The ontogeny of feeding in rats: IV. Taste development as measured by intake and behavioral responses to oral infusions of sucrose and quinine.

Delivered infusions of sucrose or quinine through cannulas implanted in Charles River CD rat pups' mouths. Intake was measured, and behavioral responses were scored. Responsiveness to sweet and bitter tastes emerged over the 1st 2 wks of postnatal life. Pups showed discrimination between water and sucrose in their mouthing behavior and general activity from 3 days of age, but in their intake only from 6 days of age. Discrimination between water and quinine was not shown until 9 days of age in either behavior or intake. Even then, the stereotypic aversion reactions (paw treading, chin scraping) that characterize the adult response to quinine were not apparent until 12 days. By 15 days of age, preferences for sucrose and aversions to quinine were robust, resembled those of adult rats, and did not depend on previous experience with either solution. (31 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)     

Ingestive responses to homeostatic challenges in rats with ablations of the anterolateral neocortex.

Because rats with either anterolateral neocortical (AN) or lateral hypothalamic (LH) damage initially display similar feeding and drinking deficits and recovery patterns, the present study examined the possibility that anterolateral neocortical ablations would also produce similar chronic ingestive impairments to glucoprivic and hydrational challenges. 73 male Sprague-Dawley rats received AN or dorsoposterior neocortical lesions or served as unoperated controls. Ss with AN ablations exhibited normal feeding responses to food deprivation and glucoprivation induced by insulin (4–26 U/kg, sc) or 2-deoxydextroglucose (2-DG [125 or 250 mg/kg, ip]), but their response to 500 mg/kg or 2-DG was impaired. These Ss also drank normally in response to hypertonic saline injections and following water deprivation but only if food was available during the test session. Results indicate that, although the anterolateral neocortex and LH are anatomically related, these brain regions appear to be functionally dissimilar in terms of the regulation of ingestion. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of feeding in rats: III. Thermal determinants of early ingestive responding.

High ambient temperatures (38°C) stimulated high spontaneous levels of activity and high frequencies of behaviors normally associated with ingestion (mouthing and probing), particularly in young, 3- and 6-day-old Charles River CD rat pups (Exp I). The level of spontaneous behavior was highly correlated with body temperature and also depended on deprivation condition. Temperature played an important role in determining responses to food stimuli as well. When Ss were fed by oral infusion (Exp II) or by placing milk on the floor beneath them (Exp III), warm ambient temperatures were required for active ingestion. In Exp IV, body temperature and ambient temperature were manipulated independently to assess their relative importance for Ss' feeding behavior. Ss with a low (29°C) or normal (34°C) core temperature at the start of testing were fed in either a 24°C or a 34°C ambience. Regardless of body temperature, Ss' levels of intake, activity, mouthing, and probing were higher in a warm than in a cool ambience. Therefore, the suppressed ingestive behavior of Ss fed at cool temperatures occurred not simply because Ss became hypothermic and inactive. Perceived warmth appears to be a significant contextual cue that regulates pups' responses to food stimuli. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Little and often: Ingestive behavior patterns following hippocampal lesions in rats.

Lesions of both dorsal and ventral hippocampus were produced by multiple infusions of the excitotoxin AMPA. Meal patterns recorded before and after lesioning showed no change in total food intake, but a striking behavioral syndrome in which the lesioned rats took smaller meals 2–3 times as frequently and showed a similar change in drinking. In addition, lesioned rats alternated more frequently between feeding and drinking during a single bout of ingestive behavior. There were no group differences in the satiety sequence that followed a meal. In an open field test, lesioned rats showed enhanced locomotion in the periphery and reduced rearing. An olfactory habituation–dishabituation task showed that the lesioned rats investigated olfactory stimuli less but dishabituation to a changed stimulus was normal. The data are discussed in terms of changes in behavioral switching or a possible interoceptive agnosia following hippocampal damage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ingestive responses of human newborns to salty, sour, and bitter stimuli.

