Biomedical subjects

J R West

Publications and source records attributed to J R West.

At least 19 recordsLinked to original sources

PubMed2000

Glial-derived neurotrophic factor (GDNF) prevents ethanol-induced apoptosis and JUN kinase phosphorylation.

Ethanol exposure during neural development leads to substantial neuronal loss in multiple brain regions. Our previous research indicated that exogenous glial-derived neurotrophic factor (GDNF) attenuated ethanol-induced cerebellar Purkinje cell loss. Additionally, ethanol decreased GDNF release suggesting that ethanol disrupts GDNF-signaling pathways. The present experiments utilized a homogeneous GDNF-responsive neuroblastoma cell line (SK-N-SH) to test the hypothesis that exogenous GDNF could attenuate ethanol-induced cell loss by suppressing cytotoxic signaling pathways and cell suicide. We measured two independently regulated markers of apoptosis, DNA fragmentation and the externalization of phosphatidylserine to the outer cell membrane leaflet. Ethanol induced a dose-related increase in both apoptosis and necrosis. Lower concentrations of ethanol (34 and 68 mM) specifically increased DNA fragmentation, while all concentrations (up to 137 mM) increased phosphatidylserine translocation, suggesting that ethanol induction of apoptosis is not a unitary process. Furthermore, only higher concentrations of ethanol (103 and 137 mM) induced necrosis. Additionally, ethanol specifically induced phosphorylation of c-jun N-terminal-kinase (JNK), a mitogen-activated protein (MAP) kinase selectively associated with apoptosis. In contrast, ethanol did not alter the phosphorylation of another MAP kinase, the extracellular signal-regulated kinases (ERK) that mediate cell survival. Thus, ethanol activated specific intracellular cell death-associated pathways and induced cell death. GDNF, in turn, prevented both ethanol-induced apoptosis and the activation of the death-associated JNK cascade. Therefore, GDNF may regulate multiple pathways to prevent ethanol-induced cell loss.

Annexin A5↗

PubMed1999

Early postnatal alcohol exposure produced long-term deficits in brain weight, but not the number of neurons in the locus coeruleus.

The locus coeruleus (LC), a small nucleus in the pontine tegmentum with clusters of norepinephrine (NE) containing neurons, projects to more brain regions than any other nucleus in the central nervous system. Therefore, any neuroanatomical deficits in the LC may have wide-ranging functional implications. Previous studies have shown that heavy alcohol exposure during development can damage several brain regions receiving extensive innervation from the LC (e.g., cerebellum and olfactory bulb). In this study, we examined the effects of early alcohol exposure during development on neuronal numbers in the LC of the adult rat. Sprague-Dawley rat pups were reared using artificial rearing techniques during the brain growth spurt period (part of the third trimester equivalent). The pups in the alcohol group received 4.5 g/kg per day in two of their 12 daily feedings from postnatal days (PDs) 4-9. Gastrostomy and suckle control groups were also included. On PD 90, the animals were sacrificed and their brains were processed for stereological cell counting. Whole brain weight, the number of neurons in the LC, the volume and neuronal density of the LC were assessed. There was a significant reduction in whole brain weight of the alcohol group compared with that of the gastrostomy control group, demonstrating a long lasting effect of alcohol on overall brain growth. Nevertheless, there were no differences in neuronal number, density and volume of the LC between alcohol and gastrostomy groups. Results were discussed in relation to the issues of temporal and regional vulnerabilities.

Animals↗

PubMed1999

Alcohol exposure during the first two trimesters equivalent alters granule cell number and neurotrophin expression in the developing rat olfactory bulb.

