Journal of Veterinary Medical Science最新文献

Ovariectomized (OVX) mice serve as a key model for studying postmenopausal metabolic changes, particularly obesity, as they mimic the hormonal state of postmenopausal women. However, our understanding remains limited regarding how hormonal and dietary factors affect different adipose tissues. Furthermore, precise documentation of experimental procedures and their effects on specific adipose tissue depots is essential for reproducible translational research. This study investigated depot-specific adiposity development in OVX mice fed a high-fat diet (HFD), focusing on how reduced estrogen levels and dietary intervention affect distinct fat depots. We composed subcutaneous and visceral white adipose tissue (WAT) depots from sham-operated (Sham) and OVX female C57BL/6JJcl mice on a regular diet (RD) and high-fat diet (HFD) for 20 weeks. OVX mice on HFD gained significantly more weight than Sham controls. Adiposity increased in abdominal subcutaneous WAT (sWAT) and perirenal WAT (prWAT) of OVX mice, but not in mesenteric WAT (mWAT). Analysis of adipose tissue morphology revealed that OVX mice exhibited enlarged adipocyte cross-sectional areas under low estrogen (E2) conditions, suggesting enhanced adipogenesis in an estrogen-deficient state. These findings suggest that low estrogen condition accelerated adiposity, in a tissue site-dependent manner.

Our previous reports showed that exposure to the neonicotinoid pesticide clothianidin (CLO) at a no-observed-adverse-effect-level (NOAEL) dose during fetal development and lactation in mice led to higher rates of maternal neglect and infanticide. Although the demonstrated association between decreased oxytocin secretion and decreased maternal parenting behavior implies a link to declining oxytocin levels, no evidence has yet emerged in CLO to clearly establish such an association. This study investigated the effects of CLO on maternal behavior and oxytocin in C57BL/6N mice exposed during pregnancy and lactation (F0 mothers) as well as in their adult female offspring (F1 mothers). The effects were assessed using nest building assays during pregnancy and pup retrieval assessment after delivery. The results showed a decrease in oxytocin secretion and a marked decrease in pup retrieval behavior among the F0 mothers in the CLO exposure group compared to those in the control group. Their offspring, the F1 mothers, showed significantly lower nest-building scores during pregnancy. In conclusion, this study is the first to examine the potential mechanisms by which CLO exposure in mothers at the NOAEL dose during pregnancy and lactation results in reduced plasma oxytocin levels, subsequently leading to a decline in maternal behaviors such as pup retrieval. Furthermore, these effects may impair maternal behaviors in the next generation, when the offspring mice become mothers.

This study aimed to investigate the effects of cell differentiation status and neurotropic viral infectivity on the susceptibility of undifferentiated and differentiated SH-SY5Y cells to herpes simplex virus type 1 (HSV-1) and Japanese encephalitis virus (JEV) infections. Notably, undifferentiated SH-SY5Y cells were susceptible to both HSV-1 and JEV infections. However, differentiated cells exhibiting a phenotypically mature neuron-like morphology and markedly increased neuronal marker levels showed low susceptibility to JEV infection. Overall, these findings suggest that SH-SY5Y cells become more resistant to JEV infection as they mature. This cell culture model is useful to elucidate the molecular mechanisms regulating the maturation state-specific resistance of neurons to JEV.

The diagnosis of canine mast cell tumor (MCT) via cytology carries the risk of triggering life-threatening anaphylactic reactions due to massive histamine release. Since mast cells release various lipid mediators, which are excreted in urine, we aimed to explore urinary lipid metabolites as potential non-invasive diagnostic markers for MCT. Liquid chromatography-mass spectrometry-based analysis detected 32 types of lipid metabolites in the urine of MCT dogs. Among these, urinary levels of 15-deoxy-δ-12,14-PGJ₂, lyso-PAF, 9,10-DiHOME, and 12,13-DiHOME were significantly elevated in MCT dogs compared to healthy dogs. These urinary lipid metabolites could serve as novel non-invasive biomarkers for canine MCT.

