Antidipsogenic role of the E-prostaglandins.

Prostaglandin E? (PGE?) is antidipsogenic when administered into the lateral cerebral ventricle of the rat. In 8 experiments with a total of 211 male Sprague-Dawley rats, PGE?, at a dose of 1 μg, suppressed water intake induced by centrally administered angiotensin II (AII) or carbachol, sc administered polyethylene glycol, and water deprivation. Even at this high dose, PGE? did not reduce water intake due to cellular dehydration. As the dose of PGE? was reduced, its suppressant effects became more specific to AII-induced drinking, with a dose of 10 ng yielding a significant suppression only in the case of AII-induced drinking. Even at a high dose (1 μg), the PGE? suppression of ingestion was specific to water intake. Although PGE?-treated Ss reduced food intake if they were not hydrated prior to access to food, no reduction in food intake was seen when they received water by gavage before food presentation. Since PGE?-like substances are synthesized in the brain, these data suggest the possibility that the prostaglandin may be involved in the regulation of water balance as a component of a reciprocal system in which water intake initiated by the activation of the renin-angiotensin system is halted by the synthesis and release of PGE. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enforced water drinking induces changes in burying behavior and social interaction test in rats

The effect of water deprivation and water intake on experimental anxiety in rats was tested using burying behavior (BB) and social interaction (SI) anxiety paradigms. Two groups of animals were studied: a control group with free access to water, and a 72-h water-deprived experimental group. Anxiety was studied in a water-deprived group or following a 10-min period of ad lib water drinking. An increase in the mean time of defensive burying in animals deprived for 72 h was observed, whereas an important reduction occurred in the levels of burying behavior immediately after the animals were allowed to drink ad lib for 10 min. These results suggest that the observed increase in defensive burying in the water-deprived animals represents an anxiogenic effect, whereas the decrease in this behavior in water-satiated animals is considered an anxiolytic action. The temporal course of reduction in burying behavior, observed after water drinking, revealed that the anxiolytic action lasts 5 min, whereas 15-30 min after drinking, burying behavior levels were similar to those in the control group. In the social interaction experiment a partial anxiogenic/anxiolytic effect of water deprivation and water intake was observed. The adaptive meaning of anxiogenic and anxiolytic changes linked to consummatory behaviors in rats is discussed on the basis of behavioral and biochemical data.     

Relation between food and water intake in the pigeon (Columba livia).

In 4 experiments with 40 male White Carneaux pigeons, continuous monitoring of feeding and drinking activity under ad-lib conditions showed that food and water intake were closely associated temporally with 70.0% of water intake occurring just prior to, during, and immediately following a meal. There was a significant positive correlation between 24-hr food and water intake. However, the association between food and water intake varied temporally during ad-lib and food-restriction schedules. Under ad-lib conditions, there was a significant correlation between food and water intake during a 2-hr period in the morning but not the afternoon. Likewise, when food was restricted for a 2-hr period in the morning, water intake was significantly correlated with food intake. During total food deprivation, drinking was primarily confined to the light portion of the light–dark cycle. Data suggest that the amount of water ingested as well as the temporal pattern of water intake is not solely dependent on food intake and may be determined by an underlying temporal rhythm of drinking. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of anorexia and behavioral activation in amphetamine-induced suppression of feeding: Implications for understanding tolerance.

48 male Sprague-Dawley albino rats administered chronic injections of either saline or dextroamphetamine (DAM) sulfate (2 or 4 mg/kg, intraperitoneally) were given milk either directly into the mouth through an intraoral cannula or in a standard drinking tube. Results reveal that bottle-fed Ss given DAM showed substantially greater suppression of intake than cannula-fed Ss. Saline-treated Ss showed almost identical milk intake with the 2 methods. Recovery of intake occurred in all drugged Ss except those given 4 mg/kg and fed by bottle. In the tolerant groups, Ss fed by bottle and given 2 mg/kg recovered at a faster rate than cannula-fed Ss at either dose. Findings demonstrate that in a normal drinking condition, the initial suppression of intake is caused by a combination of anorexia and behavioral interference and that tolerance occurs to both of these effects. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abdominal vagotomy inhibits osmotically induced drinking in the rat.

