Abdominal vagotomy attenuates the inhibiting effect of mannitol on the ingestive behavior of rats.

Intact and abdominally vagotomized rats were offered for ingestion during a 30-min period a saccharin and glucose solution or another with 0.1 M mannitol added. The addition of mannitol to the test solution caused a large reduction in intake of intact rats caused by a very rapid decline in the rate of licking during the test. This did not occur with the vagotomized rats. This demonstrates that abdominal vagal nerves are necessary for the inhibitory effect of mannitol on the ingestive behavior of rats. Vagotomized rats also differed from the intact ones by ingesting less of the mannitol-free solution. This was suggested to result from accelerated gastric clearance, leading to abnormally rapid stimulation of negative feedback from the small intestine conveyed to the CNS by extravagal pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cholecystokinin changes the duration but not the rate of licking in vagotomized rats.

Abdominal vagotomy markedly reduces or abolishes the inhibitory effect of cholecystokinin (CCK-8) on meal size. To investigate the rate and microstructure of licking underlying this phenomenon, licking was measured throughout a meal of milk in intact and vagotomized rats after intraperitoneal injections of isotonic saline or CCK-8. CCK-8 increased the slope of the decay of licking, decreased the efficiency of licking, and decreased the duration of licking in intact rats but had no effect on either the slope of the decay of licking or the efficiency of licking, but it increased the duration of licking in vagotomized rats. These results demonstrate that abdominal vagal nerves are necessary for CCK-8 to increase the rate of decay of licking, but nonvagal mechanisms mediate the effect of CCK-8 on duration of licking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ovariectomy and estradiol affect postingestive controls of sucrose licking

Ovariectomy (OVX) has been shown to increase, and estradiol replacement to decrease, meal size in rats. Because little is known about how estradiol influences meals, we conducted two experiments to examine the effects of OVX and beta-estradiol 3-benzoate (EB) replacement on the microstructure of licking behavior. In both experiments, patterns of licking were analyzed in adult female Sprague-Dawley rats during an 0.8 M sucrose test meal. In Experiment 1, meal microstructure was determined preOVX and 10-12 days postOVX. Rate of licking following OVX was not changed during min 1 of the meal, but was significantly faster during min 2-4 of the meal (p < 0.03). The numbers of bursts (runs of licks separated by 250-500 ms) and numbers of clusters (runs of licks separated by > 500 ms) were significantly increased during min 2-4 (p < 0.05). In Experiment 2, OVX rats received EB replacement. Rate of licking after EB replacement was not changed during min 1 of the meal, but was significantly slower during the remainder of the meal (min 2-4, min 5-7, and min 8-10). Burst size, cluster size, and interburst interval were less after EB replacement during min 5-7 of the test meal (all p < 0.05). Because both OVX and EB replacement failed to alter the rate of licking during min 1, estrogen did not appear to alter the palatability of sucrose. OVX and EB replacement did appear to affect a postingestive mechanism(s) that is engaged within 2-4 min of meal onset.     

Analysis of the microstructure of the rhythmic tongue movements of rats ingesting maltose and sucrose solutions.

Analyzed interlick interval distribution of rats ingesting maltose under real and sham feeding conditions and while ingesting 7 concentrations of sucrose under real feeding conditions. The analysis revealed that the licking behavior of rats is organized into bursts of licking at a high rate. These bursts occurred in clusters that were separated by brief (250–500 msec) interruptions. The clusters were separated by intervals that ranged from 500 msec to many hundreds of seconds. Sham feeding increased the length of the meal by increasing the number but not the size of the clusters. Increasing the concentration of sucrose increased monotonically the size of the clusters but varied the number of clusters as an inverted-V-shaped function. Analysis revealed the details of the central nervous system's (CNS) control over ingestive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of neuropeptide Y on feeding microstructure: Dissociation of appetitive and consummatory actions.

