Rhythm Of Food Intake Research Articles

Social influences on the orcadian rhythm of locomotor activity and food intake of guinea pigs

Abstract Locomotor activity (LA) and food intake (FI) were recorded in 12 adult male and 8 female guinea pigs of the inbred strain 2 kept initially under social conditions and later separated. The groups consisted of two, and in one case, of 4 animals. Some animals were regrouped again after separation. In addition, four individual and 4 grouped animals were kept in continuous darkness (DD). The day‐night ratio, the averaged daily patterns and the chi‐square periodogram showed significant differences between the grouped and separated animals as well as the overall amount of LA and FI. Grouped animals displayed 37% of their LA during the light, decreasing to 7% during separation. FT showed lower day‐night differences than LA overall and smaller differences between grouping and separation (FI during light in grouped: x = 48%, separated: x = 31%). Both patterns were relatively consistent for each housing condition. Under the conditions of DD, regular circadian rhythms with period lengths of less then 24 hour...

Early modification of neuropeptide Y but not of neurotensin in the suprachiasmatic nucleus of the obese Zucker rat

Hyperphagia in the obese Zucker rat is characterized by the early modification of the dark/light (D/L) rhythm of food intake. This rhythm is mainly driven by the suprachiasmatic nucleus (SCN) and, more controversially, by the ventromedian nucleus (VMN). In the SCN of adult obese Zucker rat, the concentrations of neuropeptide Y (NPY), a potent stimulator of food intake, are increased whereas those of neurotensin (NT), an anorexigenic peptide, are decreased. However, nothing is actually known about the synchronicity of the dysregulation of the D/L rhythm and variations of these peptides. That is why we measured NPY and NT in the microdissected SCN and VMN of lean ( n = 16) and obese ( n = 15) Zucker rats before the occurrence of hyperphagia (day 16 of age) and a few days after weaning (day 30 of age) when the modifications are apparent. For NPY, there was a very significant effect of age ( P<0.001) for both nuclei and a significant effect of genotype ( P<0.02) for the SCN only. NPY concentrations increased between 16 and 30 days in both nuclei (+74% (SCN) and +70% (VMN) in the obese rat; +57% (SCN) and +67% (VMN) in the lean rat; P<0.001). NPY in the SCN was not different at 16 days of age between lean and obese rats but significantly increased at 30 days in the obese rat (22.6 ± 1.2 vs. 18.6 ± 1.5 ng/mg protein; P<0.05). NT was not detected in the SCN of either group at 16 days or at 30 days. In the VMN, NT concentrations were very similar in both groups whatever the age considered and amounted to about 1 ng/mg protein. This study supports, therefore, the major role of the SCN in the regulation of feeding patterns. Neurotensin likely plays an additional later role in this process whereas the early rise of NPY in the SCN suggests that this orexigenic peptide could play an important role in the establishment of the abnormal D/L rhythm of food intake found in the adult obese Zucker rats.

Role of intrahypothalamic insulin in circadian patterns of food intake, activity, and body temperature.

These experiments examined the extent to which chronic intrahypothalamic (IH) insulin infusions that alter circadian patterns of food intake (FI) affect the regulation of other diurnally varying behavior in the rat. One-week IH insulin infusion (1.5 microU/hr) significantly decreases rats' night FI and increases day FI but does not alter the diurnal pattern of activity. Mean daily core temperature increased slightly but significantly during insulin infusion, the daily peak of the body temperature rhythm did not shift significantly, and the daily range of body temperature increased. IH insulin infusion in rats living in constant light and thus without circadian rhythm of FI led to significant decreases in FI and body weight. These data support the conclusion that IH insulin infusion alters food intake and body weight through a specific effect on a neural system that regulates food intake and body weight, and not by altering circadian rhythms.

Circadian Rhythms of Food Intake, Plasma Glucose and Insulin Levels in Fed and Fasted Rabbits

The rhythm of circadian variations of plasma insulin level was similar in 48 h fasted and in fed rabbits; however, the amplitude of variations was less important in fasted animals. Plasma glucose level did not change during circadian cycle. In conclusion, we showed in rabbit a circadian rhythm of insulin with two maxima: one diurnal and the other nocturnal.

