The characteristics of higher nervous activity and of the brain benzodiazepine system in rats subjected to ethanol exposure in the prenatal period

Exposure to ethanol during pregnancy results in the alternation of 3H-diazepam binding to synaptosomal neocortical membranes from the rat offspring. In male experimental rats, 14 days of age, binding level diminished to 11%. In two-month-old control rats Scatchard plot was biphasic. It has been shown that prenatal exposure to ethanol leads to changes in the nature of binding in two-month-age experimental animals, as compared with the control ones. 3H-diazepam binding changes went along with behavioural deviations. In experimental rats locomotor activity was increased in the "open field" test, passive avoidance conditioned reflex retention was decreased and elaboration parameters of active avoidance conditioned reflex were changed, as compared with the control ones. The data obtained show that higher integrative functions were disturbed by prenatal alcoholization. Correlations between benzodiazepine receptor state and behaviour were studied.     

Effect of dalargin on the behavior of rats subjected to intrauterine ethanol exposure

Influence was studied of dalargin--synthetic analogue of enkephalin administered in early postnatal period to young rats with intrauterine ethanol injection, on their behaviour and conditioned activity. Parameters were established of spontaneous motor activity, behaviour in the open field, acquisition and preservation of conditioned reflexes of passive and active avoidance in experimental and intact rats, injected with dalargin. A reduction of sensitivity to corasol convulsive effect was observed under the influence of dalargin.     

Possible correlations between the level of alcoholic motivation and the electrophysiological structure of sleep in the rat

Using modified Porsolt's method, the electrophysiological sleep pattern was studied in normal conditions and after a single intraperitoneal ethanol injection to noninbred male albino rats divided into 2 groups ("high activity" and "low activity" rats). Voluntary alcohol intake in these rats was measured during free choice between 10% ethanol and water for 20 days. "Low activity" rats were characterized by a statistically significant 3.4-fold higher level of ethanol consumption and 2.7-fold longer REM-sleep stage, as compared to "high activity" animals. In "low activity" animals ethanol (1 g/k, 10% solution, i. p.) inhibits and in "high activity" rats it increases REM-sleep stage, thus removing differences in the sleep pattern in the two groups of rats. The data obtained suggest a possible role of REM-sleep in the development of alcohol motivation.     

The effect of acute and chronic ethanol administration on serum corticosterone concentration in rats

The effect of intraperitoneally (i.p.) and intragastrically (i.g.) administered ethanol solution, and the influence of voluntary ethanol uptake (20% v/v) on adrenocortical activity of adult male rats was studied. Both i.p. and i.g. ethanol administration resulted in a significant activation of adrenocortical mechanisms, while voluntary ethanol uptake failed to induce elevation of serum corticosterone concentration. No difference was found in blood ethanol concentration among these groups. The responsiveness of adrenocortical mechanisms was also tested in rats which were given the free choice between ethanol solution (5% v/v) and tap-water for three weeks. Unavoidable electric foot-shocks, as stressor, resulted in an elevation of serum corticosterone concentration in control animals, but this response was found to be significantly reduced in chronically ethanol drinking rats.     

Effect of a corticoliberin (CRF4-6) on the rat heart rate and behavior

The effects of tripeptide corticoliberin fragment CRF4-6 (Pro-Pro-Ile) on heart rate and behaviour of rats with simultaneous monitoring of these parameters in free-moving animals in their home cage were investigated. Intracerebroventriculary administered CRF4-6 (6, 30, 150 nmol) induces arousal effect increasing the duration of active behaviour, decreasing the duration of passive behaviour and sleep both. At the same time the tripeptide increases the heart rate during sleep, passive and exploratory activity. CRF4-6 (30, 150 nmol) also increases the heart rate in anaesthetised rats. All observed effects of the tripeptide are dose dependent. Taking into account these facts we suggest that CRF4-6 influences behaviour and heart activities independently.     

