Starvation Period Research Articles

Short-term starvation and refeeding in the greater amberjack (Seriola dumerili, Risso 1810): New insights on physiological and metabolic traits

The greater amberjack (Seriola dumerili) is a fish species with high commercial value and excellent growth rates, which has led to increasing interest in the aquaculture sector to optimize and expand its production. To gain a deeper insight into its physiological aspects, the present study aimed to evaluate the metabolic responses of S. dumerili juveniles after a short period of starvation and subsequent refeeding. For this purpose, the fish were fed ad libitum twice a day for four weeks and were then subjected to a starvation challenge followed by a refeeding period of seven days each. After one week of starvation, the fish showed weight loss but were able to adapt their metabolism by maintaining carbohydrate levels and using lipids and proteins as the main energy sources. All this was supported by decreased glycogenolytic potential during starvation, indicated by lower GP activity, and an increase in gluconeogenic pathway, as evidenced by the observed activity of FBP, LDH, and transaminases (ALT and AST). Moreover, the refeeding period stimulated growth processes by activating metabolic pathways, resulting in higher feed efficiency rates. Correspondingly, the highest plasma cortisol levels were observed during the refeeding period, stimulating anticipatory activity after starvation and contributing to metabolic recovery. In conclusion, S. dumerili can efficiently regulate its internal environment during a short period of starvation, improving feed efficiency and growth parameters after refeeding and rapidly restoring the initial metabolic state. These results could represent promising insights to enhance the feeding program for this species.

Impact of Refeeding Syndrome on the Short-Term Clinical Outcomes of Very-Premature Infants.

Refeeding syndrome (RFS) is a potentially life-threatening condition that can occur in preterm infants if nutritional support is initiated or increased after a period of starvation or malnutrition. The current study aimed to examine the short-term clinical outcomes of RFS in preterm infants born at ≤32 weeks of gestation. Infants with a gestational age of ≤32 weeks and a birth weight of <1500 g who were born and admitted to the level III neonatal intensive care unit and received parenteral nutrition upon admission were retrospectively evaluated. The modified log Poisson regression with generalized linear models and a robust variance estimator was applied to adjust the outcomes of infants. In total, 760 infants met this study's inclusion criteria. Of them, 289 (38%) developed RFS. RFS was significantly associated with a composite outcome of mortality and intraventricular hemorrhage. Based on the multivariate Cox regression analysis adjusted for significant potential confounders, RFS was significantly associated with increased mortality risk, with a hazard ratio for death in infants with RFS being 1.74-fold higher compared to those without RFS. Preterm infants born at ≤32 weeks of gestation who develop RFS within the first week of life are at increased risk for both intraventricular hemorrhage and mortality. This study underscores the need for standardized clinical approaches for managing RFS in the neonatal intensive care unit to improve outcomes. Future research should establish a unified RFS definition and conduct clinical trials to optimize parenteral nutrition strategies for this vulnerable population.

Targeted single cell expression profiling identifies integrators of sleep and metabolic state.

Animals modulate sleep in accordance with their internal and external environments. Metabolic cues are particularly potent regulators of sleep, allowing animals to alter their sleep timing and amount depending on food availability and foraging duration. The fruit fly, Drosophila melanogaster , suppresses sleep in response to acute food deprivation, presumably to forage for food. This process is dependent on a single pair of Lateral Horn Leucokinin (LHLK) neurons, that secrete the neuropeptide Leucokinin. These neurons signal to insulin producing cells and suppress sleep under periods of starvation. The identification of individual neurons that modulate sleep-metabolism interactions provides the opportunity to examine the cellular changes associated with sleep modulation. Here, we use single-cell sequencing of LHLK neurons to examine the transcriptional responses to starvation. We validate that a Patch-seq approach selectively isolates RNA from individual LHLK neurons. Single-cell CEL-Seq comparisons of LHLK neurons between fed and 24-hr starved flies identified 24 genes that are differentially expressed in accordance with starvation state. In total, 12 upregulated genes and 12 downregulated genes were identified. Gene-ontology analysis showed an enrichment for Attacins , a family of anti-microbial peptides, along with several transcripts with diverse roles in regulating cellular function. Targeted knockdown of differentially expressed genes identified multiple genes that function within LHLK neurons to regulate sleep-metabolism interactions. Functionally validated genes include an essential role for the E3 ubiquitin Ligase insomniac, the sorbitol dehydrogenase Sodh1, as well as AttacinC and AttacinB in starvation-induced sleep suppression. Taken together, these findings provide a pipeline for identifying novel regulators of sleep-metabolism interactions within individual neurons.

