Effect Of Feeding Status Research Articles

Application of Effective Day Degrees in the Assessment of Stable Isotope Patterns in Developing Seahorses under Different Temperatures.

Simple SummaryTemperature affects fish development, with especially strong influence on juvenile growth rates and metabolism. The present study provides new insights on stable isotopes (δ13C and δ15N) for the understanding of growth and food assimilation in early developing European long-snouted seahorse Hippocampus guttulatus under different temperature levels. The effects of feeding status, ontogeny and temperature regimes on stable isotope patterns were assessed and modelled as function of development. We argue that chronological time is not a convenient developmental scale and we encourage the use of D°eff as temperature-independent developmental index in stable isotopes studies involving temperature comparisons.Relations between nutrient assimilation and growth rate in fishes may vary with abiotic factors such as temperature. The effects of feeding status, ontogeny and temperature regimes (15, 18 and 21 °C) on stable isotope (δ13C and δ15N) patterns were assessed in juveniles of the seahorse Hippocampus guttulatus. The use of effective day degrees (D°eff), day degrees (D°) and chronological time (age) were compared as development progress indices. Newborn seahorses were maintained at three temperature levels both deprived of food (5 days) or fed (30 days) on copepods or/and Artemia. Isotopic signatures in fed seahorses clearly differed from those in unfed juveniles. Temperature had a significant effect on δ13C values in fed juveniles throughout the experimental period. δ15N values also varied significantly with age, but not with temperature level. Faster growth and food assimilation in seahorses held at 18 and 21 °C were supported by faster variations in isotopic values. Our findings demonstrate that effective day degrees should be preferred over chronological time as index of developmental progress in temperature fluctuating scenarios or for comparative studios.

Effects of feeding status on nucb1 and nucb2A mRNA expression in the hypothalamus of Schizothorax davidi.

NUCB1 and NUCB2, two novel nucleobindins, have attracted extensive attention for their role in the appetite regulation in mammals. However, little is known about the appetite regulation of NUCB1 and NUCB2 in fish species. Therefore, we investigated the role of these peptides in the regulation of feeding in Schizothorax davidi (S. davidi). In this study, full-length cDNA sequences of nucb1 and nucb2A of S. davidi were obtained for the first time. Additionally, the tissue distribution and the effects of different energy status on nucb1 and nucb2A mRNAs abundance were assessed, showing that nucb1 and nucb2A are widely distributed in 18 detected tissues, with the highest expression in the cerebellum. The abundances of nucb1 and nucb2A increased in the hypothalamus at 1h and 3h post-feeding. Furthermore, fasting and re-feeding experiments showed that the expressions of nucb1 and nucb2A in hypothalamus significantly decreased after fasting for 7days, and returned to the control level after re-feeding for 3 or 5days. In conclusion, the present study suggests that both NUCB1 and NUCB2A are involved in the short-term and long-term appetite regulation, as an anorexigenic factor, in S. davidi. These results can provide a basis for further investigation into the appetite regulatory role of NUCB family in teleost.

Offspring sex-ratio and environmental conditions in a seabird with sex-specific rearing costs: a long-term experimental approach

Sex allocation studies among birds and mammals are notoriously inconsistent with theoretical predictions. One explanation is the difficulty of collecting data on costs and benefits of sex-ratio adjustments, which prevents the investigation of underlying assumptions. Some predictions may thus have been tested in species where they should not have been expected. Here, we focus on the “cost of reproduction hypothesis”, which states that parents with low investment capacity should avoid producing the most expensive sex to minimise the decrease in their residual reproductive value. In the black-legged kittiwake (Rissa tridactyla), sons are energetically more expensive than daughters. Using 10 years of data (1172 chicks from 790 broods) from a long-term feeding experiment, we predicted a stronger decrease in the probability of producing a son with deteriorating environmental conditions among Control than among supplementally Fed parents. To test this prediction, we used three proxies of environmental conditions and a recent sliding window approach. We found no support for our prediction. Hence, we investigated between-year sex-ratio variation in relation to feeding status to detect a response to an unmeasured environmental variable. There was no interaction between year and feeding status, nor any effect of feeding status itself. However, the probability of producing a male increased with time, which could be a response to an oceanic regime shift that occurred around our colony, but that our proxies failed to capture. Our study further highlights the difficulty of explaining sex-ratio variation in long-lived species with complex life-histories where multiple selective pressures can occur simultaneously.

