Ethanol-treated Group Research Articles

Effects of ethanol on peripheral benzodiazepine binding sites in the mouse cerebellum and brain stem.

[3H]PK 11195 binding to the peripheral benzodiazepine binding site was investigated in the brain and liver of mice treated with ethanol (4 g/kg, p.o.) daily for 5 days. In the brain stem, Bmax was decreased by 78% in the ethanol-treated group with unaltered Kd (2 nM). The ethanol-withdrawn group did not differ from the control group in both parameters. In the cerebellum, Bmax was decreased by 74% but the binding affinity increased 5-fold as the Kd decreased from 10 to 2 nM. The ethanol-withdrawn group did not differ significantly from the ethanol-treated group. No changes were observed in the cerebrum and liver. These results further support the idea that [3H]PK 11195 binding may be a useful marker for ethanol consumption. The observed changes in these binding sites may represent a functional adaptive response to the ethanol insult and/or a role in the mediation of the effects of ethanol.

Protective influence of zinc against the deleterious effects of ethanol in postimplantation rat embryos in vivo.

Zinc is a cofactor for alcohol dehydrogenase, the ethanol metabolizing enzyme. Ethanol-induced zinc deficiency could decrease ethanol metabolism, resulting in an increase in circulating and tissue ethanol levels. This may cause retardation in embryonic growth and development. The influence of zinc supplementation on ethanol-induced embryopathy was studied by the simultaneous administration of ethanol and zinc to pregnant SD rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet and zinc was administered intraperitoneally. The ethanol group received the liquid ethanol diet, the ethanol+zinc group received the ethanol diet and zinc and the pair-fed control group was given an isocaloric control diet. Embryos were explanted from all groups on day 12 of gestation. Embryos of animals treated with ethanol alone exhibited a significantly higher rate of resorption and retarded embryonic growth and development compared to the pair-fed control group. The embryonic protein content, crown-rump length, the number of somites and embryonic morphological score were significantly reduced in the ethanol-treated group. In addition, serum zinc concentration also was lower. Compared to embryos from ethanol-treated animals, embryos from ethanol+zinc treated animals showed a significantly higher number of somites; cardiac development was more advanced and embryonic protein content was higher. These observations suggest that zinc supplementation of ethanol-treated pregnant rats may have some protective influence against the embryopathic effects of ethanol.

CHOLECYSTOKININ RECEPTOR BINIDIING AFTER LONG-TERM ETHANOL TREATMENT IN RATS

Brain cholecystokinin (CCK) receptors have been implicated in anxiety disorders and suicidal behaviour. We have examined the radioligand binding ability of CCK and benzodiazepine receptors in rat brain after long-term intermittent voluntary vs voluntary and forced low-dose ethanol exposure. During 58 weeks, one group of rats had a choice between ethanol and water as the drinking fluid for 24 hr each week. Another group of rats had the same weekly choice between ethanol and water, but at the end of each 24 hr choice period, ethanol (2.0 g/kg) was injected. During the second period of ethanol treatment, lasting for 32 weeks, both ethanol-treated groups had continuous free access to ethanol and water. These two treatments have previously been shown to induce partially different neurochemical alterations. In the present investigation, benzodiazepine receptor binding in the frontal cortex, hippocampus and striatum was similar in both ethanol treatment groups compared to controls. CCK receptor binding in the hippocampus and striatum did not differ between the three groups; however, in the frontal cortex, there was an increase in the apparent number of CCK binding sites in the group of rats submitted to voluntary plus forced ethanol exposure as compared to the control group or the voluntary intake group. These results suggest that long-term ethanol treatment may lead to alterations in brain CCK-ergic neurotransmission, but that the changes are specific to the treatment schedule.

