Dietary salt and doca-salt treatments modify ethanol self-selection in rats

Angiotensin II reduces alcohol intake and choice in water- or food-restricted rats

Two experiments were conducted to assess the effects of administration of the neuropeptide and hormone angiotensin II (AII) on ethanol intake and choice. First, 18 male Wistar rats were water deprived for 23 h and given access to 5% w/v ethanol for 30 min, followed by 30 min of access to water; food was ad lib. Following adaptation to this schedule, rats were randomly assigned to receive an IP injection of 0, 100, or 200 micrograms/kg of AII at either -30 or 0 min prior to ethanol access. Each AII injection decreased ethanol intake only if injected immediately before access; water and food intake were unaffected. Secondly, rats were given food daily at 2% of body weight with ad lib water and randomly assigned to receive either only water or 4% w/v ethanol ad lib on alternate days. Following adaptation, rats were randomly assigned to receive IP saline or 200 micrograms/kg of AII prior to presentation of a choice of ethanol or water for 1 h. AII reduced ethanol intake and increased water intake at 0-30 min after injection. Results confirm previous reports of inhibition of alcohol consumption by peripheral AII, and indicate a temporal constraint on AII's effect, which is consistent with a role as a short-term satiety factor.

Inhibition of nitric oxide formation reduces voluntary ethanol consumption in the rat

Brain nitric oxide is involved in the mechanisms that regulate ingestive behavior. To test whether this compound plays a role in alcohol preference, we studied the effects of different doses of NG-nitro-L-arginine (L-NO arg), an inhibitor of nitric oxide synthase (NOS), on voluntary consumption of ethanol and on blood alcohol levels produced by a single intraperitoneal dose of alcohol in the rat. L-NO arg produced a significant and dose-dependent reduction of ethanol intake (P < 0.001) without influencing total fluid consumption or feeding behavior. L-NO arg did not influence the kinetics of alcohol. Our data show that inhibition of nitric oxide formation accompanies reduction of ethanol intake and suggest a possible role for nitric oxide in ethanol self-administration.

Acetaldehyde inhibits serum aminopeptidases

Aminopeptidase A (APA)- and aminopeptidase M (APM)-like activity were assayed in Moni-Trol ES with L-alpha-aspartyl-beta-naphthylamide and L-alanyl-beta-naphthylamide, respectively. Upon preincubation of the serum with 89.4, 223.5, and 447 mM acetaldehyde at room temperature for 30 min, a reduction in 26.8%, 55.3%, and 75.8% aminopeptidase A activity was observed. Similarly, aminopeptidase M activity was reduced by 26.5% and 53.1% upon preincubation with 223.5 and 447 mM acetaldehyde. Ethanol at 84.9, 212.3, and 427.9 mM did not significantly affect the enzymic activity. Because aminopeptidase A and aminopeptidase M also degrade the pressor substance, angiotensin II, it is suggested that inhibition of aminopeptidase A- and aminopeptidase M-like activity by acetaldehyde, the product of ethanol metabolism, may lead to higher levels of circulating angiotensin II and, consequently, hypertension, in alcoholics. The hydrolysis of lysine-p-nitroanilide, an aminopeptidase B substrate, was also inhibited upon addition of acetaldehyde to Moni-Trol ES serum.

Increased alcohol consumption in weight-reduced rats is modulated by the renin-angiotensin system

Weight reduction and food restriction increase the self-administration of alcohol and other drugs of abuse, but the underlying physiological mechanisms have not been identified. Because weight reduction alters angiotensin (ANG) II activity, and ANG II is known to modulate alcohol intake, ANG II may play a role in the enhanced alcohol consumption of food-deprived weight-reduced rats and in the drop in alcohol intake when these rats are refed. Two groups of rats were reduced to and maintained at 80% of their free feeding weights and offered daily 40 min access to a 6% (w/v) alcohol solution and water. Water was available ad lib. After alcohol intake stabilized, one group was given daily injections of the angiotensin converting enzyme inhibitor captopril (5.0 mg/kg) for 6 days while the other group received the saline vehicle. Following this, each group continued to receive either captopril or vehicle injections but was returned to ad lib feeding. Captopril did not alter alcohol intake when the rats were food-deprived and weight-reduced, but did significantly attenuate the decline in alcohol consumption compared to the vehicle group when both groups were refed and regaining weight. These findings suggest that the increase in alcohol intake with food restriction and its decline following refeeding are, in part, related to changes in ANG II activity.

