Voluntary Food Intake Research Articles

Use of a novel three-dimensional anatomical plating system for treatment of caudal mandibular fractures in cats: 13 cases (2019-2023).

A total of 13 cases of cats with a caudal mandibular fracture treated with a novel surgical technique using the Ramus Anatomical Plate system were reviewed. Preoperative, immediate postoperative and a minimum of 8 weeks postoperative CT images were required as inclusion criteria. The outcome and complications were determined from clinical data and radiographic follow-up examinations. All cases achieved adequate anatomical reduction, resulting in a functional and atraumatic occlusion postoperatively. No intraoperative complications were reported. Time to voluntary food intake was in the range of 1-25 days. No evidence of disruptions to the implants or screw loosening was observed in the 8-week postoperative CT imaging, with radiographic evidence of complete osseous union in all fractures. The most common postoperative complication was swelling at the surgical site. Two cats had postoperative exophthalmos due to retrobulbar haemorrhage, and one cat exhibited partial wound dehiscence 5 days postoperatively, which resolved with medical management. Longer-term complications included intraoral plate exposure in one cat, which required plate removal 10 months postoperatively. In this case series, rigid internal fixation of caudal mandibular fractures using the Ramus Anatomical Plate osteosynthesis system was associated with a minimal complication rate, and satisfactory radiographic and clinical outcomes. The reported outcomes of this novel technique are favourable when compared with previous techniques described for the management of these fracture types.

Protection against overfeeding-induced weight gain is preserved in obesity but does not require FGF21 or MC4R

Overfeeding triggers homeostatic compensatory mechanisms that counteract weight gain. Here, we show that both lean and diet-induced obese (DIO) male mice exhibit a potent and prolonged inhibition of voluntary food intake following overfeeding-induced weight gain. We reveal that FGF21 is dispensable for this defense against weight gain. Targeted proteomics unveiled novel circulating factors linked to overfeeding, including the protease legumain (LGMN). Administration of recombinant LGMN lowers body weight and food intake in DIO mice. The protection against weight gain is also associated with reduced vascularization in the hypothalamus and sustained reductions in the expression of the orexigenic neuropeptide genes, Npy and Agrp, suggesting a role for hypothalamic signaling in this homeostatic recovery from overfeeding. Overfeeding of melanocortin 4 receptor (MC4R) KO mice shows that these mice can suppress voluntary food intake and counteract the enforced weight gain, although their rate of weight recovery is impaired. Collectively, these findings demonstrate that the defense against overfeeding-induced weight gain remains intact in obesity and involves mechanisms independent of both FGF21 and MC4R.

Multigenerational inheritance of breathing deficits following perinatal exposure to titanium dioxide nanoparticles in the offspring of mice

BackgroundThe utilization of titanium dioxide nanoparticles (TIO2NPs) has experienced a significant surge in recent decades, and these particles are now commonly found in various everyday consumer products. Due to their small size, TIO2NPs can penetrate biological barriers and elicit adverse interactions with biological tissues. Notably, exposure of pregnant females to TIO2NPs during the perinatal period has been shown to disrupt the growth of offspring. Furthermore, this exposure induces epigenetic modifications in the DNA of newborns, suggesting the possibility of multigenerational effects. Thus, perinatal exposure to TIO2NPs may induce immediate metabolic impairments in neonates, which could be transmitted to subsequent generations in the long term.ResultsIn this study, we utilized perinatal exposure of female mice to TIO2NPs through voluntary food intake and observed impaired metabolism in newborn male and female F1 offspring. The exposed newborn mice exhibited reduced body weight gain and a slower breathing rate compared to non-exposed animals. Additionally, a higher proportion of exposed F1 newborns experienced apneas. Similar observations were made when the exposure was limited to the postnatal period, highlighting lactation as a critical period for the adverse effects of TIO2NPs on postnatal metabolism. Importantly, the breathing deficits induced by TIO2NPs were transmitted from F1 females to the subsequent F2 generation. Moreover, re-exposure of adult F1 females to TIO2NPs exacerbated the breathing deficits in newborn F2 males.ConclusionsOur findings demonstrate that perinatal exposure to TIO2NPs disrupts postnatal body weight gain and respiration in the offspring, and these deficits are transmissible to future generations.

