Views of diverse primary care patients on the roles of healthcare providers and staff and the influence of other variables in their weight management.

The prevalence of overweight/obesity is disproportionately higher among racial/ethnic minority and low-income patients. The purpose of this study was to survey racially diverse, low-income patients regarding their experiences with and desires regarding their providers' involvement in weight management. Adult patients (N = 529), including mostly African American (42.7%), White (44.6%) and low-income (55.5% with incomes <$30 000) patients from 7 Patient-Centered Medical Homes voluntarily completed a brief anonymous survey while waiting to see their providers. Only 19.8% of the patients said that their primary care provider frequently or very frequently talked with them about their weight. Older patients as compared to younger patients, as well as males compared to females, were more likely to have their primary care provider talk to them about their diet and physical activity during the last year. It was also found that 56.9% of the patients were interested in getting help from their doctor to connect with resources for weight management in their community. African American patients, as compared to White patients, were more interested in getting such help. These results suggest that there is a need to establish healthcare policies and training in primary care settings that are designed to ensure that primary care providers routinely talk with all of their patients, including their female and older patients, about their weight and weight management services. Additionally, primary care administrators need to play an increased role in identifying, developing, and advocating for affordable weight management services, particularly in African American and low-income communities.

Effect of high-fat diet on stress responsiveness in borderline hypertensive rats.

Stress in combination with genetic susceptibility is a factor in the development of hypertension. We used borderline hypertensive rats to investigate whether exposure to high-fat and/or junk-food diet at different stages of ontogeny has programing consequences on stress responses. Wistar dams were fed a high- or low-fat diet for 6 weeks prior to mating with spontaneously hypertensive males, and during gestation. At birth, litters were fostered either to a dam in the same or an alternative diet condition as during gestation. After weaning, male offspring were fed either a control-chow diet or an intermittent junk food fatty diet. Between postnatal days 57-61, half of the rats in each dietary group received daily social defeat sessions using a resident-intruder protocol, and the other half were unstressed controls. Blood pressure was measured indirectly both before and after each defeat session. On the final day, rats were killed for physiological measures. Socially defeated rats showed large increases in serum corticosterone concentration and adrenal hypertrophy, indicating the effectiveness of this non-adapting stressor. Serum corticosterone level was also higher in rats fed with the junk-food diet post-weaning compared with those fed with chow only, but there were no significant effects of gestational or lactational dietary history.

Matching salt intake to physiological need in rats using foraging protocols

Several studies of the quantitative relationship between sodium need and sodium intake in rats are reviewed. Using acute diuretic treatment 24 h beforehand, intake matches need fairly accurately when intake is spread out in time by using a hypotonic solution of NaCl. In contrast, using a hypertonic solution, intake is typically double the need. Using the same diuretic treatment, although the natriuresis occurs within ~1 h, the appetite appears only slowly over 24 h. Increased plasma levels of aldosterone parallel the increased intake; however, treatment with metyrapone blocks the rise in aldosterone but has no effect on appetite. Satiation of sodium appetite was studied in rats using sodium loss induced by chronic diuretic treatment and daily salt consumption sessions. When a simulated foraging cost was imposed on NaCl access in the form of a progressive ratio lever press task, rats showed satiation for NaCl (break point) after consuming an amount close to their estimated deficit. The chronic diuretic regimen produced hypovolemia and large increases in plasma aldosterone concentration and renin activity. These parameters were reversed to or toward non-depleted control values at the time of behavioral satiation in the progressive ratio protocol. Satiation mechanisms for sodium appetite thus do appear to exist. However, they do not operate quantitatively when concentrated salt is available at no effort, but instead allow overconsumption. There are reasons to believe that such a bias toward overconsumption may have been beneficial over evolutionary time, but such biasing for salt and other commodities is maladaptive in a resource-rich environment.

Matching salt intake to physiological need in rats using foraging protocols.