Results of a study with 35 male Sprague-Dawley rats show that after complete bilateral transection of the abdominal vagus (Vgx-C9), with the hepatic branch left intact, Ss drank later and less than normal after cellular dehydration induced by hypertonic saline. When access to water was delayed for 1 hr after cellular dehydration, Vgx-C Ss initiated drinking quickly with normal latency, but (a) a gastric water preload was a more effective stimulus for drinking suppression in Vgx-C than in normal Ss; (b) gastric emptying of a water or phenol red solution preload was more rapid in Vgx-C than in normal Ss; and (c) when gastric emptying dysfunction in Vgx-C Ss was removed by having Ss sham drink, Vgx-C and normal Ss sham drank equivalent amounts of water. Thus, disordered preabsorptive satiety caused by abnormally rapid gastric emptying of water was a factor in the decreased drinking of Vgx-C rats after cellular dehydration. Disordered satiety for ingested water could not, however, account for the abnormal latency to initiate drinking after cellular dehydration in Vgx-C rats. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyperactivity to quinine associated with osmotic thirst in the rat.

Studied cellular and extracellular fluid depletion in 5 experiments with Sherman female albino rats (N = 103). Drinking in response to cellular dehydration, but not in response to water deprivation, was severely disrupted by mild quinine adulteration of the drinking fluid. Cellular dehydration in conjunction with deprivation, although enhancing the intake of water, actually suppressed quinine intake. In contrast, intravascular fluid depletion added to water privation enhanced intake both of water and of quinine solutions. It is concluded that the heightened reactivity to quinine which accompanies cellular dehydration reflects a specific property of the osmotic-thirst mechanism. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orogastric, hydrational, and behavioral controls of drinking following water deprivation in rats.

Studied drinking and its associated behaviors in 168 female Sprague-Dawley rats deprived of fluid for 8, 24, or 48 hrs. The behavior of Ss drinking water could be divided into 3 successive stages: (a) an initial intense burst of drinking that could not be easily disrupted; (b) intermittent drinking, often distinguished by the brief appearance of conflict behavior directed at the drinking spout; and (c) termination of drinking. Drinking stopped well before the fluid loss, reflected in a sizable extracellular deficit, was restored. Intake of water was terminated when serum hyponatremia and hypoosmolality (and presumably cellular overhydration) developed in temporal continguity with drinking. These and other considerations suggest that the cellular fluid phase exerts significant inhibitory as well as excitatory control over drinking. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sucrose-water preference reversal in the water-deprived rat.

Exposed 4 water-deprived male albino Carworth rats to each of 3 preference conditions. When given a 15-min preference test between a 7.4% sucrose solution and water, Ss ingested 81-91% of their total fluid intake from the sucrose bottle. When given a choice between 1 lick of water and 1 lick of the sucrose solution, Ss consistently preferred water. To determine if this water preference was related to dehydration, Ss were allowed to drink water immediately before the 1-lick preference test. In general, water preference was inversely proportional to amount of pretest drinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of L-arginine on angiotensin II-related water and salt intakes

Nitric oxide (NO) has been implicated centrally as an inhibitory neuromodulator, acting in short feedback loops. Neurons capable of NO synthesis have been localized in various thirst-related hypothalamic nuclei. Intracerebroventricular (icv) injection of L-arginine (L-arg), the precursor for NO, has previously been shown to attenuate both dehydration- and angiotensin II (Ang II)-induced drinking behavior. The present study further examines the effects of L-arg on drinking. We confirmed that icv administration of L-arg (50 microg) reduced water intakes induced by both 24 h water deprivation and icv Ang II (250 ng). We additionally showed that L-arg inhibited the water intake induced by peripheral injection of Ang II and the intake of 0.3 M NaCl following 24 h sodium depletion. We demonstrated the behavioral specificity of L-arg treatment by showing that it did not inhibit the intake of sucrose in food deprived rats and did not act as an unconditional stimulus for the formation of a conditioned taste aversion. These results lend further support to the idea that NO plays a role in modulating fluid balance and drinking behavior.     