Managing the inappetent hospitalised cat: International Society of Feline Medicine guidelines

Inappetence (also called hyporexia or anorexia) is a common presenting symptom in cats, but suboptimal nutrition can have many negative effects on feline patients, including prolonged hospitalisation and shortened survival. Cats are strict carnivores with a high protein requirement, and when starvation is combined with the hypermetabolic state found in sick cats, a loss of lean body mass can occur. This can have negative effects on wound healing, immune function and gut function. Inappetence in hospitalised cats is not just caused by the underlying illness; it can be exacerbated by stress, as well as factors such as pain, nausea, ileus, constipation and the adverse effects of medication. All contributing factors should be managed, along with the primary disease process, to correct malnutrition. Nutritional assessment of each hospitalised cat allows the identification of patients who require prompt intervention. Appetite stimulants can encourage voluntary food intake and feeding tubes allow provision of nutrition, fluids and medications, and can be managed at home to expedite discharge. The food intake of hospitalised cats should be closely monitored and inappetence should not be ignored, nor intervention delayed.

Extradural anaesthesia-analgesia in dogs undergoing cholecystectomy: A single centre retrospective study.

ObjectivesTo assess the effects of extradural anaesthesia-analgesia (EAA) in dogs undergoing cholecystectomy.Materials and methodsMedical records of dogs undergoing cholecystectomy between 2011 and 2019 were retrieved and allocated to two groups depending if analgesia was provided systemically (group SA) or extradurally (EAA). Preoperative data, intraoperative antinociceptive medications, postoperative analgesia, perioperative complications, and food intake were compared.ResultsOverall 41 medical records were included in the study: 19 and 22 dogs were allocated to groups SA and EAA, respectively. In group EAA, an extradural catheter was placed preoperatively in 8 dogs; in the remaining, it was placed postoperatively but an extradural injection was performed preoperatively. The extradural catheter tip was between the 4th lumbar and the 10th thoracic vertebrae. Intraoperatively, nociception was more likely to occur in group SA [OR 55.42 (2.97–1,035.06)]. During the first 24 and 48 h postoperatively, more dogs in group SA required methadone [OR 24 (2.81–268.4) and OR 11.56 (2.37–45.06), respectively] and additional analgesic drugs [OR 25 (3.47–281.9) and OR 35.29 (1.86–668.2), respectively] compared to group EAA. Voluntary postoperative food intake was also significantly higher in group EAA.Clinical significanceCompared to systemic analgesia, the use of extradural anaesthesia-analgesia reduced perioperative analgesic requirement and promoted postoperative food intake in dogs undergoing cholecystectomy.

Use of feeding tubes in 112 cats in an internal medicine referral service (2015-2020).

The aims of this study were to describe diseases, complications and outcomes associated with the use of feeding tubes in a population of sick cats with appetite disturbance managed at an internal medicine referral service. Clinicopathological data from cats receiving nasoenteral (NE) or oesophagostomy (O) tubes were studied. Cats were categorised according to their underlying disease and divided into subgroups (NE or O tube). The following factors associated with survival were analysed: disease category, type of tube and return to appetite. Included in the study were 112 cats, representing 118 cases. Of the 118 cases, 98 (83%) and 20 (17%) received NE or O tubes, respectively. The most common underlying conditions were digestive (13.5%), hepatobiliary (11%) and upper urinary tract (11%) disorders. Hepatobiliary (50%) and upper respiratory tract (30%) conditions were predominant in the O tube group. Digestive (15%) and upper urinary tract (12%) diseases were more common in the NE tube group. Complications following tube placement occurred in 22/118 cases (18.6%). The global survival rate was 73% and did not differ between NE (71.4%) and O tube (80%) groups (P = 1.00) or disease categories (P = 0.61). Return of appetite before feeding tube removal occurred in 56 cases (47%), within a median of 3 days (range 1-30) and was not associated with mirtazapine administration (P = 1.00). Appetite returned earlier for cats with NE tubes (3 days, range 1-17) than for those with O tubes (33 days, range 5-60; P <0.05). Voluntary food intake was positively associated with survival (odds ratio 15.17). After discharge and feeding tube retrieval, return of appetite was observed in 67% of cases. Feeding tubes were predominantly placed for the management of appetite disturbance in cats with digestive, hepatobiliary and upper urinary tract diseases. While complications were frequent, they were mostly mild, easily managed and did not preclude feeding tube use. Return to appetite occurred in a large proportion of cats during or after assisted enteral feeding and was associated with survival.