Effects of cholecystokinin octapeptide sulphate ester and unsulphated cholecystokinin octapeptide on active avoidance behaviour in rats

The effects of peripherally administered cholecystokinin octapeptide sulphate ester and its unsulphated form on the active avoidance behaviour of rats were studied. The acquisition of avoidance behaviour was impaired, while extinction was facilitated, following cholecystokinin octapeptide sulphate ester or unsulphated cholecystokinin octapeptide treatment. These peptides had no action on open-field activity. It is concluded that peripherally administered cholecystokinin octapeptide influences acquisition and extinction of active avoidance behaviour and this effect is unrelated to general motor activity of the animals.     

Liver alcohol dehydrogenase activity in the female rat: Effects of ovariectomy and estradiol administration

The effects of ovariectomy and administration of estradiol on the activity of liver alcohol dehydrogenase and on the rate of ethanol elimination were determined in female Sprague-Dawley rats. The activity of the enzyme and the rates of ethanol elimination in the female sham-operated animals were higher than obtained previously in male rats of the same age. Ovariectomy had no effect on liver alcohol dehydrogenase and on rates of ethanol elimination. Estradiol administration resulted in an increase in liver weight and in total liver alcohol dehydrogenase activity per animal in sham-operated but not in ovariectomized animals. The increase in enzyme activity after estradiol administration in sham-operated animals was not associated with a significant increase in the rate of ethanol elimination, suggesting that the enzyme activity in female rats is not rate-limiting in in vivo ethanol oxidation.     

Relationship between myeloperoxidase activity and the ontogenic response of rat gastric mucosa to ethanol.

We have examined the gastric luminal content of Na+, K+, and protein and mucosal levels of myeloperoxidase in rats between the ages of 10 and 60 days in response to luminal instillation of ethanol (20 and 50% w/v). In control animals the appearances of ions and protein and myeloperoxidase activities were low and similar in all age groups. Luminal content of cations and protein increased in response to both 20 and 50% ethanol and were greater in animals older than 20 days when compared with younger rats. However, ethanol treatment resulted in a significant degree of mucosal cellular disruption and erosions in both young and mature rats. Myeloperoxidase activities in response to ethanol were not greater than control until animals were older than 20 days. Treatment of rats aged 10-60 days with intraperitoneal glycogen (1%) resulted in peritoneal granulocyte infiltration. The concentration of peritoneal cells increased as animals aged. With the exception of day 15, the myeloperoxidase content of the peritoneal leukocytes did not vary significantly at other ages examined. These data suggest that (1) mucosal efflux of Na+, K+, and protein in response to luminal ethanol increase as rats age from 10 to 60 days; (2) the ontogenic development of ethanol-induced cation and protein appearance parallel the increase in myeloperoxidase activity in the gastric mucosa; and (3) the increase in mucosal myeloperoxidase activity in response to ethanol likely reflects increased granulocyte infiltration as rats age.     

Sphingolipid Turnover in the Hippocampus and Cognitive Dysfunction in Alcoholized Rats: Correction with the Help of Alimentary <Emphasis Type="Italic">n</Emphasis>-3 Fatty Acids

We studied the effect of long-lasting (during 60 days) consumption of 15% ethanol solution by 2- to 4-month-old rats on the turnover of sphingolipids in the hippocampus and cognitive functions in these animals. It was found that chronic action of ethanol led to a decrease in the content of newly synthesized sphingomyelin and to an increase in the level of ceramide and the ceramide/sphingomyelin ratio in the hippocampus; this was accompanied by significant worsening of conditioned-reflex activity in experimental rats (testing of active avoidance in a shuttle chamber). The addition of fish oil containing a considerable amount of n-3 fatty acids to the diet of animals consuming ethanol prevented, to a considerable extent, the development of disorders of sphingolipid turnover and cognitive functions.     