Although alcohol has been shown to affect brain development adversely, the underlying mechanism of alcohol's actions are poorly understood. The present study addressed the hypothesis that alcohol affects growth factor availability during critical periods of neural growth by measuring the mRNA expression of brain-derived neurotrophic factor (BDNF), a potent developmental growth factor. Multiple offspring of timed-pregnant rat dams given alcohol (6.0 g/kg per day) or control treatments during gestation were sacrificed at either embryonic (E) day 21 or E33 (usually postnatal day 10) when their olfactory bulbs were processed for molecular analyses or neuron counting. BDNF mRNA levels were measured by reverse-transcription-polymerase chain reaction, and DNA methylation of the BDNF gene was quantified by Southern blot analyses following digestion with methylation-sensitive enzymes. Estimates of total granule cell number were obtained by counting those cells using unbiased stereological techniques. There was a significant decrease in BDNF mRNA levels in the alcohol-exposed offspring of both ages compared with controls. In addition, the number of olfactory bulb granule cells significantly decreased in the E33 but not the E21 rat pups exposed to alcohol compared with their appropriate aged controls. Finally, BDNF DNA of alcohol-exposed animals was less susceptible to digestion with the methylation-sensitive enzyme HpaII compared with controls, suggesting that the DNA of the alcohol exposed pups was hypermethylated. Our results indicate that exposure to alcohol during early brain development in the rat, a period equivalent to the first two trimesters in humans, can have a detrimental effect on normal development of the olfactory bulb by reducing the number of BDNF-synthesizing neurons. Although the exact mechanism for the alcohol-induced neuronal loss is unknown, the inappropriate transcription of the BDNF gene is one mechanism that may account for the complexity of effects observed in offspring exposed to heavy alcohol exposure in utero.

Animals↗

PubMed1999

Postnatal ethanol exposure blunts upregulation of GABAA receptor currents in Purkinje neurons.

Recently, we found that early postnatal ethanol exposure inhibits the maturation of GABAA receptors (GABAARs) in developing medial septum/diagonal band (MS/DB) neurons, suggesting that these receptors may represent a target for ethanol related to fetal alcohol syndrome (FAS). To determine whether GABAARs on other neurons are also sensitive to a postnatal ethanol insult, postnatal day (PD) 4-9, rat pups were artificially reared and exposed to ethanol (4.5 g kg-1 day-1, 10.2% v/v). The pharmacological profile of acutely dissociated cerebellar Purkinje cell GABAARs from untreated, artificially reared controls and ethanol-treated animals was examined with conventional whole-cell patch clamp recordings during PD 12-16 (juveniles) and PD 25-35 (young adults). For untreated animals, GABA (0.3-100 microM) consistently induced inward Cl- currents in a concentration-dependent manner showing an age-related increase in maximum response without change in EC50 or slope value. Acute ethanol (100 mM) consistently inhibited 3 microM GABA currents (10-20%); positive modulators, pentobarbital (10 microM), midazolam (1 microM) and loreclezole (10 microM), consistently potentiated; the negative modulator, Zn2+ (30 microM), inhibited GABA currents across both juvenile and young adult groups. Loreclezole potentiation increased while Zn2+ inhibition decreased with age in untreated Purkinje neurons. Postnatal ethanol exposure (PD 4-9) decreased GABAAR maximum current density in young adult Purkinje cells but not in juvenile neurons. However, sensitivity to allosteric modulators did not change after ethanol. These data are consistent with the hypothesis that postnatal ethanol exposure during the brain growth spurt can disturb GABAAR development across the brain, although the mechanism(s) underlying this action remains to be determined.

Allosteric Regulation↗

PubMed1999

DNA fragmentation during exposure of rat cerebella to ethanol under hypoxia imposed in vitro.

To gain a better understanding into the mechanisms of damage incurred by neurons in periods following heavy alcohol exposure during development, we used an in vitro system to monitor the effects of alcohol and hypoxia on cell survival and DNA integrity. Samples representing the first few hours of exposure to alcohol and hypoxia were compared to those resulting from hypoxia alone. Measurements were taken from cell counts using Trypan blue exclusion and TUNEL assays as well as digital scans of the ethidium bromide fluorescence of genomic DNA isolated from the treated tissue. We found that DNA degradation from hypoxia was accelerated by several hours in the presence of 100 mM ethanol. This result depended on age, with adult animals (>8 months) having a similar response to 4-day postnatal animals, while the effect on 10-day postnatal animals and those of intermediate age (45 days postnatal) was increasingly delayed. Different methods of inducing the processive degradation of DNA produced laddering typical of apoptosis, a biphasic degradative process, or patterns usually associated with necrosis.

Age Factors↗

PubMed1999

Ethanol attenuates lactate production in hypoxic postnatal day 4 rat cerebella.

