Effect of a short-term diet based on precooked corn flour on the muricidal behavior of male SM Wistar rats

The aim of this research is to observe if the lack of cerebral serotonin, obtained by a diet almost devoid of tryptophan (precooked yellow corn meal) is able to trigger the muricide behaviour in male Rats naturally non-muricide. To determine the tryptophan content in the food used and in 4 types of selected maize flour (Zea mays: indurata, indentata, opaque/2 and synt. marano), 3 different methods have been used (ion-exchange chromatography, spectrofluorometry, spectrophotometry). The muricide behaviour, or the interspecific attack, has been tested by comparison Rat-Mouse. The results show that the feeding with a diet "short term" (4 days), composed of precooked corn meal, with a very low content of tryptophan, induces the appearance of muricide or aggressive behaviour towards the Mouse in more than half of the Wistar Rats, bred in a room constantly lighted by sodium steam light. The appearance of the above-mentioned behaviour is connected with the decrease in cerebral serotonin.     

Short term diet of precooked corn meal almost lacking in tryptophan and interspecific rat-mouse aggressive behaviour.

The content of tryptophan in a precooked corn meal and in 4 types of selected corn seeds: Zea mays indurata, identata, opaque/2 and Marano synth., has been determined by three different methods: ion-exchange chromatography, spectrofluorometry and spectrophotometry. This content is very low, less than 0.080% d.w. Alimentation for 4 d with a diet composed of precooked corn meal with a tryptophan content less than 0.025% induced the appearance of aggressive-cidal or aggressive non-cidal behaviour towards the mouse in more than half of Wistar rats bred in a room constantly lighted by a sodium steam light. The appearance of this behaviour is probably connected with a decrease in brain serotonin.     

Effect of various environmental illumination modalities on the muricidal behavior of male Wistar rats

The aim of this research is to study the effects of different modalities of environment lighting on the appearance of the muricide behaviour in the Wistar male Rat. Indeed it is known that the exposition of Rats in environment to continuous light determine a reduction of the cerebral content of serotonin, which is known to unchain the muricide behaviour in naturally not muricide Rats. The animals are kept in different situations of environment lighting: 1) L/D = the natural light of the day alternated with the dark of the night; 2) L/L sodium = continuous light emitted by a sodium steam lamp; 3) L/L neon = continuous light issued from fluorescent neon tubes. The muricide behaviour is studied by comparison Rat-Mouse. The results obtained show that the continuous sodium steam light (L/L, sodium) remarkably increase the percentage of the animals which become muricide compared to the control animals bred in natural environment with a normal succession day-night (L/D). On the contrary the percentage is remarkably reduced compared to the control animals in Rats of the same group when these animals are exposed to continuous light issued from fluorescent neon tubes (L/L, neon).     

环境光照对东方田鼠自主活动等行为的影响

目的了解不同环境光照对东方田鼠行为的影响,为制订东方田鼠环境标准提供依据。方法利用动物行为观察装置,观察三组东方田鼠在不同环境光照条件下的自主活动、玩耍、摄食、饮水等行为表现并进行定量测定和分析。结果 24 h黑暗（24D）组的东方田鼠自主活动总数最多,而24 h光照（24L）组则最少,12L/12D组跟24D组接近：无论是24L,还是24D处理,动物的相对活动没有明显的节律性,但在12L/12D条件下,动物活动节律随着光照处理而变化,呈现其一定的节律性。玩耍行为12L/12D组最多,但24D组动物玩耍行为比24L组多;当24L处理时,动物很少处于中央格,而24D处理和12L/12D处理时,动物有不同程度穿梭中央格,其中12L/12D处理时,动物穿梭次数最多;摄食与饮水次数12L/12D组次数最多,24L组次数最少。结论室内有规律的环境光照处理,可改变东方田鼠固有的依季节变化的行为规律,产生实验室控制的光周期应答行为,并表明12L/12D环境光照比24L和24D环境光照对东方田鼠造成的生活压力要小。     

Environmental lighting and muricidal behaviour in the male Wistar rat.