Increased alcohol drinking in isolate-housed alcohol-preferring rats.

Alcoholism is a complex disorder influenced by interactions between genetic and environmental risk factors. This study examined the influence of isolate housing on ethanol intake in alcohol-preferring (P) and non-alcohol-preferring (NP) rats. Rats were isolate-housed or pair-housed for 8 weeks when between 45 and 96 days old. Ethanol drinking was assessed using a 24-hr preference test (10% ethanol vs. water) and 20-min limited access tests. A behavioral test battery was used to assess anxiety-like, depressive-like, acoustic startle, and motor behavior. Isolate housing increased home cage drinking in both lines and increased limited access drinking selectively in P rats. Isolation also reduced swim test immobility and prepulse inhibition in P rats and increased locomotor stereotypies in NP rats. Taken together, these data demonstrate that Line × Environment interactions influence the effects of isolation. Furthermore, isolation selectively increased ethanol intake in high drinking P rats. This effect was not correlated with changes in other behaviors. Selective enhancement of limited access ethanol drinking in P rats may represent a model whereby genetic liability to excessive drinking is enhanced by specific environmental exposures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calcium and magnesium in drinking water and risk of death from rectal cancer

The possible association between the risk of rectal cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal-cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with a sample of deaths from other causes (986 controls), and the levels of calcium and magnesium in the drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes, and the controls were pair-matched to the cases by gender, year of birth and year of death. Compared with those with calcium levels below 22.0 mg/liter, the adjusted odd ratios (95% confidence interval) were 0.72 (0.53-0.98) for the group with water calcium levels between 22.0 and 40.8 mg/liter and 0.63 (0.45-0.87) for the group with calcium levels of 40.9 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and rectal cancer. The results of the present study show that there may be a significant protective effect of calcium intake from drinking water on the risk of rectal cancer.     

Calcium supplementation of hen drinking water

Two experiments with White Leghorn hens (42 and 56 wk old, respectively) examined the effects of calcium supplementation through drinking water in the presence of adequate and inadequate dietary calcium. Each experiment was of 28 d duration with six replicate pens of five individually caged hens in each treatment. Treatments were a combination of either 2.25 or 3.5% dietary calcium coupled with tap water or water supplemented with .2% calcium from calcium lactate. In both studies, specific gravity of eggs was significantly improved when low dietary calcium was supplemented with .2% calcium in the drinking water. Egg production and egg weight were not influenced by waterborne calcium. Daily water intake was reduced by calcium lactate in all cases. Feed consumption was also depressed by waterborne calcium in both studies when 3.5% dietary calcium was given, and in Experiment 1 when 2.25% was fed. Waterborne calcium as calcium lactate was found to be effectively utilized for eggshell quality improvement when dietary sources were inadequate.     

Differences in food, water, and food-deprivation water intake in 16 strains of rats.

Measured daily food and water intake during 24-hr food deprivation in 181 adult male rats of 15 inbred strains and 1 outbred stock of Rattus norvegicus. Strain differences in absolute and relative food intake were moderate but significant, whereas strain differences in absolute and relative water intake under both conditions were dramatic. During food deprivation, some strains showed little depression of daily water intake, while other strains consumed less than 20% of their usual ad lib intake. Both genetic and environmental explanations for the divergent patterns of water intake during food deprivation are presented. In light of such strain differences, generalizations about the drinking behavior or water intake regulation of the rat must be made with caution. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forebrain lesions differentially affect drinking elicited by dipsogenic challenges and injections of muscimol into the median raphe nucleus.