Effect of ethanol on intestinal lipid absorption in the rat

The effect of ethanol infusion on intestinal lipid absorption was studied in rats with a duodenal cannula. Rats were infused with ethanol overnight and ethanol was included in a trioleoylglycerol emulsion infusion given for 3 hr the next day. These rats were compared to control animals infused with glucose (isocalorically). The ethanol-infused rats had a greatly impaired lipid absorptive capacity. The monoacylglycerol and free fatty acid contents in the intestinal lumen in the ethanol-infused rats were 4- and 7-fold greater, respectively, than controls. The inhibition of absorption was not due to an effect of ethanol on lipolytic activity. The lipase content of the ethanol-infused rats was greater than controls and the separate infusion of monoacylglycerol and fatty acids demonstrated impaired absorption of these end products of lipolysis as compared to controls. To observe if these changes were due to an effect of ethanol on the enterocyte brush border membrane, the membrane lipids were analyzed. The phosphatidylcholine, lysophosphatidylcholine, and phosphatidylethanolanine content was reduced but not the neutral lipids, sphingomyelin, or phosphatidylserine. The uptake of fatty acid into intestinal rings was also shown to be impaired by ethanol infusion. Lastly, the specific activity of the neutral lipids remaining in the intestinal lumen after [3H]glycerol-labeled trioleoylglycerol-infusion was similar to controls even though the mass was much greater. It is concluded that ethanol impairs neutral lipid absorption due to an effect on the enterocyte brush border membrane and by increasing the efflux of low specific activity lipid from the enterocyte back out into the intestinal lumen. A potential pathway for this efflux is the recently described increased porosity of the apical junctional complex in response to ethanol infusion.     

Changes in autoregulation of coronary blood flow in rats with various sensitivity to stress

The purpose of work: study of a role of endothelial nitric oxide in development of stress-induced changes in autoregulation of coronary blood flow in rats with various types of behaviour. The experiments were performed on isolated hearts of female-rats, in the "open field" test, depending on the type of impelling and searching activity of animals subdivided into two groups: "active" and "passive". After a 6-hour immobilization stress only in "passive" rats an increase of volumetric velocity of coronary flow; a decrease of an autoregulation index, coronary reserve against the background of intravascular pressure reduction, were found out. The blockade of nitric oxide synthesis in this group completely eliminated the stress-induced decrease of coronary vascular tone and essentially limited the caused by stress dissociation of coronary flow and the contractility function of the myocardium. In blood plasma of "passive" animals the nitrite/nitrate contents was by 55% more than of the "active" rats. After the transferred stress, in "passive" animals the nitrite/nitrate concentration in blood plasma increased by 29% and in "active" rats--by 136%; the absolute values, however, did not differ between the groups. Thus the autoregulation of coronary flow seems to be subject to action of stress in the rats showing a "passive" type of behaviour in the test "open field", and practically does not change in "active" animals; secondly, in spite of the fact that the stress-induced amplification of NO-producing function andothelium of coronary blood vessels is stereotyped in different rats, in "passive" rats, apparently, sensitivity of coronary vessels to nitric oxide is higher than at "active" those.     

Mechanism of action of ethanol on enkephalinase A activity in the rat brain

The influence of ethanol, its metabolites and some opiates on enkephalinase A activity was studied in rat experiments in vitro after acute and chronic administration of ethanol. It was demonstrated that addition of ethanol to the reaction mixture activated enkephalinase A of the midbrain and hypothalamus of intact rats, the maximal effect being attained at an ethanol concentration of 10(-3) M. Multiple washings with buffer of the ethanol-preincubated membranous fraction of these brain structures in the control rats did not lead to a significant reduction in the activating effect of ethanol on enkephalinase A. No activation was recorded upon the use of an enzymatic preparation of the brain from chronically alcoholized animals. Morphine, naltrexon, beta-carbolines, salsolinol (10(-4) M) and acetaldehyde (10(-8)-10(-2) M) did not activate the enzyme. It is suggested that enkephalinase A activation in rats given ethanol is determined by a direct action of ethanol on the enzyme.     

In vivo relationship between monoamine oxidase type B and alcohol dehydrogenase: effects of ethanol and phenylethylamine

