Differential effects of ethanol on bid, tBid, and Bax:tBid interactions in postnatal day 4 and postnatal day 7 rat cerebellum.

Background: Exposure to ethanol (EtOH) during central nervous system (CNS) development can lead to a wide array of neuroanatomical, behavioral, and cognitive abnormalities, broadly subsumed under the fetal alcohol spectrum disorder classification. One mode of EtOH-induced interference in the normal developmental program appears to be through induction of apoptotic processes mediated by the Bcl-2 family of survival-regulatory proteins. The present series of studies investigated the role of the Bcl-2-related, pro-apoptotic Bid protein, and its truncated, apoptotically active fragment, tBid, in developmental EtOH neurotoxicity.

Ethanol influences on Bax associations with mitochondrial membrane proteins in neonatal rat cerebellum.

These studies investigated interactions taking place at the mitochondrial membrane in neonatal rat cerebellum following ethanol exposure and focused on interactions between proapoptotic Bax and proteins of the permeability transition pore (PTP), voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT) of the outer and inner mitochondrial membranes, respectively. Cultured cerebellar granule cells were used to assess the role of these interactions in ethanol neurotoxicity. Analyses were made at the age of maximal cerebellar ethanol vulnerability (P4), compared to the later age of relative resistance (P7), to determine whether differential ethanol sensitivity was mirrored by differences in these molecular interactions.

Differential effects of ethanol on c-jun N-terminal kinase, 14-3-3 proteins, and Bax in postnatal day 4 and postnatal day 7 rat cerebellum.

These studies investigated ethanol effects on upstream cellular elements and interactions which contribute to Bax-related apoptosis in neonatal rat cerebellum at ages of peak ethanol sensitivity (postnatal day 4 [P4]), compared to later ages of relative resistance (P7). Analyses were made of basal levels of the pro-apoptotic c-jun N-terminal kinase (JNK), Bax, and the 14-3-3 anchoring proteins, as well as the responsiveness of these substances to ethanol at P4 versus P7. Dimerization of Bax with 14-3-3 was also investigated at the two ages following ethanol treatment, a process which sequesters Bax in the cytosol, thus inhibiting its mitochondrial translocation and disruption of the mitochondrial membrane potential.

Ethanol influences on Bax translocation, mitochondrial membrane potential, and reactive oxygen species generation are modulated by vitamin E and brain-derived neurotrophic factor.

Background: This study investigated ethanol influences on intracellular events that predispose developing neurons toward apoptosis and the capacity of the antioxidant α-tocopherol (vitamin E) and the neurotrophin brain-derived neurotrophic factor (BDNF) to modulate these effects. Assessments were made of the following: (i) ethanol-induced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane, a key upstream event in the initiation of apoptotic cell death; (ii) disruption of the mitochondrial membrane potential (MMP) as a result of ethanol exposure, an important process in triggering the apoptotic cascade; and (iii) generation of damaging reactive oxygen species (ROS) as a function of ethanol exposure.

Methods: These interactions were investigated in cultured postnatal day 8 neonatal rat cerebellar granule cells, a population vulnerable to developmental ethanol exposure in vivo and in vitro.

Effects of acute ethanol exposure on regulatory mechanisms of Bcl-2-associated apoptosis promoter, bad, in neonatal rat cerebellum: differential effects during vulnerable and resistant developmental periods.

Background: Prenatal alcohol exposure produces anatomical and behavioral abnormalities associated with fetal alcohol syndrome (FAS). Animal FAS models have demonstrated temporal windows of vulnerability in the developing cerebellum, with substantial ethanol (EtOH)-mediated apoptotic activation during these periods. In rodents, the cerebellum is most sensitive to EtOH on postnatal days 4 to 6 (P4 to P6).

Effect of bax deletion on ethanol sensitivity in the neonatal rat cerebellum.

The developing cerebellum is highly sensitive to ethanol during discrete neonatal periods. This sensitivity has been linked to ethanol-induced alterations in molecules of the Bcl-2 survival-regulatory gene family. Ethanol exposure during peak periods of cerebellar sensitivity, for example, results in increased expression of proapoptotic proteins of this family, while overexpression of the antiapoptotic Bcl-2 protein in the nervous system protects against ethanol neurotoxicity.

