Sources of reactive oxygen species (ROS) generation have been compared in microsomal and mitochon... more Sources of reactive oxygen species (ROS) generation have been compared in microsomal and mitochondrial fractions of brain and liver from ethanol-treated and control rats. Rates of ROS generation were quantitated with the fluorescent probe precursor, 2'7'-dihydrochloroflurescin diacetate, whose validity has been previously established. The production of active pro-oxidant species was measured in the presence of various selective inhibitors of enzymes potentially able to contribute to oxidative events. Several steps in the arachidonic acid cascade appeared to constitute a large fraction of total ROS generating capacity. Chelation of intrinsic iron with desferoxamine greatly reduced such capacity, especially in cerebral tissue. Aldehyde oxidases were active in generating ROS in both tissues. Inhibition of catalase dramatically enhanced ROS in liver but not in brain microsomes. While no ethanol-treatment effects were found in brain, there was evidence that ethanol consumption decreased hepatic levels of catalase, aldehyde oxidases and cyclooxygenase. However, despite these reductions, total basal ROS production was elevated in liver but not brain fractions from treated animals. The addition of an exogenous iron salt enhanced ROS formation to a lesser extent in ethanol-consuming rats than in controls. The elevation of basal hepatic ROS levels in ethanol-treated rats may thus be compatible with the release of cytosolic low molecular weight free iron compounds into the cytosol.
The actions of ethanol on membrane fluidity were examined. All assays were carried out using fluo... more The actions of ethanol on membrane fluidity were examined. All assays were carried out using fluorescence techniques in the P2 fraction of crude synaptosomes isolated from rat brain. Subchronic treatment of rats with ethanol revealed a significant increase in order at the membrane interior. In vitro addition of ethanol to P2 fractions prepared from treated rats revealed a significant rise in fluidity at the membrane core that was not found in corresponding P2 fractions from untreated rats. The withdrawal of ethanol from subchronically treated rats revealed no significant alterations in membrane fluidity. However, in vitro addition of ethanol to P2 fractions prepared from these animals produced an increase in fluidity at the membrane centre. This effect was not observed in corresponding control rats. Rat pups that were gestationally exposed to ethanol also failed to show any significant differences in membrane fluidity compared with control rats. However, in vitro addition of a challenge dose of ethanol to P2 fractions resulted in a significant rise in fluidity not found in pups from untreated mothers. These findings suggest that the process of adaptation to chronic ethanol may be dissected into two separable events: one frequently reported effect that alters membrane fluidity and one that modulates membrane susceptibility to ethanol-induced perturbations.
Phencyclidine is a widely used drug of abuse and is known to produce a wide variety of psychoacti... more Phencyclidine is a widely used drug of abuse and is known to produce a wide variety of psychoactive effects. PCP abuse by pregnant women has been reported to result in the birth of infants exhibiting irritability, jitteriness and hyperactivity with high pitched cries. The present study was designed to evaluate the distribution of PCP in the maternal and fetal brain and the neurochemical effects produced by gestational exposure. Pregnant Sprague-Dawley rats were treated sc with 5 mg/kg PCP on 3 consecutive days (GD 9-11, 12-14, 15-16, or 18-20). On gestational day (GD) 21 all rats were killed by decapitation and maternal and fetal blood was collected for PCP analysis. Brains were dissected from dams and fetuses for PCP and neurochemical analyses. On GD 21 after exposure on GD 18-20, the fetal: maternal ratio of brain PCP concentrations was 11:1. PCP exposure on GD 12-14, 15-17, and 18-20 significantly decreased fetal brain PCP binding sites on GD 21, whereas maternal values were unch...