The role of acute ethanol (2.5 g/kg i.p.) and phenylethylamine (100 mg/kg i.p.) on the brain and platelet monoamine oxidase activities, hepatic cytosolic alcohol dehydrogenase, redox state and motor behaviour were studied in male rats. Ethanol on its own decreased the redox couple ratio, as well as, alcohol dehydrogenase activity in the liver whilst at the same time it increased brain and platelet monoamine oxidase activity due to lower Km with no change in Vmax. The elevation in both brain and platelet MAO activity was associated with ethanol-induced hypomotility in the rats. Co-administration of phenylethylamine and ethanol to the animals, caused antagonism of the ethanol-induced effects described above. The effects of phenylethylamine alone, on the above mentioned biochemical and behavioural indices, are more complex. Phenylethylamine on its own, like ethanol, caused reduction of the cytosolic redox ratio and elevation of monoamine oxidase activity in the brain and platelets. However, in contrast to ethanol, this monoamine produced hypermotility and activation of the hepatic cytosolic alcohol dehydrogenase activity in the animals. The results suggest that some of the toxic actions of ethanol in rats may be mediated through the activation of monoamine oxidase type B, with the consequent depletion of the endogenous levels of phenylethylamine. The data appear to support the concept of phenylethylamine involvement in affective disorders.     

Effect of ethanol on the levels of dopamine and its metabolites in the brain of rats with different degree of sensitivity to stress

It was shown, that content of dopamine and its metabolites (DOPAC and HVA) are the same in two groups of rats with different time of immobilization in forced swimming test. One group of low active (LA) animals experienced the immobilization more than 300s, other high active (HA) rats for less than 120 s. Ethanol (2 g/kg per oris) increased the level of DA in the striatum and medial prefrontal cortex only in LA rats and besides, the concentration of dopamine after ethanol administration was higher in the n. accumbens of LA rats, than in that of HA rats. The authors suggest that differences in dopamine content between LA and HA rats are connected with different levels of voluntary alcohol consumption. The opportunity to use both groups of HA and LA rats for developing models of pathogenic heterogeneity of alcoholism is discussed.     

The behaviour of rats selected for their voluntary ethanol consumption

New strains of rats, preferent (HAP) and non-preferent (NAP) for ethanol were selectively outbred from a Wistar stock. The strains have now been raised to the F13 generation. The F9/10 animals, selected for this behavioural investigation, exhibited a significant phenotypic drinking behaviour and/or ethanol consumption. During a free choice between tap water and 10% ethanol solution (v/v), the mean daily alcohol intake for male and female HAP rats was 8.42 +/- 0.69 g/kg/24 h (n = 20 o) and 11.50 +/- 0.42 g/kg/24 h (n = 20 o), for male and female NAP rats 0.74 +/- 0.09 g/kg/24 h (n = 20 o) and 1.76 +/- 0.20 g/kg/24 h (n = 20 o), respectively. The NAP rats exhibited a strong aversion to the 10% ethanol solution when it was the only source fluid. In the open-field test (OFT), as compared to the NAP rats, male individuals of the HAP strain showed a lower motility in the first minute, in penetration into the inner squares, showed a longer latency to start exploration (latency to leave the center), exhibited larger rearing and grooming activity and shorter latencies to start these activities. The defecation rate was smaller and latency to defecation prolonged. Female HAP rats showed higher activity scores in penetration of outer and inner squares and a shorter latency to start exploration. They also had higher rearing but smaller grooming activity. The females exhibited identical defecation but different urination behaviour in comparison to the males. The time-to-emerge latencies of HAP rats were longer than in NAP individuals.     

Effect of age increase on metabolism and toxicity of ethanol in female rats

Age-dependent change in the effects of acute ethanol administration on female rat liver was investigated. Female Sprague-Dawley rats, each aged 4, 12, or 50 weeks, received ethanol (2 g/kg) via a catheter inserted into a jugular vein. Ethanol elimination rate (EER), most rapid in the 4 weeks old rats, was decreased as the age advanced. Hepatic alcohol dehydrogenase activity was not altered by age, but microsomal p-nitrophenol hydroxylase activity was significantly greater in the 4 weeks old rats. Relative liver weight decreased with age increase in proportion to reduction of EER. Hepatic triglyceride and malondialdehyde concentrations increased spontaneously in the 50 weeks old nai;ve rats. Ethanol administration (3 g/kg, ip) elevated malondialdehyde and triglyceride contents only in the 4 and the 12 weeks old rats. Hepatic glutathione concentration was increasingly reduced by ethanol with age increase. Ethanol decreased cysteine concentration in the 4 weeks old rats, but elevated it significantly in the older rats. Inhibition of gamma-glutamylcysteine synthetase activity by ethanol was greater with age increase, which appeared to be responsible for the increase in hepatic cysteine. The results indicate that age does not affect the ethanol metabolizing capacity of female rat liver, but the overall ethanol metabolism is decreased in accordance with the reduction of relative liver size. Accordingly induction of acute alcoholic fatty liver is less significant in the old rats. However, progressively greater depletion of glutathione by ethanol in older rats suggests that susceptibility of liver to oxidative damage would be increased as animals grow old.     