Dietary salt and voluntary ethanol consumption in golden hamsters

Adult male golden hamsters were maintained on powdered Purina chow and tap water, and were permitted continuous access to either a 15% or a 30% ethanol solution (v/v); after an initial 4-5 weeks of ethanol availability, hamsters had stabilized their intakes and were deriving an average of 1.25 and 1.96 g/day of absolute ethanol from the 15% and 30% solutions, respectively. When salt was added to the diet in increasing concentrations ranging from 4% to 10% over a period of 40 days, hamsters reduced chow-derived calories by up to 35%, increased tap water consumption by up to 50%, and increased consumption of ethanol solutions by up to 100%; when unadulterated Purina chow was reinstated, intakes of chow-derived calories, tap water, and ethanol solutions returned to baseline levels. Hamsters that were continuously maintained on unadulterated Purina chow, but with chow-derived calories matched to that of animals on the salt-adulterated diet, significantly increased their ethanol intake, but not their tap water intake; the increase in their ethanol intake was only about half as large as that of hamsters that had salt added to the diet, but the increase persisted even after ad lib feeding was reinstated. The results indicate that the addition of salt to the diet of hamsters produces large increases in ethanol consumption; furthermore, the increased ethanol intake is not simply the result either of a nonselective increase in fluid consumption or of the reduction in food intake that accompanies the addition of salt to the diet. Results are related to the possible role of the renin-angiotensin system in the control of ethanol consumption in the golden hamster.

Consumption of sweet, salty, sour, and bitter solutions by selectively bred alcohol-preferring and alcohol-nonpreferring lines of rats

To determine whether selective breeding for high or low oral ethanol consumption is associated with different preferences for nonpharmacological solutions with various flavors, the oral intake of a range of concentrations of sucrose (0.5-64.0 g/100 ml), NaCl (0.025-3.2 g/100 ml), citric acid (0.008-2.048 g/liter), and sucrose octaacetate (0.002-0.512 g/liter) was studied in alcohol-preferring (P) and alcohol-nonpreferring (NP) rats. Separate groups of 7-8 rats from each line were tested for consumption of each of the four flavors. The flavored solutions were presented continuously with water and food always available, and the concentrations were doubled every 48 hr. Although rats from both lines showed a strong preference for the sucrose solutions, P rats consumed greater amounts than NP rats [F(7,98) = 5.57, p < 0.001]. Rats of the P line drank less of the NaCl solutions than NP rats [F(7,98) = 3.88, p < 0.001], but the effect was not as robust as the line differences seen with sucrose. The P and NP rats did not differ in citric acid or sucrose octaacetate intake at any of the concentrations tested. Selective breeding for high oral ethanol preference appears to be positively associated with consumption of sweet solutions and negatively associated with intake of salty solutions.

Brain angiotensin receptor subtypes in the control of physiological and behavioral responses

This review summarizes emerging evidence that supports the notion of a separate brain renin-angiotensin system (RAS) complete with the necessary precursors and enzymes for the formation and degradation of biologically active forms of angiotensins, and several binding subtypes that may mediate their diverse functions. Of these subtypes the most is known about the AT1 site which preferentially binds angiotensin II (AII) and angiotensin III (AIII). The AT1 site appears to mediate the classic angiotensin responses concerned with body water balance and the maintenance of blood pressure. Less is known about the AT2 site which also binds AII and AIII and may play a role in vascular growth. Recently, an AT3 site was discovered in cultured neoblastoma cells, and an AT4 site which preferentially binds AII(3-8), a fragment of AII now referred to as angiotensin IV (AIV). The AT4 site has been implicated in memory acquisition and retrieval, and the regulation of blood flow. In addition to the more well-studied functions of the brain RAS, we review additional less well investigated responses including regulation of cellular function, the modulation of sensory and motor systems, long term potentiation, and stress related mechanisms. Although the receptor subtypes responsible for mediating these physiologies and behaviors have not been definitively identified research efforts are ongoing. We also suggest potential contributions by the RAS to clinically relevant syndromes such as dysfunctions in the regulation of blood flow and ischemia, changes in cognitive affect and memory in clinical depressed and Alzheimer's patients, and angiotensin's contribution to alcohol consumption.

