Angiotensin and salt appetite: Physiological amounts of angiotensin given peripherally increase salt appetite in the rat.

In 2 experiments, adrenalectomized male Sprague-Dawley rats were maintained ad lib on distilled water, 3% saline, and sodium-free food. In Exp I, 45 Ss were given desoxycorticosterone acetate (DOCA [.1–2 mg/kg/day, intramuscularly]) for 5 days to determine the dose of DOCA that would produce the lowest voluntary saline intake, and 800 μg/kg/day was found to produce the nadir in saline intake. In Exp II, 40 Ss were placed ad lib on distilled water, saline, and sodium-free food as described above, maintained on 800 μg/kg/day DOCA, and infused with 4, 25, or 100 μg/kg/day angiotensin II (AII) or 0.9% saline. The 3 AII groups showed significant percentage changes in their saline intake above pre-AII levels; the saline control group showed no change in saline intake from pre-AII level. Results demonstrate the production of salt appetite in rats by peripheral administration of physiological doses of AII. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subfornical organ participates in salt appetite.

The effects of subfornical organ (SFO) lesions on salt and water intakes after sodium depletion were studied. Water and salt intakes were measured over 45 hr during a regimen that combined furosemide diuresis and access to low-sodium diet. Water was solely available for 23 hr after diuresis, and water and 0.3 M NaCl solution were available in choice for the next 22 hr. After diuresis, rats with SFO lesions drank significantly less water in 2 hr than controls but achieved equivalent water and sodium balances before salt access 20 hr later. After salt access, rats with SFO lesions drank significantly less saline and water in 2 hr than controls but had similar saline and water intakes over the next 20 hr. Thus, SFO lesions blunted acutely, but not chronically, saline and water intakes to sodium depletion, and the blunted intakes are not explainable by hydrational status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preoptic angiotensin and salt appetite.

Two experiments were designed to test whether angiotensin (ANG) synthesis or receptor activation in the ventral preoptic region is critical for ANG-induced salt appetite in rats. In Experiment 1, infusions of ANG into the subfornical organ (SFO) produced water drinking without saline intake, but infusions near the organum vasculosum laminae terminals (OVLT) produced both water and saline drinking. Thus, forebrain areas that support water drinking to ANG do not all support salt appetite. In Experiment 2, rats were given oral captopril (CAP) to enhance daily intake of water and saline solution by increasing ANG II synthesis in the brain. CAP microinjected into the SFO reduced CAP-enhanced water drinking without affecting saline intake, but CAP in the OVLT reduced enhanced saline intake without affecting water drinking. Thus, ANG acting in the OVLT, the most ventral part of the median preoptic nucleus, or other nearby structures is important for ANG-induced saline appetite. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory effects of estrogen on stimulated salt appetite in rats.

Adult male rats consumed 50–250% more 0.5 M NaCl solution than females did during a 7-hr drinking test when robust salt appetite was elicited by dietary sodium deprivation for 8 days, daily injections of deoxycorticosterone, or adrenalectomy followed by 2 days of sodium deprivation. In contrast, male rats drank much less saline after systemic treatment with the natriuretic agent furosemide, adrenalectomy followed by 1 day of sodium deprivation, or subcutaneous/ly (sc) treatment with colloid solution after 2 days of sodium deprivation, and female rats drank comparably small volumes. Conversely, 30-day-old prepubescent male and female rats showed equally robust salt appetites after 8 days of sodium deprivation. These and other findings support an inhibitory role of estrogen on salt appetite in rats, which appears to occur only when the appetite is especially pronounced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery of salt appetite after lateral hypothalamic lesions: Effects of preoperative salt drive and salt intake experiences.