Effects of different conditions of environmental lighting on the appearance of the muricidal behaviour in male Wistar rats have been studied. The animals were kept under different conditions of environmental lighting: 1) natural day light alternated with the dark of the night; 2) sodium, continuous light emitted by a sodium steam lamp; 3) neon, continuous light emitted by fluorescent neon tubes. The continuous sodium steam light increased the percentage of animals becoming muricide when compared to animals bred in a natural environment with a normal succession of day-night lighting. On the contrary, this percentage decreased if the rats of the same group are exposed to continuous light emitted by fluorescent neon tubes. As the exposure of rats to an environment under continuous light causes a reduction of the cerebral content of serotonin, the muricidal behaviour provoked in naturally non-muricide rats by this type of lighting could be related to this depletion.     

The effect of restricted feeding on the wheel-running activity rhythms of the predatory marsupial Dasyurus viverrinus

Summary The effects of restricted feeding schedules on the circadian rhythms of wheel-running of Dasyurus viverrinus were examined under a light/dark cycle and in constant darkness (experiment 1) and in constant light (experiment 2). The results of the 2 experiments showed that: (1) in contrast to the light/dark cycle, restricted feeding is only a weak zeitgeber for the wheel-running activity rhythms of D. viverrinus; (2) restricted feeding elicits meal anticipatory activity in D. viverrinus comparable to that elicited by restricted feeding in the rat; (3) transient cycles of the anticipatory activity free-run with a period different to that of the main component of activity for several cycles after the termination of restricted feeding; and (4) activity suggestive of beating between 2 oscillators occurs during restricted feeding and after the termination of restricted feeding. Taken together the latter 3 observations suggest that the activity rhythms of D. viverrinus are controlled by at least 2 separate circadian oscillators.     

Differential effects of meal size and food energy density on feeding entrainment in goldfish

The synchronizing stimulus, its transduction site, and the afferent pathways responsible for feeding entrainment remain unknown. In fish, the role of the diet in the development of feeding anticipatory activity (FAA) is not well understood and fundamental questions on the mechanisms of feeding entrainment, such as the meal characteristics required to develop FAA, remain unexplored. To test the entraining properties of daily meals with different sizes and energy densities, activity rhythms were studied after a 12-h shift of the feeding cycle in individual goldfish under constant light. In the 1st experiment, the energy content of a control diet (16.7 kJ/g) was diluted by replacing 50% (8.3 kJ/g) or 90% (1.7 kJ/g) of the diet with cellulose. However, the number of days required to stabilize FAA after the shift did not differ statistically between diets. In the 2nd experiment, meal size was modified by reducing the daily feeding ration to 0.5% and 0.1% b.wt.d(-1). In this case, differences in the entraining properties of the two feeding rations appeared because goldfish fed at 0.1% b.wt.d(-1) resynchronized faster than those fed at 0.5% b.wt.d(-1). These results revealed that the dilution of the dietary energy up to 1.7 kJ/g had no significant effect on the entraining properties of the feeding-entrainable oscillator (FEO), whereas the reduction of the meal size to 0.1% b.wt.d(-1) provoked a faster resynchronization after shifting the daily meal cycle. Taken together, these results suggest that gut distension may be involved in feeding entrainment, as a reduction in meal size but not in the amount of dietary energy supplied significantly shortened the time required for resynchronization and highlighted the different synchronizing properties of meal size and energy density as zeitgebers for the FEO.     

Comparison of rectal and vaginal temperature daily rhythm in dogs (Canis familiaris) under different photoperiod

To investigate the daily rhythm of rectal and vaginal temperature, we used six mongrel dogs with a mean body weight of 15±3 kg, aged between 2 and 3 years old. Rectal and vaginal temperatures were recorded every 3 h over 48-h period during three different lighting regimes: natural light/dark (L/D) cycle (sunrise 06:25, sunset 17:05), constant light (L/L) and constant darkness (D/D). A daily rhythm of rectal temperature was observed in both days of monitoring in all experimental conditions. Vaginal temperature showed a daily rhythmicity in L/D and D/D cycle. During the L/L cycle, daily rhythm was disrupted. Rhythmic parameters (MESOR, amplitude, acrophase and robustness) did not change between the different photoperiod and the site of temperature collection. In conclusion, the monitoring of vaginal temperature can be considered a valid alternative to the monitoring of body temperature as well as rectal temperature under natural lighting conditions in canine medicine.     