Effects of dietary zinc deficiency on the expression of hepatic microsomal cytochrome P450 2E1 in rats

The objective of this study was to investigate if the altered 2E1 drug metabolism capacity in rats is due to effects of dietary zinc deficiency on the expression of hepatic microsomal P450 2E1 in rats. Rats were given free access to either a zinc-adequate diet or a zinc-deficient diet for 3 weeks. A second control group, the pair-fed control, was also included. At the end of the feeding trial, each dietary group was further divided into the drug control and ethanol treatment group. Ethanol (EtOH, 8 mL/kg body weight, intubation) was given once a day for 3 consecutive days. Within the drug control group, zinc deficiency reduced total P450 concentration but had no effect on the level of NADPH-P450 reductase, 2E1 protein, and 2E1 mRNA. 2E1 activity, which was indicated by N-nitrosodimethylamine demethylase (NDMA), aniline hydroxylase (AH), and p-nitrophenol hydroxylase (NH) activity, was also not affected by dietary zinc deficiency. The NDMA demethylase activity and 2E1 mRNA level were higher in zinc pair-fed rats than in zinc-adequate rats. EtOH treatment induced total P450 concentration in zinc-adequate and zinc-deficient rats and NADPH-P450 reductase level in zinc-adequate rats. 2E1 activity was induced by EtOH, while the level of 2E1 protein and 2E1 mRNA was unchanged. In conclusion, the constitutive expression of hepatic microsomal 2E1 was not affected by zinc deficiency per se; however, the prolonged severe depression of feed intake caused by zinc deficiency increased the level of 2E1 mRNA in rats. An acute EtOH treatment markedly induced 2E1 activity without affecting the level of 2E1 protein and mRNA. ( J. Nutr. Biochem. 5:308–313, 1994.)

Effects of chronic ethanol consumption on gestation and lactation in rats.

Chronic consumption of ethanol during pregnancy and lactation may lead to abnormalities in the fetus or infant. A group of female Wistar rats was submitted to ethanol treatment over a period of a month. A pair-fed control group received sucrose solution isocaloric to ethanol and the control group received water "ad libitum." Afterward, the females were mated with males over a period of 20 days. At birth, each litter was maximized to eight pups and the remaining ones were decapitated to remove the fetal blood and brains. No significant difference was observed in fetal body and brain weight at birth. During lactation the ethanol and pair-fed groups gained less weight than the control group. After weaning, their weight became similar. Fetal blood glucose levels were decreased in the ethanol-treated group. One hundred percent of the pair-fed and control females delivered live fetuses at term and all survived; only 40% of the females in the ethanol group delivered, and one pup did not survive. Chronic ethanol treatment pointed to a possible reduction in the fertility. It seems likely that the change in body weight of ethanol-fed dams was caused by undernutrition.

Effect of maternal ethanol consumption on in vitro tumor necrosis factor, interleukin-6 and interleukin-2 production by rat milk and blood leukocytes.

It has been shown that the transfer of immunity via lactation plays an important role in providing early protection to the neonate. Maternal ethanol consumption also results in a reduced transfer of immunity to their neonates against a Trichinella spiralis infection. Because of the known presence of cytokines in milk and their important role in inflammation, we tested the effects of maternal ethanol consumption on cytokine production by milk and blood cells from T. spiralis-infected rats. With T. spiralis antigen, Concanavalin A (Con A) or lipopolysaccharide stimulation, milk cells from both ethanol-treated and pair-fed groups were capable of producing tumor necrosis factor (TNF), interleukin (IL)-6 and IL-2. There were no differences between groups for TNF or IL-6 production by milk cells. Milk cells from the ethanol group produced a significantly higher amount of IL-2 upon Con A stimulation, as compared with that from the pair-fed group (16 +/- 4 units/10(6) cells vs. 4 +/- 1 units/10(6) cells, p < 0.05). After stimulation with Con A, blood cells from the ethanol group produced significantly lower amounts of TNF (17 +/- 15 units/10(6) cells) than that from the pair-fed group (102 +/- 64 units/10(6) cells, p < 0.05). The amount of TNF and IL-6 produced by milk cells was significantly lower, as compared with that produced by blood cells. This study suggests that ethanol consumption has some modulatory effects on cytokine production by milk and blood cells.