75 male mongrel rats were divided into lateral hypothalamic (LH)-lesion or intact control groups. The LH-lesion groups (1) had no salt experience prior to induction of lesions, (2) had experience of both salt drive and saline intake, (3) had salt drive but no saline experience, or (4) had no salt drive experience but saline intake experience. Results confirm earlier findings that preoperative salt experiences can protect the rat against the usual deficit in regulatory salt intake that follows such lesions. However, results suggest that there may be no specific feature of the preoperative salt experience that is critical for the protective effect, since both salt drive experience without concomitant salt intake experience and salt intake experience without concomitant salt drive experience were effective. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interaction of hydration and subfornical organ lesions in sodium-depletion induced salt appetite.

The authors tested whether the level of hydration after furosemide diuresis and 22 hrs of sodium depletion affects the amount of water or 0.3 M NaCl solution consumed by rats with intact brains or with lesions of the subfornical organ (SFO). Rats received 2 (underhydrated) or 10 (euhydrated) ml/kg water by gavage as the only fluid input 2, 4, and 20 hrs after 10 mg/kg furosemide. These hydration treatments had little or no effect on the amount of saline consumed in 2 hrs by intact rats. SFO lesions reduced water intake regardless of hydration condition. Euhydrated, SFO-lesioned rats drank a normal amount of saline, but underhydrated, lesioned rats drank less saline than any other group. Thus, euhydration may facilitate salt appetite in SFO-lesioned rats, and the deficits in salt appetite noted in SFO-lesioned rats may result from deficits in water ingestion rather than from a destruction of angiotensin II receptor sites that directly provoke salt appetite. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypnosis, verbal satiation, vigilance, and personality factors.

62 postgraduate students were subjected to tests of auditory vigilance, verbal satiation, and hypnosis and later filled out the Maudsley Personality Inventory (MPI) and the Personal Friends Questionnaire (measuring rigidity). Positive correlations were obtained between hypnosis and low verbal satiation (r =.667) and low verbal satiation and errors in vigilance r =.757). A significant biserial r of .40 was obtained between errors in vigilance and hypnosis. Hypnosis was negatively correlated (r =-.436) with MPI Lie scores and positively with rigidity (r =.514). (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Refined salt appetite methodology for rats demonstrated by assessing sex differences.

Describes a refined method for inducing and measuring salt appetite for studying behavioral and neurological functions. The efficiency and reliability of the procedures were demonstrated by parametric studies comparing the appetite behaviors of male and female rats. The method for inducing salt appetite coupled 2 days of dietary sodium deprivation with a brief diuretic treatment. The measurement procedure involved a 2-hr period of access to one of several NaCl solutions differing in palatability or concentration. The induction procedure allowed precise control of drive levels, and the measurement procedure yielded highly reliable results as a function of the properties of the incentives. 32 female mongrel rats consistently ingested about twice as much NaCl solution as did 32 male Ss, regardless of the palatability of the solution or of body sodium levels. At the same time, female Ss lost less sodium in urine following diuretic treatment. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethanol-induced changes in plasma proteins, angiotensin II, and salt appetite in rats.

Sodium depletion in rats elicits a sodium appetite that results from a cerebral action of angiotensin II (ANG II) and aldosterone. Alcohol also activates the renin-angiotensin system, but the mechanism is poorly understood and not related to sodium excretion. In this study, 2.5 g/kg intraperitoneal/ly (ip) ethanol produced a 20% decline in plasma volume and plasma protein concentration 1–2 hrs and elicited salt appetite beginning in 3–4 hrs. Blockade of ANG II synthesis in the brain and periphery with the angiotensin-converting enzyme inhibitor captopril eliminated the thirst and salt appetite. Peripheral captopril alone enhanced fluid intake, which indicated that alcohol elevated renin secretion. Ethanol-induced suppression of hepatic plasma protein secretion and the consequent fall in plasma colloid osmotic pressure apparently resulted in hypovolemia and renin secretion, which then produced thirst and salt appetite through an action of ANG II on the brain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preoperative latent place learning preserves salt appetite following damage to the central gustatory system.