2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat.

Inappetence may have many origins and, as a presenting sign or observation in the hospitalised patient, is common in feline practice. Nutritional assessment of every patient is encouraged, to identify the need for, and appropriate type of, intervention indicated. The impact of malnutrition may be significant on the feline patient, perpetuating illness, delaying recovery, slowing wound healing and negatively impacting gut health and immunity. Delayed intervention may result in the cat's deterioration; hence prompt control of contributing factors such as the underlying illness, pain, nausea, ileus and stress is vital to optimise voluntary food intake. Management is multimodal, comprising reduction of stress, medications and assisted nutrition in the form of tube feeding or parenteral nutrition. Use of antiemetic, analgesic, prokinetic and appetite stimulant medications may restore appetite, but placement of feeding tubes should not be delayed. Feeding tubes are generally well tolerated and allow provision of food, water and medication with minimal stress, although clinicians must be aware of complications such as stoma site infections and refeeding syndrome. Cats are vulnerable to malnutrition owing to their unique metabolism and specific nutritional requirements. Moreover, their nature as a species means they are susceptible to stress in the hospital environment, which may result in reduced food intake; previous negative experiences may compound the problem. In particular, an inappropriate clinic environment and/or handling may cause or exacerbate inappetence in hospitalised patients, with negative impacts on recovery. Postponing interventions such as feeding tube placement to await improvement, owing to clinician or caregiver apprehension, may hinder recovery and worsen nutritional deficits. The 2022 ISFM Consensus Guidelines on Management of the Inappetent Hospitalised Cat have been created by a panel of experts brought together by the International Society of Feline Medicine (ISFM). Information is based on the available literature, expert opinion and the panel members' experience.

Seasonal investigation of fallow deer cellular cementum from Mediterranean ecosystems and its implications for reliable cementochronology applications

We aim to extend our understanding of the seasonal formation of cellular cementum, and its functional relationships in fallow deer (Dama dama) from Mediterranean ecosystems, in order to achieve reliable cementochronology applications. We provide a specific reference for fallow deer in a specific ecosystem, as needed for forensic, paleontological and wildlife ecology research. A semi-quantitative rating of the last outermost increment deposited in the cellular cementum interradicular pad of the lower first molar (M1), together with the knowledge of the animal's date of death, provided the methodological basis of this study. We also analyzed the occurrence of each cementum state by season, as well as the influence of the photoperiod and seasonal diet quality variations, using indices such as cell wall digestibility (CWD), protein (N), and carbohydrate (C). In adults more than 4 years old we detected a significant seasonal cementum growth pattern in spring-summer, whereas the formation of rest lines took place mainly from October to February. All of our findings show a photoperiod control of cementum seasonal growth patterns, linked to the organism's annual growth cycle, whereas N and C probably do not influence seasonal deposition patterns. The deposition of the cementum begins to stop when the photoperiod begins to decrease, i.e. when the days begin to be shorter, which in the Mediterranean ecosystems of southern Spain takes place in the autumn and winter months. At this time, the amount of dry matter in food consumed increases, and voluntary food intake decreases. The amount of dietary protein and carbohydrate seems to influence the amount of cementum deposited each year, rather than the seasonal deposition pattern, at least in adults. No significant seasonal pattern was found for the younger fallow deer. Until this seasonal pattern is clarified, young specimens should be excluded from cementochronology applications, such as season-at-death estimations. Studies on the quantitative thickness of cementum increments should also be performed in order to confirm cementochronology as a useful tool for studying climatic variations and their biological impacts.

Food intake: an overlooked driver of climate change casualties?

Reduced voluntary food intake is a common response of endotherms to warmer temperatures. However, the implications of this are rarely considered for wild animals exposed to higher temperatures caused by climate change. We provide a conceptual model to demonstrate the potential consequences of elevated temperatures on food intake and survival.

Fecal glucocorticoid metabolites reflect hypothalamic-pituitary-adrenal axis activity in muskoxen (Ovibos moschatus).