Ghrelin serves as a signal of energy utilization and is involved in maintaining energy homeostasis in broilers

Ghrelin, one of the most important appetite regulating peptides, is involved in the regulation of energy homeostasis. The anorexia effect of ghrelin in chickens is contrary to that of ghrelin in mammals. In the present study, the effects of feeding status and dietary energy level on plasma total ghrelin levels and expression were studied in broilers. The gene expression of ghrelin and its receptor GHS-R1a were measured in the hypothalamus, proventriculus, duodenum, liver, and abdominal fat pad. The results showed that ghrelin mRNA and GHS-R1a mRNA are moderately expressed in liver and abdominal fat. Ghrelin secretion was increased by fasting and refeeding. The gene expression of ghrelin and GHS-R1a in the hypothalamus, proventriculus, liver, and abdominal fat pad were changed by feeding status and dietary energy level. The results suggest that ghrelin is a signal of energy utilization in chickens. The abundant expression of ghrelin and GHS-R1a in liver and abdominal fat pad may be associated with energy balance.

Feeding influences adipose tissue responses to exercise in overweight men.

Feeding profoundly affects metabolic responses to exercise in various tissues, but the effect of feeding status on human adipose tissue responses to exercise has never been studied. Ten healthy overweight men aged 26 ± 5 yr (mean ± SD) with a waist circumference of 105 ± 10 cm walked at 60% of maximum oxygen uptake under either fasted or fed conditions in a randomized, counterbalanced design. Feeding comprised 648 ± 115 kcal 2 h before exercise. Blood samples were collected at regular intervals to examine changes in metabolic parameters and adipokine concentrations. Adipose tissue samples were obtained at baseline and 1 h after exercise to examine changes in adipose tissue mRNA expression and secretion of selected adipokines ex vivo. Adipose tissue mRNA expression of pyruvate dehydrogenase kinase isozyme 4 (PDK4), adipose triglyceride lipase, hormone-sensitive lipase (HSL), fatty acid translocase/CD36, glucose transporter type 4 (GLUT4), and insulin receptor substrate 2 (IRS2) in response to exercise were lower in fed compared with fasted conditions (all P ≤ 0.05). Postexercise adipose IRS2 protein was affected by feeding (P ≤ 0.05), but Akt2, AMPK, IRS1, GLUT4, PDK4, and HSL protein levels were not different. Feeding status did not impact serum and ex vivo adipose secretion of IL-6, leptin, or adiponectin in response to exercise. This is the first study to show that feeding before acute exercise affects postexercise adipose tissue gene expression, and we propose that feeding is likely to blunt long-term adipose tissue adaptation to regular exercise.

Effect of feeding status on mortality response of adult bed bugs (Hemiptera: Cimicidae) to some insecticide products.

Fresh and aged residual deposits of several insecticide products were tested against bed bug adults to determine if a recent bloodmeal affected their mortality response to the residues. The bed bugs with a recent bloodmeal survived significantly longer compared with the unfed ones on their exposure to fresh or aged residual deposits of chlorfenapyr and aged residual deposits of deltamethrin on a wooden substrate. Even though the survival time of fed bed bugs was significantly longer than that of unfed ones on their exposure to fresh residue of deltamethrin and aged residue of desiccant pyrethrin dust, these treatments resulted in similarly high final mortalities regardless of feeding status of the insects. Mortality responses of fed and unfed bed bugs were similar to fresh or aged residual deposits of imidacloprid + cyfluthrin combination and fresh residual deposits of desiccant pyrethrin dust. Topical application assays indicated that a recent bloodmeal significantly increased the bed bug's survival time for chlorfenapyr, but not for deltamethrin. Pyrethroid-resistant bed bugs also showed a similar increase in their survival time for chlorfenapyr after a bloodmeal. The comparison of mortality responses between fed and unfed bed bugs treated with similar amount of chlorfenapyr per fresh body weight indicated that increased body mass was not the primary cause for this bloodmeal-induced tolerance increase for chlorfenapyr. Because the surviving bed bugs can continue ovipositing, the effectiveness of chlorfenapyr residual deposits in bed bug harborages could be significantly affected by the feeding status of the adult bed bug populations.