The effects of intracerebroventricular application of Neuropeptide Y (NPY) on licking microstructure for sucrose, saccharin, and water solutions were evaluated. In Experiment 1, NPY increased meal size for three sucrose concentrations (0.03 M, 0.3 M, and 1.0 M) by increasing licking burst number but not size and by extending meals more than four-fold in duration with a slow, sustained rate of ingestion in late phases of the meal. Results are consistent with the interpretation that NPY suppressed inhibitory postingestive feedback. Experiment 2 supported this conclusion. NPY significantly increased the number of meals initiated for water, 0.1% saccharin, and 1.0 M sucrose solutions, but meal size was only increased for 1.0 M sucrose. Therefore, NPY also increased appetitive feeding behaviors, but its consummatory effects were limited to caloric solutions. The results are discussed with regard to their potential to explain current discrepancies in the literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms for enhanced feeding in the cold in rats.

The effect of environmental cold upon feeding, food-motivated behavior, and gastric clearance of food was studied in 36 female Sherman rats in 4 experiments. Ss ate liquid diet in either a 5 or 22Deg. C ambient temperature (T-sub(a)) following (a) 24-hr food deprivation at T)a) of either 5 or 22Deg. C or (b) 0- or 48-hr food deprivation at T-sub(a) 22Deg. C. Ss ate more at 5 than at 22Deg. C regardless of the ambient temperature during deprivation. Ss increased feeding in the cold by increasing meal frequency but not meal size. Cold (5Deg. C) also enhanced the urge to eat. Ss barpressed for food more often in the cold on a VI 30-sec schedule when gastric clearance of food was prevented by a pyloric noose and when food cleared from the stomach normally. Quinine adulteration of food suppressed food intake only in the 22Deg. C. Cold (5Deg. C) enhanced gastric clearance of liquid food within 20 min of ingestion. Results support the view that the peripheral sensation of cold is an adequate stimulus for feeding and that cold T-sub(a) can stimulate feeding directly by increasing the urge to eat and indirectly, secondary to increased gastric clearance. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of licking responses in rats: Effects of cholecystokinin and bombesin.

Compared the effects of cholecystokinin (CCK) and bombesin (BBS) on the consummatory response in male albino rats in 3 experiments. The normal licking response pattern did not change as the meal progressed; no predictor was found to indicate when the meal would terminate. Licks normally occurred at about 6/sec, but there were a few licks that occurred at about 3/sec with no licking occurring in the intermediate range; thus, a distinctive bimodal frequency distribution of the interlick interval was formed. CCK reduced the intake of milk and the related licking indices as expected, but it also induced an unusual licking pattern: The contact duration was shortened, the interlick interval was lengthened, and there was an increase in the proportion of licks with long interlick intervals, the effects that accentuated the bimodality of the distribution of interlick intervals. BBS reduced the intake and the related licking indices. The CCK effect may be mediated partially by a change in the motor aspect of the consummatory response; however, BBS reduced intake by simply decreasing the number of licks and shortening the intake duration. BBS may be a candidate for a natural satiety hormone. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2-2''-Pyridylisatogen, a selective allosteric modulator of P2 receptors, is a spin trapping agent

We studied the role of parasympathetic division of vegetative nervous system in regulation of the intestine activity in rats subjected to bilateral subdiaphragmal vagotomy, the response of the neuromuscular apparatus of the small intestine to stimulation by aceclydine taken as an example. Intravenous injection of aceclydine (0.5 mg/kg) into intact animals is accompanied by characteristics changes in the electrical and contractile activities of the intestine, which reflect its enhanced motor activity. Vagotomy leads to changes of response of the intestine to pharmacological stimulation, most expressed within 3, 7, and 30 days. It was proposed that distortion of reactive properties of the intestine contractile system under these conditions is related to functional changes in rhythm-setting neurons of intramural ganglia and M-cholinoreceptors of neuromuscular synapses.     