Angiotensin and captopril increase alcohol intake

Reportedly both angiotensin II (ANG II) and angiotensin-converting enzyme (ACE) inhibitors reduce ethanol intake when they are injected SC into certain chronic experimental conditions in the rat. The ACE inhibitors are suggested to reduce ethanol intake by increasing ANG II synthesis in the brain. The present results show that several different methods can produce opposite effects of ANG II and the ACE inhibitor captopril on ethanol intake. Continuous intraventricular infusions of ANG II for 7 days or low doses of oral or SC-infused captopril for up to 12 days increased the intake of ethanol. The only reduction of ethanol intake resulted from a universal blockade of all ACE in both the brain and periphery, a condition in which ANG II could not possibly mediate the decrease. The results contradict the hypothesis that ethanol intake is suppressed by centrally acting or centrally synthesized ANG II. ACE inhibitors may reduce ethanol intake only when they affect the brain as well as the periphery.

The amino acid composition of angiotensin alters its ability to reduce alcohol consumption in rats

The voluntary consumption of alcohol has been shown to be reduced by a variety of manipulations which enhance activity in the renin-angiotensin system, including the administration of the bovine form of angiotensin II-[Val5]-ANG II. The present study investigated the relationship between the amino acid composition of angiotensin II and its ability to reduce alcohol intake by administering a number of different forms or fragments of the parent peptide. [Ile5]-Angiotensin II ([Ile5]-ANG II), two endogenous fragments of angiotensin II [( Des-Asp1]-ANG II and [Des-Phe8]-ANG II) were administered subcutaneously in rats across a range of doses. [Ile5]-ANG II reduced alcohol intake at all doses tested between 20 and 400 micrograms/kg while [Des-Asp1]-ANG II reduced alcohol intake only at the 400 micrograms/kg dose. [Des-Phe8]-ANG II had no effect on alcohol intake at any dose tested. Administration of the antagonist [Sar1-Thr8]-ANG II by itself did not enhance alcohol intake. While the pressor and dipsogenic properties of these fragments sometimes correlated with the reduction in alcohol intake they were not a causal factor in decreasing the intake. These results indicate that variations in the peptide composition of angiotensin can significantly alter its ability to reduce the consumption of alcohol.

Regulation of alcohol consumption by the renin-angiotensin system: a review of recent findings and a possible mechanism of action

The renin-angiotensin system has traditionally been associated with the regulation of fluid and electrolyte balance. In this review we summarize the data which ascribes a completely new function to this system, i.e., the regulation of alcohol consumption. In addition, we suggest a possible mechanism for this effect based on the concept of a satiety or stop process. The approach taken was to examine the effect on alcohol intake of a wide variety of drug, genetic, dietary, surgical and neurosurgical manipulations, each of which has a range of biological effects characteristic of that manipulation, but all of which share the common property of altering activity in the renin-angiotensin system. The effect of these manipulations on alcohol intake was most parsimoniously explained by reference to their ability to raise or lower activity in the renin-angiotensin system. Any intervention which modulates activity in this system, either directly or indirectly, is likely to have consequences for alcohol consumption.

The tachykinin NH2-senktide inhibits alcohol intake in alcohol-preferring rats

The present study evaluated the effect of the intracerebroventricular injection of the tachykinins, substance P, neurokinin A and [Asp5.6,MePhe8]substance P(5-11) (also referred to as NH2-senktide), on the alcohol intake of genetically selected, alcohol-preferring rats. Animals were offered both water and 8% ethanol 2 h/day; tachykinins were administered just before access to fluids. Neurokinin A and substance P did not modify alcohol intake at doses up to 1000 and 2000 ng/rat, respectively. On the other hand, NH2-senktide potently suppressed alcohol intake at doses of 31.2-500 ng/rat. At the same doses, however, it did not significantly affect water intake. This finding suggests that its effect on alcohol intake might be rather selective and not due to general impairment of the behavior. Activation of tachykinin NK-3 receptors, for which NH2-senktide is a highly selective agonist, produces angiotensin II release in the brain; however, the effect of NH2-senktide on alcohol intake is probably not mediated by angiotensin II, as suggested by the fact that it is not modified by captopril pretreatment.

