Dehydration inhibits suckling behavior in weanling rats.

Determined the relation between dehydration and suckling behavior in 567 Sprague-Dawley weanling rats 15, 20, and 23 days of age. After 15 days of age, intra- and extracellular dehydration sharply reduced both the number of Ss that suckled and the amount of milk consumed. Rehydration returned both behaviors to control levels. Thus, during the weaning period, the internal determinants of suckling are not homologous with those of drinking, but are more homologous with those governing feeding. (29 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)     

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)     

ACTH and ACTH4–20 modification of neophobia and taste aversion responses in the rat.

A series of 6 experiments assessed the effects of ACTH and the ACTH analog ACTH4–20 on drinking in conditioned taste aversion and neophobic situations using a total of 168 male Sprague-Dawley rats as Ss. Both substances delayed the extinction of a conditioned taste aversion established by a single pairing of lithium chloride with milk (Exp I). However, in this situation, the ACTH parent peptide was more potent behaviorally. ACTH supressed milk consumption in Ss with no toxicosis experience (Exp II). This effect was apparently not due to the conditioning of a taste aversion (Exp III) with ACTH serving as a weak aversive UCS. Exogenous ACTH (Exp IV) or ACTH4–20 (Exp V) did not enhance neophobia; however, repeated injections of ACTH suppressed drinking. This ACTH suppression was related to the familiarity/novelty of the substance being consumed. The neophobic response to milk was not accompanied by pituitary-adrenal activation (Exp VI). Both neophobic and conditioned taste aversion situations appear to be useful for assessing peptide effects on consummatory behavior. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of feeding in rats: II. Independent ingestive behavior.

In 4 experiments, Charles River rat pups 3 days of age and older consumed large quantities of milk, sucrose, and wet mash when the Ss were placed in warm containers in which one of these diets had been spread on the floor. The volume of Ss" intake was directly related to the severity of food deprivation. Ingestive behavior occurred in the early part of the 30-min test, but later in the test, Ss stopped feeding and became quiescent. Their ingestive behavior thus resembled that of adults in (a) the motor aspects of feeding responses (licking and lapping), (b) the dependency on deprivation for intake, and (c) the pattern of intake termination. However, in Exp IV, when diet was restricted to a small area of the test container, young Ss consumed little diet. They did not appear able to direct or focus their ingestive responding. It was not until 9–12 days of age that Ss successfully consumed milk from a localized source. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Broad-spectrum behavioral treatment for chronic alcoholics: Effects of training controlled drinking skills.

Evaluated drinking skills training for 62 male chronic alcoholic veterans (mean age 46.1 yrs) by assigning 10 successive cohorts to trained or untrained conditions in a randomized block experimental design. All Ss received broad-spectrum behavioral treatment consisting of alcohol education, group therapy, individual therapy, self-management training, job-seeking and interpersonal-skills training, drink-refusal-skills training, and relaxation training. Cohorts assigned to the controlled drinking skills condition received 15 hrs of blood-alcohol-level discrimination training, responsible-drinking-skills training, and social-drinking practice sessions. Six-month posttreatment follow-up revealed that Ss in the drinking skills condition had significantly fewer abstinent days and more abusive drinking days than Ss in the untrained condition. Differences between groups were not significant in follow-up Months 7–22, although trends continued. No differences were obtained on moderate drinking days or any adjunctive measures of psychosocial adjustment. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electromyographic patterns associated with nonnutritive sucking in 11–13-day-old rat pups.

Three experiments used an EMG technique to measure the frequency, duration, and intensity of nonnutritive sucking (NNS) in 56 11–13 day old Wistar pups. Ss were separated from their mothers for 2–6 or 20–24 hrs and then allowed to suckle an anesthetized dam for up to 3 hrs without receiving any milk. Jaw-muscle EMG and nipple detachments were recorded. EMG patterns representing 2 discrete modes of sucking were reliably discerned, as were changes in overall intensity of EMG. 20–24 hr separated Ss engaged in more frequent NNS bouts and bouts of longer duration than 2–6 hr separated Ss. Ss separated by 20–24 hrs also engaged in a mode of NNS not seen in 2–6 hr separated Ss. Overall EMG intensity was higher and frequency of nipple detachments was lower in Ss separated for 20–24 hrs. In both groups, but particularly the 20–24 hr Ss, frequency of some NNS patterns decreased as the length of the "dry" suckling increased. EMG intensity also decreased over time in both groups, and frequency of nipple detachments increased in 2–6 hr separated Ss. Data indicate that some aspects of NNS are highly labile and respond to variations of both deprivation from the mother and nutritive deprivation. (27 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)     

Septal hyperdipsia: Specific enhancement of drinking to angiotensin in rats.