In 2 experiments a total of 204 16-90 hr old neonates were offered 2 fluids differing in taste for 3 min each. The volumes ingested were measured. Ss offered water and bitter and sour solutions did not ingest them differentially, which corroborated earlier observations with weaker solutions. A sucrose solution was used to raise baseline ingestion above that of water. Ss offered the sucrose solution with and without urea, citric acid, or sodium chloride consumed less of it when citric acid was added. They were indifferent to the addition of urea or sodium chloride. The failure to observe intakes lower than that of water suggests that newborns maximally inhibit their ingestion of water. The effect of sex, age, birth weight, and individual consistency on intake were assessed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of feeding in rats: V. Influence of texture, home odor, and sibling presence on ingestive behavior.

Determined with Charles River rat pups in 3 experiments that terry-cloth texture, home odor, and the presence of siblings modulated Ss' ingestive behavior. Unlike warmth, which affected ingestion in pups until at least 15 days of age, the relative importance of other cues varied with age. At 3 days, ingestion was dependent on warmth but was not influenced by the other cues. At 6 days, texture and home odor enhanced ingestive behavior (intake, activity, mouthing, and probing), but the presence of siblings had no effect. Home odor or terry-cloth texture did not alter the ingestive behavior of 12-day-olds, but the presence of siblings enhanced milk intake. Thus, during development, the external sensory controls for ingestion became progressively more complex. Warmth served as a primary permissive cue for ingestion, but as Ss grew older, such other cues as odor, texture, or social stimuli also gained significance. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Day-night variations of behavioral and autonomic thermoregulatory responses to lipopolysaccharide in rats

This study investigated the day-night differences in behavioral and autonomic thermoregulatory responses to bacterial lipopolysaccharide (LPS) in rats. Male rats were housed individually in cages with a 12: 12 h light dark cycle at an ambient temperature of 24 degrees C. The rats were placed in a box with a temperature gradient and intraperitoneally injected with LPS (10 micrograms/kg). The preferred ambient temperature (Tpr) was estimated by the location of the rats in the box, and intraperitoneal temperature (Tb) was measured by a biotelemetry system. Measurements were taken during the light and dark phases of the day. LPS produced fever in both phases. The magnitude of rise in Tb did not differ between the two periods. In the dark phase, Tpr significantly increased during the development of fever and decreased during the defervescence, while it did not change throughout the febrile course during the light phase. In a separate experiment, rats were loosely restrained and placed in a direct calorimeter. Their colonic temperature (Tcol), evaporative and nonevaporative heat loss and heat production were measured before and after intraperitoneal injections of LPS (10 micrograms/kg). Measurements were taken during the light and dark phases of the day. LPS induced fever in both phases. The magnitude of change in T col, heat loss, and heat production due to LPS did not differ between the two periods. These results suggest that the fertile response of rats to intraperitoneal LPS is not affected by the time of day. However, it seems that during LPS-induced fever, thermoregulatory behavior is not fully activated during the light phase of the day.     

Wheel access duration in rats: I. Effects on feeding and running.

The effects of 0-, 2-, and 24-hr wheel access on the pattern of running, feeding, and weight were explored over 24 days in 3 groups of 8 male rats. Both 2 and 24 hr of wheel access suppressed feeding by about 15% for about 8 days before feeding gradually returned to normal. Weight in these 2 groups was similar and was suppressed for the 24 days. Like the pattern seen with drug self-administration (S. H. Ahmed & G. F. Koob, 1998, 1999), running levels stayed low with short, 2-hr daytime wheel access, but with long, 24-hr access, rats' running escalated over days to chronically high levels. These results may have relevance for the understanding of addiction and anorexia nervosa. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional and behavioral responses to aversive interpersonal behaviors.