Vasopressin does not mediate the inhibition of ethanol drinking by the renin-angiotensin system

Manipulations which are known to enhance activity in the renin-angiotensin system (RAS) have been found to reduce the voluntary consumption of ethanol in rats. Since angiotensin II is a potent stimulus for the release of vasopressin (VP), it is possible that the RAS modulates ethanol (ETOH) consumption through a mechanism involving VP. The present investigation examined the effect of peripheral injections of arginine-VP (AVP) and desglycinamide-AVP (DGAVP) on ETOH consumption in rats given daily one-hour access to ETOH. Daily subcutaneous treatment with AVP or DGAVP had no effect on ETOH consumption at doses ranging from 2 to 200 micrograms/kg (SC). Blood pressure was substantially elevated following a single 20 microgram/kg injection of AVP, indicating that AVP was biologically active at doses which failed to alter ethanol consumption. These findings indicate the VP does not affect established ETOH drinking and furthermore is not likely a critical factor in the reduction of ETOH intake by the RAS.

Alcohol intake is inversely related to plasma renin activity in the genetically selected alcohol-preferring and -nonpreferring lines of rats

Studies involving both animals and humans strongly suggest that alcoholism is, in part, genetically determined. One approach to studying this genetic component is to determine whether rats, genetically selected to prefer (P line) or avoid (NP line) alcohol, show differences in those physiological systems which modulate alcohol intake. It has previously been shown that alcohol intake in randomly bred stock rats is sensitive to and inversely related to manipulations which alter activity in the renin-angiotensin (R-A) system. In the present report the basal level of activity in the R-A systems of the P and NP rats as measured by plasma renin activity (PRA) was first assessed following which continuous access to alcohol (10% v/v) and water was offered for a period of five days. PRA was found to be inversely related to the amount of alcohol that was consumed. The P rats drank significantly larger amounts of alcohol than the NP rats who basically avoided the drug. The P rats had a significantly lower PRA than the NP rats. It is suggested that the genetic selection that favored different levels of alcohol consumption in the P and NP rats may have brought about this effect through differences in the activity of the renin-angiotensin systems in the two lines.

Angiotensin II-induced suppression of alcohol intake and its reversal by the angiotensin antagonist Sar-1 Thr-8 angiotensin II

The effects of three doses of angiotensin II (AII) on alcohol consumption using the limited access procedure were studied. Fifty and 100 micrograms/kg AII administered subcutaneously (SC) did not alter alcohol intake while 200 micrograms/kg suppressed alcohol intake. These findings confirm previous work and show that AII begins to be effective in reducing alcohol intake in the range of 200 micrograms/kg. In the second part of the study, the AII antagonist Sar-1 Thr-8 AII (500 micrograms/kg SC) was given immediately prior to the administration of either saline or 200 micrograms/kg AII. In the control group treated with saline, the antagonist had no effect of its own on intake but completely blocked the suppressive effect of the 200 micrograms/kg dose AII on alcohol consumption. These findings indicate that the reduction in alcohol intake produced by AII is mediated by events occurring at the receptor level.

Area postrema and alcohol: effects of area postrema lesions on ethanol self-administration, pharmacokinetics, and ethanol-induced conditioned taste aversion

An investigation was carried out to test the hypothesis that the area postrema (AP) may detect ethanol as a blood-borne toxin and thereby mediate aversive postingestinal effects of the drug. These aversive effects in turn may impose an upper limit on the amount of drug that can be consumed. In Experiment 1 rats had continuous access to water and a 4% ethanol solution. Animals with AP lesions drank more ethanol than sham-operated controls. No differences in drug disposition or metabolism were found when these rats were injected with ethanol and blood ethanol levels were measured. If the AP lesions resulted in increased ethanol drinking because of a reduction in the aversive effects of the drug, then the lesions might also be expected to attenuate a conditioned taste aversion induced by ethanol. In Experiment 2, groups of lesioned and sham-operated rats drank a novel tasting fluid and then were given i.p. injections of ethanol (0.9, 1.2, or 1.6 g/kg) or vehicle. Similar degrees of aversion to the taste of the fluid developed in both the lesioned and the sham-control groups. Since the AP lesion did not result in the attenuation of the ethanol-induced conditioned taste aversion, it was suggested that the AP may not mediate the aversive consequences of ethanol and that the increased ethanol self-administration observed in Experiment 1 may be due to other effects of the lesion.