Ethanol consumption during pregnancy may lead to a low oxygen supply to the brain of the developing fetus. Such a reduction in the oxygen supply will result in changes in intra- and extracellular lactate production, which subsequently may lead to cytoplasmic acidosis, changes in cerebral metabolism, and eventually, cell death. We used a novel application of gas chromatography to measure lactate changes, on a global level, in the cerebellar tissue of postnatal day (PD) 4 and PD 10 rat pups following in vitro exposure of either hypoxia or hypoxia plus ethanol (hypoxia/ethanol). The results showed hypoxia-induced increases in lactate concentrations as a function of treatment time in both PD 4 and PD 10 cerebellar tissue. However, there was a differential response to the additional ethanol treatment between the two age groups assessed, with an attenuation of the time-dependent increase of lactate production following hypoxia treatment in PD 4 cerebellar tissue. The results also indicated that PD 4 cerebellar tissue had increased oxygen utilization when compared with PD 10 tissue exposed to the same conditions. The ethanol-induced reduction in lactate is hypothesized as being due to limitations in glucose transport and utilization under ethanol/hypoxia exposure. It is believed that such limitations in cellular function may initiate a sequence of events that produce at least some of the cerebellar neuronal loss reported in the fetal alcohol literature.

Age Factors↗

PubMed1999

Fetal alcohol exposure and temporal vulnerability: regional differences in cell loss as a function of the timing of binge-like alcohol exposure during brain development.

This study was conducted to determine the temporal and regional vulnerability of the brain as a function of exposure to alcohol during brain development. Our goal was to manipulate the timing of alcohol exposure and assess the relative risk of cell loss in two different brain regions. Groups of timed pregnant Sprague-Dawley rats received binge-like alcohol exposure during either the first 10 days (first-trimester equivalent) or second 10 days of gestation (second-trimester equivalent), or the combination of first- and second-trimester equivalents for prenatal treatments. Offspring from some of the animals exposed to alcohol during the combined first- and second-trimester equivalent were reared artificially from postnatal days (P) 4 through 9 (part of the third-trimester equivalent) and also received binge-like alcohol during this period, producing animals that were exposed to alcohol during all three trimesters equivalent. Offspring from untreated dams were also reared artificially and received alcohol from only P4-9, thus creating animals that were exposed to alcohol only during part of the third-trimester equivalent. All pups were perfused on P10. Appropriate controls (nutritional and normally reared) were matched to every alcohol treatment combination. Peak blood alcohol concentrations were not different among the treatment groups for a given sampling time. Total cell numbers in the cerebellum (Purkinje and granule cells) and the olfactory bulb (mitral and granule cells) were estimated by the unbiased stereological technique, the optical disector. In terms of temporal vulnerability, alcohol exposure during the equivalent of all three trimesters resulted in a greater reduction in cerebellar Purkinje cell numbers compared with exposure to alcohol during the third-trimester equivalent, whereas both groups had a significant reduction in cell number compared with all other timing groups. Cerebellar granule cell number was reduced after alcohol exposure during all three trimesters equivalent, compared with all other timing groups. Alcohol exposure during the third-trimester equivalent resulted in a decrement in the number of olfactory bulb mitral cell numbers compared with all other groups, but there were no differences among the timing groups in numbers of olfactory bulb granule cells. When the cell loss in the two regions was compared within each alcohol treatment group to determine the relative regional vulnerability, the primary salient finding was that cerebellar Purkinje cells were more vulnerable to alcohol-induced loss subsequent to exposure during all three trimesters equivalent. No other regional differences were detected. These results extend earlier findings by showing that alcohol exposure during different periods of brain development results in regional differences in cell loss as a function of the timing of alcohol exposure during brain development and illustrate the variability of alcohol-induced neuronal loss.

Alcohol Drinking↗

PubMed1999

Effects of alcohol and nicotine on developing olfactory bulb: loss of mitral cells and alterations in neurotransmitter levels.