Several studies of the quantitative relationship between sodium need and sodium intake in rats are reviewed. Using acute diuretic treatment 24 h beforehand, intake matches need fairly accurately when intake is spread out in time by using a hypotonic solution of NaCl. In contrast, using a hypertonic solution, intake is typically double the need. Using the same diuretic treatment, although the natriuresis occurs within approximately 1 h, the appetite appears only slowly over 24 h. Increased plasma levels of aldosterone parallel the increased intake; however, treatment with metyrapone blocks the rise in aldosterone but has no effect on appetite. Satiation of sodium appetite was studied in rats using sodium loss induced by chronic diuretic treatment and daily salt consumption sessions. When a simulated foraging cost was imposed on NaCl access in the form of a progressive ratio lever press task, rats showed satiation for NaCl (break point) after consuming an amount close to their estimated deficit. The chronic diuretic regimen produced hypovolemia and large increases in plasma aldosterone concentration and renin activity. These parameters were reversed to or toward non-depleted control values at the time of behavioral satiation in the progressive ratio protocol. Satiation mechanisms for sodium appetite thus do appear to exist. However, they do not operate quantitatively when concentrated salt is available at no effort, but instead allow overconsumption. There are reasons to believe that such a bias toward overconsumption may have been beneficial over evolutionary time, but such biasing for salt and other commodities is maladaptive in a resource-rich environment.

Brain ethanol levels in rats after voluntary ethanol consumption using a sweetened gelatin vehicle.

A novel procedure for initiation of voluntary ethanol consumption in the rat was evaluated in terms of ease of initiation, consistency, and resulting brain ethanol levels. The "jello shot" consists of 10% ethanol in gelatin along with a caloric source (Polycose). Initiation of "jello shot" consumption in Sprague-Dawley rats required no food or water restriction and resulted in initial daily (8.4+/-0.6 g/kg body weight) and eventual hourly (1.1+/-0.1 g/kg body weight) intake of ethanol comparable to other procedures using either alcohol-preferring or non-genetically selected rats. Rat intake of ethanol via "jello shots" recovered quickly from environmental alterations and surgical implantation of a guide cannula. During 1-h free access sessions, consumption of the "jello shot" occurred during the initial 10 min and resulted in a dose-related increase in ethanol levels in nucleus accumbens measured using microdialysis. These brain ethanol levels were comparable to those achieved using other self-administration methods. However, when 0.5 g/kg ethanol was gavaged either in "jello shot" or saline, there was about a 20% decrease in brain ethanol concentrations after gavage of the "jello shot" compared to saline. Even so, lack of a need for initial food or water deprivation and the rapidity with which stable self-administration can be achieved both suggest utility of the "jello shot" as a completely voluntary ethanol procedure.

Effects of oral preload, CCK or bombesin administration on short term food intake of melanocortin 4-receptor knockout (MC4RKO) mice.

We investigated whether either heterozygous (HET) or homozygous (knockout, KO) disruption of the melanocortin type 4 receptor (MC4R) gene alters post ingestive responsiveness of mice. Specifically, we tested the hypothesis that hyperphagia in MC4RKO mice might be due to a deficit in processes that sustain intermeal intervals (satiety) and/or processes that terminate ongoing episodes of eating (satiation). To test satiety, mice drank an oral preload and then we monitored intake of a subsequent liquid diet test meal. To test satiation, we examined the effect of exogenous administration of cholecystokinin (CCK) and bombesin (BN) on the size of a liquid diet meal. Experiment 1 was comprised of two studies. In the first, we determined that the intake of all three genotypes following fasts of either 6, 12, or 24h were comparable, and so chose 12h deprivation for the subsequent studies. In the second, 12h fasted mice were allowed to consume a fixed preload, approximately 50% of their expected mean intake and, following delays of either 30 or 60 min, were allowed to consume to satiation. Compared with no preload, the preload significantly reduced meal size comparably in all three genotypes. The reduction in intake was greater when the test meal was presented 30 compared with 60 min after the preload, again with no genotype differences in this decay of satiety. In experiment 2, we administered either CCK or BN and examined suppression of meal size after a 12h fast. Mice were tested repeatedly with CCK-8 (2, 6, or 18 microg/kg ip) or BN (2, 4 or 8 microg/kg ip) with vehicle injection days intervening. The 30 min intakes of HET and KO mice were suppressed more than those of WT following either CCK or BN. These experiments suggest that diminished responsiveness to nutrients or gut satiety hormones is not responsible for hyperphagia in MC4RKO mice.

Food motivated behavior of melanocortin-4 receptor knockout mice under a progressive ratio schedule.