The effect of change in the rhythm of food intake and sleeping time during ramadan on the diurnal variation of fibrinolytic activity

Consecutive measurements of blood coagulation and fibrinolytic parameters were undertaken at 9.00 am, 4.00pm, 9.00 pm and 4.00am in eleven healthy subjects, observing the dawn to sunset fast of the holy Muslim fasting month of Ramadan. Measurements were repeated in an ordinary ‘non-fasting’ day. No statistically significant fluctuations were noted in prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen, plasminogen, and tissue plasminogen activator (t-PA) either during Ramadan or in a non-fasting day. However, markedly elevated levels of the plasminogen activator inhibitor (PAI) activity were noted at 9.00 am in Ramadan and at 4.00 am on a non-fasting day. Both increases were determined after several hours overnight sleep; the waking time in Ramadan being 8.30 am and 4.30 am in non-Ramadan day. Thus the circadian variation in PAI activity levels are influenced more by sleep pattern rather than food intake or the normal activities of a working day.

Pineal involvement in the alimentary behavior and taste preferences in the rat

The purpose of this experiment was to explore the effects of pinealectomy or sham pinealectomy on circadian rhythms of taste preferences, food and fluid intake and body weight gain in rats. We compared the body weight gain, the amounts of food eaten and that of deionized water, total fluid, salt, sour, sweet and bitter near-threshold solutions consumed by rats before all surgical manipulations and after pinealectomy or sham pinealectomy. The results showed that the pineal gland does not exert a major influence on circadian organization of taste preferences, drinking, feeding and body weight modifications in the rat. The failure of pinealectomy to modify light/dark rhythms of taste preferences and other related alimentary behaviors may be explained by the fact that pinealectomy does not completely eliminate circulating melatonin.

Effect of continuous vasopressin infusion on circadian rhythms of food and water intake, diuresis, and electrolyte excretion in brattleboro rats

In the experiments on rats a significant decrease of resistance to the contracture and arrhythmogenic effect of increased Ca2+ on the isolated hearts of animals after short term immobilization stress has been shown. After a long term stress (6 hours) the changes of the studied physiological parameters of the isolated hearts were not observed. Transport in the homogenates of the rat hearts was measured by the Ca--selective electrode on the ionometer ORION EA 940. After a 1-hour stress the rate of Ca--transport in sarcoplasmic reticulum (SR) substantially decreased as compared with the control (3.5 fold at 20 mcM), but at the higher concentration the Ca-transport was inhibited. The long term stress lead to a slower damage of functional Ca-transport system of SR--at 20 mcM the rate decreased by 25% as compared with control and at the higher concentration of Ca2+ depression of transport was not observed.

Rhythms of reproduction, metabolism and coat growth in deer: a model for all non-domesticated seasonal ungulates?

Seasonally-breeding deer living in cool temperate environments exhibit pronounced seasonal rhythms of voluntary food intake, growth rate and fattening and the growth and development of the coat. All of these rhythms are considered to be entrained by photoperiod and melatonin, although so far this has only been demonstrated to be the case in one species, the red deer. This paper reviewed current data on seasonal rhythms in several species of deer. A comparison of two species with different breeding seasons, the red deer and the Pere David's deer, indicated that seasonal reproduction, appetite and coat growth rhythms are linked and may be controlled by a single circannual rhythm generator. All of these seasonal rhythms should be considered as adaptive for species living in cool temperate environments with marked fluctuations in food supply and climatic conditions.

Lithium Chloride SCN Injection Alters the Orcadian Rhythm of Food Intake

Effect of lithium injections through chronically implanted cannulae into the bilateral suprachiasmatic nuclei (SCN) on the circadian rhythm of food intake was investigated in the rat. It was observed that the circadian rhythm was disrupted by injections of lithium at the beginning of the light as well as the dark phase of the LD cycle. In either case the percentage of the food consumed during the 12-hr light period increased while that during the dark period decreased without any significant change in the total daily intake. Disruptions in the circadian rhythm of food intake failed to show any dose-response relation. Injections of saline into the SCN or lithium into the nearby SCN area did not produce a disruption of the circadian rhythm of food intake.

Circadian rhythms of food intake in gastroduodenally-ulcerated rats: effects of three anti-ulcer drugs.

The effects of three anti-ulcers drugs on the temporal distribution of food intake and of the two parameters, meal size and meal frequency, were studied in ulcerated and non-ulcerated rats exposed to light-dark (LD 12:12) cycles. Experimental ulceration with indomethacin reduces the amplitude of meal frequency and brings the acrophase forward, compared with non-ulcerated animals. These effects were reversed by the oral administration of either ranitidine, sucralfate or pirenzepine along with the food. However, the administration of either pirenzepine or sucralfate alone to non-ulcerated rats is accompanied by significant (P less than 0.05) changes in the circadian patterns of meal size and meal frequency without the total daily food intake being affected in any way (pirenzepine treatment caused large intake of food during the light period while sucralfate treatment resulted in marked food intake during the dark period). The results indicate that circadian modification of meal patterns in the ulcerated rats are attributable to indomethacin-induced gastrointestinal mucosal injury and anti-ulcer medications.