Prenatal ethanol exposure affects the activity and mRNA expression of neuronal membrane enzymes in rat offspring

In order to elucidate molecular mechanisms underlying brain dysfunction in offspring exposed to ethanol in utero, subclinical doses of ethanol that do not have apparent structural effect on the offspring were administered intraperitoneally to pregnant rats at various gestational stages. We measured the activity of membrane marker enzymes and the level of mRNA of myelin proteins of the offspring brain. The activity of a myelin specific enzyme, 2′, 3′-cyclic nucleotide 3′-phosphodiesterase (CNP) decreased in ethanol-exposed offspring. This effect was not related to the period of gestation or the dose of ethanol. Perikaryonal enzymes, acetylcholinesterase and Na +, K +−ATPase, were significantlyffected in groups exposed to ethanol at early fetal stage and in high doses. Expression of mRNAs of CNP and myelin basic proteins decreased significantly in the ethanol-treated group, with abnormal development profile suggesting a relationship with delayed myelination in offspring exposed to ethanol in utero. The present findings suggest that in spite of the low doses of ethanol that do not cause clinical symptoms in the offspring, prenatal exposure to ethanol affects the level of mRNA of membrane enzyme proteins in the offspring brain, consequently causing a corresponding reduction in enzyme activity, that may lead to neuronal dysfunction. In a separate study, blood ethanol levels were found to reach a maximum level within 30 min after injection and be undetectable after 5 to 10 h. No accumulation effects due to daily injection were observed.

The differential mechanisms of mild irritants on adaptive cytoprotection.

The protective action of mild irritants has been established. However, the mechanisms as to how they antagonize the injurious action produced by the subsequent challenge with an ulcerogenic stimulus are still unclear. The present study examined the different protective mechanisms of an oral administration of the three mild irritants, 20% ethanol, 0.3 mol/L HCl or 5% NaCl against the gastric injurious actions of absolute ethanol in rats. In an attempt to clarify the pathways and mediators involved in the adaptive cytoprotection, [D-Pro2, D-Trp7,9]-substance P (substance P antagonist), Nw-nitro-L-arginine methyl ester (L-NAME), indomethacin, capsaicin, lidocaine, atropine or hexamethonium was given. The protective action of 20% ethanol but not the other two mild irritants, was antagonized by L-NAME, indomethacin and capsaicin, which are the inhibitors of nitric oxide (NO) and prostaglandins (PG) synthesis, and afferent sensory neuron blocker, respectively. Substance P antagonist, lidocaine or atropine given alone, prevented mucosal damage; however, only substance P antagonist enhanced the anti-lesion action of 20% ethanol, while atropine and lidocaine increased the protective effect of NaCl and HCl. The three mild irritants increased the residual gastric secretion. Only 20% ethanol and 5% NaCl but not 0.3% HCl significantly increased the basal adherent mucus and also attenuated the mucus depletion by absolute ethanol. It is concluded that the cytoprotective action of either ethanol or NaCl seems to be mediated through the increase of residual gastric secretion and adherent mucus. In the ethanol-treated group, these actions could act through the afferent sensory fibres, with NO and PG as the possible mediators.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of ethanol-inducible cytochrome p-450 2E1 in the development of hepatocellular carcinoma by the chemical carcinogen, N-nitrosodimethylamine

Cytochrome P-450 2E1 is a specific isozyme of cytochrome P-450 induced by ethanol. P-450 2E1 may also be the only enzyme that metabolizes N-nitrosodimethylamine at a very low concentration. Because N-nitrosodimethylamine is a procarcinogen, the possibility that induction of P-450 2E1 by alcohol abuse may accelerate the carcinogenic action of a very small dose of N-nitrosodimethylamine should be considered. To investigate this possibility, effects of ethanol on the hepatic carcinogenic action of a very small dose of N-nitrosodimethylamine were analyzed in rats. Sixty Wistar male rats were divided into two groups (ethanol and control) according to the liquid diets they were fed. After preliminary feeding, N-nitrosodimethylamine in two concentrations (1.5 ng/ml and 3.0 micrograms/ml) in drinking water was given with the diets for 40 or 60 wk. To avoid metabolic competition between ethanol and n-nitrosodimethylamine, we gave N-nitrosodimethylamine and the diets alternately. The average amount of N-nitrosodimethylamine consumed per day was 11 to 37 ng/kg body weight in the 1.5-ng group and was 27 to 37 micrograms/kg body weight in the 3.0-microgram group. Hepatic P-450 2E1 content was six times higher in the ethanol-treated groups than in the control groups throughout the experiment. Visible nodules and enzyme-altered foci were not found in rats in any group at the end of the fortieth week. These preneoplastic changes were found at the end of the sixtieth week only in rats in the groups treated with both ethanol and N-nitrosodimethylamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of short-term ethanol treatment on voltage-dependent calcium channels in Kupffer cells