Levels of ornithine decarboxylase activity were measured in brain regions and in adrenal glands o... more Levels of ornithine decarboxylase activity were measured in brain regions and in adrenal glands of adult male rats exposed to electroshock. Five hours after shock at levels causing transient loss of consciousness and fore and hindlimb tonic extensor seizures, major increases in ornithine decarboxylase activity were found in adrenals, hippocampus, brain stem, frontal cortex, and cerebellum, but striatal levels were unchanged. These increases were reversed by 24 h after electroshock. When lower levels of shock, which caused no loss of consciousness, were also used, a clear dose-response relationship of shock intensity and ornithine decarboxylase activity was found for hippocampus and brain stem. The ornithine decarboxylase response in brain increased with higher shock levels. However, the changes of ornithine decarboxylase in adrenal glands were maximal at intermediate, and diminished at maximal shock values, as were levels of circulating testosterone. These data suggest a differing role for cerebral and adrenal ornithine decarboxylase in the mature rat. The brain enzyme may be primarily related to metabolic repair processes, whereas adrenal ornithine decarboxylase may function in the activation of secretion.
Aluminum is highly oxophilic and its minerals are usually found surrounded by six oxygen atoms. A... more Aluminum is highly oxophilic and its minerals are usually found surrounded by six oxygen atoms. A role for the metal has been established in dialysis encephalopathy and Al-induced osteomalacia. The metal has been implicated in Alzheimer's disease but the issue is at present controversial. Human cell lines of neural origin were utilized to study the effect of lipophilic aluminum acetylacetonate and non-lipophilic aluminum sulfate on cell proliferation and viability. Although analysis of Al species in the cell culture media demonstrated that there are positively charged Al species present in solutions prepared with both Al salts, only the aluminum acetylacetonate salt caused changes in cell proliferation and viability. Therefore, the lipophilic nature of the organic Al salt is a critical determinant of toxicity. The effect of aluminum acetylacetonate was dose-dependent and time-dependent. Neuroblastoma (SK-N-SH) cells were more susceptible to decreased cell proliferation although the lipophilic Al salt was more toxic to the glioblastoma (T98G) cells. While the toxicity of aluminum acetylacetonate was inhibited in the T98G cells by the addition of phosphate, the same treatment did not reverse cell death in the SK-N-SH cells. Thus, the mechanism of Al toxicity appears to be different in the two cell lines. It is possible that the principal neurotoxic target of the metal is glial and when these cells are in a compromised state, this may secondarily impact the neuronal population and thus eventually lead to neurodegeneration.
Sources of reactive oxygen species (ROS) generation have been compared in microsomal and mitochon... more Sources of reactive oxygen species (ROS) generation have been compared in microsomal and mitochondrial fractions of brain and liver from ethanol-treated and control rats. Rates of ROS generation were quantitated with the fluorescent probe precursor, 2'7'-dihydrochloroflurescin diacetate, whose validity has been previously established. The production of active pro-oxidant species was measured in the presence of various selective inhibitors of enzymes potentially able to contribute to oxidative events. Several steps in the arachidonic acid cascade appeared to constitute a large fraction of total ROS generating capacity. Chelation of intrinsic iron with desferoxamine greatly reduced such capacity, especially in cerebral tissue. Aldehyde oxidases were active in generating ROS in both tissues. Inhibition of catalase dramatically enhanced ROS in liver but not in brain microsomes. While no ethanol-treatment effects were found in brain, there was evidence that ethanol consumption decreased hepatic levels of catalase, aldehyde oxidases and cyclooxygenase. However, despite these reductions, total basal ROS production was elevated in liver but not brain fractions from treated animals. The addition of an exogenous iron salt enhanced ROS formation to a lesser extent in ethanol-consuming rats than in controls. The elevation of basal hepatic ROS levels in ethanol-treated rats may thus be compatible with the release of cytosolic low molecular weight free iron compounds into the cytosol.
The actions of ethanol on membrane fluidity were examined. All assays were carried out using fluo... more The actions of ethanol on membrane fluidity were examined. All assays were carried out using fluorescence techniques in the P2 fraction of crude synaptosomes isolated from rat brain. Subchronic treatment of rats with ethanol revealed a significant increase in order at the membrane interior. In vitro addition of ethanol to P2 fractions prepared from treated rats revealed a significant rise in fluidity at the membrane core that was not found in corresponding P2 fractions from untreated rats. The withdrawal of ethanol from subchronically treated rats revealed no significant alterations in membrane fluidity. However, in vitro addition of ethanol to P2 fractions prepared from these animals produced an increase in fluidity at the membrane centre. This effect was not observed in corresponding control rats. Rat pups that were gestationally exposed to ethanol also failed to show any significant differences in membrane fluidity compared with control rats. However, in vitro addition of a challenge dose of ethanol to P2 fractions resulted in a significant rise in fluidity not found in pups from untreated mothers. These findings suggest that the process of adaptation to chronic ethanol may be dissected into two separable events: one frequently reported effect that alters membrane fluidity and one that modulates membrane susceptibility to ethanol-induced perturbations.