Analytical issues in the evaluation of food deprivation and sucrose concentration effects on the microstructure of licking behavior in the rat

A microstructural analysis of licking behavior in nondeprived and 23-hr food-deprived rats (n = 15) presented with various sucrose solutions (0.03-1.0 M) in daily single-bottle, 1-hr sessions was conducted. Food deprivation and concentration interacted to increase total licks. The effects of food deprivation and concentration on burst size (BS), burst number (BN), and other parameters varied as a function of the pause criterion (PC; 0.3-100 s) used to define licking bursts. A rationale for selecting a 1-s PC for further analysis is presented. Despite the lack of correlations between temporally contiguous burst and pause combinations, mean BS decreased and pause duration increased as meals progressed. At the 1-s PC, BS increased linearly with concentration, implying that this microstructural parameter is influenced in part by taste. Food deprivation did not affect BS but rather increased BN and proportionally extended the meal duration.     

Patterns of bulbar respiratory neurons during and after artifical hyperventilation

A test meal consisting of food (Galactomin 18), and a barium preparation (Raybar) was given to 47 patients who had undergone truncal vagotomy combined with either antrectomy or gastric drainage, and to five normal subjects. The radiological findings were correlated with the symptomatology. Total gastric emptying was not significantly different between normal controls, post-operative but asymptomatic cases, or those in whom dumping of diarrhoea was provoked. Small intestinal transit was significantly faster in cases of post-cibal diarrhoea than in other groups, and was also more rapid than normal when dumping was provoked. Colonic entry time was also faster than normal in these two groups. Marked dilution of the meal in the small bowel only occurred in the presence of the dumping syndrome. Jejunal interposition prevented the occurrence of dumping and restored the radiological appearances in the intestine to normal. The test meal gave excellent correlation with the patients' symptomatology. The relationship of the findings to the mechanisms of post-cibal diarrhoea and the dumping syndrome is discussed.     

An experimental study on the replacement of the anterior cruciate ligament of the rabbit''s knee using an augmented substitute

This study was designed to test the putative role of plasma cholecystokinin (CCK) in eating behaviour by examining the relationships between bioassayed plasma CCK concentrations and rated sensations of satiety and hunger following the ingestion of an appetizing nutrient-dense meal and between plasma profiles of CCK and scintigraphically determined gastric emptying in nine healthy male volunteers. Mean plasma CCK levels from the whole group showed a significant negative correlation with mean hunger ratings (r = -0.64) and a positive correlation with fullness (r = +0.68). However, there was considerable interindividual variation and negative correlations with hunger were only seen in three out of nine subjects and positive correlations with fullness in four out of nine subjects. In contrast, there was a strong relationship between the plasma CCK produced over the first 2 h after the meal and the half time for gastric emptying of the meal (r = -0.81). These data do not support a direct role for circulating levels of CCK in the control of hunger and satiety following a meal. Instead, the strong correlation with gastric emptying is compatible with release of CCK in response to nutrient delivery into the small intestine.     

Effects of lateral hypothalamic lesions and vagotomy on meal patterns in rats.

Studied meal patterns with liquid diets in 4 female Carworth CFE albino rats with lateral hypothalamic (LH) lesions and in 4 Ss with sham lesions, both before and after vagotomy. LH Ss reduced total intake following lesions but showed no differences from controls after vagotomy on measures of total daily intake, mean meal size, and frequency of feeding. Identical frequency distributions of meal sizes and intermeal interval durations were found in LH and control Ss after vagotomy. However, although sham-lesioned Ss showed significant positive correlations between meal size and subsequent intermeal-interval durations in all phases of the experiment, the LH Ss showed no such correlation following vagotomy. Thus, indices of microregulatory controls may be more sensitive in indicating feeding deficits. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coordinated release of acylation stimulating protein (ASP) and triacylglycerol clearance by human adipose tissue in vivo in the postprandial period