In a conceptual replication of A. Biglan et al (see record 1989-39898-001), 288 Ss rated their emotional and behavioral responses to aggressive, distressed, and neutral behaviors. The stimulus behaviors occurred in the context of casual relationships and were portrayed by male and female actors. Consistent with Biglan et al, it was found that aggressive behaviors evoked angry emotions and negative behavioral responses; distressed behaviors evoked both angry and concerned emotions and supportive behavioral responses. However, in contrast to the original results, evidence was also found of negative (primarily avoidant) behavioral responses to distressed behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Affective and behavioral responses to health-related social control.

Social control has the potential to encourage engagement in a healthy lifestyle, but its effectiveness may depend on the nature of the influence attempt. Participants (N = 282) described a situation in which someone attempted to influence their health-related behavior. Experiencing positive social control was associated with a greater tendency to change the behavior and less ignoring/doing nothing, whereas negative social control was associated with a lesser tendency to change the behavior and more hiding of unhealthy behavior. These associations could be accounted for by affective responses to the social control attempts. Results emphasize the need to better understand the regulatory influence of relationships on health behavior and the conditions under which social control is most likely to have health-promoting effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult rats stressed as neonates show exaggerated behavioral responses to both pharmacological and environmental challenges.

Adult rats that were isolated from the mother and nest for 1 hr per day from Postnatal Day 2 to 9 were studied. Controls consisted of handled littermates as well as separate litters that were never handled. As adults, animals were given either a pharmacological challenge (1.0 or 2.0 mg/kg amphetamine) or an environmental challenge (restraint). Previously isolated animals demonstrated increased activity compared to controls at both drug doses. Similarly, isolated animals manifested exaggerated inhibition of activity after restraint. Previously isolated animals usually did not show differences compared to controls under baseline conditions (saline injection or no restraint). The neuroplastic changes that result from the neonatal experience are long lasting and appear when the system is challenged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of ZnCl2 pretreatment on behavioral and histological responses to kainic acid in rats

Kainic acid evokes behavioral convulsions and causes lesions in hippocampal pyramidal cell layers in rats. The effects of ZnCl2 pretreatments on these events were examined. Rats were given ZnCl2 (35 mg/kg, subcutaneously (s.c.)) 15 min prior to kainic acid administration (12 mg/kg, intraperitoneally (i.p.)). Another group of animals was given an additional dose of ZnCl2 (35 mg/kg, i.p.) 24 h prior to the s.c. ZnCl2 and i.p. kainic acid. All rats that received kainic acid, whether saline controls or ZnCl2 pretreated, experienced wet dog shakes (WDS) and convulsions. No significant differences were seen between groups in number or latency of WDS or convulsions. Two days after behavioral data were collected, the brains were perfused and the extent of lesioning among hippocampal CA1 and CA3 pyramidal cells was quantified. A single dose of ZnCl2 had either no effect or a slight protective effect on cell lesioning induced by kainic acid. However, lesioning was more pronounced in animals treated twice with zinc. It is concluded that zinc, co-administered with kainic acid, augments kainate cytotoxicity when the dose and timing of zinc exposure are within a critical period.     

Sex differences in electrophysiological and behavioral responses to NaCl taste.

We tested the hypothesis that sex differences in preference for NaCl are attributable to estrogen-mediated alterations in gustatory processing. Electrophysiological responses of the chorda tympani nerve to NaCl were blunted by estrogen treatment in ovariectomized female rats, suggesting that females are less sensitive to concentrated NaCl solutions during high estrogen conditions. In contrast, after a taste aversion was conditioned to 150-mM NaCl, estrogen- and oil-treated ovariectomized rats generalized the aversion to a lower concentration of NaCl than did males, suggesting that females are more sensitive to the taste of dilute NaCl solutions regardless of estrogen. Thus, sex differences in NaCl preferences may be attributable to differences in NaCl taste processing that involve both acute and developmental effects of estrogen. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactance and the coronary-prone behavior pattern: The role of self-attribution in responses to reduced behavioral freedom.