Previous research from our laboratory has shown that [ethanol (EtOH)] exposure during the brain growth spurt is detrimental to olfactory bulb development. This study extends those findings by examining the effects of EtOH, nicotine (NIC), and the combination of these drugs (EtOH/NIC) on olfactory bulb mitral cell numbers, as well as on various major neurotransmitter levels in neonatal rats. An artificial rearing paradigm was used in the present studies. These artificially reared pups were given 4 g/kg/day of EtOH and/or 6 mg/kg/day of NIC on postnatal day (PD) 4 to PD 9, except in the case of the acute neurochemistry study, in which the pups received treatment on PD 9 only. An artificially reared gastrostomy control group (GC) and a suckle control group were included. The mean total numbers of mitral cells in the EtOH and NIC groups were significantly reduced from that of the GC, as well as the volume of the left main olfactory bulb. There was no difference among any of the groups in mitral cell density. As for neurochemistry data, there was no difference in neurotransmitter levels among any of the groups in the repeat exposure regimen. There were, however, changes after the acute exposure (exposure on PD 9 only). Both serotonin and GABA levels were significantly increased only after NIC exposure. However, norepinephrine levels were significantly decreased after acute exposure in all three drug treatment groups, compared with that of the control group. Except for the GC control group, dopamine levels were not detected consistently after acute exposure to EtOH, NIC, or EtOH/NIC. Collectively, these findings demonstrate that exposure to EtOH or NIC individually during the brain growth spurt results in developmental deficits in the olfactory bulb, suggesting that both EtOH and NIC are neuroteratogens. Furthermore, this study demonstrated the capability of NIC to antagonize (protect) EtOH-induced mitral cell loss in the developing olfactory bulb.

Animals↗

PubMed1999

Ethanol induces cell death and cell cycle delay in cultures of pheochromocytoma PC12 cells.

Animal models have clearly established that ethanol exposure can deplete neurons in the developing nervous system. However, the mechanism by which ethanol reduces cell number is unclear. In our study, cultures of pheochromocytoma cells, a neuronal-like cell line, were maintained in media, which supported cell proliferation. Although cell numbers continued to increase in the presence of ethanol, this increase was partially inhibited by ethanol exposure. This inhibitory effect was concentration and duration dependent. Cell proliferation was still partially inhibited after removal of ethanol, but this inhibition was temporary and disappeared after a 24-hr recovery period in ethanol-free conditions. Further study indicated that ethanol partially inhibited the increase in cell numbers by two mechanisms: (1) studies with vital stains indicated that ethanol induced cell death; (2) experiments using synchronized pheochromocytoma cell cultures showed that ethanol can induce cell cycle delay, thereby lengthening the doubling time of the cells. Analysis by flow cytometry indicated that with ethanol exposure, the cells accumulated in the G1 phase of the cell cycle. Our results suggest that in the developing nervous system, ethanol may limit the numbers of proliferating, neuronal precursor cells by two simultaneous mechanisms, cell death and cell cycle delay.

Animals↗

PubMed1999

Ethanol decreases Glial-Derived Neurotrophic Factor (GDNF) protein release but not mRNA expression and increases GDNF-stimulated Shc phosphorylation in the developing cerebellum.

BACKGROUND: Ethanol exposure during development leads to substantial neuronal loss in multiple regions of the brain. Although differentiating Purkinje cells of the cerebellum are particularly vulnerable to ethanol exposure, the mechanisms underlying ethanol-induced Purkinje cell loss have not been well defined. Our previous research indicated that exogenous Glial-Derived Neurotrophic Factor (GDNF) attenuated ethanol-induced Purkinje cell loss in cerebellar explant cultures, which suggests that ethanol, in turn, may decrease endogenous trophic factor-mediated survival mechanisms. METHODS: The present experiments used an explant culture model of the developing rat cerebellum to test the hypothesis that ethanol decreases endogenous trophic support by limiting the availability of trophic factors, such as GDNF, or by altering the activation of key adapter proteins such as Shc (Src homology domain carboxy-terminal) that couple GDNF binding to multiple intracellular signaling pathways. GDNF mRNA and protein levels were measured by reverse northern blot analysis and sandwich enzyme-linked immunosorbent assay respectively, whereas Shc phosphorylation was measured by immunoprecipitation/western immunoblot analysis. RESULTS: The developing cerebellum expresses both GDNF mRNA and protein in vitro. Ethanol exposure (68, 103, or 137 mM) had no effect on cerebellar levels of GDNF mRNA. However, ethanol (68 and 137 mM) decreased levels of GDNF protein released into culture medium. In addition, ethanol itself had no effect on She phosphorylation. However, in the presence of the highest dose of ethanol (137 mM) GDNF did stimulate Shc phosphorylation. CONCLUSIONS: Together, these results suggest that ethanol decreases GDNF-mediated trophic support of Purkinje cells in the developing cerebellum. However, GDNF in turn activates intracellular signaling pathways throughout the developing cerebellum as part of its Purkinje cell-selective neuroprotective response to ethanol exposure.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Development of GABAA receptors on medial septum/diagonal band (MS/DB) neurons after postnatal ethanol exposure.