Functional mechanisms of apoptosis-related proteins in neonatal rat cerebellum are differentially influenced by ethanol at postnatal days 4 and 7.

Exposure of the developing nervous system to ethanol (EtOH) produces neurological aberrations associated with fetal alcohol syndrome. During a well-defined period, cerebellar neurons are highly susceptible to EtOH-induced death, primarily through apoptosis. Neonatal rodent cerebellum is exquisitely sensitive to EtOH on postnatal days 4-6 (P4-6); however, at slightly later developmental ages (P7 and later), EtOH effects are minimal.

Mitochondrially targeted vitamin E and vitamin E mitigate ethanol-mediated effects on cerebellar granule cell antioxidant defense systems.

Ethanol (EtOH) disrupts the structure and function of the developing nervous system, sometimes leading to birth defects associated with fetal alcohol syndrome (FAS). Animal FAS models indicate that cellular membrane peroxidation, intracellular oxidant accumulation, and suppression of endogenous antioxidant enzymes contribute to the toxic effects of EtOH. Mitochondrially targeted vitamin E (MitoVit E), a chemically engineered form of vitamin E (VE) designed to accumulate in the mitochondria, has been shown to inhibit intracellular oxidant accumulation and cell death more effectively than VE.

Ethanol-induced reduction of neurotrophin secretion in neonatal rat cerebellar granule cells is mitigated by vitamin E.

Ethanol exposure during nervous system development produces a range of abnormalities, and in humans may lead to the fetal alcohol syndrome. Among the mechanisms hypothesized to play roles in ethanol neurotoxicity are altered expression of supportive neurotrophic factors (NTFs), and cellular disturbances in oxidative processes. In this study, ethanol effects on secretion of two NTFs, brain-derived neurotrophic factor, and neurotrophin-3 were analyzed in neonatal rat cerebellar granule cells, and the potential of the antioxidant vitamin E to modulate ethanol effects was investigated.

Protective mechanisms of pycnogenol in ethanol-insulted cerebellar granule cells.

Pycnogenol (PYC), a patented combination of bioflavonoids extracted from the bark of French maritime pine (Pinus maritima), inhibits apoptosis and necrosis of developing neurons exposed acutely to ethanol (EtOH). The present study shows that the protective mechanisms of PYC in EtOH-exposed postnatal day 9 cerebellar granule cells (P9 CGCs) include (1) reduction of reactive oxygen species (ROS) production; (2) counteraction of suppressed copper/zinc superoxide dismutase (Cu/Zn SOD) and glutathione peroxidase/reductase (GSH-Px/GSSG-R) system activities; (3) upregulation of Cu/Zn SOD protein expression; (4) mitigation of the EtOH-mediated exacerbation of catalase (CAT) activity; and, (5) specific binding and inhibition of active caspase-3. These results indicate that the mechanisms by which PYC antagonizes EtOH-induced oxidative stress include oxidant scavenging and modulation of endogenous, cellular proteins.

Vitamin E amelioration of ethanol neurotoxicity involves modulation of apoptotis-related protein levels in neonatal rat cerebellar granule cells.

Developmental ethanol exposure leads to a variety of abnormalities in the central nervous system (CNS). Mechanisms proposed as underlying these effects include alterations of protective antioxidant support, increased generation of harmful free radicals, and altered expression of apoptosis-related proteins. In prior studies, exogenous antioxidant application has been found to reduce ethanol neurotoxicity, but the mechanisms by which this protection is afforded have not been defined.

Pycnogenol and vitamin E inhibit ethanol-induced apoptosis in rat cerebellar granule cells.

Pycnogenol (PYC), a patented combination of bioflavonoids extracted from the bark of French maritime pine (Pinus maritima), scavenges free radicals and promotes cellular health. The protective capacity of PYC against ethanol toxicity of neurons has not previously been explored. The present study demonstrates that in postnatal day 9 (P9) rat cerebellar granule cells the antioxidants vitamin E (VE) and PYC (1) dose dependently block cell death following 400, 800, and 1600 mg/dL ethanol exposure (2) inhibit the ethanol-induced activation of caspase-3 in the same model system; and (3) reduce neuronal membrane disruption as assayed by phosphatidylserine translocation to the cell surface.

