Feeding Patterns Of Rats Research Articles

Tympanic Membrane Rupture During Stereotaxic Surgery Disturbs the Normal Feeding Behavior in Rats.

Stereotactic surgery is a widely used procedure in neuroscience research to study the brain’s regulation of feeding behavior. In line with this notion, this study aims to assess how food consumption and feeding patterns are affected in response to the use of auditory bars that preserve or damage the tympanic membrane during stereotactic surgery. Our previous observations led us to hypothesize that the traumatic tympanic membrane rupture affects food intake and feeding patterns in rats undergoing stereotactic procedures. Thereby, female and male rats were cannulated in the third ventricle (3V) using both types of auditory bars. Post-surgical pain was assessed using the grimace scale. Food intake, meal patterns and weight gain or loss were analyzed for 5–7 consecutive days after surgery. Normal food intake, increased body weight and regular meal patterns were observed from postoperative day 2 when the stereotactic procedure was performed using auditory bars that maintain the integrity of the tympanic membrane. However, tympanic membrane rupture prevented the expected recovery of food intake and body weight. This effect was accompanied by an alteration in eating patterns, which was persistent over 7 days of recovery. Thus, tympanic membrane preservation during surgery is necessary to evaluate short-term feeding patterns. This study demonstrates auditory bars that do not damage the tympanic membrane should be used when performing stereotactic surgery for subsequent analysis of rat behavior.

A Novel Automated System Yields Reproducible Temporal Feeding Patterns in Laboratory Rodents

ABSTRACTBackgroundThe impact of temporal feeding patterns remains a major unanswered question in nutritional science. Progress has been hampered by the absence of a reliable method to impose temporal feeding in laboratory rodents, without the confounding influence of food-hoarding behavior.ObjectiveThe aim of this study was to develop and validate a reliable method for supplying crushed diets to laboratory rodents in consistent, relevant feeding patterns for prolonged periods.MethodsWe programmed our experimental feeding station to deliver a standard diet [StD; Atwater Fuel Energy (AFE) 13.9% fat] or high-fat diet (HFD; AFE 45% fat) during nocturnal grazing [providing 1/24th of the total daily food intake (tdF/I) of ad libitum–fed controls every 30 min] and meal-fed (3 × 1-h periods of ad libitum feeding) patterns in male rats (Sprague-Dawley: 4 wk old, 72–119 g) and mice [C57/Bl6J wild-type (WT): 6 mo old, 29–37 g], and ghrelin-null littermates (Ghr−/−; 27–34 g).ResultsGrazing yielded accurate, consistent feeding events in rats, with an approximately linear rise in nocturnal cumulative food intake [tdF/I (StD): 97.4 ± 1.5% accurate compared with manual measurement; R2 = 0.86; tdF/I (HFD): 99.0 ± 1.4% accurate; R2 = 0.86]. Meal-feeding produced 3 nocturnal meals of equal size and duration in StD-fed rats (tdF/I: 97.4 ± 0.9% accurate; R2 = 0.90), whereas the second meal size increased progressively in HFD-fed rats (44% higher on day 35 than on day 14; P < 0.01). Importantly, cumulative food intake in grazing and meal-fed rats was identical. Similar results were obtained in WT mice except that less restricted grazing induced hyperphagia (compared with meal-fed WT mice; P < 0.05 from day 1). This difference was abolished in Ghr−/− mice, with meal initiation delayed and meal duration enhanced. Neither pattern elevated corticosterone secretion in rats, but meal-feeding aligned ultradian pulses.ConclusionsWe have established a consistent, measurable, researcher-defined, stress-free method for imposing temporal feeding patterns in rats and mice. This approach will facilitate progress in understanding the physiologic impact of feeding patterns.

The effects of energy intake of four different feeding patterns in rats.

