Prior episodes of sodium depletion increase the need-free sodium intake of the rat.

Prior episodes of sodium depletion increase the daily 3% NaCl intake of rats. They ingest large volumes and continue to do so for as long as 3 months after recovery from sodium deficit while eating sodium-rich food and while plasma sodium concentration and renal function are normal. The increased daily intake of sodium is, therefore, need-free. There is a marked sex difference in the need-free intake of 3% NaCl. Female rats drink more salt than do male rats when they are sodium replete and depletion naive. Repeated depletions raise the need-free intakes of both sexes but the effect is greater in females. Plasma concentrations of angiotensin II and aldosterone, which are markedly elevated by each episode of sodium depletion, return to basal levels between and after depletions, and are not the cause of the chronically increased need-free salt intake of the multi-depleted rat. These results suggest that the persistent increase in daily 3% NaCl intake that occurs in the rat with a history of repeated sodium depletions is a permanent, nonpathological increase in avidity for the taste of salty substances that results in life-long overconsumption of salt. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in energy intake and expenditure

Four patients with rheumatoid arthritis developed heavy proteinuria after five to 12 months of treatment with D-penicillamine. Light microscopy of renal biopsy samples showed minimal glomerular capillary wall thickening and mesangial matrix increase, or no departure from normal. Electron microscopy, however, revealed subepithelial electron-dense deposits, fusion of epithelial cell foot processes, and evidence of mesangial cell hyperactivity. Immunofluorescence microscopy demonstrated granular capillary wall deposits of IgG and C3. The findings were similar to those in early membranous glomerulonephritis, differences being observed however in the results of staining for the early-acting complement components C1q and C4. It is tentatively concluded that complement was activated by the classical pathway.     

Suckling behavior and intake control in the developing rat pup.

Studied the behavioral development of suckling and intake control in 2 experiments with Charles River CD strain rat pups. Ss were observed at the initiation, during the course, and at the termination of suckling from their anesthetized mothers. Diet was delivered intraorally through a fine tongue cannula which enabled control of timing and volume. The control of diet intake and the behavior at termination of suckling showed correlated changes from 5 to 20 days of age. When deprived of suckling (and food and water) for 8 hr, 5- and 10-day-old Ss consumed large volumes of diet (10% of body weight or greater) and terminated suckling only in the presence of extreme gastrointestinal filling. These Ss were immediately lethargic and slept after intake termination. Five-day-old Ss persisted in reattaching to the nipple when manually stimulated; 10-day-old Ss eventually refused to reattach. In contrast, 20-day-old Ss consumed more moderate volumes of diet (5% of body weight). These Ss also remained awake for a period after feeding and engaged in the exploratory and grooming activities characteristic of adult rats at the termination of feeding. These observations demonstrate major changes in suckling behavior during development. They suggest that intake control processes shift from indirect to direct and become more effective and specifically food intake related in older pups. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal cortex and the regulation of food intake in the rat.

Studied the postoperative regulation of food and water intake in a total of 103 male Wistar albino rats with aspiration lesions to either the medial frontal or orbital frontal projection fields of thalamic nucleus medialis dorsalis (prefrontal cortex). These projection fields proved functionally dissociable in that orbital frontal lesions impaired immediate postoperative regulation of food and water intake for up to 2 wks, while medial frontal lesions produced finickiness. Neither lesion affected response to cellular dehydration or recovery from extended deprivation. Data are consistent with data from rhesus monkeys with prefrontal lesions and differ from animals with lateral hypothalamic lesions. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship between absolute body-fluid deficits and fluid intake in the rat.

In 5 experiments acute absolute body-fluid deficits were induced in a total of 36 male albino Sprague-Dawley rats by injection of the diuretic drug furosemide, which caused up to 20% reduction of extracellular fluid volume and up to 2% reduction of intracellular fluid volume. Water and .3 M NaCl were subsequently made available to allow the Ss to replace their body fluids by drinking. The Ss increased their intake of both fluids, but replaced less than half of the total deficit, thereby tolerating larger and larger voluntary body-fluid deficits as the size of the diuretic fluid loss increased. Plasma measures showed that the Ss sustained hypovolemia after drinking, while intracellular fluid volume was apparently restored. Fluid-depleted Ss drank normally in response to intracellular dehydration induced by a sodium chloride load. Results demonstrate that incomplete restoration of body-fluid balance after body-fluid depletion is due to a failure to drink in response to extracellular dehydration. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in the relationship between activity and weight loss in the rat.