The impact of 'binge-like' ethanol exposure on postnatal days (PD) 4-9 was examined on development of gamma-aminobutyric acid type A receptors (GABAAR) during the first month of life in the rat. Whole-cell patch-clamp recordings in acutely isolated medial septum/diagonal band (MS/DB) neurons were used to define effects of rapidly applied ethanol and other allosteric modulators on bicuculline-sensitive GABA currents. Three age groups were examined including 'pups' (PD 4-10), 'juveniles' (PD 11-16) and 'young adults' (PD 25-35). In untreated neurons, maximum responses to GABA and the apparent GABA EC50 increased approximately 2-fold during the first month of life. Potentiation of GABA responses by pentobarbital, midazolam, and loreclezole all increased with age, while Zn2+ inhibition declined. Initial inhibition by ethanol switched to potentiation of GABA responses during this time. In vivo, binge-like ethanol treatment (4.5 g kg-1 day-1 divided into two doses, 2 h apart on PD 4-9) reduced both the GABA maximal response and GABA EC50 measured on PD 11-16. These measures returned to control levels by PD 25-35. After binge-like postnatal ethanol exposure, age-dependent loss of Zn2+ inhibition of GABA responses was increased, while potentiating actions of in vitro ethanol were blocked. GABAAR modulation by other drugs was unaffected. These data suggest that early postnatal ethanol exposure disrupts the expected developmental pattern of GABAAR function in MS/DB neurons, an action that could contribute to neurobehavioral deficits associated with the fetal alcohol syndrome. Whether these changes are due to cellular damage, delayed gene expression or post-translational modification needs to be determined.

Algorithms↗

PubMed1998

Alcohol-induced Purkinje cell loss depends on developmental timing of alcohol exposure and correlates with motor performance.

Several reports indicate that neonatal ethanol exposure induces cerebellar Purkinje and granule cell loss if exposure occurs before postnatal day (PD) 7, and that cerebellar damage may underlie ethanol-induced motor deficits. The present study used an unbiased stereological method, the optical fractionator, to count total cerebellar Purkinje cell number in groups of Sprague-Dawley rats given binge-like ethanol exposure at different neonatal ages. Correlations between Purkinje cell number (of 55-day-old rats) and parallel bar motor performance (previously tested on PD 30-32) were also evaluated. One group was given binge-like exposure to 6.6 g/kg per day of ethanol via artificial rearing on PD 4 and 5 (PD 4/5); a second group on PD 8 and 9 (PD 8/9); and a third group on both PD 4 and 5 and 8 and 9 (Comb). Gastrostomy (CG) and suckle (SC) control groups were also included. Purkinje cells were significantly reduced in all three ethanol-treated groups compared to controls, but the severity of loss was significantly greater in the PD 4/5 and Comb groups (reduced by 42% and 45%, respectively, relative to GC) compared to the PD 8/9 group (reduced by 15%). Across treatment groups, the total cerebellar Purkinje cell number was significantly correlated with successful parallel bar traversal (r = +0.74), supporting the contention that ethanol-induced motor deficits may be associated with cerebellar cell loss. These data confirm the presence of windows of vulnerability of Purkinje cells to neurotoxic effects of binge ethanol treatment, and demonstrate that both the behavioral and neuroanatomical consequences of binge exposure depend on the developmental timing of the exposure.

Aging↗

PubMed1998

Neonatal alcohol and nicotine exposure limits brain growth and depletes cerebellar Purkinje cells.