Kupffer cells, the resident hepatic macrophages, are activated by calcium, and several reports indicate that their function (e.g., phagocytosis and cytokine production) is altered by ethanol. We recently found that Kupffer cells contain L-type voltage-dependent Ca2+ channels. The purpose of this study, therefore, was to evaluate the effect of short-term ethanol treatment on voltage-dependent Ca2+ channels in Kupffer cells. Kupffer cells were isolated from rats 2 hr after intragastric administration of ethanol (5 gm/kg intragastrically). Cytosolic free calcium concentration of cultured Kupffer cells was measured with the fluorescent Ca2+ indicator fura-2. In Kupffer cells isolated from control rats, partial replacement of extracellular Na+ by K+ caused an increase in cytosolic free calcium concentration in a concentration-dependent manner (halfmaximal effect was observed with 81 mmol/L K+), presumably because of membrane depolarization. Acute ethanol treatment in vivo shifted the concentration-response curve for K+ to the right (half-maximal effect was observed with 94 mmol/L K+) and reduced the maximal elevation of cytosolic free calcium concentration by means of K+. Significantly, the dihydropyridine-type calcium channel agonist BAY K 8644 (1 μmol/L) shifted the concentration-response curve for K+ to the left in control and ethanol-treated groups (half-maximal effect was observed with 61 and 77 mmol/L K+, respectively). Moreover, the dihydropyridine-type calcium channel blocker nitrendipine (10 μmol/L) prevented the increase in cytosolic free calcium concentration in both groups. When extracellular Ca2+ was omitted from the incubation medium, the increases in cytosolic free calcium concentration due to depolarization were prevented completely. However, direct addition of ethanol to the cell cultures was without effect. Thus these data indicate that short-term ethanol treatment in vivo reduces the probability that L-type voltage-dependent Ca2+ channels in Kupffer cells would be open. This phenomenon could be involved in the mechanism of the effect of ethanol on phagocytosis and cytokine production by Kupffer cells. (HEPATOLOGY 1993;18:400–405).

Effect of short-term ethanol treatment on voltage-dependent calcium channels in kupffer cells

Kupffer cells, the resident hepatic macrophages, are activated by calcium, and several reports indicate that their function (e.g., phagocytosis and cytokine production) is altered by ethanol. We recently found that Kupffer cells contain L-type voltage-dependent Ca2+ channels. The purpose of this study, therefore, was to evaluate the effect of short-term ethanol treatment on voltage-dependent Ca2+ channels in Kupffer cells. Kupffer cells were isolated from rats 2 hr after intragastric administration of ethanol (5 gm/kg intragastrically). Cytosolic free calcium concentration of cultured Kupffer cells was measured with the fluorescent Ca2+ indicator fura-2. In Kupffer cells isolated from control rats, partial replacement of extracellular Na+ by K+ caused an increase in cytosolic free calcium concentration in a concentration-dependent manner (half-maximal effect was observed with 81 mmol/L K+), presumably because of membrane depolarization. Acute ethanol treatment in vivo shifted the concentration-response curve for K+ to the right (half-maximal effect was observed with 94 mmol/L K+) and reduced the maximal elevation of cytosolic free calcium concentration by means of K+. Significantly, the dihydropyridine-type calcium channel agonist BAY K 8644 (1 mumol/L) shifted the concentration-response curve for K+ to the left in control and ethanol-treated groups (half-maximal effect was observed with 61 and 77 mmol/L K+, respectively). Moreover, the dihydropyridine-type calcium channel blocker nitrendipine (10 mumol/L) prevented the increase in cytosolic free calcium concentration in both groups. When extracellular Ca2+ was omitted from the incubation medium, the increases in cytosolic free calcium concentration due to depolarization were prevented completely. However, direct addition of ethanol to the cell cultures was without effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Ethanol on the Development and Maturation of Synapses in the Rat Hippocampus: A Quantitative Electron-Microscopic Study

The effects of chronic ethanol administration on the development and maturation of synapses in the strata radiatum and lacunosum-moleculare of CA1 in the hippocampus were quantitatively examined in rats exposed to ethanol for the entire period of fetal life as well as the whole period of postnatal life. Synapse densities in the strata radiatum and lacunosum-moleculare of the ethanol-treated group were significantly lower than those of the control group at 2, 14, 21, and 70 days of age. However, the rates of density reduction did not change between either of the strata that receive different groups of afferent fibers. The ratio of axospinous to axoshaftic synapses also did not change between control and ethanol-treated groups. These data suggest that chronic administration of ethanol reduces the density of synapses in this area and that this effect is not specific to neither the type of afferent fibers nor the type of synapses.