Points out that rats given the experience of tasting saline before receiving lesions in the region of the thalamic taste relay are protected from the usual lesion-induced deficits in salt appetite. In the present study with 48 male Sprague-Dawley rats, the location of the saline during postoperative testing was varied from the location during preoperative training for some Ss and kept the same for others. A clear protective effect was evident when the preoperative and postoperative locations were the same but not when they were different. This protective effect may be due to place learning because it is known that rats can remember tasting saline in a particular place and then return there when in a state of sodium need. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Forebrain sites of action for drinking and salt appetite to angiotensin or captopril.

Three-hour infusions of angiotensin II (ANGII) agonists and antagonists were used to determine the relative sites of action of ANG in producing water drinking and salt appetite. In the first experiment, lateral ventricular (LV) but not fourth ventricular (4V) ANG II elicited water and saline intake, and LV but not 4V sarile, a competitive ANG II receptor blocker, reduced saline intake aroused by ip injections of 10 mg/kg furosemide and 6 mg/kg captopril. In the second experiment, water, but not saline, intake to furosemide-captopril treatment was reduced by sarile infusions into the subfornical organ (SFO). It is concluded that (a) brain ANG receptors for water and saline intakes are more accessible from the forebrain than the hindbrain ventricles and (b) receptors for water drinking, but not saline intake, after captopril reside in part in the SFO. Salt appetite appears to be dependent on ANG II receptors somewhere in the forebrain other than in the SFO. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal satiation and personality.

"The following hypotheses were confirmed: 1. Prolonged visual exposure of a stimulus word results in a word association response less common than that elicited under brief exposure. 2. Individuals categorized as 'impermeable' (sensitive, imaginative, extravert) and 'impermeable' (less sensitive to stimuli, rigid, withdrawn, introvert) differ with respect to satiation effects. The results are congruent with a response probability theory of conceptual processes." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further studies on salt appetite following lateral hypothalamic lesions: Effects of preoperative alimentary experiences.

Lateral hypothalamic lesions impair salt appetite, but rats with lesions show enhanced saline ingestion following natrorexigenic treatments if given preoperative salt drive experiences. In the present study, with 118 male Holtzman rats, the preoperative drive to ingest salt (without the consummatory experience of saline ingestion) was found to be both necessary and sufficient for this effect. Exposure to saline, or the treatments of water deprivation or insulin-induced feeding, were not protective when given preoperatively. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verbal satiation and the role of concurrent activity.

2 studies, including 16 Ss in each, were performed to investigate the effect of concurrent activity on the maintenance of word meanings (verbal satiation). It was found, in both studies, that words repeated with activity maintained their meanings significantly longer than words repeated without activity. Word meaning maintenance was also found to relate to the kind of concurrent activity: words were more facilitated by actions customarily paired with them (e.g., push with pushing activity) than by actions not customarily paired with them. In addition, results indicated that a word could be maintained longer when the concurrent activity included (Experiment II) the added sensory input of vision. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social deprivation and stimulus satiation in the albino rat.

Conducted 2 experiments, with a total of 288 male Sprague-Dawley albino rats, to explore the mechanisms whereby social deprivation leads to increased sociability in rats. Exp I housed Ss alone or in pairs with additional nonsocial stimulation, with additional response opportunities, or with no added social surrogates for 3 wks prior to testing for sociability. Social deprivation led to a strong increase in sociability, and this was not ameliorated by stimulus or response enrichment. Exp II exposed alone or pair-housed Ss to handling, human contact, or no stimulation and found that human exposure did serve a social surrogate function. This result suggests that sociability in rats represents to some degree a search for complex and unpredictable stimulation. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensitization of salt appetite is associated with increased "wanting" but not "liking" of a salt reward in the sodium-deplete rat.