Melanocortin-4 receptor knockout (MC4RKO) mice are hyperphagic and develop obesity under free feeding conditions. We reported previously that MC4RKO mice did not maintain hyperphagia and as a result lost weight when required to press a lever to obtain food on a fixed ratio procurement schedule. To assess the generality of this result, we tested MC4RKO mice and their heterozygous and wild type littermates using progressive ratio (PR) schedules that are believed to be sensitive indicators of motivation. Mice lived in operant chambers and obtained all of their food (20mg pellets) via lever press responding. Food was available according to a PR schedule so that within a meal, food became progressively more costly, and we expected this would provide a stringent test of mechanisms controlling meal size. The schedule reset after either 3 or 20min of no responding, so defining meals, and the highest ratio completed before the reset was defined as the breakpoint. The average daily number of meals was lower and mean size of meals was higher at the 20 compared with the 3min reset condition. Mean daily food intake did not differ between the two reset criteria but did differ as a function of genotype, with MC4RKO mice eating about 25% more than heterozygous or wild type mice. Hyperphagia in the MC4RKO mice was characterized primarily by larger meals (higher breakpoints) and they emitted about twice as many responses as wild type mice. Thus, using a PR schedule, MC4RKO mice exhibit hyperphagia, and show a high level of motivation to support large meal sizes.

Meal patterns and foraging in melanocortin receptor knockout mice.

We report the meal patterns of mice with the deletion of either the melanocortin type 3 or 4 receptors (MC3RKO or MC4RKO) compared with that of the wild type (WT) under conditions of varying foraging costs. Mice lived in two-lever operant chambers; the completion of a designated number of responses (termed procurement fixed ratio or PFR) on the "foraging" lever activated the other lever. On this second lever, the completion of a designated number of responses (termed consumatory fixed ratio or CFR) caused the delivery of a 20-mg food pellet. Animals could complete as many CFRs as they wished to constitute a meal, but whenever 10 min elapsed without pressing on this second lever, the meal was terminated and pressing on the "foraging" lever was again required to initiate a new meal. At lower PFRs, mice of all three genotypes took 5-7 well-defined meals per day of approximately 35 pellets/meal. At the highest PFR, mice of all three groups took about half this number of meals, with some increase in meal size, and total intake was slightly reduced. MC4RKO mice were obese compared with WT or MC3RKO but failed to eat more food in the operant chambers and, as a consequence, lost weight, regardless of PFR. Thus, changes in meal-taking strategies as a function of imposed foraging cost are not critically dependent on either MC3 or MC4 receptors, but these conditions did not allow us to study meal patterns in MC4RKO mice that are hyperphagic.

Acute anorectic effect of single and combined drugs in mice using a non-deprivation protocol.

RATIONALE: Studies of the effect of anorectic drugs such as fenfluramine in mice have indicated the desirability of using experimental protocols that do not involve deprivation. OBJECTIVE: We have developed a non-deprivation or "dessert" protocol for use in mice that are maintained in standard housing conditions, and examine the effects of a serotonergic agent dexfenfluramine (DFEN), a dopaminergic agent phentermine (PHEN), and a selective norepinephrine uptake inhibitor thionisoxetine (TNIX) alone and in combination. METHODS: Female C57BL/6J mice were adapted to 30 min daily presentation of a gelatinized form of sweetened milk using a holder that hooks over the side of the cage during tests; food spillage and contamination are minimal. Dose-inhibition curves were determined for DFEN, PHEN, and TNIX alone and for fixed ratio combinations of DFEN with either PHEN or TNIX. RESULTS: Each drug produced a near linear dose-inhibition curve with the 50% inhibitory doses (DI50) of 5.6, 3.2 and 12.2 mg/kg, respectively. By isobolographic analysis, the effects of the drug combinations were strictly additive. CONCLUSION: The procedure described is highly suitable for testing anorectic drugs in mice and is adaptable to a variety of housing conditions and diets. The DFEN+ PHEN combination was additive, which contrasts with its reported supra-additive effect in rats.

Cross tolerance between anorectic action and induction of Fos-ir with dexfenfluramine and 5HT1B/2C agonists in rats.