Food Deprivation Increases the Expression of the Prepro-Orexin Gene in the Hypothalamus of the Barfin Flounder,Verasper moseri

Orexins (orexin-A and -B) are involved in the regulation of food intake in mammals. In the barfin flounder, Verasper moseri, we previously reported that orexin-A-like-immunoreactive (ir) cell bodies are localized in the hypothalamus, which is a possible orexigenic center in fish. However, the physiological roles of orexin in the barfin flounder remain unclear. Here, we cloned prepro-orexin cDNA and examined the effects of feeding status on orexin gene expression in the barfin flounder to obtain a better insight into the roles of orexins in feeding regulation. A molecular cloning study showed that barfin flounder prepro-orexin cDNA encodes a 145 amino acid (aa) polypeptide containing orexin-A (43 aa) and orexin-B (28 aa). Prepro-orexin gene transcripts were detected in the hypothalamus, pituitary, and several peripheral organs such as the eyeball, gills, head kidney, body kidney, spleen, testis, and the skin on the eye-side of the flounder's body. Furthermore, the mean prepro-orexin mRNA expression level in the hypothalamus was significantly higher in fasted than in fed fish. These results show that fasting regulates orexin mRNA in the hypothalamus and suggest that orexin is involved in feeding regulation in barfin flounder.

Effect of Feeding Status on Adjuvant Arthritis Severity, Cachexia, and Insulin Sensitivity in Male Lewis Rats

We studied the effect of food restriction, overfeeding, and normofeeding on cachexia, inflammatory and metabolic parameters, and insulin sensitivity in chronic adjuvant arthritis (AA) in rats. Food restriction during AA increased circulating ghrelin, corticosterone, decreased leptin, and ameliorated arthrogram score and systemic inflammation compared to normofeeding. Overfeeding worsened arthrogram score and systemic inflammation, and led to lipid accumulation in the liver, but not to alterations of adipokine and ghrelin plasma levels relative to normofeeding. Independently of feeding status, AA induced cachexia, in which modulation of mRNA expressions for appetite-regulating neuropeptides (NPY, AgRP, POMC, CART) in the arcuate nucleus (ARC) does not play a primary role. The overexpression of IL-1β mRNA in the ARC suggests its role in the mechanisms of impaired energy balance during AA under all feeding conditions. Normal HOMA index in all arthritic groups does not indicate the development of insulin resistance by feeding interventions in these rats.

Oral and intravenous administration of nimesulide in the horse: rational dosage regimen from pharmacokinetic and pharmacodynamic data

The selective COX-2-inhibitor nimesulide is used extra-label in equine veterinary practice as an anti-inflammatory agent. However, there are no data on which to base the rational use of the drug in this species. To determine the effective COX selectivity of nimesulide in the horse, and suggest a suitable dosing schedule. The pharmacokinetics of nimesulide in the horse after oral administration (1 mg/kg bwt), and oral and i.v. administration (1.5 mg/kg bwt) were investigated, effects of feeding status on bioavailability determined, and plasma protein binding of the drug and its principal metabolites measured. Compartmental and noncompartmental pharmacokinetic analyses were performed. The plasma concentration-time profile was used, together with in vitro literature data on nimesulide inhibition of COX isoforms, to determine the effective COX selectivity of nimesulide in the horse, and suggest a suitable dosing schedule. The findings suggest that 1.5 mg/kg bwt may produce adequate clinical effects, and the dosing interval should be 12-24 h depending on condition severity. However, at that dose, the concentration in the animal exceeds the in vitro IC50 for both isoforms, so that COX-1/COX-2 selectivity is lost and side-effects due to COX-1 inhibition are a possibility. Nimesulide should therefore be used with caution in equine clinical practice.