The present study examined the effects of coexposure of alcohol and nicotine during the brain growth spurt period on brain weights and cerebellar Purkinje cell numbers. Sprague-Dawley rat pups were randomly assigned into five groups (four artificially reared groups and one suckle control). Artificially reared pups were given alcohol (0 or 4 g/kg/day) and/or nicotine (0 or 6 mg/kg/day) daily from postnatal days (PDs) 4 to 9, and the suckle controls received no experimental treatments. The results are summarized below. (1) Surprisingly, nicotine reduced the peak blood alcohol concentration from about 300 to 230 mg/dl, but alcohol did not affect urine cotinine levels (approximately 12,000-13,000 ng/ml). (2) Alcohol significantly reduced the weights of forebrain, cerebellum, and brain stem, but nicotine limited only the growth of the forebrain. (3) Purkinje cell numbers in the cerebellar vermis were significantly reduced in response to alcohol, nicotine, and the combination of both drugs. (4) No statistically significant interactive effect was found following the cotreatment of alcohol and nicotine. Collectively, the present study replicated our previous findings demonstrating alcohol's detrimental effects on brain development; it also presented new evidence documenting nicotine's neuroteratogenic effects on restricting brain growth and depleting cerebellar Purkinje cells during the brain growth spurt.

Animals↗

PubMed1998

The nitric oxide-cyclic GMP pathway plays an essential role in both promoting cell survival of cerebellar granule cells in culture and protecting the cells against ethanol neurotoxicity.

NMDA has two beneficial effects on primary neuronal cultures of cerebellar granule cells (CGCs) established from 10-day-old rat pups. First, NMDA is neurotrophic and will enhance survival of CGCs in culture in the absence of ethanol. Second, ethanol exposure will induce cell death in CGC cultures, and NMDA can lessen this ethanol-induced cell loss, i.e., NMDA is neuroprotective. Because NMDA can stimulate production of nitric oxide (NO), which can in turn enhance synthesis of cyclic GMP, this study tested the hypothesis that the NO-cyclic GMP pathway is essential for NMDA-mediated neurotrophism and neuroprotection. Inhibiting the synthesis of NO with N(G)-nitro-L-arginine methyl ester eliminated both the NMDA-mediated neurotrophic and neuroprotective effects. Similarly, inhibiting production of cyclic GMP with the agent LY83583 also abolished these effects. The NO generator 2,2'-(hydroxynitrosohydrazono) bisethanamine produced neurotrophic and neuroprotective effects that were similar to those induced by NMDA. Also, 8-bromo-cyclic GMP produced neurotrophic and neuroprotective effects that were quite similar to the effects produced by NMDA. In conclusion, NMDA enhances survival of cerebellar granule cells and protects the cells against ethanol-induced cell death by a mechanism(s) that involves the NO-cyclic GMP pathway.

Aminoquinolines↗

PubMed1998

Fetal alcohol syndrome: a review for Texas physicians.

Fetal alcohol syndrome (FAS) is commonly believed to be the leading known cause of mental retardation in the United States, although surveillance at state and national levels is problematic. The most serious consequence of fetal alcohol exposure is central nervous system (CNS) dysfunction. While the facial features of FAS become more subtle with age, growth deficits and, particularly, the CNS impairment appear to be permanent. Among factors that affect the risk and severity of fetal alcohol damage are the timing of the alcohol exposure, binge drinking that produces high blood alcohol concentrations, polydrug use, and genetic variations. From various studies, the incidence of FAS ranges from 0.2 to 3.0 affected birth per 1000 live births. The methods of measuring FAS occurrence are fraught with difficulties and inaccuracies, as are surveys of alcohol use by women during pregnancy. Still, indirect studies both in Texas and the United States suggest that the occurrence of FAS is increasing. A first, important step to reducing the incidence of FAS and related problems is to increase the awareness of physicians and other health care providers about the issues of FAS diagnosis, prevention, and treatment. Referral and information resources about FAS are provided.

Adult↗

PubMed1998

Electrophysiological characterization of cerebellar neurons from adult rats exposed to ethanol during development.

The purpose of this study was to investigate the spontaneous activity of mature rat cerebellar neurons that had been exposed to ethanol (EtOH) during postnatal days 4 to 10, which corresponds to the third trimester in humans. Newborn Sprague-Dawley rats were implanted with gastric feeding tubes and were artificially reared from postnatal days 4 to 10 with two different diets. The experimental group received 4.5 g/kg/day of EtOH delivered in a milk solution. Controls received similar feeding with an isocaloric supplement replacing the EtOH. Electrophysiological evaluations were performed after an EtOH-free rearing period. Although lobules IX and X of the cerebellar vermis appeared morphologically smaller in the animals neonatally exposed to EtOH, compared with controls, extracellular recordings from both Purkinje cells and Golgi interneurons in adult rats showed no differences in spontaneous activity or firing pattern between the control and EtOH-exposed animals. Similarly, excitations and inhibitions of Purkinje neuron activity evoked by parallel pathway stimulation appeared unaffected by the developmental EtOH exposure. However, we did observe a significant decrease in the proportion of Purkinje neurons generating complex spike bursts in the group exposed to EtOH neonatally. These data suggest that, although fewer Purkinje neurons may survive the brain growth spurt if exposed to EtOH during this critical period of development, those that do survive appear to function normally. The observed abnormality in complex spike production may result from EtOH effects on developing neurons in the inferior olive that give rise to the climbing fibers that cause this bursting pattern in Purkinje neurons.