RATIONALE: We have shown that the anorectic effect of dexfenfluramine (DFEN), an agent that acutely increases synaptic availability of serotonin (5-HT), shows complete tolerance after 2-3 prior applications when using acute feeding protocols and low dosages. It is unlikely this is due to either accumulative weight loss or presynaptic 5-HT depletion. In this study, we examined the possible contribution of 5-HT1B/2C receptors to behavioral tolerance by testing for cross tolerance between DFEN and the 5-HT1B/2C receptor agonists, m-chloro- and trifluoromethyl-substituted phenylpiperazines (mCPP and TFMPP). Additionally, we sought neuronal correlates of the behavioral changes by study of the induction of Fos-like immunoreactivity (ir) in discrete brain regions. METHODS: Sprague-Dawley rats received two or three pre-injections, at 2-day intervals, of 2 mg/kg DFEN or vehicle. The rats were then food deprived for 24 h and, 30 min prior to a 1-h feeding test, received a s.c. injection of either DFEN, TFMPP (1 mg/kg), or mCPP (2 mg/kg). Additional groups received mCPP preinjections and test injection of either DFEN or mCPP. Rats in Fos-ir studies received similar injection regimens but were not food deprived and were perfused 1.5 h after the test injection. RESULTS: DFEN-pretreated rats showed complete anorectic tolerance to DFEN, TFMPP, and mCPP. However, rats given this regimen of mCPP pretreatment were tolerant to neither mCPP nor DFEN. Fos-ir induced by DFEN in each brain region examined was either significantly reduced or abolished by prior DFEN injections. TFMPP induced less Fos-ir in these regions than DFEN and this was attenuated by prior DFEN. CONCLUSIONS: The behavioral data indicate that tolerance to DFEN anorexia is mediated partially or completely by functional subsensitivity at 5-HT1B and/or 5-HT2C receptors. The brain regions implicated include the paraventricular hypothalamus, medial striatum, lateral parabrachial nucleus, and nucleus of the solitary tract.

Anorectic effect of dehydroepiandrosterone combined with dexfenfluramine or thionisoxetine.

Free feeding rats given supplementary 1 h access per day to a palatable dessert test meal were tested for the anorectic effect of dehydroepiandrosterone alone or in combination with either the serotonin releasing agent dexfenfluramine or the norepinephrine uptake inhibitor thionisoxetine (LY 368975). Isobolographic analysis showed that the effect of dehydroepiandrosterone combined with either dexfenfluramine or thionisoxetine was within the range predicted for additivity of action.

Perinatal dietary NaCl level: effect on angiotensin-induced thermal and dipsogenic responses in adult rats.

We have shown previously that administration of angiotensin II (Ang II) produces an apparent decrease in thermoregulatory set point. Exposure to high salt diets either perinatally or later in life has been shown to increase pressor responsiveness to administration of Ang II, so in the present studies we examine whether high dietary NaCl would also increase the thermal responsiveness to Ang II. In the first study, we show that exposure to a basal NaCl diet (0.12%) during gestation through 4 weeks postnatally produced very large elevations in plasma renin activity (PRA) and aldosterone concentrations in the offspring. Exposure to high salt diet (3%) did not decrease the levels of these parameters below those fed mid salt diet (1%). In the second study, we show that rats raised through 4 weeks of age on basal diet, but then fed standard chow until adulthood, showed greater changes in tail skin (T(sk)) and colonic (T(c)) temperatures following administration of Ang II (200 microg/kg sc) than either mid- or high-salt-raised groups. In the third study, we confirmed this finding and extended it to show that rats raised on a very high salt diet (6%) also did not differ from the mid-salt group. In both studies, acute water intake measured in a separate test following administration of Ang II did not differ as a function of perinatal salt diet. In a fourth study, the period of exposure to the diets was extended from the perinatal period through adulthood and, surprisingly, there was no longer an enhanced thermal response to Ang II in basal diet rats compared with rats fed the very high salt diet. In the final study, rats raised on a regular diet but exposed only as adults to the test diets showed a nonsignificant trend toward a decreased thermal response in the basal group. Thus, dietary salt level may have opposite effects on Ang II effects on adult thermoregulation, depending on the age at the exposure.

Effects of the cannabinoid receptor antagonist SR 141716, alone and in combination with dexfenfluramine or naloxone, on food intake in rats.