Effect of Changing the Light/Dark Schedule, the Time of Onset of the Light or Dark Period, or the Daylength, on Rhythms of Epidermal Cell Proliferation

Rhythms of labeling and mitotic indices were studied in the hindlimb epidermis of the anuran tadpole Rana pipiens under different light/dark (LD) cycles and daylengths in order to examine the role of the various parameters of the lighting regimen in setting the periods of the rhythms and the timing of the cell proliferation peaks. Altering the time of, or inverting, the 12 h light period on a 24 h day resulted in phase shifting of basically bimodal circadian rhythms with peaks in the light and dark. Thus the cell proliferation rhythms were entrained to the LD cycle. These rhythms also entrained to noncircadian schedules since they lengthened on a 15L : 15D cycle and shortened on a 9L : 9D cycle, although the bimodal characteristic of a peak in the light and a peak in the dark remained. Studies of 18L: 6D and 6L : 18D cycles in which either the time of onset of light or dark was changed relative to the 12L: 12D control indicated that the onset of dark may regulate the timing of the labeling index peaks while the onset of light may determine the time of occurrence of mitotic index peaks. Control of the timing of labeling and mitotic index peaks by different parameters of the LD cycle suggests a mechanism for cell cycle regulation by the environmental lighting schedule. Analysis of the rhythms on all the cycles studied suggested that labeling index rhythms equal the length of, or twice the length of, the dark period. Mitotic index rhythms equal the daylfength or a multiple of the length of the dark period.     

Diurnal variations in the effects of an unsaturated-fat-containing diet on fatty acid and cholesterol synthesis in rat hepatocytes.

Rats were fed ad libitum on either a standard high-carbohydrate diet, or a standard diet supplemented with 15% corn oil. Hepatocytes were prepared either during the light phase (L2-hepatocytes) or during the dark phase (D6-hepatocytes) of the diurnal cycle. In hepatocytes from rats fed on the fat-containing diet, fatty acid synthesis (lipogenesis) was suppressed to a much greater extent at D6 than at L2. The magnitude of the increase in plasma-free fatty acid concentration was similar at the two times of day. The rate of cholesterol synthesis was also significantly suppressed in the D6- but not in the L2-hepatocytes. This differential inhibition resulted in the abolition of the normal diurnal rhythm of cholesterogenesis. The initial activity of 3-hydroxy-3-methylglutaryl-CoA reductase in hepatocytes was also suppressed by corn-oil feeding at D6 but not at L2. In D6-hepatocytes, the inhibitory effect of the high-fat diet on the conversion of lactate into cholesterol and fatty acids was greater than that on total carbon flux into these substances for all endogenous sources. Despite this, under these conditions a high concentration of lactate and pyruvate resulted in a several-fold stimulation of total carbon flux into fatty acids. In hepatocytes prepared at L2, fat-feeding had little effect on the degree of stimulation of lipogenesis by insulin or inhibition by glucagon. However, at D6, fat-feeding blunted the response of lipogenesis to both these hormones.     

The effect of continuous light on prolactin secretion in prepubertal Holstein bulls

Effects of 16 (16 light:8 dark) and 8 (8L:16D) h of daily light were compared with continuous light (24L:0D) exposure on prolactin (PRL) concentrations in serum of prepubertal bulls. Concentrations of PRL in serum were 2 to 3 fold greater in bulls exposed to 24L:0D or 16L:8D as compared with 8L:16D. However, PRL concentrations attained a maximum approximately 3 weeks later in calves exposed to 24L:0D than in calves given 16L:8D. Continuous low intensity (11 to 16 lux) lighting supplemented with 16 or 8 h of high intensity (449 to 618 lux) light per day increased PRL concentrations in serum of prepubertal bulls 1.5 to 2.5 fold relative to 8L:16D (470 lux). We found that relative to 8L:16D, 1) photoperiods of 16 or 24 h of light per day increased serum concentrations of PRL in prepubertal bulls; however, the time required to achieve maximum PRL concentrations was longer in animals exposed to 24L:0D, 2) continuous low intensity lighting supplemented with 16 or 8 h of high intensity daily light also increased concentrations of PRL in serum.     