Muskoxen (Ovibos moschatus), a taxonomically unique Arctic species, are increasingly exposed to climate and other anthropogenic changes. It is critical to develop and validate reliable tools to monitor their physiological stress response in order to assess the impacts of these changes. Here, we measured fecal glucocorticoid metabolite (FGM) levels in response to the administration of adrenocorticotropic hormone (ACTH) in the winter (1 IU/kg) and summer (2 IU/kg) using two enzyme immunoassays, one targeting primarily cortisol and the other targeting primarily corticosterone. Fecal cortisol levels varied substantially within and among individuals, and none of the animals in either challenge showed an increase in fecal cortisol following the injection of ACTH. By contrast, two of six (winter) and two of five (summer) muskoxen showed a clear response in fecal corticosterone levels (i.e., maximal percentage increase as compared to time 0 levels > 100%). Increases in fecal corticosterone post-ACTH injection occurred earlier and were of shorter duration in the summer than in the winter and fecal corticosterone levels were, in general, lower during the summer. These seasonal differences in FGM responses may be related to the use of different individuals (i.e., influence of sex, age, social status, etc.) and to seasonal variations in the metabolism and excretion of glucocorticoids, intestinal transit time, voluntary food intake, and fecal output and moisture content. Results from this study support using FGMs as a biomarker of hypothalamic–pituitary–adrenal axis activity in muskoxen, advance our understanding of the physiological adaptations of mammals living in highly seasonal and extreme environments such as the Arctic, and emphasize the importance of considering seasonality in other species when interpreting FGM levels.

Potent health-promoting effects of a synbiotic formulation prepared from Lactobacillus acidophilus NCDC15 fermented milk and Cichorium intybus root powder in Labrador dogs

To ascertain potent health-promoting effects of a synbiotic prepared using a combination of Lactobacillus acidophilus NCDC15 fermented milk and Cichorium intybus root powder in Labrador dogs, 15 Labrador adult female dogs were randomly distributed into three groups following a completely randomized design. Group I was fed a homemade basal diet alone and served as control (CON), while the other two groups were fed the same basal diet supplemented with low- (LSL) and high- levels (HSL) of the synbiotic. The experiment duration was of 9-weeks. The results of the study indicated that there were no variations (P > 0.05) among the groups with respect to voluntary food intake and digestibility of DM, OM, CP and EE. However, the digestibility of crude fibre tended (P = 0.051) to be higher in both the supplemented groups as compared to CON. Physical characteristics of faeces remained unaltered (P > 0.05) due to dietary treatments. However, faecal lactate was increased (P < 0.05) in both the synbiotic fed groups with a concomitant reduction in faecal ammonia compared to control. The faecal lactobacilli and bifidobacteria population exhibited higher (P < 0.05) counts in LSL and HSL groups than the CON. There was a lower population of clostridia and coliform in LSL and HSL groups than in CON. The delayed-type hypersensitivity response to PHA-P and antibody response to sheep erythrocytes showed improved (P < 0.05) immune status in response to dietary synbiotic supplementation. Overall, the findings of this study led to the conclusion that the synbiotic preparation has a beneficial impact on canine gastrointestinal health and immunity, and the response to synbiotic supplementation at lower and higher doses was similar.

Phenotypic plasticity following weaning: winter body mass trends and food intake in relation to temperature by an arctic ungulate

Our knowledge is limited on how weaned mammals adjust to environmental events in the absence of maternal assistance in the polar north. With the expectation that weaned offspring should express the adaptive potential of the mature phenotype, we determined their appetite and body mass responses to extreme cold. Between December and May when mean daily temperature (Ta, °C) was between − 48 and 2.3 we provided five naturally weaned reindeer calves (Rangifer tarandus L.) ad libitum a pelleted feed of 11% crude protein with access to snow only in individual fenced outdoor pens in interior Alaska (64° N 147° W). We predicted voluntary food intake would meet maintenance of body mass, but that extreme cold would result in an increase in appetite that would be compensated for by access to warm water. A linear mixed effect model indicated a moderate daily increase in body mass from 55.9 ± 1.6 kg on 9 December to 59.2 ± 0.6 kg on 14 May and a moderate increase in intake that was evidence for maintenance of thermal homeostasis. However, at both low (≤ 30) and high (≥ 10) Ta (°C) intake increased and we estimated a lower critical temperature of − 22 and upper critical temperature at − 10 that was indicative of high total-body insulation. Despite the appetite response at low Ta, provision of warm water did not affect intake. Thus, whereas adult reindeer restrict intake by mobilization of endogenous reserves the calf thermogenic response was an increase in appetite that indicated the importance of access to a food base for calves in winter.