To examine the role of incentive sensitization in the potentiation of salt appetite by prior depletions, the authors assessed the motivation to obtain salt ("wanting") and the palatability of salt ("liking") independently in salt-sensitized rats. Breakpoint on a progressive ratio reinforcement schedule was used to measure salt wanting and taste reactivity was used to measure salt liking in rats with and without a history of Na+ depletion. Salt-sensitized rats displayed higher breakpoints relative to controls. However, a history of Na+ depletion was not associated with a greater positive shift in taste reactivity measures. The data suggest that these components of reward are separable in this model and support the general proposition that sensitization may alter wanting but not liking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationships between individual differences in salt appetite of sheep and their plasma electrolyte status

A pasture was prepared so that an equilibrium of fresh and ageing eggs of Taenia hydatigena was present. This was done by placing dogs with patent infections on it for six months. Five months after their introduction, groups of lambs were grazed there for two, four, eight, 16 or 32 days. The dogs were then removed. Three and six months later, further groups of sheep were grazed there for a similar period. The infection pressures and the indices of clustering of the eggs were calculated by an examination of the lambs for cysts at autopsy. When the dogs were present, the daily rate of infection was about 60 per cent of the flock. This was reduced to 6.5 per cent then to 3.5 per cent within three and six months respectively after their removal. Very high cyst counts were obtained in some animals and the indices of dispersion diverged from a Poisson model during the period when the lambs were maintained on the pasture in the presence of the dogs. There was a trend for a reduction in the mean cyst counts and the index of dispersion tended to conform more closely to a Poisson model the longer the dogs were excluded. There was also a corresponding reduction in the survival rate of the cysts. It was suggested that an asymptote of less than 100 per cent in the prevalence rate may be accounted for by the acquisition of resistance without the persistence of infection and this was induced in some animals by the initial ingestion of ageing organisms which gradually formed the predominant type after the removal of the dogs from the pasture.     

Full expression of the exaggerated salt appetite of the spontaneously hypertensive rat requires a prenatal factor

1. The spontaneously hypertensive rat (SHR) exhibits a lower bodyweight in utero and an exaggerated salt appetite post partum. To determine whether salt appetite is affected by the perinatal environment, we measured the salt appetite of embryo-cross-transferred SHR and Wistar Kyoto (WKY) rats at maturity. 2. One-cell embryos were collected from the oviducts of donor rats and transferred into the oviducts of recipients through the infundibulum. The salt appetite of the resultant female offspring for 0.10 and 0.15 mol/L saline was measured at 20-30 weeks of age. 3. Salt intake of SHR gestated in WKY rats was significantly lower than that of SHR gestated in SHR, while that of WKY rats gestated in SHR was higher than that of WKY rats gestated in WKY rats. 4. Therefore, some maternal factor plays a role in the development of the exaggerated salt appetite of the SHR. This factor is also able to affect the later salt appetite of WKY rat offspring born to SHR surrogates.     

The present status of the Kohler-Wallach theory of satiation.

The purpose of this review is to bring together all of the research on satiation theory with particular emphasis on the apperception of the brain-damaged. Figural aftereffects are explained by the theory of satiation, however, "it does less well when it moves into the field of ambiguous and hidden figures, apparent motion, and autokinesis, and breaks down or leads to absurdities when used as a complete explanation of the perception of the brain-damaged." Several suggestions for further research using the theory of satiation are made. 106-item bibliography. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sodium appetite in lactating rats.

Lactating rats that were given free access to sodium-deficient food, water, and 0.51 M NaCl solution showed no evidence of sodium appetite. The estimated daily loss of 1–2 mEq Na in milk was replaced by basal daily intake of 2–5 ml of saline. Sodium loss in urine was minimal, but milk sodium concentration was unchanged, and pups grew normally. Saline intake was enhanced when lactating rats that had been maintained on standard laboratory chow were injected with 30% polyethylene glycol solution to reduce plasma volume but no more so than when virgin female rats or male rats were similarly colloid-treated. Lactating rats markedly increased their intake of NaCl solution after simply depriving them of dietary sodium for 4 days, whereas male and virgin female rats did not. These findings indicate that pronounced sodium appetite does not invariably accompany lactation in rats, although it can occur whenever such animals become hypovolemic or sodium deficient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)