Prefeeding Activity Research Articles

The Food-entrainable Oscillator Is a Complex of Non-SCN Activity Bout Oscillators Uncoupled From the SCN Circadian Pacemaker

The food-entrainable oscillator, which underlies the prefeeding activity peak developed by restricted daily feeding (RF) in rodents, does not depend on the circadian pacemaker in the suprachiasmatic nucleus (SCN) or on the known clock genes. In the present study, to clarify the roles of SCN circadian pacemaker and nutrient conditions on the development of prefeeding activity peak, RF of 3-h daily feeding was imposed on four groups of adult male mice for 10 cycles at different circadian times, zeitgeber time (ZT)2, ZT8, ZT14, and ZT20, where ZT0 is the time of lights-on in LD12:12. Seven days after the termination of RF session with ad libitum feeding in between, total food deprivation (FD) for 72 h was imposed. Wheel-running activity and core body temperature were measured throughout the experiment. Immediately after the RF or FD session, the PER2::LUC rhythms were measured in the cultured SCN slices and peripheral tissues. Not only the buildup process and magnitude of the prefeeding activity peak, but also the percentages of nocturnal activity and hypothermia developed under RF were significantly different among the four groups, indicating the involvement of light entrained circadian pacemaker. The buildup of prefeeding activity peak was accomplished by either phase-advance or phase-delay shifts (or both) of activity bouts comprising a nocturnal band. Hypothermia under FD was less prominent in RF-exposed mice than in naïve counterparts, indicating that restricted feeding increases tolerance to caloric restriction as well as to the heat loss mechanism. RF phase-shifted the peripheral clocks but FD did not affect the clocks in any tissue examined. These findings are better understood by assuming multiple bout oscillators, which are located outside the SCN and directly drive activity bouts uncoupled from the circadian pacemaker by RF or hypothermia.

The Effect of Implementing Initial Emergency Care Bundle on Early Outcomes among Acute Ischemic Stroke Patients

Implementing an initial emergency care bundle for acute stroke patients bridges the gap between evidence-based and clinical practice to improve patients outcomes. Aim: To evaluate the effect of implementing the initial emergency care bundle on early outcomes among acute stroke patients. Setting: This study was conducted at the emergency department and neurocritical care unit at Mansoura University Hospital, Egypt. Method: An experimental research design was utilized in this study. A random sample of 120 adults patient with acute stroke was selected and divided into two equal groups of 60 patients in each group. Two tools were utilized to collect data: Tool (I): Tool I: Stroke patient assessment. Tool II: Stroke patients' outcomes assessment. Results: It was noticed that nearly one-third (30.0%) of patients of the control group were died compared to only 11.7% of the study group during 7 days post-admission to the intensive care unit. Also, there were highly statistically significant improvements among patients of both control and study groups regarding patient outcomes which include physiological parameters, pre feeding assessment, hydration status, and activity level on admission, 3 days, and 7 days following implementation of stroke care bundle. Conclusions: Acute stroke patients who received the initial emergency care bundle had a statistically significant reduction in mortality rate, higher independency, and normal pre-feeding assessment compared to those who receive routine care on admission, 3 days, and 7 days post-admission Recommendations: The recent evidence-based practice should be integrated into the management of acute stroke patients to improve the patients' outcomes.

Effects of Three Strawberry Entomopathogenic Fungi on the Prefeeding Behavior of the Aphid Myzus persicae

Entomopathogenic fungi are essential participants in ecosystems that help regulate arthropod communities. Many of them have a symbiotic-endophytic relationship with plants, endowing them with insecticidal or insect-repellent traits, which could be exploited for insect control in agriculture. Among insects, aphids are one of the most harmful taxa; they damage plants directly by sucking plant sap or indirectly by transmitting economically important viruses. Plant infestation by aphids depends on prefeeding activities related to host identification, particularly leaf walking and short probing. Although several aspects of aphid prefeeding activities have been studied in different hosts, this behavior has not been examined on plants colonized by entomopathogenic fungi. Here, we studied the effects of three strawberry endophytic entomopathogenic fungi, namely, Beauveria bassiana, Isaria fumosorosea and Metarhizium anisopliae var. robertsii, on the prefeeding activity of the aphid Myzus persicae by monitoring aphids feeding on leaves of fungus colonized and uncolonized plants. Our analysis revealed that the endophytes significantly affected aphid prefeeding behavior, which was typified by a reduction of the expected mean number of short probes, an avoidance to make a second probe, and a high propensity for abandoning the leaf. We discuss possible mechanisms of fungal interference with aphid activity.

