Short-Term Housing in Metabolic Caging on Measures of Energy and Fluid Balance in Male C57BL/6J Mice (Mus musculus)

Metabolic caging is an important tool for quantitative urine and feces collection in rodents, although significant limitationsand problems accompany its use. Despite strong opinions among investigators regarding the effects of metabolic caging onenergy and fluid homeostasis, careful quantitative analysis of the impact of this caging type—particularly when used for mice—is lacking. The current study assessed the effects of metabolic caging, with or without modifications such as plastic platform inserts, on ingestive behaviors, energy expenditure, accuracy of urine and fecal collection, and ambulatory activities in male C57BL/6J mice. Housing mice in metabolic cages, regardless of platform inclusion, increased energy expenditure without modifying food intake, presumably due to the inability of mice to perform normal thermoregulatory behaviors (burrowing and huddling). Surprisingly, mice in metabolic cages actively avoided platforms, and the inclusion of platforms modified the behavior of the mice and had position-dependent effects that reduced the accuracy of urine collection. Moving mice from cohousing to individual housing in home cages also increased ingestive behaviors and energy expenditure. We conclude that single housing of male C57BL/6J mice increases energy expenditure, that this increase is potentiated in metaboliccaging conditions, and that platforms in metabolic cages alter mouse behavior and urine collection. Additional future workis needed to determine the potential benefits of using higher ambient temperature for studies of mice in metabolic cagingand whether the above effects occur in females and other strains of mice and other rodent species.

Impact of Lameness on Attributes of Feeding Registered with Noseband Sensor in Fresh Dairy Cows

We hypothesized that lameness in fresh dairy cows (1–30 days after calving) has an impact on attributes of feeding registered with a noseband sensor. The aim of this study was to investigate the impact of lameness in fresh dairy cows on attributes of feeding (registered with the RumiWatch noseband sensor): rumination time (RT), drinking time (DT), eating time (ET), rumination chews (RC), eating chews (EC), chews per minute (CM), drinking gulps (DG), bolus count (B), and chews per bolus (CB). The measurement registration was started at the first day after calving and continued until 30 days after calving. There were 20 Lithuanian black and white breed cows selected. Lameness diagnosis was performed by trained staff based on a locomotion score system and it was diagnosed on average on the 15th day after calving. The causes of lameness were categorized as sole ulcer, abscess and foot rot. Special attention was paid to attributes of feeding registered 14 days before and 13 days after diagnosis. The 10 lame cows (LG) used in this experiment had a lameness score of 3–4 presented with severe lameness: they were reluctant to move and unwilling to complete weight transfer off the affected limb. The 10 healthy cows (HG) were given a lameness score of 1. We found that lameness of fresh dairy cows has an impact on inline registered ingestive behaviors biomarkers—the mean RT of HG cows was as much as 2.19 times higher than that of LG cows on the day of diagnosis of lameness, later this difference between the groups decreased to the sixth day of treatment, then increased again and decreased at the end of the experiment. The lowest eating time was found on diagnosis day and the highest on the ninth day before determination of lameness. Drinking time was higher in the HG group, with the exception of 10 and 9 days prior to clinical signs of disease in LG cows. A downward trend in rumination chews was observed in LG cows from day 7 until the onset of clinical symptoms. The bolus count decreased from day 3 before diagnosis to day 1 after diagnosis in LG cows. The largest difference in this indicator between groups was found on day of diagnosis. Analysing the pattern of CM values in the LG group, we found a decrease from 10 days before to 2 days after diagnosis. The CB value was almost the same in both groups of cows at the end of the experiment, but largest difference between the groups was found on day 7 after clinical sings of lameness.

