Food deprivation is used in many experimental models and is becoming increasingly prevalent in human diets. The impact of food deprivation on specific brain regions, including the nucleus of the tractus solitarius (NTS), a region that is involved in hunger and satiety sensing, remains to be determined. The NTS is a heterogeneous nucleus that includes corticotropin releasing factor receptor 1 (CRF1) neurons. CRF1 is implicated in both stress and appetite regulation, but the effects of food deprivation on CRF1 NTS neurons are unclear. We used immunofluorescence to examine the effects of 24-hour food deprivation on NTS activity in male and female Sprague-Dawley (SD) rats and CRF1-cre rats using cFos, an immediate early gene and neuronal marker of activation. NTS activity was increased in food deprived male but not female SD rats. In food deprived CRF1-cre rats, males had an increased proportion of active CRF1 + neurons with no change in females. In CRF1-cre rats, increased global NTS activity was observed in food deprived and refed males. Activation of CRF1 + neurons was also increased after deprivation but was reduced by refeeding. In females, food deprivation decreased global NTS activity that was then increased by refeeding, while CRF1 activity was unchanged. Collectively, these data suggest the NTS is differentially activated after food deprivation in a sex-specific manner, whereby males are more sensitive than females. These results provide insight into the role of brainstem stress circuitry in changes associated with conditions including intermittent fasting and eating disorders like anorexia.

We studied the effect of enteral administration of GABA on the gastric mucosa in male Wistar rats (n=47) with modeled metabolic stress (food deprivation for 9 days with free access to water). The relative weights of the adrenal glands and thymus were determined, and histological examination of the stomach was performed. In control rats, modeling the metabolic stress was accompanied by the development of erosive damage to the gastric mucosa related to blood supply disturbances. Administration of GABA prevented erosions and exhibited a pronounced gastroprotective effect. Thus, administration of GABA can be a promising method for the prevention and treatment of erosive gastric lesions associated with metabolic stress.

Mammals have evolved sex-specific adaptations to reduce energy usage in times of food scarcity. These adaptations are well described for peripheral tissue, though much less is known about how the energy-expensive brain adapts to food restriction, and how such adaptations differ across the sexes. Here, we examined how food restriction impacts energy usage and function in the primary visual cortex (V1) of adult male and female mice. Molecular analysis and RNA sequencing in V1 revealed that in males, but not in females, food restriction significantly modulated canonical, energy-regulating pathways, including pathways associated waith AMP-activated protein kinase, peroxisome proliferator-activated receptor alpha, mammalian target of rapamycin, and oxidative phosphorylation. Moreover, we found that in contrast to males, food restriction in females did not significantly affect V1 ATP usage or visual coding precision (assessed by orientation selectivity). Decreased serum leptin is known to be necessary for triggering energy-saving changes in V1 during food restriction. Consistent with this, we found significantly decreased serum leptin in food-restricted males but no significant change in food-restricted females. Collectively, our findings demonstrate that cortical function and energy usage in female mice are more resilient to food restriction than in males. The neocortex, therefore, contributes to sex-specific, energy-saving adaptations in response to food restriction.

To examine the effects of decreased food consumption on toxicological parameters in juvenile rats, rats on postnatal day 21 were fed 40%, 50% (only four weeks), and 60% less food, compared to that of controls for four or eight weeks, and clinical observations, measurement of body and organ weights, morphological differentiation analysis, clinical pathology, and macroscopic and microscopic examinations were conducted. The body weight decreased depending on the degree of food restriction (FR). Cleavage of the balano-preputial skinfold was delayed, and cell debris in the epididymal lumen was noted as a related finding after four-week FR. Vaginal opening was also delayed, and some histopathological findings, such as absence of corpus luteum in the ovary, mucinous degeneration in the vagina, and immature uterus, were noted after eight-week FR. Erythrocyte count increased after four-week FR, but slightly decreased in males only after eight-week FR, and decreased leukocyte and/or reticulocyte counts, accompanied by related histopathological findings were noted after four- and eight-week FR. In blood chemistry, the levels of total protein including globulin, glucose, triglyceride, and calcium decreased, and sodium and chloride increased after four- and eight-week FR. Increases in activities of aspartate transaminase and lactate dehydrogenase and total bilirubin levels were noted after four-week FR, which were attenuated after eight-week FR. The effects of FR seemed to be more remarkable after four weeks. In drug safety evaluation, findings caused by malnutrition should be considered in juvenile toxicity studies when decreased food consumption is observed.