Ethanol‐Induced Oxidative Stress and Nutritional Status

The ability of dietary ethanol, administered over a 10-day period, to elevate production rates of reactive oxygen species and to alter glutathione levels has been determined in both liver and cerebellum, a brain region known to be susceptible to ethanol-induced damage. Two groups of ethanol-consuming rats were used. One set of treated animals that received an all-liquid ethanol-containing diet experienced weight gain, and this gain was matched in a pair-fed control group. The other ethanol-treated group that had free access only to solid chow and water containing ethanol lost weight during the exposure period. The corresponding control group that received unlimited water and chow was allowed to gain weight normally. In animals that lost weight as a consequence of ethanol in the drinking water, evidence of oxidative stress was enhanced relative to that in animals receiving ethanol by way of the liquid diet. This latter set gained weight, despite higher blood ethanol levels than the group that lost weight. An excess prooxidant condition prevailed in the liver and cerebellum of the ethanol-dosed malnourished group. In the case of liver, this difference may relate to a greater lability of iron-containing proteins in the rats that experienced weight loss, leading to the appearance of low molecular weight iron in the cytosol.

Effects of maternal alcohol consumption on milk and blood lymphocytes and IgG antibody levels from Trichinella spiralis-infected rats.

Immunity to the intestinal parasite Trichinella spiralis can be transferred from the mother to the neonate during lactation. Previous studies in our laboratory showed that the passage of immunity to pups from ethanol-treated dams was depressed. This study examined the effect of ethanol consumption during pregnancy and lactation on the T. spiralis-associated immune components in milk and blood. Groups of female rats were fed either ethanol-containing or isocaloric liquid diets for 30 days before T. spiralis infection, mated and maintained on corresponding diets through pregnancy and lactation. Two-color flow cytometric analysis was performed for lymphocyte populations, enzyme-linked immunoabsorbent assay for specific IgG, and radial immunodiffusion assay for total IgG. The percentage of total T cells and their subsets, T helper cells and T cytotoxic/suppressor cells in milk and those in blood were similar between pair-fed and ethanol-treated animals. However, the percentage of natural killer cells in milk from ethanol animals was significantly reduced compared with the pair-fed group (33% vs. 54%). The percentage of activated or memory type T helper cell subset (OX2-W3/25+) was significantly increased in the blood of the ethanol-treated group. Pair-fed animals showed higher T. spiralis-specific IgG antibody levels in both in milk and blood compared with ethanol-treated animals. In ethanol-treated animals, specific IgG levels and total IgG concentration in milk were significantly lower than those in blood, whereas in pair-fed animals, only total IgG concentration in milk was lower than that in blood. This study indicates that ethanol consumption during pregnancy and lactation alters the maternal immune system.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effects by oral administration of ginsenoside Rh2 on the growth of human ovarian cancer cells in nude mice.

Recently two new compounds, ginsenosides Rh1 and Rh2, have been isolated from an ethanol extract of the processed root of Panax ginseng CA Meyer, and Rh2 (but not Rh1) has been found to cause growth inhibition of cultured B16 melanoma cells. We have also demonstrated that Rh2 caused inhibition of cultured human ovarian cancer cell (HRA) proliferation. The effect of oral administration of Rh2 on tumor growth and survival of nude mice bearing HRA cells was examined. Nude mice were inoculated subcutaneously in the right flank with 10(6) HRA cells. After 7 days of tumor inoculation 2 mg/kg cis-diamminedichloroplatinum(II) (cisplatin) was administered intraperitoneally once a week for 5 weeks. In Rh2-treated groups. Rh2 was dissolved in absolute ethanol, adjusted with distilled water to 1, 15, and 120 microM, and 0.4 ml of each concentration was administered orally by canula every day for 90 days, from the next day of tumor inoculation. The tumor volume, hematocrit and body weight were measured every week. On days 56 and 63 after tumor inoculation, the tumor volumes in all groups treated with Rh2 were significantly less than those in an ethanol-treated control group and also in cisplatin treated group. After 70 days, the tumor growth in nude mice treated with 15 microM and 120 microM Rh2 was significantly inhibited compared to that in a cisplatin treated group as well as a control group. Consequently, the survival of nude mice treated with 15 microM and 120 microM Rh2 was also significantly prolonged, compared to that of cisplatin treated mice. No toxic effects were observed in any of the mice.

