcohol syndrome (FAS) is now well documented, but factors that affect the severity of the accompanying central nervous system damage are still not well understood. In a series of experiments, artificially reared neonatal rats were exposed to alcohol during postnatal days 4-10 (during the brain growth spurt of the rat) to evaluate the consequences of various patterns of alcohol consumption in contributing to the severity of alcohol-related brain damage. In the first experiment, groups of rat pups were given different doses of alcohol (6.6 to 9.8 g/kg) in a milk formula in eight 15-min feedings over each 24 hr. Measures of brain weight on day 10 indicated an inverse relationship between dose and brain weight. Re-evaluating the results with respect to blood alcohol concentration (BAC) revealed an even stronger correlation between BAC and microencephaly. A series of experiments followed in which various doses of alcohol were condensed into fewer and fewer hours each day. Condensing the dose produced higher BACs for a given dose and produced more severe microencephaly, greater neuronal loss, behavioral hyperactivity and impaired spatial navigation. Some of these effects were permanent with females more affected than males on some measures. These data suggest that patterns of alcohol consumption that produce high BACs, such as binge drinking, may be especially harmful to the brain of the developing fetus.

Microencephaly and hyperactivity in adult rats can be induced by neonatal exposure to high blood alcohol concentrations.

To investigate whether or not blood alcohol concentration during the brain growth spurt has an influence on the permanency of alcohol-induced central nervous system damage, an artificial rearing technique was used to administer a daily dose of alcohol (6.6 g/kg/day) to neonatal rats during postnatal days 4 to 10. The alcohol was administered either in a condensed pattern over 8 h resulting in cyclic blood alcohol concentrations with high peaks, or uniformly over each 24-h period resulting in stable, but low peaks. The condensed alcohol exposure resulted in considerable microencephaly (20% to 25%), with significant growth deficits in the cerebrum, cerebellum, and brain stem of rats of either sex at day 10; there still was significant microencephaly (16% to 19%) in adult rats that received the condensed alcohol exposure as neonates. Furthermore, activity at day 90 in rats of either sex that had condensed alcohol exposure was elevated compared with that of the gastrostomy control group. In contrast, the rats having uniform alcohol exposure had only nonsignificant changes in brain weight both on day 10 and day 90 and did not exhibit hyperactivity at day 90. Thus, neonatal alcohol exposure producing high blood alcohol concentrations caused permanent deficits in brain growth and significant changes in activity, whereas the same daily dose of alcohol administered in a pattern that resulted in consistently low blood alcohol concentrations failed to produce either permanent microencephaly or increased activity. These data support the hypothesis that patterns of alcohol exposure that produce high concentrations in the blood, such as "binge-drinking," increase the risk of permanent damage to the developing brain.

Differential deficits in regional brain growth induced by postnatal alcohol.

Neonatal rats were exposed to alcohol during a period of brain development equivalent to part of the human third trimester. Rat pups were fed a milk formula containing either alcohol (9.8 g/kg/day) or isocaloric maltose/dextrin using artificial rearing techniques from postnatal days 4-10. Blood alcohol concentrations reached 345.8 +/- 15.6 mg/dl on postnatal day 6. All animals, including a group of normally reared suckle controls, were sacrificed on postnatal day 10, and the brains were perfused and processed for the Timm histochemical technique. Significant microencephaly (30% reduction in brain growth) was found in the alcohol-exposed animals. Growth deficits also were found in specific brain regions of the alcohol-exposed rats. The overall area of the hippocampus proper at a midtemporal level was reduced by 26.1% compared to controls. Sublaminae within the hippocampus were stunted as much as 40.5%. An overall reduction of 14.5% was found in the midsagittal (vermal) cerebellum. In contrast, growth of the dentate gyrus appeared much less affected (6.8% deficit) by the alcohol exposure. These data indicate that not all regions of the brain are affected equally by alcohol exposure during the third trimester equivalent.

Severity of alcohol-induced deficits in rats during the third trimester equivalent is determined by the pattern of exposure.

The pattern of alcohol exposure has been suggested to be an important determinant of fetal alcohol effects. Rats were exposed to alcohol and reared artificially on postnatal days (PD) 4-10. A uniform alcohol exposure group received alcohol (6.6 g/kg/day) in 12 daily feedings (every 2 hrs) resulting in stable BACs below 100 mg/dl. A condensed alcohol exposure group also received 6.6 g/kg/day but the alcohol was concentrated in 4 of 12 daily feedings giving peak BACs above 400 mg/dl. Condensed alcohol exposure induced a large degree of microencephaly on PD 10 which was still present on PD 90. Uniform exposure caused a mild degree of microencephaly on PD 10 which could not be detected at PD 90. Correlated with these brain changes were changes in behavior during development. Condensed exposure to alcohol increased locomotion during postnatal days 14 to 20. Condensed alcohol exposure caused delays in the development of balancing ability and coordinated hindlimb movements. Thus, the pattern of alcohol exposure appears more critical than the dose in determining the degree of damage inflicted by alcohol to the developing central nervous system.

Blood alcohol concentration: a critical factor for producing fetal alcohol effects.

A dose of 6.6 g/kg of alcohol, delivered in 12 equally-spaced fractions each 24 hours via an artificial rearing procedure during postnatal days 4-10, produced mean blood alcohol concentrations (BACs) that were low (46.6 mg/dl), but stable with time. This relatively constant alcohol exposure did not limit brain growth in neonatal rats when measured on postnatal day 10. The same daily dose concentrated into 6 fractions over 12 hours (with 6 alcohol-free fractions the remaining 12 hours) resulted in cyclic BACs having high peaks (270.2 mg/dl). The cyclic regimen produced a significant reduction in brain growth. Thus, the peak blood alcohol concentration is a critical factor in determining the minimum dose for producing microencephaly and must be considered when estimating the relative teratogenic risks of alcohol intake during pregnancy.