Energy intake can affect the metabolism. But it is not very clear that how and to what degree the metabolism can be changed by energy intake quantity and change. Here we applied four feeding patterns in male Sprague-Dawley rats--normal ad libitum diet (NFal), high-fat diet (HFal), caloric restriction (CR) after HFal (HFal-NFcr), and refeeding from CR to ad libitum (HFal-NFcr-NFal). Food intake and body weight, along with fat mass, insulin sensitivity, fasting plasma insulin, and glucose level were used to calculate the energy efficiency and compared the quantitative effects of energy intake. Energy intake changed little in NFal or HFal group; while it changed greatly and suddenly in HFal-NFcr or HFal-NFcr-NFal group. All the parameters we detected were different between these four feeding patterns. Excess of energy intake from high-fat diet induced adverse outcomes with low energy efficiency. CR reversed the impairment of high-fat diet with very high energy efficiency in a short period. However, dramatic response with high energy efficiency induced by recovery to feeding ad libitum after CR, which was possible harmful to health. In conclusion, energy intake quantity and change are key determinants of metabolism. Different energy intake quantity and change affect body weight, white adipose tissue weight, insulin sensitivity, etc. at different degrees and speeds because of different energy efficiency.

Polyphenol-rich extract of Vernonia amygdalina (Del.) leaves ameliorated cadmium-induced alterations in feeding pattern and urine volume of male Wistar rats.

Aim:To determine the effects of a polyphenol-rich extract of the leaves of Vernonia amygdalina (PEVA) on the feeding pattern of rats that are exposed to cadmium (Cd) toxicity.Materials and Methods:Thirty male Wistar rats, weighing 160-180 g, were divided into 6 groups of 5 rats each as follows; Group 1 received distilled water orally (0.2 ml a 100 g rats), daily, throughout the period of study. Group 2 received Cd alone (in the form of CdSO4) at 5 mg/kg/day via intraperitoneal route for 5 consecutive days. Group 3 were pre-treated with Cd as Group 2 and thereafter left untreated for a period of 4-week. After the oral lethal dose of PEVA was determined, Groups 4, 5, and 6 received graded doses of PEVA at 100, 200 and 400 mg/kg/day (0.2 ml per 100 g rats), respectively via oral route for 4 weeks after they were pre-treated with Cd as Group 2. Blood samples were collected for some plasma biochemical assays while urine samples were collected using metabolic cages.Results:PEVA administration significantly increased (P < 0.05) the body weight and feeding patterns that were significantly reduced (P < 0.05) by Cd toxicity. PEVA also significantly reinstated the plasma antioxidant status, as well as glucose and urine volume of the rats toward control values (P < 0.05).Conclusion:PEVA can be an herbal alternative in the treatment or management of subjects manifesting alterations in feeding pattern and urine volume that is Cd-induced.

Altered feeding patterns in rats exposed to a palatable cafeteria diet: increased snacking and its implications for development of obesity.

BackgroundRats prefer energy-rich foods over chow and eat them to excess. The pattern of eating elicited by this diet is unknown. We used the behavioral satiety sequence to classify an eating bout as a meal or snack and compared the eating patterns of rats fed an energy rich cafeteria diet or chow.MethodsEight week old male Sprague Dawley rats were exposed to lab chow or an energy-rich cafeteria diet (plus chow) for 16 weeks. After 5, 10 and 15 weeks, home-cage overnight feeding behavior was recorded. Eating followed by grooming then resting or sleeping was classified as a meal; whereas eating not followed by the full sequence was classified as a snack. Numbers of meals and snacks, their duration, and waiting times between feeding bouts were compared between the two conditions.ResultsCafeteria-fed rats ate more protein, fat and carbohydrate, consistently ingesting double the energy of chow-fed rats, and were significantly heavier by week 4. Cafeteria-fed rats tended to take multiple snacks between meals and ate fewer meals than chow-fed rats. They also ate more snacks at 5 weeks, were less effective at compensating for snacking by reducing meals, and the number of snacks in the majority of the cafeteria-fed rats was positively related to terminal body weights.ConclusionsExposure to a palatable diet had long-term effects on feeding patterns. Rats became overweight because they initially ate more frequently and ultimately ate more of foods with higher energy density. The early increased snacking in young cafeteria-fed rats may represent the establishment of eating habits that promote weight gain.