Injections of muscimol into the median raphe nucleus (MR) elicit intense drinking in normally hydrated rats. To determine whether this response is dependent on forebrain systems mediating other aspects of water intake, the authors examined the effects of lesions of the subfornical organ (SFO), median preoptic nucleus (MnPO), lateral preoptic area (LPO), or lateral hypothalamus (LH) on the drinking. Lesions of the SFO or LH attenuated muscimol-elicited drinking, whereas lesions of the MnPO or LPO increased water intake after the treatment. All of the lesion groups showed a deficit in drinking to injections of polyethylene glycol and at least one of the doses of hypertonic saline. Only the SFO- and LH-lesioned groups showed a suppression of drinking to systemic injections of angiotensin II, suggesting that the drinking elicited by intra-MR injections of muscimol may involve changes in the central circuits mediating angiotensin-induced drinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schedule-induced polydipsia: Effect of water temperature, ambient temperature, and hypothalamic cooling.

Conducted 3 polydipsia experiments with a total of 26 female Sprague-Dawley rats, 6 of which were implanted with thermodes and thermistors and 2 of which were implanted with thermistors alone in the medial preoptic area or posterior hypothalamus. A cold (5.C) ambient temperature reduced the amount of water consumed by food-deprived Ss tested with a VI schedule of reinforcement, while a warm (30.C) ambient increased water intake. Response rate in the cold was twice that in a neutral temperature. A hot (38.C) ambient suppressed the rate of responding and drinking. Cooling the hypothalamus substantially reduced water intake in a neutral ambient temperature. Ambient temperature affected the volume of a drink but not the frequency of drinking, while hypothalamic cooling affected both volume and frequency. Water temperature had little effect on polydipsia although less cold water was consumed than warm water. It is concluded that schedule-induced polydipsia is a temperature-dependent phenomenon. (39 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in self-stimulation at stimulation-bound eating and drinking sites in the lateral hypothalamus during food or water deprivation, glucoprivation, and intracellular or extracellular dehydration.

Examined the effects of hunger induced by food deprivation, 2-deoxy-{d}-glucose (200 mg/kg), or insulin (2 U/kg) and thirst induced by water deprivation, sodium chloride (4 M), or polyethylene glycol (5 ml of 30% w/w) on lateral hypothalamic self-stimulation in 40 male Long-Evans rats. Changes in self-stimulation were evaluated at electrodes that produced stimulation-bound eating and/or drinking or neither behavior. Daily 30-min test sessions consisted of 3 5-min periods of self-stimulation alternated with 3 5-min periods when barpresses resulted in 5-sec time-out from experimenter-delivered stimulation (stimulation escape). Food deprivation significantly increased self-stimulation; insulin, 2-deoxy-{d}-glucose, and sodium chloride significantly suppressed self-stimulation; water deprivation mildly inhibited self-stimulation; and polyethylene glycol had no effect. This pattern of findings was noted at electrodes that did and those that did not elicit eating and/or drinking. Findings do not support the hypothesis that the magnitude of lateral hypothalamic self-stimulation is differentially and predictably controlled by specific drive mechanisms indexed by the consummatory behaviors also elicited by the stimulation. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Independent effects of estradiol on water and food intake.

Conducted 6 experiments to examine the effects of estradiol on ingestive behaviors of guinea pigs. Estradiol treatment was found to reduce water intake independently of its actions on food intake and body weight. In the 1st experiment, minimum intake and body weight of 17 intact female guinea pigs coincided with rupture of the vaginal membrane, the estimated time of ovulation. In Exp II, injections of 3 μg of estradiol benzoate (EB)/day to 7 ovariectomized females significantly depressed food intake, water intake, and body weight, compared with 7 Ss that received oil injections. Reducing food rations to 30% below ad lib levels in Exp III by itself had no significant effect on drinking in ovariectomized Ss. In Exp IV, therefore, ovariectomized females were first placed on a food ration 30% below ad lib levels and then injected daily with either 3 μg of EB or oil. Compared with oil injections, these EB injections significantly reduced water intake, while food intake did not decline significantly. Findings indicate that estradiol operates through different mechanisms to affect water intake and food intake. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial septal lesions: Disruptions of microregulatory patterns and circadian rhythmicity in rats.