Feeding-induced changes of melanin-concentrating hormone (MCH)-like immunoreactivity in goldfish brain

Intracerebroventricular (ICV) injection of melanin-concentrating hormone (MCH) influences feeding behavior in the goldfish and exerts an anorexigenic action in goldfish brain, unlike its orexigenic action in mammals. Despite a growing body of knowledge concerning MCH function in mammals, the role of MCH in appetite has not yet been well studied in fish. The aim of the present study was to investigate the involvement of endogenous MCH in the feeding behavior of the goldfish. We examined the distribution of MCH-like immunoreactivity (MCH-LI) in the goldfish brain and the effect of feeding status upon this distribution. Neuronal cell bodies containing MCH-LI were localized specifically to four areas of the hypothalamus. Nerve fibers with MCH-LI were found mainly in the neurohypophysis, with a few in the telencephalon, mesencephalon, and diencephalon. The number of neuronal cell bodies containing MCH-LI in the dorsal area adjoining the lateral recess of the third ventricle in the posterior and inferior lobes of the hypothalamus showed a significant decrease in fasted fish compared with that in normally fed fish, although other areas showed no evident differences. We also administered an antiserum against fish MCH (anti-MCH serum) by ICV injection and examined its immuno-neutralizing effect on food intake by using an automatic monitoring system. Cumulative food intake was significantly increased by ICV injection of the anti-MCH serum. These results indicate that MCH potentially functions as an anorexigenic neuropeptide in the goldfish brain, and that the further study of the evolutionary background of the MCH system and its role in appetite is warranted.

The effect of feeding status on sexual attractiveness of Ixodes ricinus (Acari: Ixodidae) females.

Sexual attractiveness of unengorged, semiengorged and fully engorged females of both field and laboratory populations of Ixodes ricinus was studied under laboratory conditions by means of a computerised video tracking system. A male and a female were allowed to walk freely in a glass arena during 1 h and their behavioural interactions were observed. Obtained results revealed that the feeding status of L. ricinus females affects their sexual attractiveness. The highest attractiveness was observed in engorged females, the lowest in unengorged females of the field population. Copulation occurred in all experimental groups with the highest frequency observed in the unengorged virgin laboratory females. Despite engorged females being highly attractive for males on distance, the frequency of copulation was low. Differences between field and laboratory populations were found in both behavioural parameters and frequency of copulation.

Regulation of Mitochondrial sn-Glycerol-3-phosphate Acyltransferase Activity: Response to Feeding Status Is Unique in Various Rat Tissues and Is Discordant with Protein Expression

Triacylglycerol plays a critical role in an organism's ability to withstand fuel deprivation, and dysregulation of triacylglycerol synthesis is important in the development of diseases such as obesity and diabetes. Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the initial and committed step of glycerolipid synthesis and is therefore a potential site for regulation of triacylglycerol synthesis. Because several studies suggest that triacylglycerol synthesis is linked to the mitochondrial isoform, we studied mitochondrial GPAT expression and the effect of feeding status on the regulation of mitochondrial GPAT in various rat tissues. Liver, adipose, and soleus muscle have high levels of GPAT mRNA, but low protein expression, whereas heart and adrenal, tissues with low GPAT mRNA abundance, have the highest GPAT protein expression. In addition, heart, which has the highest expression of mitochondrial GPAT protein, has low mitochondrial GPAT specific activity (0.02 nmol/min/mg). Liver and adipose have the highest mitochondrial GPAT specific activity (0.17 nmol/min/mg), but very low protein expression. Discrepancies between GPAT protein expression and activity suggest that mitochondrial GPAT may be regulated acutely. In response to a 48-h fast, liver and adipose mitochondrial GPAT protein expression and activity decrease 30–50%. After 24-h refeeding of either chow or high-sucrose diet, mitochondrial GPAT protein expression and activity overshoot normal levels 30–60%. In kidney, mitochondrial GPAT protein and activity increase 65 and 30%, respectively, with refeeding, whereas in the heart, mitochondrial GPAT activity increases 2.3-fold after a fast, with no change in protein expression. We also found that hepatic mitochondrial GPAT activity in the neonatal rat constitutes a lower percentage of the total GPAT activity than in the adult. We postulate that GPAT expression is modulated uniquely in each tissue according to specific needs for triacylglycerol storage.