Kerin O'Dea: improving the health of Indigenous Australians

Kerin O'Dea: improving the health of Indigenous Australians

Your brain on fat: dietary-induced obesity impairs central nutrient sensing

the past decade has witnessed a rejuvenated interest in the ability of the central nervous system (CNS) to sense and respond to changes in nutrient availability. This interest has been driven in part by a conceptual framework where the CNS receives signals regarding nutrient availability that are

Food Entrainment to 4-h T Cycles in Rats Kept Under Constant Lighting Conditions

The effect of 4-h feeding cycles on the feeding pattern of rats kept under constant light and constant darkness, was analysed. In both cases, the scheduled pattern of food-approach behavior elicited dissociation of the feeding activity into several components associated to the feeding times (CAFT), which coexisted with the previous circadian free-running rhythms. In LL rats and in the rest phase of DD animals, the CAFT was characterized by an increased number of food approaches confined exclusively to the period of food availability, with poor anticipatory activity. However, in the active phase of some DD rats, CAFT included an additional anticipatory activity. The interaction between the CAFT and the free-running rhythms involved modulation of the CAFT, depending on the free-running periodicity. After termination of the feeding-restriction schedule, some DD and LL animals retained the CAFT for at least 3 days. However, when the access to food was blocked 10 days after ending the restricted schedule, rats did not show any feeding activity associated to the previous feeding times. A spontaneous feeding pattern similar to that imposed by the previous feeding schedule emerged immediately after food deprivation in two of the DD animals. Although these results are compatible with the existence of a food-entrainable pacemaker, the existence of a multioscillatory light-entrainable pacemaker with some oscillators entrained by food pulses and others free-running may explain our results.

Exercise Training Decreases Body Fat More in Self-Selecting Than in Chow-Fed Rats

Rieth, N. and C. Larue-Achagiotis. Exercise training decreases body fat more in self-selecting than in chow-fed rats. PHYSIOL BEHAV 62(6) 1291–1297, 1997.—This study was designed to examine the influence of exercise training on body weight gain and feeding pattern in rats placed on a self-selection or a chow diet regimen. Adult, male, Wistar rats were submitted to daily 2-h treadmill exercise for 28 days (about 50% of VO 2 max) at the beginning of the nocturnal period. Two other groups of rats were examined during the same time: a sedentary group that was deprived of food and water during the training session and a control group without any treatment. Food intakes were continuously recorded. For both feeding regimens, trained rats, relative to their respective controls, showed at the end of the experiment a reduction in body weight gain due to a reduced body fat deposit. Moreover, white adipose tissue (WAT) mass of self-selecting rats was smaller than in chow-fed rats. Exercise training decreased plasma glucose level in chow-fed rats and plasma insulin level in self-selecting rats. In self-selecting rats, food intake was slightly increased due to enhanced protein intake during the nocturnal period and fat intake increased both during the nighttime and daytime periods, whereas in chow-fed rats, food intake was decreased during the daytime period. These results show that, in rats placed on a self-selection regimen, exercise training increased fat consumption but reduced WAT. This could be a consequence of an increased lipolytic capacity of adipocytes in self-selecting trained rats. Thus, it appears from these results that the diet’s carbohydrate-to-fat ratio can be an important parameter in shaping the interaction between exercise and body weight.

Feeding patterns of rats when food-access cost is alternately low and high

Rats living in a laboratory foraging paradigm began each meal by bar pressing to procure access to food and then could eat any amount. In different conditions the procurement price changed from low (10 bar presses) to high (200 or 400 bar presses) every ten days, five days, or one day, or on schedules of one-day-low/two-days-high, or one-day-low/four-days-high. In a final condition, the price alternated at every meal. Meals were less frequent and larger on high-price days. In the ten- and five-day alternations, the rats adjusted meal frequency on the first day of a price, but changed meal size gradually over the first few days; by the fifth day, daily intake was not different on low- and high-price days. In the one-day alternations, the rats ate less food, and in some cases did not eat at all, on high-price days, and lost weight. Intake was greater than normal, and body weight recovered, on low-price days. This pattern saved foraging cost at the expense of greater-than-normal daily fluctuations in food intake and body weight. When two or four days of high price alternated with one day of low price, the rats did eat on the first day of high price, suggesting they may integrate costs over a time window greater than 24 h.

Olfactory bulbectomy in rats modulates feeding pattern but not total food intake

The role of olfactory input in the regulation of food intake and feeding patterns in rats was investigated by performing bilateral olfactory bulbectomy. Compared to control rats, bulbectomized rats ate the same amount of food, but did so via a decrease in meal size, and a doubling in meal number. Although no increase in meal duration occurred, the exploratory behavior of sniffing during meals and between meals also increased significantly. While it is not yet clear how the olfactory bulbs participate in regulating food intake configuration resulting in changed feeding patterns, their clinical role can be appreciated by observing the acute changes in feeding pattern that occur when their input to the lateral hypothalamic area is damaged experimentally.