Alcohol-induced microencephaly during the third trimester equivalent: relationship to dose and blood alcohol concentration.

Alcohol was administered in different doses to groups of neonatal rat pups from postnatal days 4-10 using an artificial rearing technique. Blood alcohol concentrations (BACs) were monitored in pups on postnatal day 6. Brain weights were measured on postnatal day 10 and the extent of microencephaly was correlated with dose and BAC. Doses of 7.4 g/kg/day and above resulted in microencephaly. Although BACs varied considerably among individual animals at each dose tested, the amount of microencephaly increased with the BAC, and the amount of brain growth reduction was more dependent on BAC than dose. The BAC threshold for producing microencephaly was between 140 and 197 mg/dl. Deficits in the brain weight to body weight ratio ranged from 14% to 25% as BACs increased to approximately 280 mg/dl. Higher BACs did not produce significantly more microencephaly, although BACs above 425 mg/dl were lethal. Sex-related differences were also examined. There were significant differences in the brain weights and the BACs between males and females of the same dose groups. These data indicate that increasing the amount of alcohol during the third trimester equivalent increases the amount of microencephaly. However, BAC is a better predictor than dose of the adverse affects of alcohol on brain growth.

The effect of in utero ethanol exposure on hippocampal mossy fibers: an HRP study.

Adult rats, exposed to ethanol in utero exhibit aberrant mossy fiber-like Timm staining in the distal infrapyramidal region of the hippocampus at midtemporal levels. The present study utilized the anterograde transport of HRP to verify that the aberrant pattern of Timm staining represented a terminal field of the dentate granule cells. One or more HRP-labeled mossy fiber bundles were shown to cross to the infrapyramidal side of the pyramidal cell layer primarily, but not exclusively, at the same septotemporal level where the aberrant terminal field was located.

Delay in brain growth induced by alcohol in artificially reared rat pups.

The effect of alcohol on body and brain growth of the neonatal rat was examined. An artificial rearing procedure was used to administer a milk formula containing 2.8% alcohol to rat pups during days 4-10 postpartum. Mean blood alcohol levels taken at hourly intervals between feelings at the end of the second day of exposure ranged between 151 and 163 mg/dl. Body growth in both groups of artificially reared pups was similar to that of the suckle control pups. Gross measurements indicated that while alcohol exposure did not arrest body growth, it did arrest several parameters of brain growth. There were deficits in brain weight and volume and in the brain weight to body weight ratio. Furthermore, there were sex-related differences. The brain weight to body weight ratio was significantly decreased in females and there was also a trend toward a greater deficit in brain volume as well. However, deficits in gross measures were not reflected in the development of the hippocampal formation. Areal measurements of the hippocampus and dentate gyrus failed to indicate any differential effects on the growth of the pyramidal and granule cell layers, or their dendritic fields and corresponding Timm-stained sublaminae, due to the alcohol exposure. These data suggest that the blood alcohol concentrations reached in the present study may be near the threshold dose for producing deficits in brain growth, and that the females have a lower threshold than the males.

Increased rates of polypeptide chain elongation in placental explants from human diabetics.

Average rates of polypeptide chain elongation were determined in placental explants of first trimester and term placentas from both normal and diabetic human pregnancies. Average ribosome half-transit times were determined by measuring the kinetics of transfer of labeled polypeptides from polysomal-bound to released polypeptides. The average half-transit time decreases from 75 sec per ribosome in first trimester explants to 56 sec per ribosome in term placentas. The average polypeptide molecular weights synthesized by explants from first trimester and in term are 49,300 and 49,600, respectively, which are not significantly different. The average elongation rates for first trimester and term placental explants are 172 and 231 amino acids per minute per ribosome, respectively, which are significantly different. Moreover, the average polypeptide molecular weight synthesized by term placentas from diabetic pregnancies is 48,200, while the average ribosome half-transit time is 40 sec. Thus, ribosomes from explants of term placenta from diabetics move along the average message at a much higher speed than do ribosomes in normal term tissue. The assembly rate of amino acid into polypeptide in explant of placenta of diabetic mothers is 314 amino acids per minute, which is significantly faster than 231 amino acids per minute in normal term tissue. These findings indicate that during placental development and in diabetic pregnancy there is a large change in the actual rates at which amino acids are added to the nascent polypeptide chain--i.e., the rates in polypeptide chain elongation. Therefore, translation-level regulation of protein synthesis in placenta plays a significant part in the magnitude of the response to developmental and other physiological stimulations.

Prenatal and early postnatal exposure to ethanol permanently alters the rat hippocampus.

Three separate groups of pregnant Sprague-Dawley rats were (1) fed a liquid diet containing 35% ethanol-derived calories, or (2) pair-fed this diet containing an isocaloric amount of maltose-dextrin instead of ethanol,or (3) fed laboratory chow ad libitum. Their offspring were killed after reaching at least 60 days of age, and their brains were processed with the Timm's or horseradish peroxidase histochemical techniques. Both procedures revealed that intrauterine exposure to ethanol produced a dramatic change in the topography of hippocampal mossy fibres. An aberrant distal infrapyramidal mossy fibre terminal band was present at mid-temporal levels (where it does not normally occur). Pair-fed controls did not show the aberrant band. Rats exposed to ethanol after birth (using an artificial rearing procedure) showed even greater aberrations in the mossy fibre terminal field than rats exposed to ethanol in utero. Thus, postnatal exposure to ethanol (equivalent to the third trimester in the human) produced more striking changes in the mossy fibre terminal field than exposure to ethanol during the entire length of gestation in the rat (equivalent to the first and second trimesters in the human).