Effects of prenatal exposure to alcohol on the binding of H3-diazepam to the synaptic membranes of the cerebral hemisphere cortex at various stages of ontogenesis in the rat offspring

Exposure to ethanol during pregnancy results in the alteration of (3H)-diazepam binding to synaptosomal neocortical membranes from the rat offspring. In male rats, 14 days of age, binding level diminished to 11%. In two-month-old control rats Scatchard plot was biphasic. It has been shown that prenatal exposure to ethanol leads to changes in the nature of binding in two-month-old experimental animals, as compared with the control ones. Possible relationship is discussed between the brain benzodiazepine system disorders and behaviour.     

Gender-related effects of chronic ethanol ingestion on rat hepatic acyl-CoA:cholesterol acyltransferase

The influence of chronic ethanol ingestion on hepatic acyl-CoA: cholesterol acyltransferase activity was investigated to determine the relationship between alcohol intake and cholesterol ester accumulation. Rats were given nutritionally complete liquid diets supplemented with 6.3% ethanol or an isocaloric equivalent of dextrin-maltose for 5 weeks. During this period, the hepatic acyl-CoA: cholesterol acyltransferase activity of ethanol-fed male rats remained constant, whereas the same activity in pair-fed controls as well as chow-fed rats exhibited a 30% decrease in activity. Unlike alcohol-fed male rats, the hepatic acyl-CoA: cholesterol acyltransferase activity of female rats decreased by approximately 30% by the fifth week of ethanol ingestion. Despite the fact that the gender of the animals led to disparate levels of acyl-CoA: cholesterol acyltransferase activity in response to ethanol ingestion, similar levels of cholesteryl ester accumulation were observed. The altered levels of acyl-CoA: cholesterol acyltransferase activity caused no significant change in the cholesterol concentration, cholesterol/phospholipid ratio, phospholipid fatty acid composition, or the membrane fluidity of the hepatic microsomes. We conclude that the altered hepatic acyl-CoA: cholesterol acyltransferase activity of ethanol-fed female rats cannot be directly responsible for ethanol-induced accumulation of cholesteryl esters.     

The effect of the acute administration of ethanol on the realization of behavior and its neuronal support

In experiments on rabbits trained to instrumental food procuring behaviour it was cleared up, which changes of activity of neurones of the limbic cortical area corresponded to disturbances of this behaviour (increase in time of realization and in the number of errors) caused by intraperitoneal injection of 12% ethanol solution in a dose of 1 g/kg. In comparison with control (administration of isotonic solution), the number of active cells singled out in the microelectrode track was reduced by 1/3; the pattern of behavioural specialization of neurones involved in provision of the disturbed behaviour was changed. The content of neurones of the most recent systems formed during animals learning instrumental behaviour, decreased from 27 to 11%, and of neurones providing for realization of systems formed at previous stages of individual development increased from 18 to 36%.     

Various features of the emotional behavior of animals with pronounced alcoholic motivation

Testing of animals with different degrees of manifestation of attraction to ethanol showed that in conditions of zoosocial conflict rats--potential dipsomaniacs have less competition abilities in their struggle for the aims of biological value as compared to the rats, who are not dipsomaniacs. Their failure in a conflict situation leads to the fact, that while getting in the same or some other stress conditions for the second time, the animal fully gives up activity and makes no attempts to overcome these situations. This weak behavioural activity of such rats is based on a great tendency to the development of depressive-like state. Alcohol in certain doses (0.5 g/kg) normalizes the behaviour of rats--potential dipsomaniacs. This, probably, explains the appearance of alcoholic motivation in these animals.