Impact of extended starvation conditions on bioelectrocatalytic activity of a methane-producing microbial electrolysis cell

The performance of a methane-producing microbial electrolysis cell (MEC) markedly relies on the activity and resilience of its electroactive anodic biofilm. Here, the capability of an MEC anodic biofilm to recover following extended starvation periods (90 days) and to function under different applied anode potentials (i.e., +0.20 and −0.10 V, vs. Standard Hydrogen Electrode-SHE) was investigated. Cyclic voltammetry proved to be an insightful means to characterize the biofilm electrocatalytic activity and to track the dynamics of biofilm reactivation. Under all tested conditions the anodic biofilm rapidly and completely recovered from starvation in less than 144 h. However, starvation reduced the electron transfer redundancy of the biofilm causing the disappearance of redox sites operating at the more positive potentials (around 0.0 V vs. SHE) and retaining those having a formal potential lower than −0.18 V vs. SHE. This study presents compelling evidence for the resilience and efficiency of methane-producing MEC.

The Impact of Hyperemesis Gravidarum on Fetal Development and Birth Outcomes: A Systematic Review and Meta-Analysis

Background: Hyperemesis gravidarum (HG) is a condition characterized by severe nausea and vomiting experienced during pregnancy, with an incidence rate estimated to affect between 0.3% and 2% of pregnant individuals. As HG results in prolonged periods of maternal starvation and multiple nutritional deficiencies, it can potentially disrupt the delicate balance of nutrients and metabolic processes required for optimal fetal growth and development. This systematic review aims to analyze the impact of HG on fetal development and birth outcomes. Methods: The following databases were searched from January 2000 to March 2024: PubMed, Web of Science, Science Direct, Medline (Ovid), and Embase (Ovid). The search focused on HG and its pathogenesis, treatment, fetal development, and pregnancy-related adverse outcomes. Results: 6 out of 907 studies were included which focused on HG with fetal development and birth outcomes. All 6 studies were cohort studies and the quality was high. Meta-analysis revealed that HG is associated with an increased risk of preterm birth (odds ratio (OR): 1.2; 95% confidence interval (95% CI): 1.17–1.23) and small for gestational age (SGA) (OR: 1.30; 95% CI: 1.22–1.40). Conclusions: A limited number of studies have investigated the effects of HG on fetal development and birth outcomes. The present systematic review indicated an increased risk of preterm birth and SGA associated with HG; however, high heterogeneity among the limited included studies should be noted.

Evaluating the Effects of Diet on the Sensitivity of Hyalella azteca to an "Eco-friendly" Deicing Agent.

Salting of roadways contaminates local waterways via snowmelt and precipitation runoff, eliciting various toxicological impacts on aquatic ecosystems. Recently, "eco-friendly" deicing alternatives have been introduced in hopes of mitigating environmental impacts of deicing agents, while maintaining human safety. These "eco-friendly" alternatives may pose their own set of environmental concerns that require further study. While the potential toxicity of road salts has been evaluated for various aquatic species, the environmental factors that may influence this toxicity are less understood; and for emerging deicing alternatives, there is a lack of literature documenting these potential implications. For aquatic organisms, the highest exposure to road salts may coincide with reduced food availability, namely during the winter months. The present study evaluates the effect of a conditioning diet on the sensitivity of adult Hyalella azteca to an "eco-friendly"-labeled beet deicer (Snow Joe MELT Beet-IT). Various conditioning diets were examined, including TetraMinTM, TetraMin and diatom (Thalassiosira weissflogii) combinations, and TetraMin and conditioned Acer sacharum leaves. For each diet type, 48- and 96-h water-only toxicity bioassays were conducted with adult H. azteca. These results were compared to organisms which experienced a 96-h starvation period prior to exposure and culture organisms. Diet types representing excess quality and quantity of food significantly decreased the toxicity of beet deicer to the organisms. However, starvation likely increases the toxicity of road salts to H. azteca. Therefore, the quantity and quality of food available to H. azteca may influence their sensitivity to deicing agents. Environ Toxicol Chem 2024;00:1-8. © 2024 SETAC.