Examined the microregulatory patterns of food and water intake in 10 male and 10 female Long-Evans rats bearing medial septal lesions and in sham-operated controls. Medial septal ablation, although not affecting the total amount of food or water ingested, resulted in a profound disruption of the pattern of intake. Circadian rhythmicity was disrupted for a period, returning to normal by 25 days postlesion. Permanent disruptions occurred in feeding patterns in that Ss with septal lesions ingested more frequent but smaller meals. There was also a marked increase in food-intake-associated drinking and a decrease in non-food-intake-associated drinking. Results reflect 2 separate independent effects, a general circadian disruption and an alteration in regulatory behavior produced by a chronic depletion of body fluid. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of 6-hydroxydopamine lesions of the nucleus accumbens septi and olfactory tubercle on feeding, locomotor activity, and amphetamine anorexia in the rat.

In Exp I with 24 male albino Wistar rats, bilateral 6-hydroxydopamine lesions of the nucleus accumbens septi (NAS) and olfactory tubercle (OT) caused enhanced intake of wet mash in 23-hr-food-deprived Ss tested in photocell activity cages during restricted 30-min sessions. This mild hyperphagia was accompanied by a significant hypoactivity in the group with NAS/OT lesions. No hyperphagia was observed during a prolonged 120-min test session or in free-feeding tests conducted in the home cage. Anorexia induced by dextroamphetamine (.5 and 1.5 mg/kg) was unaltered by the lesion, although the locomotor stimulant action of the drug was attenuated. Results of Exp II, with 36 Ss, show that the NAS/OT lesion also enhanced food intake in the photocell cages during 30-min sessions with dry food pellets but that food-associated drinking was concomitantly reduced. Results are consistent with the hypothesis that the behavioral changes caused by mesolimbic neuron destruction result in part from an inability to switch from one behavioral activity to another. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transforming growth factor-betas and their signaling receptors are coexpressed in Crohn's disease

Two studies were performed to examine the influence of fasting and food intake on the absorption and retention of nickel added to drinking water and to determine if nickel sensitization played any role in this regard. First, eight nonallergic male volunteers fasted overnight before being given nickel in drinking water (12 micrograms Ni/kg) and, at different time intervals, standardized 1400-kJ portions of scrambled eggs. When nickel was ingested in water 30 min or 1 h prior to the meal, peak nickel concentrations in serum occurred 1 h after the water intake, and the peak was 13-fold higher than the one seen 1 h after simultaneous intake of nickel-containing water and scrambled eggs. In the latter case, a smaller, delayed peak occurred 3 h after the meal. Median urinary nickel excretion half-times varied between 19.9 and 26.7 h. Within 3 days, the amount of nickel excreted corresponded to 2.5% of the nickel ingested when it was mixed into the scrambled eggs. Increasing amounts were excreted as the interval between the water and the meal increased, with 25.8% of the administered dose being excreted when the eggs were served 4 h prior to the nickel-containing drinking water. In the second experiment, a stable nickel isotope, 61Ni, was given in drinking water to 20 nickel-sensitized women and 20 age-matched controls, both groups having vesicular hand eczema of the pompholyx type. Nine of 20 nickel allergic eczema patients experienced aggravation of hand eczema after nickel administration, and three also developed a maculopapular exanthema. No exacerbation was seen in the control group. The course of nickel absorption and excretion in the allergic groups did not differ and was similar to the pattern seen in the first study, although the absorption in the women was less. A sex-related difference in gastric emptying rates may play a role. Thus, food intake and gastric emptying are of substantial significance for the bioavailability of nickel from aqueous solutions.