Classifying Ingestive Behavior of Dairy Cows via Automatic Sound Recognition

Determining ingestive behaviors of dairy cows is critical to evaluate their productivity and health status. The objectives of this research were to (1) develop the relationship between forage species/heights and sound characteristics of three different ingestive behaviors (bites, chews, and chew-bites); (2) comparatively evaluate three deep learning models and optimization strategies for classifying the three behaviors; and (3) examine the ability of deep learning modeling for classifying the three ingestive behaviors under various forage characteristics. The results show that the amplitude and duration of the bite, chew, and chew-bite sounds were mostly larger for tall forages (tall fescue and alfalfa) compared to their counterparts. The long short-term memory network using a filtered dataset with balanced duration and imbalanced audio files offered better performance than its counterparts. The best classification performance was over 0.93, and the best and poorest performance difference was 0.4–0.5 under different forage species and heights. In conclusion, the deep learning technique could classify the dairy cow ingestive behaviors but was unable to differentiate between them under some forage characteristics using acoustic signals. Thus, while the developed tool is useful to support precision dairy cow management, it requires further improvement.

A system for continuous and automated measurement of mouse home-cage drinking with automated control of liquid access

Measurement of drinking behavior in laboratory animals is an often utilized method in many areas of scientific research, including the study of ingestive behaviors and addictions. We have designed a system that measures drinking by continuously tracking fluid-filled bottle weights with load cells and calculating change in fluid weight per drinking bout. The load cells serve both as a contact sensor that detects mouse-spout contact, as well as a monitor of fluid weight change per contact bout. The design described here fulfills several key criteria, including automated and continuous recording of drinking in the home-cage, automated control of liquid access, and inexpensive/reproducible fabrication. These features may allow researchers to generate high-resolution, detailed information on drinking behavior in high-throughput experimental designs. Here, we provide an overview of the design and present results from tests to validate the system. C57BL/6J mice were offered water and ethanol concurrently, using this system. Consumption weights were determined by the system and independently by conventional approaches. The results indicated a near-perfect correlation between the two methods, indicating the system returned valid consumption weights. This system functions as a valid drinking monitor that provides temporally precise data with a low cost design.

NIH Workshop Report: sensory nutrition and disease

In November 2019, the NIH held the “Sensory Nutrition and Disease” workshop to challenge multidisciplinary researchers working at the interface of sensory science, food science, psychology, neuroscience, nutrition, and health sciences to explore how chemosensation influences dietary choice and health. This report summarizes deliberations of the workshop, as well as follow-up discussion in the wake of the current pandemic. Three topics were addressed: A) the need to optimize human chemosensory testing and assessment, B) the plasticity of chemosensory systems, and C) the interplay of chemosensory signals, cognitive signals, dietary intake, and metabolism. Several ways to advance sensory nutrition research emerged from the workshop: 1) refining methods to measure chemosensation in large cohort studies and validating measures that reflect perception of complex chemosensations relevant to dietary choice; 2) characterizing interindividual differences in chemosensory function and how they affect ingestive behaviors, health, and disease risk; 3) defining circuit-level organization and function that link and interact with gustatory, olfactory, homeostatic, visceral, and cognitive systems; and 4) discovering new ligands for chemosensory receptors (e.g., those produced by the microbiome) and cataloging cell types expressing these receptors. Several of these priorities were made more urgent by the current pandemic because infection with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the ensuing coronavirus disease of 2019 has direct short- and perhaps long-term effects on flavor perception. There is increasing evidence of functional interactions between the chemosensory and nutritional sciences. Better characterization of this interface is expected to yield insights to promote health, mitigate disease risk, and guide nutrition policy.

Ingestive behaviors in bearded capuchins (Sapajus libidinosus)

The biomechanical and adaptive significance of variation in craniodental and mandibular morphology in fossil hominins is not always clear, at least in part because of a poor understanding of how different feeding behaviors impact feeding system design (form–function relationships). While laboratory studies suggest that ingestive behaviors produce variable loading, stress, and strain regimes in the cranium and mandible, understanding the relative importance of these behaviors for feeding system design requires data on their use in wild populations. Here we assess the frequencies and durations of manual, ingestive, and masticatory behaviors from more than 1400 observations of feeding behaviors video-recorded in a wild population of bearded capuchins (Sapajus libidinosus) at Fazenda Boa Vista in Piauí, Brazil. Our results suggest that ingestive behaviors in wild Sapajus libidinosus were used for a range of food material properties and typically performed using the anterior dentition. Coupled with previous laboratory work indicating that ingestive behaviors are associated with higher mandibular strain magnitudes than mastication, these results suggest that ingestive behaviors may play an important role in craniodental and mandibular design in capuchins and may be reflected in robust adaptations in fossil hominins.