Physiological and behavioral responses to social isolation and starvation in a social fish

Changes in the social environment, such as segregating an individual who would typically reside within a social group, may elicit physiological and behavioral responses to external stimulus such as starvation. However, such changes in phenotypic traits receive a little attention in social fish. Here, we used qingbo (Spinibarbus sinensis) with high level of sociability as animal model in order to examine the physiological and behavioral responses of this fish species to social environment (isolation vs. grouping) and nutritional state (well-fed vs. starvation). We found that differences in the reduction of body masses between the group-reared and the isolation-reared fish during periods of starvation can be partially attributed to variations in water volume within the tanks. Additionally, the decrease in standard metabolic rate was more pronounced in the group-reared fish compared to the isolation-reared fish when deprived of food, except for maximum metabolic rate and aerobic scope. Interestingly, only the group-reared fish experienced a decline in constant acceleration swimming performance after food deprivation, while this was not observed in the isolated fish. Neither social isolation nor starvation had any impact on personality expression (e.g., exploration, activity, and boldness). However, both exploration and boldness exhibited temporal effects with an increase in these two personality traits. Social isolation tended to elevate anxiety-like behavior levels. Both social isolation and starvation did not affect upper thermal tolerance; however, starvation enhanced cold resistance of the fish. Our findings contribute to a better understanding of how social environment combined with trophic stress influences phenotypic traits and may offer valuable insights into animal welfare considerations for both natural habitats and aquaculture practices.

Starvation resilience in anammox-based bioreactors: A stable nitrogen removal route on partial denitrification/anammox (PD/A)

This study investigates the performance, resilience and microbial community dynamics of two anaerobic processes, i.e. pure anammox (R1) and partial denitrification/anammox (PD/A) (R2), following a 30-day starvation period. The tolerance to starvation was assessed by comparing nitrogen removal efficiency and microbial activity across both reactors. Results show that the PD/A process recovery to pre-starvation performance levels within just one day, as compared to the pure anammox process. Notably, although the activity of anammox bacteria decreased in both processes during starvation, the decay rate in R1 was 69.59 % higher than in R2, potentially explaining the quicker recovery of R2. Furthermore, enhanced secretion of extracellular polymeric substance (EPS) during starvation served as a protective mechanism. The potential functions and genes in microorganisms, as well as the pathway of nitrogen cycling, were demonstrated through analyses using the KEGG database. This research reveals essential mechanistic insights and strategic guidance for the effective implementation of anammox-based biological nitrogen removal processes.

Effects of Fasting on THP1 Macrophage Metabolism and Inflammatory Profile.

Fasting can affect the body's inflammatory response, and this has been linked to potential health benefits, including improvements for people with rheumatic diseases. In this work, we evaluated, in vitro, how changes in nutrient availability alter the inflammatory response of macrophages. Macrophage-differentiated THP1 cells were cultured, deprived of FCS or subjected to cycles of FCS deprivation and restoration to mimic intermittent fasting. Changes in the macrophage phenotype, the cells' response to inflammatory stimuli and the level of mitochondrial alteration were assessed. The results indicate that while periods of serum starvation are associated with a decrease in IL1β and TNFα expression, consistent with an anti-inflammatory response, intermittent serum starvation cycles promote a pro-inflammatory phenotype. Rapid changes in reducing capacity and mitochondrial response were also observed. Of note, while some changes, such as the production of oxygen free radicals, were reversed with refeeding, others, such as a decrease in reducing capacity, were maintained and even increased. This study shows that different fasting protocols can have diverging effects and highlights that time-limited nutrient changes can significantly affect macrophage functions in cell cultures. These findings help elucidate some of the mechanisms by which specific fasting dietary interventions could help control inflammatory diseases.

A Patent Review of Human Dihydroorotate Dehydrogenase (hDHODH) Inhibitors as Anticancer Agents and their Other Therapeutic Applications (1999-2022).