Oral and pre-absorptive sensing of amino acids relates to hypothalamic control of food intake in rainbow trout.

To assess the putative role of taste and pre-absorptive sensing of amino acids in food intake control in fish, we carried out an oral administration with l-leucine, l-valine, l-proline or l-glutamic acid in rainbow trout (Oncorhynchus mykiss). Treatment with proline significantly reduced voluntary food intake at 2 h and 3 h after oral administration, while glutamic acid showed a less pronounced satiating effect at 3 h. The mRNA expression of taste receptor subunits tas1r1, tas1r2a, tas1r2b and tas1r3 was measured in the epithelium overlying the bony basihyal of the fish (analogous to the tetrapod tongue) at 10, 20 or 30 min following treatment. No significant changes were observed, except for a tas1r down-regulation by valine at 30 min. Of the downstream taste signalling genes that were analysed in parallel, plcb2 and possibly trpm5 (non-significant trend) were down-regulated 20 min after proline and glutamic acid treatment. The signal originated in the oropharyngeal and/or gastric cavity presumably relays to the brain as changes in genes involved in the regulation of food intake occurred in hypothalamus 10-30 min after oral treatment with amino acids. In particular, proline induced changes consistent with an increased anorexigenic potential in the hypothalamus. We have therefore demonstrated, for the first time in fish, that the peripheral (pre-absorptive) detection of an amino acid (l-proline), presumably by taste-related mechanisms, elicits a satiety signal that in hypothalamus is translated into changes in cellular signalling and neuropeptides regulating food intake, ultimately resulting in decreased food intake.

Long-term sucrose solution consumption causes metabolic alterations and affects hepatic oxidative stress in Wistar rats.

ABSTRACTAs the number of overweight and obese people has risen in recent years, there has been a parallel increase in the number of people with metabolic syndrome, diabetes and non-alcoholic fatty liver disease. The consumption of artificially sweetened beverages contributes to these epidemics. This study investigated the long-term effects of ingestion of a 40% sucrose solution on serum and hepatic parameters in male Wistar rats (Rattus norvegicus). After 180 days, the glycemic response, lipid profile and hepatic oxidative stress were compared to those of rats maintained on water. Sucrose ingestion led to higher body weight, increased fat deposits, reduced voluntary food intake and reduced feeding efficiency. Rats that received sucrose solution showed early signs of glucose intolerance and insulin resistance, such as hyperinsulinemia. Serum triacylglycerol (TG), very-low density lipoprotein (VLDL), cholesterol, ALT and AST levels increased after sucrose consumption. Elevated malondialdehyde and superoxide dismutase (SOD) levels and reduced glutathione levels characterize the hepatic oxidative stress due to sucrose ingestion. Liver sample histology showed vacuolar traces and increased fibrotic tissue. Our data showed the harmful effects of chronic consumption of sucrose solution, which can cause alterations that are found frequently in obesity, glucose intolerance and non-alcoholic hepatic disease, characteristics of metabolic syndrome.

Parasite-Mediated Anorexia and Nutrition Modulate Virulence Evolution.

Temporary but substantial reductions in voluntary food intake routinely accompany parasite infection in hosts ranging from insects to humans. This "parasite-mediated anorexia" drives dynamic nutrient-dependent feedbacks within and among hosts, which should alter the fitness of both hosts and parasites. Yet, few studies have examined the evolutionary and epidemiological consequences of this ubiquitous but overlooked component of infection. Moreover, numerous biomedical, veterinary, and farming practices (e.g., rapid biomass production via high-calorie or high-fat diets, low-level antibiotics to promote growth, nutritional supplementation, nonsteroidal anti-inflammatory drugs like Ibuprofen) directly or indirectly alter the magnitude of host anorexia-while also controlling host diet and therefore the nutrients available to hosts and parasites. Here, we show that anorexia can enhance or diminish disease severity, depending on whether the current dietary context provides nutrients that bolster or inhibit immune function. Feedbacks driven by nutrition-mediated competition between host immune function and parasite production can create a unimodal relationship between anorexia and parasite fitness. Subsequently, depending on the host's diet, medical or husbandry practices that suppress anorexia could backfire, and inadvertently select for more virulent parasites and larger epidemics. These findings carry implications for the development of integrated treatment programs that consider links between host feeding behavior, nutrition, and disease severity.