Photic resetting and entrainment in CLOCK-deficient mice

Mice lacking the CLOCK protein have a relatively subtle circadian phenotype, including a slightly shorter period in constant darkness, differences in phase resetting after 4-hour light pulses in the early and late night, and a variably advanced phase angle of entrainment in a light-dark (LD) cycle. The present series of experiments was conducted to more fully characterize the circadian phenotype of Clock(-/-) mice under various lighting conditions. A phase-response curve (PRC) to 4-hour light pulses in free-running mice was conducted; the results confirm that Clock(-/-) mice exhibit very large phase advances after 4-hour light pulses in the late subjective night but have relatively normal responses to light at other phases. The abnormal shape of the PRC to light may explain the tendency of CLOCK-deficient mice to begin activity before lights-out when housed in a 12-hour light:12-hour dark lighting schedule. To assess this relationship further, Clock(-/-) and wild-type control mice were entrained to skeleton lighting cycles (1L:23D and 1L:10D:1L:12D). Comparing entrainment under the 2 types of skeleton photoperiods revealed that exposure to 1-hour light in the morning leads to a phase advance of activity onset (expressed the following afternoon) in Clock(-/-) mice but not in the controls. Constant light typically causes an intensity-dependent increase in circadian period in mice, but this did not occur in CLOCK-deficient mice. The failure of Clock(-/-) mice to respond to the period-lengthening effect of constant light likely results from the increased functional impact of light falling in the phase advance zone of the PRC. Collectively, these experiments reveal that alterations in the response of CLOCK-deficient mice to light in several paradigms are likely due to an imbalance in the shape of the PRC to light.     

Time-dependent effects of leptin on food intake and locomotor activity in goldfish

The present study investigates the possible circadian dependence of leptin effects on food intake, locomotor activity, glycemia and plasma cortisol levels in goldfish (Carassius auratus). Fish were maintained under 12L:12D photoperiod and subjected to two different feeding schedules, one group fed during photophase (10:00) and the other one during scotophase (22:00). Leptin or saline were intraperitoneally injected at two different times (10:00 or 22:00), coincident or not with the meal time. To eliminate the entraining effect of the light/dark cycle, goldfish maintained under 24 h light (LL) were fed and leptin-injected at 10:00. A reduction in food intake and locomotor activity and an increase in glycemia were found in goldfish fed and leptin-injected at 10:00. No significant changes in circulating cortisol were observed. Those effects were not observed when leptin was administered during the scotophase, regardless the feeding schedule; neither in fish maintained under LL, suggesting that a day/night cycle would be necessary to observe the actions of leptin administered during the photophase. Changes in locomotor activity and glycemia were only observed in goldfish when leptin was injected at daytime, coincident with the feeding schedule, suggesting that these leptin actions could be dependent on the feeding time as zeitgeber. In view of these results it appears that the circadian dependence of leptin actions in goldfish can be determined by the combination of both zeitgebers, light/dark cycle and food. Our results point out the relevance of the administration time when investigating regulatory functions of hormones.     

Effects of dietary l-tryptophan and lighting conditions on growth performance of European sea bass (Dicentrarchus labrax) juveniles reared in a recirculating water system

The aim of the present study was to investigate possible stressful effects on European sea bass Dicentrarchus labrax reared under constant darkness (0L‐24D) and to examine the possible anti‐stressful effect of dietary tryptophan (TRP) supplementation. Juvenile European sea bass (initial body weight 4.23 ± 0.032 g) were reared for 10 weeks under 0L‐24D and 12L‐12D and fed either a commercial diet (0.47% TRP) or the same diet supplemented with L‐TRP (2.47% TRP). Results showed that lighting conditions had no significant effect on fish growth, while a depressive effect by the TRP supplementation was obvious. All fish populations reared under 0L‐24D exhibited reduced body protein, lipid and ash content and increased food consumption. Reduced body lipids, food consumption and nutrient utilization were observed in TRP‐supplemented fed fish, along with lower liver lipids. Dietary TRP enrichment significantly lowered liver saturated and monounsaturated acids and increased poly‐ and highly‐unsaturated fatty acids, especially in combination with 0L‐24D. These changes were also considerably reflected in carcass fatty acid composition.     