Highly proliferating cells, such as cancer cells, are in high demand of pyrimidine nucleotides for their proliferation, accomplished by de novo pyrimidine biosynthesis. The human dihydroorotate dehydrogenase (hDHODH) enzyme plays a vital role in the rate-limiting step of de novo pyrimidine biosynthesis. As a recognised therapeutic target, hDHODH plays a significant role in cancer and other illness. In the past two decades, small molecules as inhibitors hDHODH enzyme have drawn much attention as anticancer agents, and their role in rheumatoid arthritis (RA), and multiple sclerosis (MS). In this patent review, we have compiled patented hDHODH inhibitors published between 1999 and 2022 and discussed the development of hDHODH inhibitors as anticancer agents. Therapeutic potential of small molecules as hDHODH inhibitors for the treatment of various diseases, such as cancer, is very well recognised. Human DHODH inhibitors can rapidly cause intracellular uridine monophosphate (UMP) depletion to produce starvation of pyrimidine bases. Normal cells can better endure a brief period of starvation without the side effects of conventional cytotoxic medication and resume synthesis of nucleic acid and other cellular functions after inhibition of de novo pathway using an alternative salvage pathway. Highly proliferative cells such as cancer cells do not endure starvation because they are in high demand of nucleotides for cell differentiation, which is fulfilled by de novo pyrimidine biosynthesis. In addition, hDHODH inhibitors produce their desired activity at lower doses rather than a cytotoxic dose of other anticancer agents. Thus, inhibition of de novo pyrimidine biosynthesis will create new prospects for the development of novel targeted anticancer agents, which ongoing preclinical and clinical experiments define. Our work brings together a comprehensive patent review of the role of hDHODH in cancer, as well as various patents related to the hDHODH inhibitors and their anticancer and other therapeutic potential. This compiled work on patented DHODH inhibitors will guide researchers in pursuing the most promising drug discovery strategies against the hDHODH enzyme as anticancer agents.

Molecular mechanism of a coastal cyanobacterium Synechococcus sp. PCC 7002 adapting to changing phosphate concentrations

Phosphorus concentration on the surface of seawater varies greatly with different environments, especially in coastal. The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still unclear. In this study, transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus sp. PCC 7002 during periods of phosphorus starvation and phosphorus recovery (adding sufficient phosphorus after phosphorus starvation). The findings indicated that phosphorus deficiency affected the photosynthesis, ribosome synthesis, and bacterial motility pathways, which recommenced after phosphorus was resupplied. Even more, most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete conditions. Based on transcriptome, 54 genes potentially related to phosphorus-deficiency adaptation were selected and knocked out individually or in combination. It was found that five mutants showed weak growth phenotype under phosphorus deficiency, indicating the importance of the genes (A0076, A0549-50, A1094, A1320, A1895) in the adaptation of phosphorus deficiency. Three mutants were found to grow better than the wild type under phosphorus deficiency, suggesting that the products of these genes (A0079, A0340, A2284–86) might influence the adaptation to phosphorus deficiency. Bioinformatics analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition strategies. These results elucidated that Synechococcus sp. PCC 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration, providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.

Respiration rate and intestinal microbiota as promising indicators for assessing starvation intensity and health status in Pacific oyster (Crassostrea gigas)

Implementing early disease warning is vital to prevent large-scale mortality of mollusks cultured in open waters. Starvation-induced emaciation syndrome is an undeniable prerequisite for mollusk mortality. Nevertheless, the indicators of mollusk response to starvation remain poorly understood. In this study, the effects of a 44-day starvation period on the physiological performance and symbiotic microbiota of oysters were investigated. Starvation resulted in reduced growth and survival and notable damage to intestinal structure, including shrinking lumens and shortened intestinal walls and villi. Analyses of the respiration rate and intestinal microbiota, including OTUs, taxonomy, and predicted functions, revealed a stepped change pattern with a tipping point on day 10, indicating that oysters employed distinct strategies to adapt to prolonged starvation. Biomarkers associated with nutrient digestion and uptake, such as Firmicutes and Staphylococcus abundance, as well as the Firmicutes/Bacteroidetes ratio, progressively declined with increasing starvation. Conversely, Proteobacteria, an indicator of energy disequilibrium and unstable gut microbiota, and pathogenic Vibrio, showed significant enrichment. As starvation progressed, bacterial competition intensified, as evidenced by the reduced network connectivity and the increasing percentage of negative correlations. Functional predictions demonstrated an early-stage enrichment of degradation functions followed by later-stage suppression during prolonged starvation. In contrast, biosynthesis functions exhibited the opposite trend, suggesting that intestinal microbiota adjusted their specific functions to cope with food deprivation. Collectively, a conceptual model of starvation stress tolerance limits (SSTL) was introduced to define critical thresholds and candidate markers for evaluating starvation intensity and oyster health. This study offers valuable insights into non-feeding mollusks' adaptation to prolonged starvation and provides potential indicators for mollusk mortality events.

