Dietary salt and voluntary ethanol consumption in golden hamsters

Cholecystokinin reduces ethanol consumption in golden hamsters

In experimental conditions, golden hamsters (Mesocricetus auratus) avidly consume ethanol solutions. However, they are relatively resistant to the deleterious effects of ethanol even after months of continuous consumption, apparently because they metabolize ethanol rapidly and efficiently. Male hamsters with ad libitum access to food and water were presented with isocaloric solutions [weight/weight (wt./wt.)] of 10% ethanol and 17.75% glucose for 40-min periods on alternate days. When hamsters were injected with 0.9% saline before solution presentation the mean intake of ethanol solution (0.55 g) was about half that of glucose solution (1.08 g). Hamsters derived a mean of 0.36 g/kg/40 min of absolute ethanol from the ethanol solution, an amount that does not seem to exceed their metabolic capacity for ethanol. An intraperitoneal injection of a 2.0-microg/kg dose of the C-terminal octapeptide of cholecystokinin (CCK-8) reduced intakes of both solutions by >50% if administered 5 min before solution presentation, but it was ineffectual if administered 45 min before presentation. When citric acid (2.5 g/l) was added to the glucose solution the baseline intakes of the two solutions were virtually equivalent, and when CCK-8 was administered over a range of doses (0.5-2.0 microg/kg) the intakes of the solutions did not differ significantly at any dose, supporting the suggestion that the pharmacological properties of ethanol play little or no role in mediating the consumption-inhibiting effect of exogenously administered cholecystokinin (CCK). Prior administration of lorglumide, a selective CCK type A receptor antagonist, completely attenuated the inhibitory effect of CCK-8. Findings are consistent with the notion that endogenous CCK plays a key role in the short-term control of ethanol intake in hamsters.

Gender difference in enzymes related with alcohol consumption in hamster, an avid consumer of alcohol

Syrian golden hamster (Mesocricetus auratus) is extraordinary among laboratory rodents in its ability to drink alcohol. After being given a free choice between 15% ethanol and water for 5 days, both male and female hamsters derived at least 85% of the fluid intake from the ethanol solution. Analysis of the alcohol-metabolizing enzymes in alcohol-naïve hamsters showed that the male had a higher activity of 57%, 58% and 34% in stomach alcohol dehydrogenase, liver cytochrome P450 1A2 and liver aldehyde dehydrogenase, respectively, compared with the female. The activity of lung angiotensin-converting enzyme, which influence fluid intake, was twofold higher in the male. After 4 weeks of ethanol consumption, the activities of the hepatic alcohol-metabolizing enzymes remained unchanged except cytochrome P450 2E1 which increased 42% and 88% in male and female hamsters, respectively. A reduction of approximately 80% in the activity of cytochrome P450 1A2 was observed in both genders. The activities of several other cytochrome P450 enzymes were also decreased. Although ethanol consumption did not increase plasma aminotransferase levels, it caused a significant increase in liver weight in female, but not male hamsters.

The effect of fat and carbohydrate content of the diet on voluntary ethanol intake in golden hamsters

Golden hamsters, which avidly consume ethanol solutions, had continuous access to food and water and to either 15% or 30% ethanol solution (v/v) over a period of weeks. Hamsters consumed approximately equal amounts of absolute ethanol when maintained on either a Purina Chow diet or a high-carbohydrate, low-fat diet (7.6 and 7.1 g/kg/day, respectively), but they consumed substantially less ethanol when maintained on a high-fat, low-carbohydrate diet (4. 4 g/kg/day). However, the pattern of differences among groups of hamsters maintained on different diets was not the same at the two ethanol concentrations. Thus, at the 15% concentration, HC hamsters consumed more than twice as much ethanol as HF hamsters, but at the 30% concentration, the difference in ethanol consumption was greatly reduced and did not prove to be statistically significant. These results indicate that it is important to consider the concentration of the ethanol solution when studying the effects of dietary macronutrient content on ethanol consumption.

Dietary energy shortage and ethanol intake in golden hamsters

Adult male golden hamsters, which are avid consumers of ethanol solutions, were maintained on powdered Purina chow and tap water, and they were permitted continuous access to either a 15% or a 30% ethanol solution (v/v). In two experiments, the effect of chronic dietary energy shortage on ethanol consumption was examined. Energy shortage was produced either by food restriction (Experiment 1) or by dilution of the diet with nonnutritive cellulose (Experiment 2). Dietary energy shortage caused increases of up to 50% in ethanol consumption, and the energy derived from ethanol offset the short-fall in food-derived energy by up to 50%. When normal feeding conditions were reinstated, hamsters maintained their enhanced intake of ethanol solutions, consuming up to 15.4 g/kg/day of ethanol. Possible factors underlying the enhanced intake of ethanol solution both during and after dietary energy shortage are discussed.

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.

Neurotensin attenuates the reduction in alcohol drinking produced by angiotensin II

Neurotensin enhances some of the behavioral effects of alcohol including motor impairment, narcosis, hypothermia and also interacts with some of the physiological actions of angiotensin (ANG) II including aldosterone release and increased blood pressure. ANG II injections also produce a dose-dependent antagonist reversible reduction in alcohol drinking. The present study is the first to examine the interaction between neurotensin and angiotensin in the behavioral context of oral alcohol self-administration. Adult male Wistar rats acquired alcohol drinking (6% w/v) using the limited access procedure which makes alcohol available for 40 min every day. When intake stabilized ANG II (400 micrograms/kg per day) or vehicle were administered subcutaneously (SC) just prior to alcohol availability but only the group receiving ANG II showed a marked reduction in alcohol intake. Following this the groups were pretreated sc with either vehicle or ascending doses of neurotensin (5, 10, 20 micrograms/kg) followed by either ANG II or vehicle. Control groups received either two vehicle injections or vehicle and neurotensin injection. Neurotensin alone did not affect alcohol intake at any of the doses tested but did attenuate, in a dose-dependent fashion, the reduction in alcohol intake produced by ANG II. These results demonstrate neurotensin's ability to alter the behavioral effect of ANG II on alcohol intake.

Surgical removal of the pregastric pouch does not affect voluntary ethanol consumption in golden hamsters

Golden hamsters underwent either surgical removal of the pregastric pouch (PGX) or sham surgery. Following recovery from surgery, hamsters were given free access to 15% (v/v) ethanol solution for 40 days, and then to 30% ethanol solution for a further 32 days. PGX and sham-operated hamsters ingested similar amounts of absolute ethanol throughout the study, with intake exceeding 15 g/kg/day when 30% ethanol solution was available. The failure to find a significant effect of surgical treatment on ethanol intake was not attributable to a lack of statistical power, but rather suggests that other factors, such as the hamster's high levels of hepatic alcohol dehydrogenase, are responsible for the hamster's unusual tolerance for ethanol.