Comparison of the effects of different kibble shape on voluntary food intake and palatability of weight loss diets in pet dogs

Altering characteristics of a dry proprietary diet can increase chewing, slow ingestion speed and reduce voluntary food intake. Panels of healthy research dogs consumed kibbled weight loss diets with either a l round (pastille) or a cross shape. Two panels (‘small-size’ panel, dogs<10 kg ‘all-size’ panel, dogs with a range of sizes) were used to determine palatability (study 1), whilst a third panel (‘consumption kinetics panel’) was used to determine voluntary food intake [VFI] and meal duration (study 2). Study 3 was a field trial where the cross kibble was fed to client-owned overweight dogs undergoing controlled weight loss, and attitudes of owners were sort. In study 1, dogs in the all-size panel consumed more of the cross-kibble diet than of the round-kibble diet (P < .001), but there was no significant difference in dogs of the small-size panel (P = 1.000). In study 2, VFI was broadly similar for both diets, with no difference in total consumption across all four meals (P = .370). However, meal duration was significantly longer for the cross kibble (meal 1: 292 s; meal 2: 650 s) compared with the round kibble (meal 1: 186 s; meal 2: 282, P < .001 for both). In study 3, owners observed more chewing behaviour (P = .031), slower ingestion speed (P = .031), and a significant decrease in food-seeking behaviour (P = .020) when eating the cross-kibble compared with the round-kibble. Altering the kibble shape of a canine therapeutic weight loss diet can decrease ingestion speed without affecting palatability, but studies are now required to determine the effect on outcomes of weight management.

The interplay between voluntary food intake, dietary carbohydrate-lipid ratio and nutrient metabolism in an amphibian, (Xenopus laevis).

Digestion of food and metabolism of frogs are little studied at the moment, and such processes could be very particular in the case of amphibians, given their ectothermic and carnivorous nature which may lead them to use nutrients through specific biochemical pathways. In the present study, 24 adult Xenopus laevis (six replicates with two frogs per treatment) were randomly assigned to two diets with different carbohydrate:fat ratio (4.5:1 and 2.1:1), changing the dietary glucogenic and lipogenic proportions. Food intake (FI) per unit metabolic body weight (MBW) as well as macronutrient digestibility were calculated, and circulating blood acylcarnitines and amino acids measured, in order to evaluate the effect of the diet treatments. Results demonstrated that food intake regulated most of the changes in the parameters evaluated; significant differences were obtained in crude protein and fat digestibilities through the effect of FI/MBW (p<0.05), whereas diet treatment had a significant effect on the levels of malonyl-CoA. Food intake also significantly impacted malonyl, isovaleryl, hydroxyisovaleryl and long chain fatty acid concentrations; significant (p<0.05) interactions between those metabolites were detected owing to diet. The findings obtained suggest that food intake was the main factor controlling digestion and metabolism in X. laevis, with frogs preferring to utilise protein and fat as primary sources for energy production in the citric acid cycle, reflecting characteristics of a strict carnivore physiological model.

Reduction in voluntary food intake, but not fasting, stimulates hypothalamic gonadotropin-inhibitory hormone precursor mRNA expression in chicks under heat stress

Heat stress is an issue of rising concern across the globe. Recently, we found that mRNA expression of gonadotropin-inhibitory hormone (GnIH), an orexigenic neuropeptide, was increased in the heat-exposed chick brain when food intake was reduced. The aim of the current study was to examine mRNA expression of GnIH and of the glucocorticoid receptors (GRs) in the hypothalamus as well as the plasma corticosterone (CORT) and metabolites in 14-d-old chicks exposed to a high ambient temperature (HT; 40 ± 1 °C for 1 or 5 h) or a control thermoneutral temperature (CT; 30 ± 1 °C), either with free access to food or fasted. Heat stress caused a voluntary reduction of food intake and reduced plasma triacylglycerol concentration, but increased rectal temperature and plasma CORT and glucose concentrations (P < 0.05). Heat stress also increased (P < 0.05) the expression of diencephalic GnIH mRNA in chicks when they reduced food intake voluntarily, but did not do so under fasting conditions. Although the expression of GR mRNA was not altered as a result of heat stress, its expression was decreased (P < 0.05) in fasted chicks at 5 h in comparison with fed chicks. In addition, the rectal temperature of fasted chicks was lower than that of fed chicks under both CT and HT. In conclusion, voluntary reduction of food intake caused an increase in brain GnIH mRNA expression, plasma CORT, and body temperature in chicks under heat stress. Interestingly, brain GnIH mRNA expression was not induced by heat stress in fasted chicks and was not accompanied by a decrease in rectal temperature. These results suggest that the increased expression of brain GnIH mRNA in chicks under heat stress could be a consequence of a mechanism mediated by the voluntary reduction of food intake, but that it is not a consequence of fasting.