Ethanol as a reinforcer for rats: factors of facilitation and constraint

This review examines some particular approaches that have been used to investigate factors that facilitate or constrain the self-administration of ethanol by rats. A technique for increasing ethanol self-administration in rats, the prandial drinking method, was examined and the effect of body-weight reduction on drug intake was discussed. Emphasis was placed on how ethanol intake may be controlled by processes in addition to the direct pharmacological actions of the drug in the CNS. These processes may be physiological. Evidence was presented for a relationship between activity in the renin-angiotensin system and the self-administration of ethanol. These processes may also be environmental. Using the place-conditioning technique, demonstrations were presented of how the context or situation in which ethanol is experienced may determine whether preference or aversion for the drug develops. Such a diversity in the factors that can potentially control ethanol intake may complicate the identification of the causes of alcohol abuse, but this same diversity also holds out greater hope that manipulations may be found to reduce excessive drinking in humans.

Attenuation of alcohol intake by a serotonin uptake inhibitor: evidence for mediation through the renin-angiotensin system

Although the serotonin uptake inhibitors have been shown to reduce alcohol intake in both animals and man, the mechanism of this effect is unclear. It is known that enhanced serotonergic activity can stimulate activity in the renin-angiotensin system and that elevated activity in the renin-angiotensin system can reduce voluntary alcohol intake. Therefore, serotonin uptake inhibitors such as fluoxetine might exert their effect on alcohol intake, in part, through the renin-angiotensin system. The present experiment assesses this possibility by examining the effect of the angiotensin converting enzyme inhibitor, enalapril, on the fluoxetine-induced decrease in alcohol intake. Four groups of rats were offered limited access to alcohol for 1 hr each day. When intake stabilized each group was injected with 2.5, 5.0 or 10.0 mg/kg of fluoxetine or the saline vehicle 1 hr prior to the access to alcohol. Fluoxetine produced a dose-dependent decrease in alcohol intake. Following this, all groups received injections of 1 mg/kg of the angiotensin converting enzyme inhibitor, enalapril, 40 min prior to the fluoxetine. Enalapril had no effect on alcohol intake in the saline group, but reversed the suppression in alcohol intake produced by the 2.5 mg/kg and 5.0 mg/kg doses of fluoxetine and partially reversed the effect of the 10.0 mg/kg dose. These findings indicate that the fluoxetine-induced reduction in alcohol intake may, in part, be mediated through the renin-angiotensin system.

Voluntary alcohol intake is attenuated in two-kidney, one-clip, but not in one-kidney, one-clip Goldblatt hypertensive rats

Voluntary alcohol intake was examined in two models of renovascular hypertension known to differ in their effects on the renin-angiotensin system. In experiment 1, Two-Kidney, One-Clip (renin-dependent) hypertensive rats (T-K,O-C) or their sham operated controls were offered limited access to alcohol for 1 hr each day. Over a four week period the T-K,O-C rats drank significantly less 3% and 6% (w/v) alcohol solution than the sham operated controls. In experiment 2, One-Kidney, One-Clip (renin-independent) hypertensive rats or their sham operated controls were offered alcohol on a similar limited access basis. Over a four week period, the O-K,O-C rats did not show a reduction in the intake of either a 3% or 6% alcohol solution compared to the sham operated controls. These results provide further documentation for the role of the renin-angiotensin system in modulating alcohol intake. The process by which this system might influence alcohol intake is outlined.

Angiotensin II reduces voluntary alcohol intake in the rat

The voluntary intake of alcohol has been shown to be attenuated by a variety of manipulations which increase activity in the renin-angiotensin system. In the present study we examined the effects of peripheral injections of the peptide angiotensin II on alcohol drinking. The peptide produced a dose-dependent decrease in alcohol intake with 20 micrograms/kg having little effect, 200 micrograms/kg reducing intake by approximately 50% and 1 mg/kg virtually abolishing all alcohol drinking. This decrease was not due to a peptide induced motor deficit, or state of sickness, and could also not be accounted for by the increased water intake, or by a change in pharmacokinetics and taste function. These data provide direct evidence that angiotensin II can modulate voluntary alcohol drinking. The possibility that the level of angiotensin II serves as a satiety signal in alcohol drinking is discussed.

Angiotensin converting enzyme inhibitors: animal experiments suggest a new pharmacological treatment for alcohol abuse in humans

The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans.