A multitude of animal species undergo prolonged fasting events at regularly occurring life history stages. During such periods of food deprivation, individuals need to suppress their appetite. The satiety signalling gut hormone ghrelin has received much attention in this context in studies looking at mammalian systems. In wild birds, however, knowledge on the ghrelin system and its role during extended fasts is still scarce. In this study, we collected plasma samples for measurements of circulating ghrelin concentrations from adult southern rockhopper penguins (Eudyptes chrysocome chrysocome) during the three to four week-long moult-fast that they repeat annually to replace their feathers. We further sampled chicks before and after feeding bouts and non-moulting adults. Circulating ghrelin levels did not differ significantly between fed and unfed chicks but chicks had significantly lower plasma ghrelin levels compared to adults. Furthermore, penguins in late moult (i.e. individuals at the end of the prolonged fasting bout) had higher ghrelin levels compared to non-moulting adults. Our results show elevated levels of circulating ghrelin during moult and generally lower levels of ghrelin in chicks than in adults regardless of feeding state. Given the scarcity or absence of knowledge on the function of ghrelin in seabirds and in fasting birds in general, our results add greatly to our understanding of the avian ghrelin system.

The endocannabinoid system (ECS) plays an important role in neuroprotection, neuroplasticity, energy balance, modulation of stress, and inflammatory responses, acting as a critical link between the brain and the body\'s peripheral regions, while also offering promising potential for novel therapeutic strategies. Unfortunately, in humans, pharmacological inhibitors of different ECS enzymes have led to mixed results in both preclinical and clinical studies. As the ECS has been highly conserved throughout the eukaryotic lineage, the use of invertebrate model organisms like the pond snail Lymnaea stagnalis may provide a flexible tool to unravel unexplored functions of the ECS at the cellular, synaptic, and behavioral levels. In this study, starting from the available genome and transcriptome of L. stagnalis, we first identified putative transcripts of all ECS enzymes containing an open reading frame. Each predicted protein possessed a high degree of sequence conservation to known orthologues of other invertebrate and vertebrate organisms. Sequences were confirmed by qualitative PCR and sequencing. Then, we investigated the transcriptional effects induced by different stress conditions (i.e., bacterial LPS injection, predator scent, food deprivation, and acute heat shock) on the expression levels of the enzymes of the ECS in Lymnaea\'s central ring ganglia. Our results suggest that in Lymnaea as in rodents, the ECS is involved in mediating inflammatory and anxiety-like responses, promoting energy balance, and responding to acute stressors. To our knowledge, this study offers the most comprehensive analysis so far of the ECS in an invertebrate model organism.

There is a link between metabolism and reproduction as metabolic hormones affect hypothalamus-pituitary-testis (HPT) hormonal functions and vice versa. The aim of the present study was to investigate the effects of negative energy balance on the reproductive system in male goldfish exposed to testosterone (T) and 17β-estradiol (E2). Following 7 days of food deprivation (FD), ANOVA models showed significant FD × sex steroid interactions on sperm quality and circulating sex steroid levels. When FD effects were investigated, 11-ketotestosterone (11-KT) level and sperm motility and velocity decreased in food-deprived goldfish in the control group. In E2-exposed goldfish, FD decreased sperm production in addition to sperm motility and velocity that coincided with an elevation of circulating E2 level. However, FD did not significantly impact sex steroids and sperm quality in T-exposed goldfish. ANOVA models showed non-significant FD × sex steroid interactions for HSI, GSI, circulating luteinizing hormone (Lh) level, and metabolic (preproghrelin, goat and nucb2) and reproductive (kiss1, gpr54 and gnrh3) mRNAs. Furthermore, results showed that FD decreased HSI, and increased Lh levels and testicular preproghrelin and goat mRNAs, while sex steroids increased mid-brain nucb2, kiss1 and gpr54 mRNAs. Together, our results suggest that FD-induced inhibition of androgenesis resulted in diminished sperm quality associated with activation of the testicular ghrelinergic system, and negative feedback of 11-KT increased Lh level. The FD-induced testicular metabolic and hormonal system was impacted in goldfish exposed to sex steroids. However, the negative effects of FD on sperm quality were accelerated in E2-exposed goldfish due to estrogenic activity. This study provides novel information to better understand metabolic-associated reproductive disorders in fish.