Growth of Allopeas gracile under starvation: does it comply with von Bertalanffy growth equation?

The growth of the land snails is a primary indicator of the fitness at the individual and population levels. Considering starvation as a limiting factor of growth, the adaptation of the land snail Allopeas gracile (Hutton 1834) (Gastropoda: Subulinidae) was assessed using von Bertanlaffy growth equation. As a starvation treatment, the laboratory reared 0-day old snails were fed at a gap of 1 to 6 days (six levels of starvation treatment) or fed regularly (control). In all instances, the shell length and the biomass (indicators of growth) increased with the time interval complying with the von Bertalanffy growth equation, but the magnitude of maximum shell length, Lmaximum, and the asymptotic length, L∞, decreased, while the growth rate coefficient (k) increased, as the duration of starvation period extended. The k and L∞ were represented as functions of the starvation gap (T) and substituted in classical von Bertalanffy equation, representing a better fit model explaining the growth. The results indicate that the food availability is a crucial factor determining the pace of growth in the land snail A. gracile. As an extension, the present model can be used for the portrayal of the growth of the macroinvertebrates under varying level of starvation.

Effect of temperature and body size on anterior and posterior regeneration in Hermodice carunculata (Polychaeta, Amphinomidae)

In recent years, population outbreaks of the annelid Hermodice carunculata (Polychaeta, Amphinomidae) are recurrently detected along the coastal zone of the Salento peninsula (Southern Italy), with impacts on marine benthic ecosystems. Annelida are renowned for their remarkable regeneration potential, enabling them to reform lost body parts. A handful of studies have reported posterior regeneration of H. carunculata, but anterior regeneration has not been fully explored. In this study, we investigated the capacity of H. carunculata collected in shallow coastal areas (Ionian Sea, 40°08’26.9” N 17°58’44.1” E) to regenerate anterior body parts under different temperature conditions (22 and 14 °C) and considering two different body sizes (∼ 4 g and 25 g). In addition, histological analysis and lipid analyses were carried out to detect changes in the reproductive cycle and lipid storage during ongoing regeneration. The results suggest that small and large-sized specimens of H. carunculata can regenerate efficiently anterior body parts in 12–20 weeks post amputation when kept at 22 °C. Small-sized worms kept at 14 °C regenerated slower but died in 24 weeks post amputation before regenerating a mouth, while large-sized worms kept at 14 °C were affected by a 100% mortality during blastema formation. In addition, lipid extraction analyses show that H. carunculata can regenerate during extended periods of starvation by de novo synthesizing lipid reserves and regeneration in H. carunculata does not negatively impact the reproductive cycle, as gametogenesis occurs also during the regenerative processes.

Compatibility of the Entomopathogenic Fungus Metarhizium anisopliae (Ascomycota: Hypocreales) and the Predatory Coccinellid Menochilus sexmaculatus (Col.: Coccinellidae) for Controlling Aphis gossypii (Hem.: Aphididae).