Reciprocal interaction of 5-hydroxytryptamine and cholecystokinin in the control of feeding patterns in rats.

1. The effect of the CCKA receptor antagonist, devazepide (100 mg kg-1) on meal parameters during the initial phase of the dark period was studied in free-feeding rats by use of a procedure for continuously monitoring feeding patterns. 2. In a second experiment, the effect of devazepide on the reduction in meal parameters induced by the 5-hydroxytryptamine (5-HT) releaser and uptake inhibitor, (+)-fenfluramine (1.5 mg kg-1) in 4 h food-deprived rats was examined. 3. The hypophagic effect of an intraperitoneal injection of cholecystokinin (CCK-8, 4 micrograms kg-1) was studied in rats treated with the 5-HT receptor antagonist, metergoline (1 and 2 mg kg-1). 4. Devazepide increased the size of the first meal in free-feeding, but not in 4 h food-deprived rats and partially antagonized the effect of (+)-fenfluramine on the size and duration of the first meal. The reduction in eating rate induced by (+)-fenfluramine was not modified by devazepide. No changes in (+)-fenfluramine or (+)-norfenfluramine levels were found in the brain of rats treated with devazepide. 5. The effect of CCK-8 on meal size was completely antagonized by 2 mg kg-1 metergoline. A significant interaction was also found between 2 mg kg-1 metergoline and CCK-8 as regards their effect on the inter-meal interval. 6. The results suggest a reciprocal interaction between 5-HT and CCK-8 in enhancing the satiating effect of food in rats.

Nocturnal cyclic versus continuous total parenteral nutrition: Food intake and feeding pattern in rats

Total parenteral nutrition (TPN), providing the equivalent of 100% of mean daily oral intake for 24 hours, depressed spontaneous food intake (SFI) in rats by a mean >80%. Whether TPN had the same effect on SFI when given either in 12-hour cycles (Cyclic-TPN) or in 24 hours (Continuous-TPN) for 8 days was tested in 16 rats with jugular catheters, placed in metabolic cages modified with an Automated Computerized Rat Eater Meter. This continuously measures food intake and its dependent indexes: meal number, meal size, meal duration, meal sniffs and intermeal sniffs. Both rat groups ate the same amounts of chow before TPN. On starting TPN, food intake decreased by >80% in Cyclic-TPN and >50% in Continuous-TPN during each first infusion period. A nadir in food intake was reached in 48 hours with Cyclic-TPN and in 72 hours with Continuous-TPN. Thereafter, there was no food intake during the 12 hours of Cyclic-TPN, with minimal food intake during the intervening 12 hours of non-TPN normal saline infusion period. In both forms of TPN infusion, a reduction in food intake was achieved by a reduction in meal number and size, and thus in meal duration. Feeding-related sniffing activity was decreased by similar amounts with Cyclic- or Continuous-TPN. Cyclic-TPN for 12 hours had no advantage over Continuous-TPN, in that there was no compensatory enhancement of food intake and meal-related behavior during the cyclic non-TPN normal saline period.

Chronic and Continuous ICV Infusion of Neuropeptide Y Disrupts the Nycthemeral Feeding Patterns in Rats

Chronic and Continuous ICV Infusion of Neuropeptide Y Disrupts the Nycthemeral Feeding Patterns in Rats

“Poison-shyness” and “bait-shyness” developed by wild rats ( Rattus rattus L.). I. Methods for eliminating “shyness” caused by barium carbonate poisoning

Colonies of wild rats, Rattus rattus L., were offered the choice between two baits — cereal grains, flours, mixtures, oily and sweet cereals, and also gram flour. The rats were poisoned in the preferred baits with barium carbonate (100 mg per 10 g food; 200 mg per 10 g food in oily baits) and then presented with the same choice of unpoisoned foods as before. Poisoning caused a change in the feeding patterns of rats. Foods mixed with barium carbonate were avoided (“poison-shyness”), the same foods then offered without poison were also rejected (“bait-shyness”). Intermittent poisoning also caused aversion to the eating of both poison and bait. Apparently, both the quality and the strength of tastes perceived in the poisonous mixtures influenced the development of “bait-shy” behaviour in the rats. The results indicate the possibility of using barium carbonate as an additional acute poison for rodent control. “Bait-shyness” can then be mitigated or eliminated by using for baits: (i) cereals in an alternative textural form; (ii) cereal baits blended with strong-tasting substances like chocolate: (iii) cereal mixed with groundnut oil; (iv) or an equivalent wt./wt. mixture of cereals containing groundnut oil (5%).