RATIONALE: Recent studies in animals have implicated endogenous cannabinoids in the regulation of palatable food intake, but it is not yet clear to what extent pharmacological agents acting on this system may have sustained actions and applicability to different feeding protocols. OBJECTIVES: In the present study, we examine the effects of the cannabinoid CB1 receptor antagonist SR 141716 on food intake of rats, and its behavioral specificity. We examine whether tolerance develops to the anorectic actions of SR 141716, and whether it has either additive or synergistic actions with dexfenfluramine or naloxone. METHODS: Undeprived rats were trained to eat a daily sweet milk dessert and on test days were administered single or combination drugs and intakes were recorded. In other studies, rats were deprived for 24 h of either food or water and intakes recorded after drug administration at the end of this time. In one study, rats were fed ad libitum chow with SR 141716 added. RESULTS: SR 141716 (1-3 mg/kg) suppressed both palatable food intake in undeprived rats and food, but not water, intake after deprivation. Using an isobolographic analysis, SR 141716 had an additive anorectic effect with dexfenfluramine. In contrast, SR 141716 in combination with naloxone had a significantly supra-additive anorectic action. SR 141716 was also effective orally and no tolerance to its anorectic effect developed over 3 days. CONCLUSIONS: These data show that SR 141716 is an effective anorectic agent using both palatable foods and bland chow, and is selective because water intake was unaffected. SR 141716 is also effective orally and has an effect sustained for at least several days. There appears to be a synergistic interaction between opioid and cannabinoid systems in the regulation of feeding, whereas the combination of a serotonin releasing agent and the CB1 antagonist is additive.

Comparison of either norepinephrine-uptake inhibitors or phentermine combined with serotonergic agents on food intake in rats.

RATIONALE: We have shown previously that the anorectic effects of the catecholamine-releasing agent phentermine (PHEN) and the serotonin (5-HT)-releasing agent dexfenfluramine (DFEN) are greater than additive in rats. In the present study, we examined whether the norepinephrine-uptake inhibitors desmethylimipramine (DMI) and thionisoxetine (TNIX) have additive effects with either DFEN or with the 5-HT-uptake inhibitor fluoxetine (FLX). We also examined whether PHEN interacts with a postsynaptically acting 5-HT agonist. METHODS: Undeprived rats were trained to eat a daily sweet-milk dessert and on test days were systemically administered single or combination drugs and the intakes recorded. RESULTS: Both DMI and TNIX produced dose-related suppressions of food intake. However, by isobolographic analysis, they did not enhance the anorectic actions of either DFEN or FLX. In contrast, confirming and extending our previous work, PHEN had a greater potentiating effect on the anorectic actions of DFEN and FLX than TNIX. Further, the anorectic action of the 5-HT2c receptor agonist TFMPP was enhanced by PHEN. CONCLUSIONS: These and other data are consistent with the idea that 5-HT agents may work "upstream" of critical catecholaminergic synapses in the production of anorexia, and explain the diminished efficacy of norepinephrine-uptake inhibitors relative to PHEN. The implications for clinically useful anorectic agents are discussed briefly.

Dexfenfluramine and norfenfluramine: comparison of mechanism of action in feeding and brain Fos-ir studies.

Dexfenfluramine (dF) and dexnorfenfluramine (dNF), its metabolite, are anorectic agents that release serotonin (5-HT) and may have a direct postsynaptic action. The effects on the anorectic effects of dF and dNF of either acute (p-chlorophenylalanine, PCPA) or chronic (5,7-dihydroxytryptamine, 5,7-DHT) brain 5-HT depletions were studied in rats and compared with the actions of a 5-HT uptake inhibitor (fluoxetine) and 5-HT(1B/2C) receptor agonists [1-(3-trifluoromethyl-phenyl)-piperazine and 1-(3-chlorophenyl) piperazine]. The anorexia caused by these agonists was enhanced in rats with 5,7-DHT lesions, possibly a result of receptor supersensitivity. In contrast, fluoxetine anorexia was somewhat reduced in one study and was unchanged in a second. Both dF and dNF anorexias were enhanced in rats with 5,7-DHT lesions. In contrast, the anorectic effects of either dF or dNF were unchanged in PCPA-treated rats relative to controls. Compared with controls, 5, 7-DHT-lesion rats showed greatly increased dF- and dNF-induced Fos-like immunoreactivity (ir) in the paraventricular (PVN) and supraoptic (SON) hypothalamic nuclei, and in the median preoptic area (MnPO), but were similar to controls in most other areas. PCPA pretreatment increased dF- and dNF-induced Fos-ir in the PVN, SON, and MnPO. In controls, equianorectic doses of dF and dNF induced Fos-ir in similar brain regions, but dNF produced relatively larger effects than dF in SON, PVN, and MnPO. The data are discussed in terms of multiple pathways in the anorectic actions of dF and dNF.

Interactive Effects of Neurochemicals on Ingestive Behavior.

Most previous research has focused on the effects of single neurotransmitters and neuropeptides on ingestive behavior. An important next step in the advancement of the science of ingestive behavior is to gain an understanding of how these different systems interact with one another. The present article is designed as an introduction to interacting systems involved in the regulation of food intake. Specifically, we review recent research on several neurochemicals that have emerged as good candidates for further study of interactions because they appear to serve integrative roles.