Conducted 3 experiments with a total of 126 hyperdipsic and 123 normal female Sprague-Dawley rats. Ss made hyperdipsic by destruction of the septal nuclei drank more water than normal Ss to thirst stimuli considered to be mediated, at least in part, by angiotensin. Specifically, they drank more than normal Ss to caval ligation, hypotension induced by the b-adrenergic agonist isoproterenol, intraperitoneal injections of renin, and intravenous infusions of angiotensin. Overdrinking was enhanced by nephrectomy when renin or angiotensin were introduced exogenously, but nephrectomy reduced drinking to hypotension. Septal hyperdipsic Ss drank more water than normal Ss when polyethylene glycol was delivered intraperitoneally but not subcutaneously. They did not drink more to cellular dehydration produced by the intravenous or intragastric injection of hypertonic saline or sucrose. The contributions of the septum to angiotensin-mediated drinking and to nonhomeostatic determinants of drinking are discussed, as are the possible mechanisms controlling drinking to intravascular depletions. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nutritive and nonnutritive determinants of milk intake of suckling rats.

Determined the factors that enhanced milk intake during deprivation in albino rats 15, 20, and 25 days of age. Ss were subjected, for 8 hrs, to 1 of 6 regimens. Results show that intake at Day 15 was reduced by the opportunity to suckle, independent of receiving a milk load. This same trend was apparent, although not as strong, among Day 20 Ss. By Day 25, nonnutritive suckling during the privation period no longer attenuated milk intake, although preloads did, whether or not they were paired with nonnutritive suckling. Thus, suckling in Ss became increasingly freed from oral demands and more responsive to the nutritive consequences. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A vagally mediated histaminergic component of food-related drinking in the rat.

Six experiments with 95 male albino Sprague-Dawley rats (1) demonstrated that exogenous histamine was a potent stimulus for drinking behavior that was dependent upon an intact abdominal vagus and (2) provided evidence for a histaminergic component of the stimulus for food-related drinking in the rat. Histamine elicited drinking in a dose-related manner typically within 5 min after sc injection in Ss. Threshold for increased drinking was 1.25 mg/kg, and 2.5 mg/kg elicited half of the maximal drinking response that followed 20 mg/kg. Bilateral subdiaphragmatic vagotomy, with the hepatic branch left intact, severely attenuated drinking in response to systemic histamine: Vagotomized Ss drank later and less than did normal Ss after doses of histamine between 1.25 and 40 mg/kg. This attenuation was attributed to the destruction of vagal afferent fibers because histamine-elicited drinking was not affected by blockade of vagal efferents with atropine methyl nitrate. Drugs antagonistic to peripheral H? histamine receptors specifically inhibited drinking in response to histamine: Cimetidine or metiamide injected ip delayed and decreased drinking after sc histamine and temporarily decreased drinking after hypovolemia produced by sc polyethylene glycol, but failed to inhibit drinking after water deprivation, cellular dehydration, or isoproterenol. Finally, cimetidine or metiamide inhibited drinking in temporal association with a meal of liquid or solid food without slowing the rate of eating or decreasing food intake. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition and extended retention of a conditioned taste aversion in preweanling rats.

Four experiments employed a taste aversion conditioning procedure appropriate for both neonatal and adult rats to investigate the ontogeny of extended retention. In Exp I, 200 outbred albino rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those Ss conditioned when 20 or 60 days old demonstrated significant taste aversions. Exps II and III, with 190 Ss, established that Ss 14–25 days old and older were able to retain significant taste aversions following a 25-day retention interval. 80 younger Ss did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Exp IV). Findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of feeding in rats: I. Ingestive and behavioral responses to oral infusions.

Reports on 3 experiments with Charles River rat pups. When milk infusions were made through oral cannulas in the front of their mouths, 1–20 day old Ss actively ingested the diet, and their intake was related to the length of deprivation. Ss decreased their ingestive responding after they had consumed large volumes of milk. In addition, 1-, 3-, and 6-day-old Ss, when 24-hr deprived, exhibited an intense behavioral activation in response to milk infusion. The behavioral activation appeared to be stimulated primarily by taste and the opportunity to swallow. Milk infusions did not produce activation in older Ss; their behavior was more exclusively ingestive and food directed. Results demonstrate that (a) from birth, rat pups are capable of an active form of ingestion, independent of normal suckling from the mother; (b) such ingestion is controlled by physiological factors; (c) food has arousing properties in young animals; and (d) as pups grow older, their ingestive responding is refined from a generalized and nondirected activation to specific and directed feeding responses. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chonically reduced body weight in rats sustaining lesions of the lateral hypothalamus and maintained on palatable diets and drinking solutions.