Access to a running wheel combined with restricted feeding produced body weight loss at an equivalent rate in male and female litter-mate rats (Experiment 1). Thus, despite weighing less and running more, females were not more vulnerable to this procedure. When factors influencing weight loss were varied, no sex difference was found in adaptation to a new feeding schedule or in the effect of single versus group housing (Experiment 2). The apparent critical difference was that body weight loss increased running in males but not in females (Experiment 3). In all rats, rapid recovery of body weight occurred when food access was no longer restricted (Experiment 1), suggesting that activity-based anorexia is a misnomer for weight loss by rats in a running wheel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences and residual effects of food deprivation in the satiated rat.

Following 100 days of food deprivation, during which 9 male and 9 female albino rats received acquisition and extinction training in a runway, and following 2 mo of ad lib feeding, Ss were given a reacquisition test under satiated conditions. Results indicate that females were significantly superior in running speed and frequency of food consumption during satiated reacquisition; while there was a large performance decrement in males following the drive shift, females performed at about the same level during satiation as during food deprivation. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Salt intake, urinary sodium, and hypercalciuria

Several studies have reported that high sodium (Na) intake increases not only urinary Na but also urinary calcium (Ca), suggesting that high Na intake could be involved in the pathogenesis of hypercalciuria. No research data are available on the relationship of Na intake to the prevalence of hypercalciuria within the general population. Moreover, it is not clear if Na intake relates only to urinary Ca or also to other indices of Ca homeostasis, including intestinal Ca absorption. In the present paper, two distinct studies addressed these points using 24-hour urinary Na as an index of salt intake in individuals on their habitual unrestricted free diet. Study 1 analyzed the relationship between 24-hour urinary Na and hypercalciuria (24-hour urinary Ca > or = 7.5 mmol in men, > or = 6.25 mmol in women) in a population sample of 203 men and women, aged 20-59 years. Study 2 analyzed the relationship between 24-hour urinary Na and intestinal strontium (Sr) absorption, used as an index of intestinal Ca absorption, urinary (24-hour and fasting) and plasma Ca, and plasma parathyroid hormone in 36 healthy men and women, aged 18-65 years. Within the population sample (study 1), 24-hour urinary Na was directly and significantly correlated with prevalence of hypercalciuria when controlling for gender, age, weight, and urinary creatinine: the relationship was continuous and linear for urinary Na ranging between 40 and 200 mmol/24 h. In the 36 volunteers (study 2), 24-hour urinary Na was related to 24-hour and fasting urinary Ca (p < 0.001) but not to intestinal Sr absorption: the relationship between 24-hour urinary Na and urinary Ca (both 24 h and fasting) was also significant, controlling for other variables. The results indicate that in adults on their habitual diet, urinary Na, which reflects dietary salt intake, correlates with the prevalence of hypercalciuria independently of intestinal Ca absorption and mainly via renal mechanisms.     

Sex differences in dehydroepiandrosterone-induced hepatocarcinogenesis in the rat

The direct quantification of antibiotics in agar allows one to study the quality of the agar matrix, the kinetics of diffusion and the bacteria-antibiotic interaction. Mueller-Hinton agar (MHA) plates from three manufacturers were tested using HPLC and the disc diffusion test of ceftazidime (CAZ). Notable differences in the chromatographic profiles of MHA plate extracts from OXOID, DID and Becton Dickinson (BD) were shown, with a higher CAZ concentration after 24 h a 6 mm in BD P. aeruginosa inoculated plates (5.1 +/- 1.7 micrograms/ml, n = 6) vs. OXOID and DID (1.6 +/- 0.3 micrograms/ml, n = 12). BD plates gave also a different inhibition zone diameter (26 +/- 0.5 mm, n = 3) with respect to DID and OXOID (29 +/- 0.5 mm, n = 3).     

Insular cortex lesions and morphine-induced suppression of conditioned stimulus intake in the rat.

The present experiment examined the influence of insular cortex (IC) lesions on the intake of a taste stimulus in a consummatory procedure that used morphine as the unconditioned stimulus. In normal rats, morphine caused a rapid reduction in saccharin intake when the taste was novel but not when it was familiar. Irrespective of stimulus novelty, morphine had little influence on the saccharin consumption of IC-lesioned rats. The results are discussed in terms of a lesion-induced disruption of (i) a reward comparison mechanism and (ii) the perception of taste novelty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of lesions in the basolateral amygdala on fluid intake in the rat.