Entrainment of Circadian Wheel-Running Rhythms of the Northern Brown Bandicoot, Isoodon macrourus, by Daily Restricted Feeding Schedules

Northern brown bandicoots (Isoodon macrourus) were subjected to restricted feeding for 3 h in the middle of the light period of a 14: 10 light/dark cycle and immediately following this in constant dark. When feeding was restricted to the middle of the light period of the light/dark cycle, all bandicoots maintained a nocturnal activity rhythm. In addition to the nocturnal rhythm, a few bandicoots showed meal-anticipatory activity during the light period. In bandicoots that did not show meal-anticipatory activity, diurnal activity was sometimes evident either during or shortly after the daily meal time. The observation of meal-anticipatory activity in some bandicoots suggests that this species may have a mechanism separate from the light-entrainable mechanism that allows the daily anticipation of periodically available food sources. In the next stage of the experiment, which was in constant dark, the meal was presented at the same time of day as it had been in the previous stage. In all bandicoots, the previously light-entrained component of activity free-ran and was eventually affected by the restricted feeding schedule to some degree. Bandicoots showed weak entrainment and relative coordination, suggesting that restricted feeding is a weak zeitgeber in this species. Evidence also suggesting that two separate but coupled pacemakers control the activity rhythms of the bandicoot was that (a) bandicoots simultaneously showed free-running light-entrainable rhythms and meal-entrained anticipatory rhythms; (b) in several bandicoots, the light-entrainable rhythm was phase advanced when it free-ran through the meal time; and (c) in one bandicoot, meal-entrained anticipatory activity was forced away from the meal time when the previously light-entrained component of activity free-ran through it.     

Effect of delta22-5beta-taurocholenic acid on hepatic cholesterol and fatty acid in gold thioglucose obese mice fed low- or high-fat diets

We previously demonstrated that hyperglycemic-obese (obob) mice fed a 1% corn oil diet accumulated 10 times as much hepatic cholesterol as did their non-obese (+/?) littermates fed this diet because of difficulty in removal of cholesterol from the liver rather than from increased synthesis. Furthermore, feeding the bile acid analog Delta(22)-5beta-taurocholenic acid completely prevented the accumulation of hepatic cholesterol in obob mice fed the 1% corn oil diet. The hypothesis to be tested in the current study is that these aspects of cholesterol metabolism in the obob mouse do not occur in the hyperinsulinemic and insulin-resistant gold thioglucose obese mouse. Gold thioglucose obese (gtgo) and non-obese (ngtgo) mice were fed diets containing either 1% corn oil or 40% lard each with or without added taurocholenic acid for 6 weeks and then given a 250 mg meal of [U-(14)C]-glucose with incorporation of label into hepatic cholesterol and fatty acid measured 2 hours later. Consistent with earlier results in the obob model, incorporation of labeled glucose was significantly increased in obese compared with non-obese mice fed 1% corn oil and significantly reduced either by feeding 40% lard or by adding taurocholenic acid to the diet. In addition, taurocholenic acid greatly increased incorporation of labeled glucose into hepatic cholesterol in obese or non-obese mice fed either diet. In contrast to obob mice, the percentage of fat in the liver of gtgo mice was increased only 50% compared with ngtgo mice. The comparable increase in obob mice was 480%. Hepatic cholesterol did not increase significantly in the liver of gtgo mice fed 1% corn oil when compared with the ngtgo controls. The comparable increase in obob mice fed 1% corn oil was 350%. Also in marked contrast to obob mice, feeding taurocholenic acid increased hepatic cholesterol compared with non-obese controls fed either diet. The results are discussed in the light of the presence of circulating leptin in gtgo but not in obob mice.     

Diet selection and eating behaviour of lactating goats subjected to time restricted feeding in choice and single feeding system