Phencyclidine is a widely used drug of abuse and is known to produce a wide variety of psychoacti... more Phencyclidine is a widely used drug of abuse and is known to produce a wide variety of psychoactive effects. PCP abuse by pregnant women has been reported to result in the birth of infants exhibiting irritability, jitteriness and hyperactivity with high pitched cries. The present study was designed to evaluate the distribution of PCP in the maternal and fetal brain and the neurochemical effects produced by gestational exposure. Pregnant Sprague-Dawley rats were treated sc with 5 mg/kg PCP on 3 consecutive days (GD 9-11, 12-14, 15-16, or 18-20). On gestational day (GD) 21 all rats were killed by decapitation and maternal and fetal blood was collected for PCP analysis. Brains were dissected from dams and fetuses for PCP and neurochemical analyses. On GD 21 after exposure on GD 18-20, the fetal: maternal ratio of brain PCP concentrations was 11:1. PCP exposure on GD 12-14, 15-17, and 18-20 significantly decreased fetal brain PCP binding sites on GD 21, whereas maternal values were unch...
Levels of ornithine decarboxylase activity were measured in brain regions and in adrenal glands o... more Levels of ornithine decarboxylase activity were measured in brain regions and in adrenal glands of adult male rats exposed to electroshock. Five hours after shock at levels causing transient loss of consciousness and fore and hindlimb tonic extensor seizures, major increases in ornithine decarboxylase activity were found in adrenals, hippocampus, brain stem, frontal cortex, and cerebellum, but striatal levels were unchanged. These increases were reversed by 24 h after electroshock. When lower levels of shock, which caused no loss of consciousness, were also used, a clear dose-response relationship of shock intensity and ornithine decarboxylase activity was found for hippocampus and brain stem. The ornithine decarboxylase response in brain increased with higher shock levels. However, the changes of ornithine decarboxylase in adrenal glands were maximal at intermediate, and diminished at maximal shock values, as were levels of circulating testosterone. These data suggest a differing role for cerebral and adrenal ornithine decarboxylase in the mature rat. The brain enzyme may be primarily related to metabolic repair processes, whereas adrenal ornithine decarboxylase may function in the activation of secretion.
Aluminum is highly oxophilic and its minerals are usually found surrounded by six oxygen atoms. A... more Aluminum is highly oxophilic and its minerals are usually found surrounded by six oxygen atoms. A role for the metal has been established in dialysis encephalopathy and Al-induced osteomalacia. The metal has been implicated in Alzheimer's disease but the issue is at present controversial. Human cell lines of neural origin were utilized to study the effect of lipophilic aluminum acetylacetonate and non-lipophilic aluminum sulfate on cell proliferation and viability. Although analysis of Al species in the cell culture media demonstrated that there are positively charged Al species present in solutions prepared with both Al salts, only the aluminum acetylacetonate salt caused changes in cell proliferation and viability. Therefore, the lipophilic nature of the organic Al salt is a critical determinant of toxicity. The effect of aluminum acetylacetonate was dose-dependent and time-dependent. Neuroblastoma (SK-N-SH) cells were more susceptible to decreased cell proliferation although the lipophilic Al salt was more toxic to the glioblastoma (T98G) cells. While the toxicity of aluminum acetylacetonate was inhibited in the T98G cells by the addition of phosphate, the same treatment did not reverse cell death in the SK-N-SH cells. Thus, the mechanism of Al toxicity appears to be different in the two cell lines. It is possible that the principal neurotoxic target of the metal is glial and when these cells are in a compromised state, this may secondarily impact the neuronal population and thus eventually lead to neurodegeneration.
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Papers by Stephen C Bondy