12 male Holtzman rats sustaining lateral hypothalamic (LH) lesions regulated their body weight at a reduced level when maintained for 1 mo postlesion upon a wet mash diet. Thereafter, for a period of 84 days, half of these Ss were offered a high fat diet, whereas the remaining Ss continued to receive wet mash. A series of palatable drinking solutions were also offered. Body weight remained at reduced levels relative to 8 intake controls regardless of the diet offered, even under conditions of high fluid intake generated by the palatable drinking solutions. Results contradict the interpretation of E. J. Mufson and R. S. Wampler (see record 1973-00428-001) that the lower body weight observed in LH-lesioned animals is secondary to lesion-produced "finickiness" and/or dehydration resulting from hypodipsia. Rather, a primary shift in the set point for body weight appears to underlie the reduced levels of weight maintenance in LH-lesioned animals. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of thirst in the rat: Effects of hypertonic saline, polyethylene glycol, and vena cava ligation.

Describes 3 experiments in which over 465 Sprague-Dawley rats of various ages either (a) were injected with hypertonic sodium chloride solutions to produce intracellular dehydration, (b) were injected with polyethylene glycol to induce hypovolemia, or (c) underwent ligation of the inferior vena cava to stimulate the renin-angiotensin system. 16-day-old Ss drank like adults after injection of polyethylene glycol. Hypertonic saline injection did not elicit adultlike drinking until 30 days of age, and vena cava ligation did not produce adult levels of water consumption until 42 days postnatally. It is concluded that treatments which have been associated with different mechanisms of thirst, therefore, first become effective at different times during ontogeny. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emetic and electric shock alcohol aversion therapy: Six- and twelve-month follow-up.

Reports follow-up data for 20 male alcoholics who received either a multifaceted inpatient alcoholism treatment program alone (controls) or emetic or shock aversion therapy in addition to that program. Results indicate that emetic treatment exerted a modest beneficial effect at the 6-mo mark, but control and emetic Ss did not differ at the 12-mo mark. Both emetic and control Ss compiled more days of abstinence than shock Ss at both follow-up intervals. Analysis of the relationship between inpatient measures of the strength of alcohol aversions and posttreatment drinking revealed an inverse relationship between heart rate response to alcohol and number of days of drinking. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separation of opioid from nonopioid mediation of affect in neonatal rats: Nonopioid mechanisms mediate maternal contact influences.

Established a causal distinction in infant rats between opioid- (OP) and non-OP-mediated determinants of behavior. Contact influences were mediated by non-OP pathways, and gustatory influences were OP-mediated. Naltrexone (NTX) did not diminish quieting exerted by contact with an anesthetized dam but reversed the quieting effects of morphine in isolated Ss. Naloxone (NLX) did not affect the latencies with which nondeprived or 8-hr deprived Ss 9, 12, 15, and 18 days old attached to nipples (NPs) of anesthetized dams, nor did NLX cause systematic change in NP attachment in 10- and 18-day old Ss from the NP when milk letdown was induced by oxytocin. NLX did not reduce milk intake in Day-10 Ss that, while suckling, received milk via indwelling cannulae in the anterior portion of the lower jaw or in Ss that obtained milk directly from their awake mother. Milk intake was significantly reduced by NTX in Day-10 Ss that obtained milk by licking it off a saturated substrate. In Day-10 Ss, intake of milk delivered via cannulae was reduced by NLX in Ss that were either isolated, in contact with an anesthetized dam, or attached to her NPs. Behavioral influences of the tactile (and possibly olfactory) qualities of the dam were not mediated by OP systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience-dependent recovery of visuospatial functioning in older alcoholic persons.

Exposed 2 groups of alcoholic males to verbal and visuospatial paired-associate learning tasks known to be sensitive to alcohol dysfunction. Group 1, with 16 Ss (mean age 52.19 yrs), received 4 task administrations 3–4 days apart, beginning 4 days after drinking stopped. Group 2, with 14 Ss (mean age 49.79 yrs), received identical administration beginning 16 days after drinking stopped. An alternate form of the tasks was administered at the final session to assess transfer of training. Two matched nonalcoholic control groups of 12 Ss each (mean age 50.79 yrs) established normative performance on both forms of the tasks. Although the alcoholic Ss' verbal learning was unimpaired, visuospatial functioning was equally impaired initially in both alcoholic groups despite differing periods of abstinence, indicating the lack of time-dependent recovery. However, practice with the visuospatial task resulted in improved visuospatial performance and positive transfer of training not significantly different from normal Ss. It is suggested that since alcoholism treatment outcome is related to neuropsychological status, rehabilitation of cognitive functioning may improve treatment success. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning of food aversions by injections of psychoactive drugs.

Injected male Sprague-Dawley rats with various drugs or saline immediately after drinking milk for the 1st time. 1 wk. later Ss were again given access to the milk. Conditioned aversion to the milk was produced by moderate doses of scopolamine, scopolamine methyl nitrate, amphetamine, lorazepam, and chlorpromazine. Conditioned aversion was not obtained if scopolamine was injected 30 min. prior to milk drinking or more than 4 hr. afterward. (22 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)