Metarhizium anisopliae (Ascomycota: Hypocreales) is an entomopathogenic fungus considered a key factor in developing integrated management of several insect pests on a variety of crops. The predatory coccinellid, Menochilus sexmaculatus (Col.: Coccinellidae), is also an important natural enemy that must be conserved for effective aphid control. Laboratory studies were conducted under controlled conditions to investigate the interaction between M. anisopliae isolate IRN. 1 and the coccinellid predator M. sexmaculatus in combating Aphis gossypii Glover (Hem.: Aphididae). The combined application of M. sexmaculatus and M. anisopliae led to significant reduction in aphid populations. The foraging behavior of M. sexmaculatus notably facilitated the dispersion of M. anisopliae conidia to uninfected plants, resulting 54 ± 1.3% decrease in aphid density after 10days. In both choice and non-choice experiments, female adult M. sexmaculatus to fungus-infected aphids was offered as prey and avoided as a food source during all starvation periods. However, live and dead non-fungus-infected aphids were fed upon. The result revealed the compatibility between M. sexmaculatus and M. anisopliae, which may provide a sustainable strategy for the effective management of A. gossypii in a cropping system.

Sildenafil and furosemide nanoparticles as a novel pharmacological treatment for acute renal failure in rats

Hospitalized patients often develop acute renal failure (ARF), which causes severe morbidity and death. This research investigates the potential renoprotective benefits of sildenafil and furosemide in glycerol-induced ARF, and measures kidney function metrics in response to nanoparticle versions of these medications. Inducing ARF is commonly done by injecting 50% glycerol intramuscularly. Rats underwent a 24-h period of dehydration and starvation before slaughter for renal function testing. We investigated urine analysis, markers of oxidative stress, histology of kidney tissue, immunohistochemistry analysis of caspase-3 and interleukin-1 beta (IL-1 β), kidney injury molecule-1 (KIM-1), and neutrophil gelatinase–associated lipocalin (NGAL), which are specific indicators of kidney tissue damage. The results of our study showed that the combination of sildenafil and furosemide, using both traditional and nanoparticle formulations, had a greater protective effect on the kidneys compared to using either drug alone. The recovery of renal tissue indicators, serum markers, and urine markers, which are indicative of organ damage, provides evidence of improvement. This was also indicated by the reduction in KIM-1 and NGAL tubular expression. The immunohistochemistry tests showed that the combination therapy, especially with the nanoforms, greatly improved the damaged cellular changes in the kidneys, as shown by higher levels of caspase-3 and IL-1β. According to the findings, a glycerol-induced rat model demonstrates that sildenafil and furosemide, either alone or in combination, in conventional or nanoparticulate forms, improve ARF dysfunction. The synergistic nanoparticulate compositions show remarkable effectiveness. This observation highlights the possible therapeutic implications for ARF treatment.

Effects of Feed Deprivation on the Biochemical Responses of Pangasianodon hypophthalmus

Effects of Feed Deprivation on the Biochemical Responses of Pangasianodon hypophthalmus

The people behind the papers - Jason Ko and Daniel Lobo.

Planarians grow when they are fed and shrink during periods of starvation. However, it is unclear how they maintain appropriate body proportions as their size changes. A new paper in Development investigates the differences between growth and shrinkage dynamics and builds a mathematical model to explore the mechanisms underpinning these two processes. To learn more about the story behind the paper, we caught up with first author, Jason Ko, and corresponding author, Daniel Lobo, Associate Professor at the University of Maryland.

Resistance to initial starvation in stage I larvae of the American lobster Homarus americanus H. Milne Edwards, 1837 (Decapoda: Astacidea: Nephropidae)

Abstract Greater embryo mass confers an advantage in the face of sub-lethal starvation for larvae of the American lobster, Homarus americanusH. Milne Edwards, 1837. We reared larvae in the laboratory and recorded body size, molt increment, stage duration, and mortality during the three larval instars and postlarval stages. Larvae were either fed continuously or subjected to starvation periods immediately after hatching. Larval mass increased with embryo mass suggesting that energetic advantages of heavier embryos are conferred to the larvae. Stage I larvae hatched from clutches with heavier embryos and had lower mortality after five days without food. Stage I duration decreased with increasing embryo mass in treatments with initial periods without food of three, four, and five days. We also observed greater size increase at first molt and larger postlarval size in some treatments. Our results suggest that larger embryos produce larvae that are more resistant to starvation, which may provide a survival advantage when experiencing variable food supply due to the patchy distribution of their planktonic prey.

Octopamine integrates the status of internal energy supply into the formation of food-related memories

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.