Lipid Peroxidation in Liver and Plasma of Rat Induced by Iron-Deficient Diet and/or Ethanol

This investigation was undertaken to elucidate the effects of iron-deficiency and/or ethanol ingestion on lipid peroxidation of rat liver and plasma.Forty Wistar female rats (about 40g b. w.) were fed a normal diet (Fe: 40ppm) or an iron-deficient diet (Fe: 5ppm) for 8 weeks. Half of them in each group were given 10% ethanol as drinking water for the last 4 weeks. The rats were killed, the liver was removed, and the homogenate was prepared for determination of the contents of thiobarbituric acid reacting substance (TBA-V), glutathione (GSH), ubiquinone (UQ), ubiquinol (UQH2), α-tocopherol (α-Toc) and the activity of superoxide dismutase (SOD).In the rats fed iron-deficient diet, lipid peroxidation as reflected by TBA-V was significantly lower in liver homogenate and plasma, and the contents of reduced and oxidized UQ (UQ9, UQH29) in liver homogenate were higher than those in the animals fed the normal diet. In the normal rats given ethanol, TBA-V did not differ significantly from that in the animals fed normal diet alone, although the content of GSH was decreased and the content of α-Toc. was increased in liver homogenate of the ethanol-treated group. In the iron-deficient animals given ethanol, there was an increase of UQH29 content in liver, but no other significant change compared with animals fed the iron-deficient diet.These data might suggest that the iron-deficient condition protects the animals against free radical attack caused by ethanol ingestion.

Effects of chronic treatment with ethanol and withdrawal of ethanol on levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum of the rat. Influence of benzodiazepines, barbiturate and somatostatin.

Administration of ethanol for 40 days, at 10.53 +/- 0.25 g/kg/day did not modify levels of dopamine (DA) or 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum of the rat; however, the concentration of homovanillic acid (HVA) and the ratio of turnover were increased in a statistically significant way (P < 0.05). Twenty-four hours after withdrawal of ethanol appears as the central time of the ethanol-induced abstinence syndrome, showing noticeable decreases in levels of DA (P < 0.05) and DOPAC (P < 0.05), with respect to control and chronically ethanol-treated groups. The concentrations of DA, DOPAC and HVA and ratio of turnover values showed a tendency to return to control normal levels of 48 hr after ethanol withdrawal, although the differences still showed statistical significance (P < 0.05). The intraperitoneal injection of saline, the water soluble benzodiazepine midazolam, the barbiturate thiopental and somatostatin, in single doses, resulted in a noticeable increase in levels of DA, DOPAC and HVA and ratio of turnover values. The intraperitoneal injection of midazolam produced statistically significant decreases in levels of DOPAC and ratio of turnover values (P < 0.01) in rats 48 hr after withdrawal of ethanol, with respect to control and chronically ethanol-treated animals, in contrast to the absence of changes produced when injecting thiopental or somatostatin.

Effect of chronic ethanol consumption upon cardiovascular reactivity, heart rate and blood pressure in spontaneously hypertensive and Wistar-Kyoto rats