Chronic Intracerebroventricular Infusion of Insulin Failed to Alter Brain Insulin‐Binding Sites, Food Intake, and Body Weight

The present study was performed to explore the role of exogenous insulin in CSF in the control of energy balance in the rat. For this purpose, adult male Sprague-Dawley rats carrying an indwelling cannula in the right lateral cerebral ventricle were infused for a maximum of 10 days with insulin (Actrapid) at various rates (starting at 0, 45, 85, 170, and 600 ng/day) or anti-insulin antibody (IgG fraction; diluted 1:10 wt/vol) with an osmotic minipump. All those treatments did not modify the growing rates; neither total daily food intake nor the circadian rhythm of food intake was further modified. The chronic insulin infusion starting at 600 ng/day resulted in a chronic significant increase in CSF insulin levels without changing the plasma insulin level. It failed to alter specific insulin binding sites to Triton X-100 solubilized microsomal membranes from various brain areas (cerebral cortex, olfactory bulbs, and lateral and medial hypothalami) at the end of the 5- or 10-day period of insulin infusion. Purification of insulin receptors on a wheat germ agglutinin did not reveal any further effect of insulin. From these results, it seems unlikely that the input to the brain insulin-effector systems could arise from CSF insulin.

The effect of marihuana (Delta-9 tetrahydrocannabinol) on pregnancy in rat

Lifestyle and genetic perturbation of circadian rhythm can trigger the incidence and severity of metabolic diseases. Time-restricted feeding (TRF) regulates the circadian rhythm of food intake that protects against metabolic disorders induced by adverse nutrient intake. TRF also executes host metabolism from nutrient availability to optimize nutrient utilization. Circadian clock and nutrient-sensing pathways coordinate to regulate metabolic health through the feeding/fasting cycle. Concurrently, TRF imposes diurnal rhythm in nutrient utilization, thereby preserving cellular homeostasis. However, modulation of daily feeding and fasting periods calibrates the circadian clock, which protects against the lethal effects of nutrient imbalance on metabolism. Therefore, TRF also improves and restores metabolic rhythms that ultimately lead to better fitness by reversing the alteration in genotype-specific gene expression. The aim of this review was to summarize that TRF is an emerging dietary approach that maintains robust circadian rhythms in support of a steady daily feeding and fasting cycle. TRF also encourages the coordination between circadian clock components and nutrient-sensing pathways via molecular effectors that exert a protective role in the prevention of metabolic diseases.

Loss of the circadian rhythms of locomotor activity, food intake, and plasma melatonin concentration induced by constant bright light in the pigeon (Columba livia).

Locomotor activity and feeding activity were measured together with circulating levels of melatonin in pigeons which were exposed to constant bright light (LLbright, 2000 lux) following light-dark (LD) cycles. Although all the pigeons showed daily rhythms of locomotor activity, feeding activity, and melatonin levels under LD cycles, they lost all the rhythms in prolonged LLbright. Acute exposure to bright light (2000 lux) during darkness reduced plasma melatonin levels. The half-time for the suppression in melatonin levels was about 30 min after short-term light exposure. These results support the hypothesis that melatonin may control the circadian rhythms of locomotor activity and feeding activity in the pigeon.

Suprachiasmatic injection of a vasopressin antagonist modifies the circadian rhythm of food intake

To study the effect on the circadian feeding rhythm, injections of AVP and its antagonist were made into the suprachiasmatic nuclei (SCN) of rats after implanting cannulae into the bilateral SCN. Injections of arginine vasopressin (AVP) antagonist at the beginning of the light and dark phases disrupted the circadian rhythm of food intake while injections of AVP during the beginning of the light or dark phase did not disrupt the circadian rhythm. It may be concluded that endogenous vasopressin has a modulatory role in the mediation of the circadian feeding rhythm at SCN.

