Hepatotoxicity of maternal ethanol consumption in rat offspring: an assessment with a study of the ontogenetic development of ethanol-oxidizing systems.

The effect of chronic maternal ethanol ingestion on the ontogenetic development of rat hepatic ethanol-oxidizing systems was investigated. Alcohol dehydrogenase (ADH) activity was first detected at day 19 of gestation. It then increased rapidly to reach adult levels by day 14 postnatally. The ontogenetic pattern, the specific activity and the affinity of the enzyme for its substrate or cofactor were not affected by chronic maternal ethanol consumption. Hepatic microsomal cytochrome P-450 content was first detected in trace amounts just prior to birth. It then increased rapidly in the first 10 days postnatally. Chronic maternal ethanol ingestion did not affect the developmental pattern but induced an increase in the total amount of P-450 detected throughout the postnatal period studied. Fat accumulation was found in fetal and postnatal livers and appeared to correlate with the emerging ability to oxidize ethanol by fetal ADH. The late appearance of the ADH and microsomal ethanol-oxidizing systems indicates that the fetal liver would be entirely dependent on maternal mechanisms to oxidize in-utero ethanol.

Adaptive changes in rat liver plasma membranes after chronic alcohol administration and its subsequent withdrawal.

Rat hepatic plasma membranes isolated after chronic alcohol feeding displayed a different buoyant density range with a significantly increased peak density value when spun isopycnically in a 30-50% sucrose (w/w) gradient. This change persisted up to 48 h of withdrawal from alcohol. Analysis of membrane lipids revealed certain significant alterations in the phospholipids as well as the fatty acyl composition in individual phospholipids of the experimental plasma membranes. During withdrawal of alcohol for 48 h, all the alcohol-induced changes in the phospholipids returned to normal. Most initial changes in fatty acids reverted to the control composition during this time, but new changes in fatty acyl distribution were also observed. These were interpreted to represent readaptation to the withdrawal of the alcohol. It is not established how long this readaptation period lasts.

Chronic maternal ethanol administration in the rat decreases the stimulation by (-) epinephrine of glycogen phosphorylase a in the livers of the progeny during development.

Previous results from this laboratory have shown that the progeny of alcoholic rats have diminished alpha 1-adrenergic receptors in the hepatic plasma membranes. Since these receptors mediate epinephrine action on glycogen metabolism, it was decided to determine whether this change might affect the activation of glycogen phosphorylase a in the livers of the alcoholic progeny. Pregnant female rats were divided into two groups of which one received a Metrecal-ethanol liquid diet throughout pregnancy and lactation. The pair-fed control group received a liquid sucrose-Metrecal diet over the same period. Phosphorylase a activity was determined in liver slices from the progeny during postnatal development. The basal hepatic phosphorylase a activity was identical between the control and experimental groups at 5, 15 and 25 days of age. Both epinephrine and phenylephrine were superior enzyme activators than was isoproterenol. Stimulation with epinephrine (10 microM) demonstrated a significantly diminished capacity of the enzyme in the alcoholic liver to be activated by the hormone. In every instance, the livers from 5, 15 and 25 day old pups from alcoholic mothers displayed diminished epinephrine-stimulated phosphorylase a activity of about 30%, compared with the controls.

Effect of maternal ethanol ingestion during pregnancy and lactation on the structure and function of the postnatal rat liver plasma membrane. Assessement with [3H]prazosin binding to the hepatic alpha 1-adrenergic receptors.

A liquid low-fat nutritionally adequate Metrecal diet in which alcohol contributed 37% of the total calories was given to pregnant rats and maintained during lactation. Control rats were pairfed with an isocaloric sucrose-Metrecal diet. After birth, litters were killed at different ages (days 1-30), and the results showed that growth and survival of progeny from the alcohol-treated rats were adversely affected. Likewise, the wet weights of livers from such pups were consistently less than from the pair-fed controls. The yield of hepatic plasma membrane protein per wet liver weight was constant and independent of either age or diet. Using [3H]prazosin as radioligand, equilibrium binding studies were carried out to monitor changes in the structure and function of the plasma membrane in the new-born pups concomitant with the development of alpha 1-adrenergic receptors. Results obtained with the alcohol-fed pups showed that the binding affinity (KD) was not altered throughout. However, the receptor density (Bmax) was decreased significantly. This decrease ranged from 60 to 70% in pups 6- to 15-days-old; 45% at 20 days; and 30% in pups at 25 and 30 days of age. These observations suggest that maternal ethanol ingestion affected the postnatal development of rat liver plasma membranes. Furthermore, by using the hepatic alpha 1-adrenergic receptor as a metabolic probe, we deduce that a possible impairment exists in the capacity of the alcoholic progeny to respond to the hormonal action of epinephrine. Such a defect may contribute to impaired growth and metabolism in these young animals.

Adaptive changes in lipid composition of rat liver plasma membrane during postnatal development following maternal ethanol ingestion.