Clarification of the effect of chronic ethanol consumption upon cardiovascular reactivity in rats. Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) normotensive rats were randomly allocated in groups of 10 to ethanol in tap water [20% (v:v) after the first week or tap water for 7-12 weeks]. Intra-arterial blood pressure and heart rate were measured at rest and in response to vibration and noise stress. Vascular reactivity was assessed in isolated paired perfused hindquarters and in mesenteric arterioles in a Mulvany-Halpern myograph. Resting intra-arterial blood pressure but not heart rate was lower in both ethanol-treated groups. The ethanol treatment increased the SHR heart rate response to sudden noise but the WKY response did not increase. Pressor responses to noise were initially greater in the ethanol-treated SHR. The ethanol had no effect upon isolated perfused hindquarter resistance at maximal dilation, dose-response curves in response to noradrenaline or vasopressin, or maximal contractile strength. Isolated mesenteric arterioles showed that ethanol had no effect upon responses to nerve stimulation or upon the 50% effective dose required for a response to noradrenaline or vasopressin. Ethanol treatment heightened the heart rate reactivity to stress without substantially affecting vascular neuro-effector characteristics in SHR. This is likely to be a central effect, caused by suppression of the central nervous inhibitory systems that influence the heart rate and baroreflex activity in a strain of rat already showing evidence of an impaired ability to modulate the heart rate and blood pressure in response to stress. The small reduction in resting blood pressure may be a consequence of the lower weight in the ethanol-treated rats, and/or may reflect a direct depressing action by the alcohol on vascular and cardiac muscle. These findings are discussed in the context of ethanol-induced hypertension in humans and possible genetic variations in central nervous, cardiac and vascular effects.

BENZODIAZEPINE METABOLISM IN ETHANOL-TREATED MALE RATS: USE OF PAIR-FED AND AGE-MATCHED CONTROLS

The effects of chronic moderate (15%) ethanol consumption and ageing on rat hepatic cytochrome P450 monooxygenase activities were examined using diazepam, nordazepam, d-benzphetamine, erythromycin, ethylmorphine and nitrosodimethylamine (NDMA) as substrates. In addition, the effects of moderate ethanol alone on the oxidation of metoprolol, morphine and temazepam were examined. Cytochrome P450 specific content increased significantly only in the 6-week ethanol-treated rats, and no changes in percentage liver to body weights were apparent in any of the ethanol-treated animals compared with pair-fed controls. Only cytochrome P450IIIA enzyme activities displayed age-related decreases, these being identified in the pair-fed animals. C3-hydroxylation of diazepam and nordazepam (36% of controls) and N-demethylation of erythromycin and ethylmorphine (58% and 64% of controls) were decreased in 6-week ethanol-treated animals, these effects being less pronounced in the 12, 24 and 48-week ethanol-treated groups. The decrease seen for diazepam and d-benzphetamine N-demethylation caused by ethanol consumption was approximately 80% of control groups for the duration of the treatment. NDMA and morphine N-demethylations were increased to 120% of control activities and metoprolol alpha-hydroxylase was increased to 140% of control activities at 6 weeks, whilst metoprolol O-demethylase activity remained unaltered. NDMA N-demethylase activity showed a two-fold induction at 24 and 48 weeks of ethanol treatment, compared with corresponding pair-fed control groups. These results support previous findings from this laboratory showing that the same or similar P450IIIA family isozymes are involved in the C3-hydroxylation of diazepam and nordazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Prenatal Ethanol Exposure on Glucocorticoid Receptors in Rat Hippocampus

Animals exposed to ethanol in utero are typically hyperresponsive to stressors in adulthood as indicated by increased adrenocortical activation and/or deficits in response inhibition or recovery following stress. In the present study we reasoned that a deficit in feedback control of pituitary-adrenal activity might underlie this hyperresponsiveness in fetal ethanol-exposed (FEE) animals. Further, we hypothesized that a long-term decrease in hippocampal glucocorticoid receptor concentration, induced by prenatal ethanol exposure, might mediate such a deficit in pituitary-adrenal feedback regulation. Male and female Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF), and control (C) treatment groups were tested in adulthood for determination of cytosolic hippocampal glucocorticoid receptor binding. No significant differences in specific binding (Bmax) or binding affinity (Kd) of either type I or type II glucocorticoid receptors were found among animals from E, PF, and C conditions. There were, however, significant sex differences in receptor concentration and binding affinity; females showed significantly greater maximal binding and significantly lower binding affinity than males. These data do not support the hypothesis that prenatal ethanol exposure induces a long-term decrease in hippocampal glucocorticoid receptors in animals tested under basal nonstressed conditions. However, these data do not preclude the possibility that receptor binding capacity may be differentially affected in E, PF, and C animals during stress.