40 Type A and 40 Type B college students (Jenkins Activity Survey) were placed in a choice elimination reactance paradigm. In addition to the standard control and choice elimination conditions, Ss were induced to attribute having a choice among evaluated items either to themselves or to the situation prior to experiencing the elimination of choice. Reactance was measured by Ss' reevaluations of the eliminated choice alternative. Results indicate that when a behavioral freedom was blocked, without manipulating attributions, only Type A's experienced reactance. When Ss were induced to attribute having a choice to themselves, the magnitude of the reactance responses increased for both Types A and B. In contrast, when Types A and B were induced to attribute having choice to the situation, neither group reacted to the loss of choice. Results are integrated with previous findings on the coronary-prone behavior pattern. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste receptors on the anterior tongue and nasoincisor ducts of rats contribute synergistically to behavioral responses to sucrose.

In 4 groups of rats, behavioral responsiveness to sucrose was tested by allowing them to lick solutions in a computer-controlled gustometer (10-sec trials; 0.01–2.0 M). Rats with cautery lesions of the nasoincisor ducts (NID) behaved no differently from controls. After bilateral chorda tympani nerve (CT) section, which removes taste input from the anterior tongue (AT), rats demonstrated a marginal attenuation in their responsiveness to sucrose. Combining the 2 lesions, however, had the greatest effect on the concentration–response curve. By shifting the curve to the right and lowering the asymptotic licking rate, the combined lesion reduced the area under the curve by one third. The effects of the combined treatments were larger than would be predicted from the sum of either one alone. This presumably reflects the central convergence of primary afferent axons from the NID and AT. Neurophysiological data have demonstrated such convergence within the nucleus of the solitary tract. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The liver and immune responses. I. Regional lymph node response in rats to injection of semi-allogeneic adult liver cells

A 12-year-old Domestic Shorthair cat with a soft, fluctuant, subcutaneous mass, approximately 5 cm in diameter on the posterior aspect of the left tarsus was diagnosed as having protothecosis. Cultures, histopathology, and fluorescent antibody reagents were used to identify Prototheca wickerhamii as the etiologic agent. Protothecosis has not previously been recorded in cats.     

Maternal influences on ontogeny of suckling and feeding rhythms in the rat.

Conducted 4 experiments to assess the effects of both maternal and endogenous factors on the ontogeny of nocturnal feeding in the rat. Day and night weight gain was determined in the sighted or blind litters of sighted or blind Sprague-Dawley dams and in young weaned at 15 days of age. It is concluded that sighted dams impose a diurnal milk-intake pattern on their young. The nocturnal patterns of solid-food intake began at 19 days of age. Blind litters also displayed nocturnal feeding when kept with sighted dams, but only until 35 days of age. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early impact of a fat-enriched diet on behavioral responses of male and female rats.

Prolonged high-fat diets have been shown to affect an organism's stress responsiveness at the neuroendocrine level. In the present study, the authors used a 7-day protocol of fat administration in adult rats of both sexes to investigate the early behavioral impact of a moderately fat (20%) diet, often used by Western societies, on rats' reaction to acute stress and novelty. Their results show that this diet can reduce the rats' active behavioral responses to subsequent stressors and influence their corticosterone secretion. Fat-fed male rats adopted a less active behavior to cope with forced swimming stress, whereas their exploratory behavior in the open field environment was rather increased compared with chow-fed males. Fat-fed female rats exhibited a less active behavioral response to both stress paradigms compared with their chow-fed counterparts. Fat diet abolished facilitation in corticosterone secretion following a subsequent stressor in both sexes. However, only in males did fat diet exaggerate corticosterone response to novelty, irrespective of the previous stress history of the rat. These data indicate that a short-term metabolic stress can modify the rats' stress coping strategy in interaction with the gender. (PsycINFO Database Record (c) 2010 APA, all rights reserved)