Feeding and osmoregulation in the euryhaline crab Neohelice granulata: digestive parameter responses

Abstract When a species often experiences variation in its environmental conditions, metabolic flexibility is required. We studied the duration of the digestive cycle and the activity of key digestive enzymes (proteolytic, amylase, lipase) at short and long times after feeding in the hepatopancreas of the osmoregulator crab Neohelice granulata from the Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). We compared these responses upon hyper-regulation and under osmoconformation conditions (10 and 35 psu). The results show the ability of this crab to hyper-regulate in different feeding states. No significant differences were observed in the duration pattern of the digestive cycle between hyper-regulation and osmoconformity. However, distinct responses after feeding were observed in the activities of the digestive enzymes studied in relation to the osmoregulatory state. In individuals exposed to 35 psu, proteolytic activity was higher at 8 h and remained constant until 72 h after feeding. At 10 psu, this activity was higher at 48 h after feeding than before feeding. At 35 psu, the amylase activity after feeding was greater than the prefeeding activity. No differences were observed in the activity of lipase at 35 psu, but at 10 psu this activity was lower 1 h after feeding than before feeding. This work constitutes a contribution to our knowledge of the physiology of crustaceans and attempts to clarify the possible mechanisms of digestive settings associated with hyper-regulation.

Crosstalking between the “gut-brain” hormone ghrelin and the circadian system in the goldfish. Effects on clock gene expression and food anticipatory activity

Ghrelin is a potent orexigenic signal mainly synthesized in the stomach and foregut of vertebrates. Recent studies in rodents point out that ghrelin could also act as an input for the circadian system and/or as an output of peripheral food-entrainable oscillators, being involved in the food anticipatory activity (FAA). In this study we pursue the possible interaction of ghrelin with the circadian system in a teleost, the goldfish (Carassius auratus). First, we analyzed if ghrelin is able to modulate the core clock functioning by regulating clock gene expression in fish under a light/dark cycle 12L:12D and fed at 10 am. As expected the acute intraperitoneal (IP) injection of goldfish ghrelin (gGRL[1–19], 44pmol/g bw) induced the expression of hypothalamic orexin. Moreover, ghrelin also induced (∼2-fold) some Per clock genes in hypothalamus and liver. This effect was partially counteracted in liver by the ghrelin antagonist ([D-Lys3]-GHRP-6, 100pmol/g bw). Second, we investigated if ghrelin is involved in daily FAA rhythms. With this aim locomotor activity was studied in response to IP injections (5–10days) of gGRL[1–19] and [D-Lys3]-GHRP-6 at the doses above indicated. Ghrelin and saline injected fish showed similar 24h activity patterns. However, ghrelin antagonist treatment abolished the FAA in schedule fed fish under 24h light, suggesting the involvement of the endogenous ghrelin system in this pre-feeding activity. Altogether these results suggest that ghrelin could be acting as an input for the entrainment of the food-entrainable oscillators in the circadian organization of goldfish.

Differential responses of circadian Per2 expression rhythms in discrete brain areas to daily injection of methamphetamine and restricted feeding in rats

Behavioral rhythms induced by methamphetamine (MAP) and daily restricted feeding (RF) in rats are independent of the circadian pacemaker in the suprachiasmatic nucleus (SCN), and have been regarded to share a common oscillatory mechanism. In the present study, in order to examine the responses of brain oscillatory systems to MAP and RF, circadian rhythms in clock gene, Period2, expression were measured in several brain areas in rats. Transgenic rats carrying a bioluminescence reporter of Period2-dLuciferase were subjected to either daily injection of MAP or RF of 2 h at a fixed time of day for 14 days. As a result, spontaneous movement and wheel-running activity were greatly enhanced following MAP injection and prior to daily meal under RF. Circadian Per2 rhythms were measured in the cultured brain tissues containing one of the following structures: the olfactory bulb; caudate-putamen; parietal cortex; substantia nigra; and SCN. Except for the SCN, the circadian Per2 rhythms in the brain tissues were significantly phase-delayed by 1.9 h on average in MAP-injected rats as compared with the saline-controls. On the other hand, the circadian rhythms outside the SCN were significantly phase-advanced by 6.3 h on average in rats under RF as compared with those under ad libitum feeding. These findings indicate that the circadian rhythms in specific brain areas of the central dopaminergic system respond differentially to MAP injection and RF, suggesting that different oscillatory mechanisms in the brain underlie the MAP-induced behavior and pre-feeding activity under RF.