This study was carried out to investigate diet selection and eating behaviour of lactating German Fawn × Hair Crossbred goats in different feeding methods and levels. Twenty German Fawn × Hair first backcross does (B₁) were allocated into 4 treatment groups (2 feeding methods single (TMR) and choice feeding × 2 feeding levels ad libitum and restricted) with 5 replicates. Restricted feeding was applied only 4 h feed allocation during day. Barley, corn, soybean meal, corn gluten meal, wheat bran and alfalfa hay were feed ingredients for single and choice feeding. Eating patterns, milk yield and composition were determined for 8 weeks. The following results were obtained: (1) the meal criteria for goats restricted single and choice-fed, ad libitum single and choice-fed were determined as 1.00 and 0.63, 12.88 and 10.23 min, respectively. (2) Ad libitum feeding increased meal size, meal length, intermeal interval, total eating duration and decreased eating rate and meal number, compared to restricted feeding (P < 0.01). Choice feeding decreased meal size (P < 0.05), meal length (P < 0.01) and increased eating rate and meal number (P < 0.01), compared to single feeding. Restricted fed goats decreased intermeal interval in single feeding compared to choice feeding (P < 0.01), but increased meal number in choice feeding (P < 0.01). (3) Ad libitum choice-fed does made a diet containing 12.79% corn, 35.41% barley, 13.21% wheat bran, 5.35% soybean meal, 1.28% corn gluten meal and 29.80% alfalfa meal while restricted choice-fed does made a diet having more corn (27.69%), corn gluten meal (5.62%) and wheat bran (16.17%) and less barley (14.37%) and soybean meal (4.51%). (4) Choice feeding decreased RUP intake (P < 0.05) without affecting milk protein, irrespective to feeding levels, while having a tendency to increase in milk yield (14.2%) and 4% FCM (8.8%). (5) Restricted feeding decreased DM, ME, ADF and NDF intakes (P < 0.05) with concomitant decreases in 4% FCM, total milk solid, ash and fat compositions (P < 0.05), irrespective to feeding methods. (6) Choice-fed goats changed their preferences for a possible synchronized nutrient intake during a daytime, as sorted barley, soybean meal and alfalfa hay from early morning to late afternoon.It could be concluded that choice-fed goats have the ability to make their diet to meet nutrient requirements and had a tendency to increase in milk yield. Restriction in feeding time resulted in lower feed intake and milk yield, although the animal changed their feed preference in favour of high quality ingredients and eating pattern with lower meal criterion and intermeal interval.     

Diurnal and circadian variations in indole contents in the goose pineal gland

ABSTRACT

The diurnal and circadian profiles of pineal indoles, except melatonin, are poorly characterized in birds. Moreover, there are no data on the effect of sudden changes in the light–dark cycle on these profiles. Therefore, we investigated the diurnal (Experiment I) and circadian variation (Experiment II) of nine pineal indoles (tryptophan, 5-hydroxytryptophan, serotonin, N-acetylserotonin, melatonin, 5-hydroxyindole acetic acid, 5-methoxytryptophol, 5-methoxyindole acetic acid, 5-methoxytryptamine) in geese, as well as the changes in the profiles of these substances in geese subjected to a reversed light–dark cycle (Experiment III). For the first 12 weeks of life, all geese were kept under a diurnal cycle of 12 h of light and 12 h of darkness (12L:12D). In Experiment I (n = 48), they were kept under these conditions for another 14 days before being sacrificed at 2-h intervals for sampling of the pineal glands. In Experiment II, the geese (n = 48) were divided into three groups (12L:12D, 24L:0D, 0L:24D) for 10 days before sampling at 6-h intervals. In Experiment III, 24 geese were exposed to a reversed light–dark cycle before sampling at 14:00 and 02:00 on the first, second and third days after light–dark cycle reversal. To determine the content of the indoles in the goose pineals, HPLC with fluorescence detection was used. We found that, with the exception of tryptophan, all the investigated indoles showed statistically significant diurnal variation. When geese were kept in constant darkness, most of the indoles continued to show this variation, but when geese were kept in constant light, the indoles did not show significant variation. When the light–dark cycle was reversed (12L:12D to 12D:12L), the profiles of NAS, melatonin, 5-MTAM and 5-MTOL reflected the new cycle within 2 days. The content of serotonin in geese in 12L:12D was higher than that observed in other birds under these conditions, which suggests that this compound may play a special role in the pineal physiology of this species. In conclusion, our results show that the daily variations in the metabolism of melatonin-synthesis–related indoles in the goose pineal gland are generated endogenously and controlled by environmental light conditions, as in other birds. However, comparison of the results obtained with the goose to those obtained with other species (chicken, duck) unambiguously shows that the profiles of pineal indoles differ markedly between species, in both the quantitative proportions of the compounds and the characteristics of the diurnal changes. These findings provide strong arguments for the need for comparative studies.