Dietary NaC1 during pregnancy and lactation: effect on brain angiotensin II receptors and behavior.

Female rats were fed diets containing either a basal (0.12%), mid- (1%) or high (3%) level of NaCl during pregnancy and lactation. Plasma aldosterone was elevated approximately 5- and 15-fold in dams fed basal compared with either the mid- or high-NaCl diets at the end of both pregnancy and lactation (Postnatal Day 21), respectively. Dams fed basal diet and killed at the end of lactation had a higher density of angiotensin II receptors in the organum vasculosum laminae terminalis, paraventricular hypothalamus, and median preoptic nucleus than did rats fed either mid- or high-NaCl diets. Other dams, treated identically, were returned to rodent chow (approximately 0.2% NaCl) at the end of lactation for intake tests during the next week. Dams that had received basal diet did not differ from mid-NaCl and high-NaCl groups in sodium appetite induced by either acute sodium depletion or mineralocorticoid administration but showed the lowest spontaneous intake of NaCl solution.

Anorectic efficacy of the fenfluramine/phentermine combination in rats: additivity or synergy?

Fenfluramine + phentermine was a widely used combination for weight loss. Fenfluramine and phentermine are believed to act via serotonin and catecholamines, respectively. To what extent these drugs interact has not been well-established. We compared the anorectic efficacy of a range of doses of the combination (using dexfenfluramine instead of fenfluramine) relative to a range of doses of the individual drugs in 90 min sweetened milk intake tests in deprived and nondeprived rats. Results were plotted on isobolograms to determine whether the anorectic effects of the combination were either additive or synergistic. Collectively, the isobolographic analysis revealed that: (1) under acute conditions, dexfenfluramine and phentermine interact for the most part in a synergistic manner, and (2) with the exception of phentermine alone, deprivation state at time of testing did not alter the efficacy of the anorectics. These findings suggest that combined drug treatment for obesity is a theoretical approach that merits further investigation.

Effects of prenatal co-administration of phentermine and dexfenfluramine in rats.

Pregnant rats were infused with phentermine plus dexfenfluramine from days 3 through 17 of gestation. Control rats were either pair-fed or were fed ad libitum. There were no effects of prenatal drug treatment on number of offspring, their birth weights, or on their motor coordination assessed at 11 days of age. Mothers and pups were sacrificed 21 days postpartum. Drug-treated mothers, but not their pups, showed a reduced density of serotonergic axons in the hippocampus compared with controls. 25% of the pups from the prenatal drug group showed mitral valve thickening.

Roles of aldosterone and angiotensin in maturation of sodium appetite in furosemide-treated rats.

When rats are treated with furosemide, there is a rapid natriuresis. However, increased sodium appetite does not occur until some time later. One hypothesis to explain this delay is that increased circulating levels of the hormones of sodium depletion prime or sensitize the brain circuits involved in sodium appetite, perhaps by induction of target gene(s). In the present study, we describe the time course of the temporal maturation of sodium appetite after furosemide treatment and the associated changes in plasma levels of ANG II and aldosterone and in plasma volume. Sodium appetite is modest 3 h after furosemide treatment, is increased after 12 h, and is still larger after 24 h. This pattern is evident with repeated testing. Plasma levels of aldosterone and plasma renin activity are substantially increased 3 h after furosemide treatment, and so the NaCl appetite cannot result simply from progressively increasing levels of these hormones. Furthermore, activation of the subfornical organ and the ventral lamina terminalis, assessed with c-Fos immunocytochemistry, did not differ across these three times. Metyrapone, an inhibitor of adrenal steroid synthesis, was used to examine sodium appetite in the absence of elevations in aldosterone after furosemide treatment. Although metyrapone effectively blocked the increase in aldosterone, it was without effect on the appetite 3 or 24 h after furosemide treatment. Furthermore, elevations of plasma aldosterone by the use of minipumps for several days before furosemide treatment did not prime or potentiate but instead tended to inhibit the induced sodium appetite, despite achieving levels of aldosterone and plasma renin activity typically associated with a robust sodium appetite. Infusions of DOCA gave a similar result. Lastly, minipump infusions of ANG II also did not potentiate sodium appetite. Thus neither addition nor subtraction of these hormones alone influenced sodium appetite under these conditions.