The fatty acid composition of constituent phospholipids and the cholesterol content of rat liver plasma membranes were determined subsequent to maternal alcohol ingestion during pregnancy and lactation. The alcoholic group was given a liquid Metrecal diet containing 37% ethanol-derived calories. The control group was pair-fed an isocaloric sucrose/Metrecal diet. Litters were killed for lipid analyses at days 5, 15 and 25 after birth. These studies revealed that the total phospholipid phosphorus was similar and increased significantly with age in both groups. Cholesterol also increased significantly with age in both groups but was greater in the alcoholic pups, resulting in a higher cholesterol/phospholipid molar ratio. While the phosphatidylethanolamine (PE) content increased with age in both groups, that of sphingomyelin decreased. Phosphatidylserine + phosphatidylinositol (PS + PI) was significantly higher in the control group at all ages studied. A consistent increase of C22:6 in phosphatidylcholine (PC), sphingomyelin, PS + PI and in the total phospholipid fraction from alcoholic pups was observed. Although other fatty acid changes were found in PC, PS + PI and sphingomyelin, PE was not affected. These results suggest that specific adaptive changes were induced in the liver plasma membrane lipids of the progeny from alcoholic rats.

Chronic alcohol feeding and its withdrawal on the structure and function of the rat liver plasma membrane: a study with 125I-labelled glucagon binding as a metabolic probe.

The effect of chronic alcohol administration on the structure and function of the rat liver plasma membranes has been investigated. Chronic alcohol administration did not affect the yield of these membranes using conventional isolation procedures. The extent of plasma membrane enrichment or contamination with other interior membranes was identical in the control and alcoholic preparations. The binding of 125I-labelled glucagon to these experimental liver plasma membranes was significantly decreased. Scatchard analysis of the high affinity sites showed a significant reduction (approximately equal to 35%) in receptor number rather than binding affinity, which was not altered. This anomaly persisted through 72-h withdrawal of alcohol. These data suggest that very stable changes were induced in these liver plasma membranes after prolonged alcohol ingestion.

Synaptosomal Na+,K+-ATPase as a membrane probe in studying the in vivo action of morphine.

The activity of membrane-bound Na+,K+-ATPase was used as a metabolic probe to study the effects of morphine in vivo in rat brain synaptosomes. Arrhenius plots were generated to study an induced perturbation within the membrane. In acute studies 0.5-h postmorphine, the drug was without effect on the basal activity of the enzyme. With dopamine-stimulated Na+,K+-ATPase morphine decreased the apparent transition temperature and specific activity of the enzyme while there was a slight stimulation in its activation energy. An increase in these parameters was observed in samples taken from animals withdrawn from the drug for 48 h. These results strongly suggest the possible involvement of the membrane phospholipids as transducer which mediates the observed biphasic effect of the drug on enzyme activity.

The influence of chronic ethanol feeding to rats on liver mitochondrial membrane structure and function.

Arrhenius plots were generated on the activity of rat liver mitochondrial cytochrome c oxidase from Metrecal-sucrose fed controls and Metrecal-alcohol fed experimentals. Chronic alcohol feeding resulted in diminished specific activity of cytochrome c oxidase and abolition of the discontinuity temperature at 17.5 degrees C found in the controls. Twenty-four hours after alcohol withdrawal, a discontinuity temperature reappeared at 14.4 degrees C; at 48 h it increased to 22.6 degrees C and returned to normal (17.4 degrees C) at 72 h. Such liver mitochondria also showed a decreased capacity to oxidize the acetyl group of acetyl carnitine immediately following prolonged alcohol feeding. When the assay was performed following withdrawal from alcohol 24 h later, oxidation was enhanced and this effect persisted for another 48 h. These latter results revealed a diminished capacity of such mitochondria to oxidize short chain fatty acids during alcohol feeding and the reverse during alcohol withdrawal. These results, complemented by thermographic data obtained through differential scanning calorimetry (DSC) reinforced the view that chronic alcoholic feeding induced adaptive changes in the fluidity of rat liver mitochondrial membrane lipids. Moreover, they demonstrated that in the microenvironment of the membrane-bound enzymes on withdrawal from ethanol, the membrane readapts to the new conditions without alcohol. This involved modulation of membrane structure and function and at the same time demonstrated a role for the membrane in the expression of tolerance and functional dependence on alcohol.

Alteration of the erythrocyte ultrastructure and blood viscosity by morphine.

The effects of acute morphine administration on intact erythrocytes and on their flow properties were studied by measuring the mean cell volume, cell geometry, and whole blood and plasma viscosities. Morphine caused a small (2-7%) increase in mean cell volume. Changes in cell geometry were found to be time dependent and most pronounced in concave portions of the red cells. Whole body viscosity was found to decrease upon morphine treatment; this may be due in part to a concurrent decrease in plasma viscosity.