The objective of this study was to determine whether Acylation Stimulating Protein (ASP) is generated in vivo by human adipose tissue during the postprandial period. After a fat meal, samples from 12 subjects were obtained (up to 6 h) from an arterialized hand vein and an anterior abdominal wall vein that drains adipose tissue. Veno-arterial (V-A) gradients across the subcutaneous adipose tissue bed were calculated. The data demonstrate that ASP is produced in vivo (positive V-A gradient) With maximal production at 3-5 h postprandially. The plasma triacylglycerol (TAG) clearance was evidenced by a negative V-A gradient. It increased substantially after 3 h and remained prominent until the final time point. There was, therefore, a close temporal coordination between ASP generation and TAG clearance. In contrast, plasma insulin and non-esterified fatty acid (NEFA) had an early (1-2 h) postprandial change. Fatty acid incorporation into adipose tissue (FIAT) was calculated from V-A glycerol and non-esterified fatty acid (NEFA) differences postprandially. FIAT was negative during the first hour, implying net fat mobilization. FIAT then became increasingly positive, implying net fat deposition, and overall followed the same time course as ASP and TAG clearance. There was a direct positive correlation between total ASP production and total FIAT (r = 0.566, P < 0.05). These data demonstrate that ASP is generated in vivo by human adipocytes and that this process is accentuated postprandially, supporting the concept that ASP plays an important role in clearance of TAG from plasma and fatty acid storage in adipose tissue.     

Self-licking deprivation and maternal behaviour in the primiparous rat.

Self-licking and/or collar licking was prevented in 25 female rats from the 21st day of age by means of a rubber collar about the neck. The ability of these Ss to deliver and maintain their litters did not differ from that of those whose collars did not restrict licking or from that of uncollared controls. This questions the hypothesis that preparturitive self-licking behavior is important for normal parturition and maternal behavior. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contribution of gastric and postgastric feedback to satiation and satiety in women

Two parallel preload studies were conducted to determine the relative contributions of inhibitory feedback from the stomach and intestine to satiation (meal termination) and postprandial satiety. In the Gastric Emptying Study, five normal-weight women each ingested an egg sandwich (307 kcal) (1) immediately after a tomato soup preload (120 kcal), (2) 20 min after a tomato soup preload, and (3) with no preload. There was 125 g more of soup in the stomach when subjects began ingesting the sandwich immediately compared to 20 min after the soup, and the emptying of the sandwich was delayed when it was ingested immediately but not 20 min after the soup. The lag times for emptying of the sandwich were 76.5 (69.1-82.4), 47.2 (20.1-67.7), and 42.4 (17.8-65.1) min for the three conditions, respectively, p < 0.05. In the Food Intake Study, 16 normal-weight women ate significantly less (p < 0.01) in test meals offered immediately (978+/-246 kcal) and 20 min (1027+/-298 kcal) after the soup preload than in a test meal with no preload (1151+/-279 kcal). Despite the different amounts of soup in the stomach, subjects' test-meal intake in the two preload conditions was not significantly different. Subjects' fullness ratings following the preloads and the test meals were not different among the treatment conditions. The results suggest that feedback from neither the gastric nor the postgastric compartment is primary in determining meal size and postprandial satiety. Instead, signals from gastric and postgastric sources are combined to determine meal size and postprandial satiety.     

The different components of gastric emptying after gastric surgery

Gastric emptying of liquid and solid meals was studied before and after operation in 22 male patients who were admitted to a prospective randomized trial of truncal vagotomy and antrectomy and proximal gastric vagotomy in the treatment of duodenal ulceration. After operation the emptying of both solid and liquid meals was biphasic, with a passive early phase and a later controlled active phase. A significant increase in early liquid emptying was produced by both operations, and after truncal vagotomy and antrectomy also with the solid meal. Active emptying of the liquid meals was unaffected by either operation, but both operations significantly prolonged the active emptying of the solid meals. The clinical symptoms of dumping were related to rapid early liquid emptying (cascading) and those of gastric retention were related to delayed active emptying of the solid meal. These findings explain how the same operation can produce the opposing symptom complexes of dumping and gastric retention and how both sets of symptoms can occur in the same individual.     