OBJECTIVE: To compare 3 perioperative feeding regimens and their effect on anesthetic complications, manure output, and colic proportion in healthy horses.
METHODS: 45 horses presenting for elective orthopedic procedures were randomly assigned to 1 of 3 groups: not fasted (NF; continuous access to hay perioperatively), fasted muzzled (FM; 10-hour preoperative fast with slow refeeding postoperatively and muzzle placement), or fasted not muzzled (FNM; same as FM without muzzle placement). Anesthetic protocol was standardized. Outcomes compared between groups included anesthesia time, arterial oxygenation, duration of hypotension, perioperative manure output, time to first passage of manure postoperatively, pain scores, and colic proportion. Comparisons were made with a mixed model and Fisher exact test with statistical significance considered at P ≤ .05.
RESULTS: No differences were seen in pain scores, oxygenation, hypotension, or colic between groups. Groups FM and FNM had a significantly greater mean reduction in postoperative manure weight (-81% and -70%; P = .003) and number of manure piles (-63% and -55%; P = .005) compared to group NF (-39% and -22%; P < .001; weight and piles, respectively). Mean ± SD minutes to passage of manure postoperatively was significantly shorter in group NF (238 ± 13 minutes) than groups FM (502 ± 174 minutes; P < .001) and FNM (444 ± 171 minutes; P = .003).
CONCLUSIONS: Horses with continuous access to hay prior to and following recovery from anesthesia passed more manure and passed manure sooner after surgery than their fasted counterparts without detrimental effect on anesthetic parameters and postoperative complications. Continuous access to hay perioperatively supports manure production in healthy horses without increase in anesthetic complications.

The aim was to evaluate the quality of the sheep skin of different sex classes submitted to different levels of feed restriction. Sheep without defined racial pattern of different sex classes (15 non-castrated males, 15 castrated males and 15 females), with initial body weight of 18.1 ± 0.4 kg and mean age of 90 days were distributed in a factorial 3 × 3, with three sex classes and 3 levels of feed restriction (ad libitum intake and restricted intake at 70 and 80%), with 5 repetitions. After slaughter, the skins were collected for physical-mechanical tests. The effect of the sex classes x levels of dietary restriction interaction was observed for transverse thickness and longitudinal rupture elongation (p < 0.05). Animals fed ad libitum had greater longitudinal transverse thickness (p < 0.05). Animals fed ad libitum and 70% feed restriction showed greater transverse elongation at break (p < 0.05). As for the difference between sex classes in the transverse thickness variable for tearing strength, the interaction sex classes x levels of feed restriction for transverse thickness, longitudinal thickness, transverse tearing strength and longitudinal tearing strength occurred (p < 0.05). Feed restriction reduces the physical quality of the skin of sheep of different sex classes, and the use of castrated male sheep in positive energy balance is recommended to obtain leather with greater thickness, longitudinal rupture elongation and transverse tear strength.

Food deprivation has been associated with the development of metabolic pathologies. Few studies have explored the repercussions of a partial food deprivation following the reestablishment of an ad libitum diet. This study investigates the impact of a partial food deprivation (an 8-hour food intake restriction coupled with a 4-hour feeding window during the active phase) and the subsequent return to ad libitum feeding on the glycemic curve, food intake, and locomotor behavior. Wistar rats aged 45 days were subjected to 6 weeks of a partial food deprivation followed by 6 weeks of ad libitum feeding. Body weight, visceral fat, food intake, circadian glycemia, oral glucose tolerance, and locomotor activity were evaluated. It was found that the partial food deprivation resulted in the reduction of both the body weight and food intake; however, it increased visceral fat by 60%. Circadian glycemic values were altered at all intervals during the light phase, and glucose sensitivity improved at 60 minutes in the oral glucose tolerance test (OGTT). In the food-deprived group, the locomotor activity rhythm was reduced, with an observed delay in the peak of activity, reduction in total activity, and a decrease in the rhythmicity percentage. After the reestablishment of the ad libitum feeding, there was recovery of body weight, no difference in visceral fat, normalization of the food intake pattern, circadian glycemia, and oral glucose tolerance. Additionally, the return to ad libitum feeding restored locomotor activity, although the duration required for its complete recovery warrants further investigation. In conclusion, partial food deprivation induces physio-metabolic changes in rats, most of which are reversed after reestablishing ad libitum feeding.