Behavioral analysis of circadian rhythms: Entraining the circadian clock and determining the food-entrainable oscillator mechanism

Circadian rhythms are oscillations in behavior and physiological functions that are regulated by internal biological clocks. In mammals, the circadian rhythms can be best studied in the hypothalamic suprachiasmatic nucleus (SCN). The SCN has been considered as the master clock of circadian rhythms. SCN lesions abolish the circadian rhythms and transplantation of the SCN restores the behavioral rhythm; these findings confirm the role of the SCN as a circadian pacemaker. Recent discovery of molecular machineries of circadian oscillation enables us to examine genetically manipulated, molecular-clock-deficient mice, and use of these animal models has enhanced our understanding of biological clocks. It has been reported that prefeeding locomotor activity under a temporal restricted feeding condition exhibits the defining characteristic of a circadian rhythm. The prefeeding activity is driven by a distinct mechanism from the SCN. Despite extensive studies performed with the lesion strategy, the anatomic location of the food-entrainable oscillator has not been determined. Furthermore, recent studies using molecular-clock deficient mice reveal that the known circadian clock is dispensable for appearance of the prefeeding activity. Thus, examining the prefeeding activity alone is not sufficient and further examination for circadian oscillatory properties of the prefeeding activity rhythm is essential for understanding the food-entrainable circadian rhythms.

The selective serotonin reuptake inhibitor fluvoxamine suppresses post-feeding hyperactivity induced by food restriction in rats

Previous studies demonstrated that rats allowed access to running wheel with food restriction schedules run excessively. This hyperactivity consisted of a pre-feeding activity (an increase in running activity before the feeding time, also termed food-anticipatory activity: FAA) and a post-feeding activity (an increase in running activity after the feeding time, succeeding activity: SA). Here we evaluated the effect of fluvoxamine, a selective serotonin reuptake inhibitor, on food restriction-induced hyperactivity in rats. Furthermore, the effect of fluvoxamine on each of the FAA and the SA was also investigated. Rats were individually housed in a running-wheel cage under food restriction for 3 h per day, and running activity was measured for 7 consecutive days. This restricted feeding significantly increased the running activity and decreased body weight. Simultaneous administration of fluvoxamine (50 mg/kg/day, p.o.) for 7 days suppressed the increase in running activity ( P < 0.05) with no modification of the decrease in body weight or food intake. Analysis of each activity revealed that fluvoxamine's efficacy was observed only in the SA ( p < 0.01). These results suggest that repeated treatment with fluvoxamine attenuates the hyperactivity, which is exclusively dependent on the substantial reduction in the SA.

Meal frequency and stereotypic behaviour in stabled horses

Locomotor stereotypies such as weaving and nodding are commonly observed as pre–feeding activity in stabled horses (Cooper, McDonald and Mills, 2001), whilst oral activities such as crib–biting and woodchewing may be associated with the post–feeding period (McGreevy and Nicol, 1998) particularly in horses fed a low–fibre concentrate (Nicol et al., 2002). In this study, we investigated the effect of increasing the number of meals of concentrate whilst maintaining the same daily concentrate intake, on the behaviour of stabled horses with particular reference to stereotypic activities such as weaving and crib–biting. The study was carried out on a working equestrian yard with stables for up to 50 horses.A pilot study was used to record incidence of stereotypic behaviour and to select subjects for the main study. In this, the behaviour of 30 warm–blooded horses was recorded during their morning (0830h) and afternoon (1630h) concentrate meals. Each meal consisted of 0.5kg of a commercial feed, mixed with 1kg of soaked sugar beet pulp and 0.5kg of chopped hay and straw mixed in a bucket.

Independence of feeding-associated circadian rhythm from light conditions and meal intervals in SCN lesioned rats

Free-running period of the feeding-associated circadian rhythm was assessed in suprachiasmatic nucleus (SCN) lesioned rats under three different conditions using a feeding-fasting (FF) paradigm; restricted feeding (RF) with meal intervals of 24 h ( T=24 h) under 24 h light-dark cycle (LD), RF with T=24 h under continuous dim light (dim LL), and RF with T=25 h under dim LL. After the termination of RF, the rats were subjected to FF regimen five times repeatedly, in which food and water were available for 7 days, followed by total food deprivation for 3 days with free-access to water. Free-running period, which was measured with reference to the prefeeding activity peak during food deprivation, was very close to 24 h and was not different under three conditions. It is concluded that the feeding-associated circadian rhythm has a major period close to 24 h, which is not affected either by light conditions nor by meal intervals.

Effect of the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 on food-anticipatory activity rhythm in the rat

When feeding was restricted to a single meal scheduled at a fixed time (1300–1700 h) in the day, rats exhibited increased prefeeding locomotor activity 1–3 h before the feeding time, which increased over 6 days. The activity increase was seen for about 5 h (1100–1600 h) on the seventh day when no food was provided (fasting day), as the rat anticipated mealtime. Thus, mealtime-associated activity rhythm on the fasting day was considered to be another good index of food-anticipatory activity. In this study, we investigated the effects of the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, which has been reported to cause impairment of spatial learning, on food-anticipatory activity.in rats. Daily injection of MK-801 (0.2 mg/kg) at 1700 h for 6 successive days impaired the development of increased prefeeding activity. The appearance of mealtime-associated activity was impaired by daily injection of MK-801 (0.2 mg/kg) at 1700 h (immediately after food restriction, FR) or at 1900 h (2 h after FR) but not at 0900 (16 h after FR). In addition, mealtime-associated activity was impaired by MK-801 injected at 1700 h in a dose-dependent manner (0.1–1 mg/kg). The present results demonstrate that NMDA receptor mechanisms were involved in learning processes of food anticipation and suggest that an impairment of food-anticipatory activity may be considered an animal model of a deficit of “temporal learning.”