Assessing Activity-based Anorexia in Mice.

Rodents develop activity-based anorexia (ABA) when exposed to a restricted feeding schedule and allowed free access to a running wheel. These conditions lead to a life-threatening reduction in body weight. However, rodents exposed to only one of these conditions ultimately adapt to re-establish normal body weight. Although increased running coupled with reduction in voluntary food intake appear paradoxical under ABA conditions, ABA behavior is observed across numerous mammalian species. The ABA paradigm provides an animal model for anorexia nervosa (AN), an eating disorder with severe dysregulation of appetite-behavior. Subjects are singly housed with free access to a running wheel. Each day, the subject is offered food for a limited amount of time. During the course of the experiment, a subject's body weight decreases from high activity and low caloric intake. The duration of the study varies based on how long food is offered daily, the type of food offered, the strain of mouse, if drugs are being tested, and environmental factors. A lack of effective pharmacological treatments for AN patients, their low quality of life, high cost of treatment, and their high mortality rate indicate the urgency to further research AN. We provide a basic outline for performing ABA experiments with mice, offering a method to investigate AN-like behavior in order to develop novel therapies. This protocol is optimized for use in Balb/cJ mice, but can easily be manipulated for other strains, providing great flexibility in working with different questions, especially related to genetic factors of ABA.

12-Week Treadmill Program Elicits Low Energy Availability Without Changes in Serum Testosterone in Male Rats

Male endurance athletes have been reported to have lower testosterone concentrations than their sedentary counterparts, which may have detrimental health effects including increased risk of musculoskeletal injury and fertility complications secondary to decreased sex hormone production. Cholesterol supplementation has been reported to increase serum sex hormones. PURPOSE: The purpose of this study was to investigate whether a treadmill endurance exercise program would cause exercise-induced reproductive dysfunction in male rats and assess the impact of increased dietary cholesterol on sex hormone levels. METHODS: Male Sprague-Dawley Rats (n=20) were randomly assigned to a control group (C) or an exercise training group (EX) that performed treadmill running 40 min/day, 6 days/wk for a duration of 12 wks. At study midpoint (wk 6), rats were randomized to receive either a High-Cholesterol (HC) Diet (n=10) or remain on standard purified diet (n=10). Fasting blood samples were collected at baseline, wk 6, and wk 12. Serum testosterone (T) and leptin were measured via ELISA. Serum lipids (TC, HDL, LDL, TG) were measured via clinical chemistry analyzer. Body weight (BW) and voluntary food intake (EI) were measured weekly. RESULTS: At end of wk 6, EX had significantly lower BW (494.3+34.7g versus 565.3+47.9g, p=0.001), mean daily EI (77.5+3.5 kcal versus 91.6+5.2 kcal, p<0.001), and serum leptin (90.8+40.1 pg/mL versus 635.7+225.6 pg/mL, p=0.001) in comparison to C. No difference was observed between EX and C in serum T (12.7+6.0 ng/mL versus 12.9+5.8 ng/mL). At end of wk 12, exercise groups (EX and EX+HC) had significantly lower BW (539.4+40.6g versus 645.1+60.7g, p<0.001), mean daily EI (81.7+2.9 kcal versus 87.8+1.9 kcal, p<0.01), and serum leptin (132.8+110.1 pg/mL versus 519.2+300.8 pg/mL, p=0.001) in comparison to C and C+HC. HC diet did not have significant impact upon serum T in comparison to standard diet (3.8+3.4 ng/mL versus 4.9+2.4 ng/mL). CONCLUSIONS: Despite low energy availability, exercise-induced reproductive changes may not occur in training programs <12 weeks. Lower EI observed in exercise groups despite higher energy expenditure may indicate that low energy availability in endurance-trained individuals may be inadvertent. Supported by American Egg Board Graduate Fellowship Research Grant