Circadian variation of food intake and digestive tract contents in the rat

The variation of food intake and digestive tract contents over a period of 24 hours was measured in the free feeding rat kept under a 12:12 hr light:dark cycle (lights on at 0700 hr). After a cessation between 0700 and 1000 hr, the rate of food intake increased progressively during daytime followed by a marked increase and a plateau after lights went off. In the dark, dry matter in the stomach was almost ten times the levels of the light phase. In the major part of the high feeding period, the rates of food intake and gastric emptying equilibrated. Dry matter content of the intestine also followed circadian variations that were specific for each segment. The time-to-time content of the mid-gut segment was closely related to gastric emptying. The extent of dry matter absorption in the proximal intestine decreased continuously from the time lights went on and reached a minimum at 22 hr. Absorption in the distal segments was much less subjected to variation over 24 hours. In the free feeding situation, the changes induced by the light cycle on the rhythm of food intake were accompanied by marked modifications of digestive tract contents including those of the intestine. Data indicate a close relationship between gastric function and the middle portion of the intestine.

The effect of neonatal administration of monosodium glutamate on the circadian control of food intake in the rat

Abstract Neonatal treatment with monosodium glutamate (MSG) results in a substantial degeneration of the inner layer of the retina and a decreased diameter of the optic nerves. Nevertheless, MSG‐treated animals entrain and re‐entrain to a light dark cycle. The question arises whether MSG selectively destroys the optic pathways which are involved in vision but not the retinohypothalamic trart that mediates entrainment. In these experiments not only entrainment and re‐entrainment of the circadian food intake rhythm of MSG‐treated rats was investigated but also the freerunning period under continuous bright and dim light It appears that MSG‐treated rats have shorter freerunning periods under continuous illumination than controls. Therefore, these results suggest that also those pathways involved in entrainment of the circadian food intake rhythm are affected by neonatal treatment with MSG.

Suprachiasmatic nuclei lesions do not eliminate the circadian rhythms of electrolyte excretion in the rat

The 24-hour variations in 2-hour diuretic and saluretic action of furosemide (4 mg/kg) given at 8, 12, 16, 20, 24 or 4 hr and the circadian rhythms of food and water intake, urine and electrolyte excretion followed for two consecutive days at 4-hour intervals were investigated in suprachiasmatic nuclei (SCN)-lesioned or sham-operated male Wistar rats. The results showed that: (1) a distinct 24-hour rhythm in furosemide-induced urine, sodium and chloride excretion persisted after SCN lesions, and (2) the lesions abolished the circadian rhythms of food and water intake but only desynchronized the individual 24-hour variations in electrolyte excretion. We concluded that SCN play a role as a central synchronizer but not as a major oscillator of the circadian rhythms of electrolyte excretion in the rat.

Influence of plane of winter nutrition on plasma concentrations of prolactin and testosterone and their association with voluntary food intake in red deer stags ( Cervus elaphus)

Blood samples were taken at weekly or 3-weekly intervals from 12 red deer stags, from 3 weeks of age until 3 years of age. Six of the stags were fed to appetite throughout the study and six were maintained on 70% as much during each winter and to appetite each summer. All plasma samples were analysed for testosterone and prolactin. Food intake was measured daily. Annual rhythms of testosterone, prolactin and food intake were evident. Peaks of prolactin, on an increasing photoperiod tended to occur slightly before peaks of food intake and troughs of food intake on a decreasing photoperiod occurred at or slightly after peaks of testosterone. The reduced plane of winter nutrition tended to delay rather than alter the amplitude of the annual cycles of testosterone, prolactin or food intake. Several of the unrestricted stags showed biannual rhythms of testosterone, prolactin and food intake accompanied by additional cycles of coat development and antler growth. These additional cycles tended to be 6 months out of rhythm with normal cycles. It is considered that this is due to the stags being stimulated by a particular day-length irrespective of whether it is decreasing or increasing and that plane of nutrition may influence the control of phase blockers.

Circadian rhythms in food intake and activity in domestic cats.

Circadian rhythms in food intake and activity in domestic cats.

Circadian rhythms in food intake and activity in domestic cats.

Daily patterns of food intake and activity were determined for normal cats and cats with pontile lesions. Food intake in the dark and in the light of LD (light/dark) cycles were determined separately by weighing the food, and a "percentage nocturnal" score was calculated. The measure of activity was infrared photobeam interruptions, with the photobeam placed in front of the cages, over the food bowl. No differences between normal cats and cats with pontile lesions were detected for any of the measures. Food intake of cats was influenced by simulated starlight and moonlight conditions and by the presence of humans. Cats in isolation from humans and human noises exhibited random patterns of activity in constant light and free-running circadian rhythms in constant dark. Idiosyncratic differences in entrainment to LD cycles were found among cats, and the relevance of this variability is noted for studies of photoperiodic phenomena in this species.