Alcohol satiety, hypertension and the renin-angiotensin system

Evidence is presented which supports the hypothesis that the renin-angiotensin (r-a) system regulates alcohol intake. Documented findings suggest that an elevated level of r-a activity represents a satiety signal which stops alcohol intake. The fact that alcohol itself is known to stimulate r-a activity suggests that its intake may in some sense be self-regulating and that levels of r-a activity below those which signal satiety may even be rewarding. The role of the r-a system in hypertension is also considered. The ability of alcohol to elevate r-a activity may be seen as a contributing factor to alcohol-induced hypertension because angiotensin is a potent pressor agent. Furthermore, the notion that lower levels of angiotensin may be rewarding permits the hypothesis that essential hypertension may, in part, be the result of a self-induced increase in endogenous angiotensin. This would explain the otherwise puzzling utility of the angiotensin converting enzyme inhibitors in the treatment of essential hypertension.

Renal artery stenosis: an example of how the periphery can modulate voluntary alcohol drinking

Voluntary alcohol drinking, using a free-access procedure, was studied in rats three weeks after unilateral renal artery stenosis was produced by applying a 0.20 mm solid silver clip to the left renal artery (Two-Kidney, One-Clip, Hypertension). The group of animals with the arterial clip drank significantly less alcohol and more water than a sham-operated group. The two groups, however, drank similar amounts of a palatable glucose solution, suggesting that they did not differ in taste sensitivity. Blood alcohol levels measured for six hours following a 2.5 g/kg intraperitoneal injection of alcohol indicated that the difference in alcohol consumption between the two groups could not be accounted for in terms of differences in drug disposition or metabolism. These findings provide an example of a previously unknown type of control which originates in the periphery and contributes to the regulation of voluntary alcohol drinking.

Increased voluntary ethanol intake after dietary salt-loading in rats

The effect of dietary salt-loading on selection for 5% ethanol compared with dilute solutions of citric acid was examined in 9 male rats. Compared with 9 control rats maintained on a normal diet, salt-loaded rats exhibited significant increases in ethanol consumption and ethanol selection. Selection for ethanol remained elevated after resumption of the normal diet.

Voluntary alcohol intake in the hypertension prone Dahl rat

Previous work in our laboratory has shown that alterations in the sodium content of the diet which alter salt appetite, can modify ethanol self-selection and intoxication. The present experiment investigates the relationship between the intakes of sodium and ethanol on the one hand and the development of hypertension, by measuring voluntary ethanol consumption and blood pressure in two rat lines, the salt sensitive (SS) and salt resistant (SR) Dahl rats, specially bred to show differential sensitivity to dietary sodium supplements. All rats were given 24 hr access to 6% (v/v) ethanol and water and first offered a control diet (0.5% Na) followed by a 4% and then an 8% sodium supplemented diet. While on the control diet there were significant between strain differences in ethanol consumption, suggesting that the SS animals came genetically prepared to consume more ethanol. Blood pressure measured at regular intervals indicated significant changes only in the SS rats even though both lines as well as a group of Wistar rats, added for purposes of comparison, all increased their ethanol intake to the salt supplemented diets. A second experiment suggested that the initial difference in consumption between the SS and SR lines may be related to central nervous system sensitivity since differences were found in salt appetite but not in taste sensitivity or in the absorption, distribution or metabolism of the drug. These findings demonstrate that the Dahl SS rat is predisposed to consume more ethanol than the SR rat even before exposure to the hypertension-inducing diet, and that this predisposition is probably central in origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of ethanol-induced motor impairment by diet, diuretic, mineralocorticoid, or prostaglandin synthetase inhibitor

Ethanol-induced motor impairment in rats was measured following a number of different dietary or drug treatments. A low sodium diet combined with injections of the diuretic furosemide, but not a low sodium diet alone, increased motor impairment while a high sodium diet decreased impairment. Blood ethanol measurements indicated that both effects were probably mediated by changes in blood ethanol levels. However, the synthetic mineralocorticoid, DOCA, and the nonsteroidal anti-inflammatory, indomethacin, both altered ethanol-induced motor impairment without concomitant changes in blood ethanol levels. The aldosterone antagonist, spironolactone, failed to produce any effect. Since all treatments can modulate activity in the renin-angiotension system, this system appears to play a role in altering some of the behavioral properties of ethanol.