Ethanol effects on neonatal rat cortex: comparative analyses of neurotrophic factors, apoptosis-related proteins, and oxidative processes during vulnerable and resistant periods.

The developing central nervous system (CNS) is highly susceptible to ethanol, with acute or chronic exposure producing an array of anomalies and cell loss. Certain periods of vulnerability have been defined for various CNS regions, and are often followed by periods of relative ethanol resistance. In the present study, neonatal rats were acutely exposed to ethanol during a time when peak cell death is found in developing cerebral cortex (postnatal day 7; P7), and during a later neonatal period of ethanol resistance (P21).

Nerve growth factor and chronic ethanol treatment alter calcium homeostasis in developing rat septal neurons.

Chronic ethanol treatment (CET) during development produces cellular adaptations resulting in tolerance to the acute effects of ethanol (EtOH). The objectives of this study were to determine whether CET during the prenatal period (PCET) followed by a period of in vitro CET (PCET-CET) altered intracellular calcium [Ca(2+)](i) and produced tolerance to acute EtOH treatment (AET), and whether nerve growth factor (NGF) modulated the effects of PCET-CET in cultured developing rat septal neurons. Fetuses were obtained from EtOH-fed and sucrose-fed (diet-control) female rats.

The role of neurotrophic factors, apoptosis-related proteins, and endogenous antioxidants in the differential temporal vulnerability of neonatal cerebellum to ethanol.

Background: Ethanol produces abnormalities in the developing nervous system, with certain regions being vulnerable during well-defined periods. Neonatal rodent cerebellum is particularly susceptible to ethanol during the early postnatal period [on postnatal days 4-5 (P4-5)], while this region is resistant to ethanol at a slightly later time (P7-9). We assessed basal levels of several substances which may be involved in differential temporal ethanol vulnerability in neonatal cerebellum, and analyzed alterations in these substances after early ethanol exposure.

Effects of ethanol on neurotrophic factors, apoptosis-related proteins, endogenous antioxidants, and reactive oxygen species in neonatal striatum: relationship to periods of vulnerability.

The developing central nervous system is extremely sensitive to ethanol, with well-defined temporal periods of vulnerability. Many brain regions are particularly susceptible to ethanol during the early neonatal period, corresponding to the human third trimester, which represents a dynamic period of growth and differentiation. For this study, neonatal rats were acutely exposed to ethanol or control conditions at a neonatal age when the developing striatum has been shown to be vulnerable to ethanol (postnatal day 3 [P3]), and at a later age (P14), when this developing region is relatively ethanol-resistant.

Ethanol-mediated generation of reactive oxygen species in developing rat cerebellum.

The neonatal cerebellum undergoes an early period of ethanol sensitivity in which profound neuronal loss is seen following acute exposure, while slightly later exposure produces no such loss. This study was designed to determine whether this differential susceptibility is related to differences in ethanol-induced generation of reactive oxygen species (ROS). We found that ethanol treatment on postnatal day 4 (P4), the peak period of cerebellar vulnerability, resulted in ROS increases, but slightly later exposure (on P7) produced no immediate changes in ROS, but reductions were seen at 12 and 24 h following exposure.

Influence of ethanol on neonatal cerebellum of BDNF gene-deleted animals: analyses of effects on Purkinje cells, apoptosis-related proteins, and endogenous antioxidants.

The sensitivity of the developing central nervous system (CNS) to the deleterious effects of ethanol has been well documented, with exposure leading to a wide array of CNS abnormalities. Certain CNS regions are susceptible to ethanol during well-defined critical periods. In the neonatal rodent cerebellum, a profound loss of Purkinje cells is found when ethanol is administered early in the postnatal period [on postnatal days 4 or 5 (P4-5)], while this neuronal population is much less vulnerable to similar ethanol insult slightly later in the postnatal period (P7-9).