Signaling in Rat Brainstem via Gpr160 is Required for the Anorexigenic and Antidipsogenic Actions of Cocaine- and Amphetamine-Regulated Transcript Peptide

Recent work identified Gpr160 as a candidate receptor for cocaine- and amphetamine-regulated transcript peptide (CARTp) and described its role in pain modulation. The aims of the present study were to determine if Gpr160 is required for the CARTp's ability to reduce food and water intake and to initially identify the distribution of Gpr160-like immunoreactivity (Gpr160ir) in the rat brain. A passive immunoneutralization approach targeting Gpr160 was used to block the behavioral effects of a pharmacologic dose of CARTp in the fourth cerebroventricle (4V) of rats and to determine the importance of endogenously produced CARTp in the control of ingestive behaviors. Passive immunoneutralization of Gpr160 in the 4V blocked the actions of CARTp to inhibit food and water intakes. Blockade of Gpr160 in the 4V, independent of pharmacologic CART treatment, caused an increase in both overnight food and water intakes. The decrease in food, but not water intake, caused by central injection of CARTp was demonstrated to be interrupted by prior administration of a GLP-1 receptor antagonist. Gpr160ir was observed in several, distinct sites throughout the rat brain, where CARTp staining has been described. Importantly, Gpr160ir was observed to be present in both neuronal and non-neuronal cell types. These data support the hypothesis that Gpr160 is required for the anorexigenic actions of central CARTp injection, and extend these findings to water drinking. Gpr160ir was observed in both neuronal and non-neuronal cell types in regions known to be important in the multiple pharmacologic effects of CARTp, identifying those areas as targets for future compromise of function studies.

A novel regulator of thirst behavior: phoenixin

There are examples of physiological conditions under which thirst is inappropriately exaggerated, and the mechanisms for these paradoxical ingestive behaviors remain unknown. We are interested in thirst mechanisms across the female life cycle and have identified a novel mechanism through which ingestive behavior may be activated. We discovered a previously unrecognized endogenous hypothalamic peptide, phoenixin (PNX), identified physiologically relevant actions of the peptide in brain and pituitary gland to control reproductive hormone secretion in female rodents, and in the process identified the previously orphaned G protein-coupled receptor Gpr173 to be a potential receptor for the peptide. Labeled PNX binding distribution in brain parallels areas known to be important in ingestive behaviors as well in areas where gonadal steroids feedback to control estrous cyclicity (Stein LM, Tullock CW, Mathews SK, Garcia-Galiano D, Elias CF, Samson WK, Yosten GLC, Am J Physiol Regul Integr Comp Physiol 311: R489–R496, 2016). We have demonstrated upregulation of Gpr173 during puberty, fluctuations across the estrous cycle, and, importantly, upregulation during the last third of gestation. It is during this hypervolemic, hyponatremic state that both vasopressin secretion and thirst are inappropriately elevated in humans. Here, we show that central administration of PNX stimulated water drinking in both males and females under ad libitum conditions, increased water drinking after overnight fluid deprivation, and increased both water and 1.5% NaCl ingestion under fed and hydrated conditions. Importantly, losartan pretreatment blocked the effect of PNX on water drinking, and knockdown of Gpr173 by use of short interfering RNA constructs significantly attenuated water drinking in response to overnight fluid deprivation. These actions, together with the stimulatory action of PNX on vasopressin secretion, suggest that this recently discovered neuropeptide may impact the recruitment of critically important neural circuits through which ingestive behaviors and endocrine mechanisms that maintain fluid and electrolyte homeostasis are regulated.