Conducted 6 experiments with 33 rats with bilateral lesions in the lateral amygdaloid region and 22 intact controls. Drinking response to hypertonic saline, a cellular thirst stimulus, and to isoproterenol, probably an extracellular thirst stimulus, was normal in lesioned Ss. The overnight water intake of the lesioned Ss was a little higher than normal. However, the lesioned Ss showed a major impairment in learning to avoid ingesting a poisonous solution of LiCl when they were thirsty and an increased preference of 25% sucrose in a 2-bottle sucrose-water test. It is concluded that the basolateral region of the amygdala is involved in the effects of previous experience on drinking and not primarily in the cellular or extracellular controls of drinking. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potassium and sodium intake and excretion in calcium stone forming patients

We reviewed the results of 15 patients (16 feet) in whom a hallux valgus procedure had failed. Salvage was by proximal crescentic first metatarsal osteotomy with distal soft-tissue reconstruction. Results based on a clinical scale considering the level of pain, activity limitations, support requirement, footwear limitations, and alignment were good in 11, fair in two, and poor in three. Patients were satisfied with the results in 10 feet, satisfied with reservations in four feet, and dissatisfied in two feet. Complications were: transfer metatarsalgia in three, hallux varus in one, and osteotomy nonunion in one. One of the patients required reoperation to bone graft a proximal osteotomy. Metatarsal osteotomy was helpful in the salvage treatment of recurrent, symptomatic hallux valgus when the first metatarsophalangeal joint was functional and painless.     

Postingestional control of sodium chloride solution drinking in the rat.

Studied the relative roles of oropharyngeal and postingestional factors in the control of sodium chloride solution drinking in 5 male albino Sprague-Dawley rats by independently manipulating the concentrations of the solutions reaching the mouth and the stomach. The usual preference-aversion function was obtained in the absence of changes in taste stimulation but not in the absence of changes in postingestional events. Results show that postingestional events alone are sufficient to produce the main features of the preference-aversion function for sodium chloride. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sodium chloride transport across the chicken coprodeum. Basic characteristics and dependence on sodium chloride intake

1. The transport characteristics of the chicken coprodeum have been examined in vitro using the isolated mucosa. The short-circuit current (I(sc)), the transepithelial electrical potential difference (p.d.), the unidirectional transmural fluxes (J(ms), J(sm)) of sodium and chloride measured in the short-circuited state, and the unidirectional influx of sodium and chloride across the brush border membrane measured under open-circuit conditions have been studied. The effect of the sodium chloride contents of the diet on these parameters have been investigated.2. The isolated mucosa depends functionally on the presence of glucose in the incubation media. This dependence reflects the need of glucose as a fuel. There is no indication of coupling between transport of sugars and sodium across the brush border membrane. For preparations from chickens on a low sodium diet a very high and stable I(sc) can quantitatively be accounted for by the net transport of sodium. Influx of sodium across the brush border membrane is not significantly different from the net flux of sodium. By feeding the chickens a high sodium diet the I(sc) is reduced by more than 95%, the net transport of sodium is abolished, and the transepithelial electrical conductance is reduced by more than 50%.3. Both unidirectional transepithelial fluxes of chloride, and the serosa to mucosa flux of sodium appear to proceed through a paracellular shunt.4. Under the conditions of the low sodium diet the paracellular pathway appears to be anion selective. Whereas, under the conditions of the high sodium regimen the paracellular route appears to be cation selective. After adaptation to a high sodium diet the influx of sodium across the brush border membrane is only moderately reduced. Consequently the decisive event in the adaptation must be localized elsewhere.     

Chronic immobilization stress reduces sodium intake and renal excretion in rats

The influence of chronic exposure to immobilization (IMO) on sodium appetite as well as sodium and potassium renal excretion in adult male Wistar rats was studied. The animals were individually housed and all variables under observation were measured in metabolic cages the first, seventh, and thirteenth days once the experiment had started. Half of the rats had access to water, and the remainder of the rats had access to both water and saline solution (1.5% NaCl). IMO reduced the intake of saline solution. Renal water, sodium, and potassium excretion in those IMO rats having access to saline were lower than in control rats. The effects of IMO were very similar during all observation days; therefore no evidence of adaptation to repeated stress was found. The present data indicate the following: (i) IMO stress reduced sodium appetite, probably as a secondary effect to the deficit in sodium renal excretion; (ii) IMO caused antidiuresis and antikaliuresis, only in those rats taking saline solution; (iii) no adaptation to repeated IMO stress was found in any of the tested variables. The reduction of sodium appetite observed in stressed rats might be a homeostatic mechanism to maintain sodium balance after impairment of renal sodium excretion caused by stress.     

Perceptual characteristics of the amiloride-suppressed sodium chloride taste response in the rat.