Influence of graded TPN concentrations on feeding pattern of rats : [formula omitted], H Liu, PD Gelling. Surgical Metabolism & Nutrition Laboratory, Departments of Surgery and Bioelectronics, University Hospital, SUNY Health Science Center, Syracuse, NY, USA

Influence of graded TPN concentrations on feeding pattern of rats : [formula omitted], H Liu, PD Gelling. Surgical Metabolism & Nutrition Laboratory, Departments of Surgery and Bioelectronics, University Hospital, SUNY Health Science Center, Syracuse, NY, USA

The metabolic basis of dual periodicity of feeding in rats

AbstractThis article examines how the depletion and replenishment of various energy stores give rise to periodic eating and how constant body-energy levels are maintained over time.Measures of the energy expended throughout the 24-hour feeding pattern in rats indicate that two different energy stores (one of small capacity and one of large) determine two superimposed feeding periodicities: one from meal to meal (prandial), the other from day to night (nycthemeral). The article reviews how experimental overrepletion or overdepletion of gastrointestinal content, blood glucose, or body fats affect food intake. These data suggest that gastrointestinal content determines both meal size and meal-to-meal periodicity. Other evidence indicates that glucose uptake rate in tissues, which is modulated by fat synthesis and fat mobilization, affects the periodic onset of feeding and the difference between nocturnal and diurnal postprandial satiety.There follows an examination of the neuroendocrine bases for the interacting mechanisms governing energy input and output balance and of the role of the ventromedial hypothalamus in body-fat regulation and the lateral hypothalamus in feeding.

Effect of liver denervation on the feeding pattern of rats.

This study was undertaken to assess the role of the hepatic innervation in the short-term regulatory mechanisms of food intake. A liver denervation was performed in male Wistar rats: the liver was entirely freed from the surrounding organs, its vessels (with the exception of the hepatic veins) and the bile ducts were stripped. Controls consisted of two groups of liver-denervated rats in which sympathectomy or vagotomy were carried out. A continuous recording of food intake was performed in a third group. The complete absence of the hyperglycemic response to trauma in adrenalectomized liver-denervated animals was taken as evidence of functional sympathectomy of the liver. The disappearance of a vagovagal reflex--heart rate variation brought about by a glucose injection into the portal vein--was taken as evidence of functional vagotomy. The analysis of the recorded feeding patterns of liver-denervated and sham-operated animals showed that, in rats, this liver denervation did not affect in any way the feeding behavior.

Long-and short-term regulation of feeding patterns in the rat.

Analysis of feeding patterns in rats showed that the amount of food eaten in relatively long intervals (24-72 hr) was correlated with mean meal size and was essentially uncorrelated with meal frequency. Similarly, the regulatory adjustment in daily food intake occurring in response to changes in environmental temperature was shown to be the result of an adjustment in mean meal size, with no change in meal frequency. On the other hand, the amount of food eaten in relatively short intervals (3-12 hr) was shown to be more highly correlated with meal frequency than with mean meal size, and a reliable correlation between meal size and the postmeal interval was obtained. It was also shown that the meal size/postmeal interval regression equation predicts the long-term relation between mean meal size and the amount of food eaten. Take together, these results indicate that meal frequency is controlled largely by short-term regulatory signals and that at least some long-term regulatory signals affect meal size directly.

Effects of alloxan induced diabetes on the feeding patterns of rats

Chronic diabetes was induced in albino rats through the injection of alloxan. After an initial decline in food intake lasting a few days, meal size increased steadily for 2–3 weeks, while meal frequency remained very near to preinjection levels. When food intake again stabilized, rats were eating meals 2–3 times as large as those they ate prior to injection. Similarities to the feeding patterns of hypothalamic hyperphagic rats are discussed.