Videotape versus verbal feedback in the modification of meal behavior of chronic mental patients.

Data from "meal behavior indexes" were calculated for 28 chronic adult psychiatric patients who received either videotape or verbal feedback and structured discussions with 2 therapists about their meal behavior. Results show no significant effects attributable to group treatments, therapists, or Therapist * Treatment interactions. The very low level of functioning of these Ss appears to account for results. It is suggested that a token economy offers more promise for this type of patient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning to avoid in older age.

The dopamine hypothesis of aging suggests that a monotonic dopaminergic decline accounts for many of the changes found in cognitive aging. The authors tested 44 older adults with a probabilistic selection task sensitive to dopaminergic function and designed to assess relative biases to learn more from positive or negative feedback. Previous studies demonstrated that low levels of dopamine lead to avoidance of those choices that lead to negative outcomes, whereas high levels of dopamine result in an increased sensitivity to positive outcomes. In the current study, age had a significant effect on the bias to avoid negative outcomes: Older seniors showed an enhanced tendency to learn from negative compared with positive consequences of their decisions. Younger seniors failed to show this negative learning bias. Moreover, the enhanced probabilistic integration of negative outcomes in older seniors was accompanied by a reduction in trial-to-trial learning from positive outcomes, thought to rely on working memory. These findings are consistent with models positing multiple neural mechanisms that support probabilistic integration and trial-to-trial behavior, which may be differentially impacted by older age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of a candidate tumour suppressor gene, MMAC1, at chromosome 10q23.3 that is mutated in multiple advanced cancers

The systemic administration of thyrotropin-releasing hormone (TRH) to rats elicits locomotor activation, wet dog shakes, jaw movements, paw licking and tail rattle. Central dopamine (DA) and 5-hydroxytryptamine (5-HT) systems and peripheral vagal afferents have been implicated in these responses. To define this circuitry further, the effects of lesions of these pathways on the behavioral responses elicited by intraperitoneal (IP) injections of TRH were assessed in rats. Lesions of the DAergic innervation of the nucleus accumbens did not affect the locomotor activation, wet dog shakes, paw licking, jaw movements or tail rattle elicited by TRH. This is consistent with our in vivo microdialysis finding that TRH did not affect the release of DA in the nucleus accumbens at a dose that strongly increased locomotor activity. Depletion of spinal 5-HT significantly decreased the wet dog shakes induced by TRH, while depletion of forebrain 5-HT had no effect on any behavior. Bilateral vagotomy did not affect the locomotor response to TRH or any of the other behaviors measured. Taken together these results suggest that the DAergic mesolimbic, the 5-HTergic projections to the forebrain and vagal afferent systems are not mediators of the behavioral responses to systemic TRH. In contrast, the raphe-spinal 5-HTergic projection system may serve to modulate the wet dog shakes elicited by this peptide.     

Microstructural pattern of palatable food intake from weaning to adulthood in male and female OLETF rats.

Ontogenetic trajectories from weaning to adulthood and sex differences in feeding patterns were examined in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of early onset overeating-induced obesity, and a natural cholecystokinin-1 receptor knockout. Overnight patterns of licking a palatable liquid diet (Ensure) were analyzed on Postnatal Days 22, 38, 60, and 90. Because different microstructure profiles may reflect alterations in the influence of positive and negative signals, we examined meal parameters to uncover developing mechanisms underlying eating behavior in this strain. OLETF rats displayed significantly greater caloric intake, larger meals (in number of licks), and more (within-meal) clusters of feeding (which were shorter in duration and contained fewer licks per cluster) than did Long-Evans Tokushima Ohtsuka (LETO) strain controls. OLETF rats also had significantly lower satiety ratios than LETO rats. Moreover, we identified sex differences in the age of emergence of microstructural patterns of obesity-related overeating, suggesting that systems other than cholecystokinin may be disrupted, possibly worsening the OLETF strain’s obesity phenotype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)