Assessed the contribution of amiloride-sensitive membrane components to the perception of NaCl taste using a conditioned taste aversion procedure with 8 groups of adult rats conditioned to avoid either 0.1M NaCl, 0.5M NaCl, 0.1M NH?Cl, or 1.0M sucrose while their tongues were exposed either to water or to amiloride hydrochloride. Differences in the acquisition of taste aversions between the amiloride- and nonamiloride-treated groups were not apparent when the conditioned stimulus (CS) was 0.5M NaCl, 0.1M NH?Cl, or 1.0M sucrose. Although the magnitude of the 0.5M NaCl aversion was similar between amiloride- and nonamiloride-treated Ss, the perceptual characteristics of the CS differed between groups. Amiloride-treated Ss avoided monochloride salts after conditioning to 0.5M NaCl but not nonsodium salts or nonsalt stimuli. Ss not treated with amiloride only generalized the 0.5M NaCl aversion to sodium salts. The "salty" taste of NaCl is related to the amiloride-sensitive portion of the functional taste response in rats. The portion of the NaCl response insensitive to amiloride has "sour-salty" perceptual characteristics and is not perceived as being salty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in hepatic sulfation of taurolithocholate in the rat

Metabolism of the bile salts by formation of sulfate esters is catalyzed by bile salt sulfotransferase, an enzyme isolated from rat liver and kidney. The activity of bile salt sulfotransferase was measured in liver and kidney of male and female rats and in oophorectomized rats with or without estrogen replacement. In vitro sulfotransferase activity was correlated with in vivo sulfation by measuring the percentage of an infused dose (0.03 micron per 100 g per min) of taurolithocholate, which was excreted in bile as the sulfate. The activity of sulfotransferase in liver was higher in females (26.3 +/- 3.0 pmoles per mg of protein per min) than in males (9.6 +/- 3.9) and was lower (12.1 +/- 3.8) after oophorectomy. The decrease in activity was prevented by replacement of estrogen. Renal sulfotransferase activity did not differ between the sexes and was unaffected by oophorectomy. Hepatic sulfotransferase activity measured in vitro correlated with in vivo sulfation of taurolithocholate. This study shows definite sex differences in hepatic bile salt sulfotransferase activity, which in females is affected by the presence of estrogen. The correlation between in vitro sulfotransferase activity and in vivo bile salt sulfation suggests that bile salt sulfotransferase is responsible for bile salt sulfation in vivo.     

A comparative study of blood pressure and sodium intake in Belgium and in Korea

A comparative blood pressure and sodium excretion were higher in Korea than in Belgium. By multiple regression and covariance analysis an independent positive association between sodium and blood pressure and a negative correlation between potassium and blood pressure were found in some population subgroups and in the total population studied in Korea. In Belgium a positive association between sodium and blood pressure was found when higher powers of age, height, weight and sodium were included in the analysis. The independent influence of sodium on blood pressure was relatively small, amounting to about 2 mm Hg of pressure rise for an increase in 24-h excretion of 100 mmol of sodium.     

The effects of deoxycorticosterone-induced sodium appetite on hedonic behaviors in the rat.

The authors tested the hypothesis that chronic treatment with a dose of deoxycorticosterone acetate (DOCA) known to elicit a robust sodium appetite can negatively affect the hedonic state of rats. Daily treatment with DOCA with no opportunity to ingest saline produced a rightward shift in the midpoint (effective current 50) of lateral hypothalamic self-stimulation (LHSS) current-response functions and reduced intakes of a palatable sucrose solution. Providing rats with 0.3 M saline during DOCA treatment prevented the rightward shift in LHSS response functions and the decrease in sucrose intake. The authors concluded that a chronic sodium appetite, with no opportunity to attenuate the appetite, can elicit a reduced responsiveness to reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do taste factors contribute to the mediation of ethanol intake? Ethanol and saccharin-quinine intake in three rat strains

Several recent studies have suggested that ethanol-preferring rodents may also have an affinity for sweet solutions (saccharin, sucrose) and, conversely, that saccharin preference may predict ethanol preference. The purpose of the present investigation was to determine whether intake of ethanol and saccharin-quinine (SQ) solutions would be related in three nonselected strains of rats who differ in their ethanol preference: Lewis, Wistar Kyoto, and Wistar. In the first phase of the experiment, all animals were presented with an ascending series of ethanol solutions (2 to 10%) in free choice with water, followed by a 10-day maintenance period of 10% ethanol with water. In the second phase, the same animals were presented with an ascending series of SQ solutions (saccharin: 0.4%, quinine: 0.001 to 0.04%) in free choice with water, followed by a 10-day maintenance period of 0.4% saccharin with 0.04% quinine and water. The results revealed an absence of a direct relationship between ethanol and SQ consumption. The ethanol-nonpreferring Lewis rats showed a greater preference for the SQ solutions than Wistar Kyoto rats, whereas the ethanol-preferring Wistar Kyoto strain consistently consumed significantly less SQ. Wistar rats showed relatively stable consumption levels for both solutions that fell between those of the other two strains. These results suggested that the relationship between ethanol and SQ preference in rats was not a direct one and did not support the findings in the literature of a simple overall positive relationship between sweet and ethanol preference. These data do, however, provide further evidence for taste factors in the mediation of self-selection of ethanol in rats.