Age-related impairment of food anticipatory locomotor activity in rats

In rats of various ages (11 weeks to 24 months), restricted feeding was carried for 6 successive days and food was withheld completely on the 7th day to assess the effect of aging on food anticipatory activity. When feeding was restricted to a single meal at a fixed time of day (1330–1730), rats exhibited intense locomotor activity from 1–3 h before feeding time (prefeeding activity). This prefeeding activity was still detected on the fasting day. In addition, intense locomotor activity was observed for 1330–1730 even on the fasting day (mealtime-associated activity). Thus, mealtime-associated activity of the fasting day became an another good index for food anticipatory activity. These results indicate that the rats had come to anticipate the mealtime. Both prefeeding and mealtime-associated activities were similar at 11 weeks and 9 months of age, but they were impaired at 12 and 24 months of age. In 11-week-old rats, there was a negative correlation between the level of mealtime-associated activity and the daily duration of access to food, but this relationship was absent in 12-month-old rats. The present study suggests that aging strongly impairs the manifestation of food anticipatory activity in rats.

Circadian rhythms and feeding time in fishes

Although several studies have described effects of meal frequency and timing of meals on growth performance and body composition of different species of fishes, the mechanisms by which such variables influence the energy partitioning processes is not known. They may interact with the natural feeding rhythm of the fish, or with various behavioural and physiological parameters that exhibit ‘circadian-like’ patterns; however, in most cases, the endogenous character of such rhythms is not clear. The time of feeding, perse, can act as a Zeitgeber and override the effect of the light/dark alternation. Fish that are fed always at the same time of day show typical pre-feeding activity. Blood levels of some nutrients and hormones also show peaks or troughs at the time of feeding, but whether these are pre-feeding or post-prandial events is not clear. These results from fish are compared with similar studies with mammals. The existence and location of an endogenous multi-oscillator system is also discussed.

Effects of diet and feeding time on daily variations in plasma insulin, hepatic c-AMP and other metabolites in a teleost fish,Dicentrarchus labrax L.

Juvenile sea bass, 1.5 years old, of mixed sex, held on long photoperiods were fed early on the photoperiod and late on the photoperiod, using different diets. Fish fed natural diets showed a daily rhythmicity of plasma insulin, liver c-AMP, plasma glucose, liver glycogen and muscle glycogen content, however, fish fed a commercial diet did not show this daily rhythmicity except for plasma insulin levels. In addition, these fish had significantly lower levels of plasma insulin, liver c-AMP and plasma glycerol than the group fed on the natural diets at similar feeding times. The time of feeding also induced different rhythmicity patterns in hormones and metabolites as well as a significant change in their mean levels. These facts are discussed in relation with the pre-feeding activity and increased appetite exhibited by the fish fed late on the photoperiod and with their implications on fish culture.

Energy expenditure and respiratory activity of sheep during feeding

Energy costs of feeding and respiratory changes during the ingestion of prepared rations were measured in experiments on penned sheep. Feeding energy increments per kilogram liveweight (increased energy expenditure attributable to the act of eating) ranged from 5.3 to 12.4 cal/min. Differences between sheep and between rations were not significant. Energy costs of eating (increased energy expenditure per gram of ration ingested) varied with the type of ration. A concentrate ration was ingested at an energy cost (per kg liveweight) of 0.3–0.6 cal/g ration, whereas chaff rations cost 1.2–1.9 cal/g ration. A marked reduction in respiratory frequencies and respiratory minute ventilations occurred during feeding whenever the pre-feeding respiratory activity was elevated due to the ambient temperature. When the respiration was eupnoeic before feeding there was a slight increase with feeding. While sheep were eating, respiratory frequencies ranged between 20 and 40 per minute and respiratory minute ventilations from 4.5 to 8.4 litres.

Time-co-ordinated prefeeding activity in fish

Fish fed daily at a regular time under controlled artificial illumination became active daily for a number of hours just before feeding time. Experiments with killifish ( Fundulus heteroclitus) in constant light and under alternating 12-hour periods of bright and dim light showed that the timing of the pre-feeding activity is influenced by shifts in the light cycle and feeding time; when feeding time in constant light was shifted 6 hours, the pre-feeding activity shifted approximately 6 hours in 1 to 3 days. The conclusion was reached that the pre-feeding activity is a consequence of conditioning the act of feeding to an endogenous cue which itself is coordinated by the time of feeding or daily changes in light.