Animals↗

PubMed1997

Glial-derived neurotrophic factor rescues calbindin-D28k-immunoreactive neurons in alcohol-treated cerebellar explant cultures.

Ethanol exposure during development leads to alterations in neuronal differentiation and profound neuronal loss in multiple regions of the developing brain. Although differentiating Purkinje cells of the cerebellum are particularly vulnerable to ethanol exposure, the mechanisms that ameliorate ethanol-induced Purkinje cell loss have not been well defined. Previous research indicates that glial-derived neurotrophic factor (GDNF), a member of the transforming growth factor-beta family, promotes the survival of several neuronal populations, including cerebellar Purkinje cells. Therefore, we examined whether GDNF could attenuate ethanol-induced Purkinje cell loss in an in vitro model system using calbindin-D28k immunoreactivity as a specific marker for Purkinje cells. We found that ethanol led to a significant dose-related decline in calbindin-D28k-immunoreactive cells in explant cultures of the developing cerebellum. However, concurrent administration of GDNF led to a significant rescue of calbindin-D28k-immunoreactive cells. Therefore, our results suggest that GDNF prevents ethanol-associated Purkinje cell loss.

Animals↗

PubMed1997

Cocaethylene exposure during the brain growth spurt period: brain growth restrictions and neurochemistry studies.

The concurrent use of alcohol and cocaine has recently attracted attention in the medical research field due to the prevalence of this drug abuse pattern and the exclusive formation of a pharmacologically active substance, cocaethylene (CE). This is the first study to examine the neuroteratogenic effects of cocaethylene exposure during the brain growth spurt (part of the third trimester equivalent) on brain growth restrictions and neurochemical profiles. For the brain growth restrictions study, three groups of artificially reared rat pups were given daily injections of 0, 10 or 20 mg/kg cocaethylene (s.c.) from postnatal days (PDs) 4 through 9. One group of normally reared pups (suckle control) also was used. These pups were perfused on PD 10 and the brains were removed and weighed (forebrain, cerebellum and brainstem). For the neurochemistry study, five groups of artificially reared pups were used and were treated identically to those in the brain growth restrictions study, with the exceptions that animals assigned to acute cocaethylene treatment groups did not receive cocaethylene from PDs 4 through 8 and all animals in this study were sacrificed on PD 9 by decapitation. One suckle control group was included to control the possible artificial rearing effects on the neurochemical measures. Blood and fresh brain tissues (cortex, subcortical structures, cerebellum and brainstem) were collected for blood cocaethylene concentration and neurochemical analyses using GC/MS and HPLC techniques, respectively. The statistical analyses indicated that daily administration of 10 or 20 mg/kg cocaethylene, but not 0 mg/kg cocaethylene, significantly restricted the brain growth (brain weights) in all three brain regions assessed. Furthermore, cocaethylene administration from PDs 4 through 9 produced region-specific alterations in various neurotransmitter concentrations. The changes in neurotransmitter levels were not a function of the responses to the last cocaethylene injection on PD 9, since the outcomes between six days of cocaethylene treatment (PDs 4 to 9) and one day acute treatment (PD 9) were notably different. Furthermore, the artificial rearing procedure appeared to produce significant alterations in various neurotransmitter levels when compared with normally reared (suckle) controls. Collectively, these results suggest that cocaethylene is neuroteratogenic to the developing brain during the third trimester equivalent and the unique formation of cocaethylene resulting from the concurrent use of alcohol and cocaine may represent an increased risk to the developing brain beyond the intrinsic neuroteratogenic effects of cocaine and alcohol individually.

Animals↗