Spontaneous cardiac disease in nonhuman primates offers a useful model of human cardiac disease. However, diagnosing heart disease generally requires specialized techniques such as ultrasonography. This study focused on cardiac hormones that can be used to detect cardiac disease from blood tests. We measured concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in healthy young Japanese macaques (Macaca fuscata) housed individually indoors, with no abnormalities in thoracic X-rays, electrocardiograms, echocardiograms, or complete blood counts and serum biochemistry tests, to establish reference values. The monkeys used in this study comprised 29 males (28-47 months old) and 29 females (22-65 months old). ANP levels were determined by immunoradiometric assay. BNP levels were determined by chemiluminescent enzyme immunoassay. Mean ANP level was 25.7 ± 9.6 pg/mL for all 58 Japanese macaques, 26.7 ± 9.6 pg/mL for the 29 males, and 24.7 ± 9.5 pg/mL for the 29 females. No significant difference was identified between sexes. No correlation was seen between ANP and age but excluded monkeys showed result of outside these range. BNP was also measured, with 22 of the 58 monkeys showing levels below the lower limit of detection (<4.0 pg/mL). Taking levels in these 22 animals as 4.0 pg/mL, mean BNP level was 5.1 ± 1.6 pg/mL and BNP elevated in two excluded monkeys. These results establish mean values for cardiac hormones in young Japanese macaques. These standards may provide useful indicators for the early detection of cardiac disease in animal models.

Although the disk diffusion method is a useful and widely utilized antimicrobial susceptibility testing method in clinical veterinary practice, the available clinical breakpoints (CBPs) for the combination of bacterial species and antimicrobials are still limited. This study aimed to establish tentative cut-off values by analyzing the relationship between minimum inhibitory concentration and the inhibition zone diameter of the disk diffusion method for Pasteurella multocida and Mannheimia haemolytica, collected by the Japanese Veterinary Antimicrobial Resistance Monitoring system (JVARM), for the antimicrobial agents approved in Japan for the treatment of respiratory diseases in cattle and swine. Among the antimicrobial agents without CBPs for the disk diffusion method in the Clinical and Laboratory Standards Institute (CLSI), we were able to determine the tentative cut-off values of ampicillin (ABPC, S≥25 mm, R≤24 mm in swine), dihydrostreptomycin (DSM, S≥8 mm in cattle, S≥12 mm in swine), kanamycin (KM, S≥16 mm in cattle, S≥17 mm in swine), tetracycline (TC, S≥21 mm, R≤20 mm in cattle) and tiamulin (TML, S≥13 mm in swine) for P. multocida, and CEZ (S≥23 mm), DSM (S≥10 mm), KM (S≥18 mm) and TC (S≥23 mm, R≤20 mm) for M. haemolytica. These results should encourage the practical use of antimicrobial susceptibility testing in the clinical field and contribute to furthering prudent use of antimicrobial agents.

A rapidly growing mass was observed in the left third mammary gland of a 5-and-a-half-year-old intact female northern tree shrew (Tupaia belangeri). Histopathologically, the mass was composed of numerous irregularly dilated mammary ducts with a pericanalicular or intracanalicular pattern. These mammary ducts showed a leaf-like structure due to the proliferations of surrounding spindle-shaped neoplastic cells with moderate to severe nuclear atypia. We diagnosed this case as a phyllodes tumor in a mammary gland of a northern tree shrew (Tupaia belangeri), which closely resembled those occurring in the human breast histopathologically. To the best of our knowledge, this is the first report of a phyllodes tumor in the mammary gland of a northern tree shrew (Tupaia belangeri).

Muscle-invasive bladder cancer (MIBC) is a common form of BC in dogs. Adjuvant chemotherapy administration is commonly applied in MIBC cases, but patients sometimes experience treatment failure and recurrence. Therefore, supplements with anticancer properties, such as traditional Chinese medicines (TCMs), are required, and they have been widely used in Japanese human medicine and may be useful in veterinary medicine. Furthermore, organoid cultures can mimic the characteristics of their original tissues, such as self-renewal and organization. We previously established a novel experimental model for MIBC using a dog BC organoid (DBCO) culture. Herein, we examined the antiproliferative effects and mechanisms of 39 substances, consisting of TCMs, TCM supplements, and crude drug extracts, on DBCOs. Among the TCMs, D3 (also known as Shibe-ria), which is a mixture of chaga (Inonotus obliquus) and notoginseng (Panax notoginseng), significantly diminished the cell viability of DBCOs. The expression of BC stem cell markers, CD44 and SOX2, was reduced considerably in the D3-treated DBCOs. Among the components of D3, chaga exerted an antiproliferative effect on DBCO, whereas notoginseng did not. The administration of D3 also significantly reduced the volume of DBCO xenografted tumors in mice in vivo. Overall, D3 may have benefits as a natural anticancer supplement in veterinary medicine.

The poultry red mite (PRM), Dermanyssus gallinae, is a hematophagous ectoparasite that significantly threatens the poultry industry, not only through blood-feeding but also as a vector for deadly pathogens. With the growing challenge of acaricidal resistance, the demand for alternative control measures is urgent. However, effective PRM research, particularly in acaricidal efficacy and new drug discovery, hinges on the availability of reliable laboratory colonies. In this study, we successfully established a stable PRM laboratory colony, originally isolated from the field in 2021 and maintained under controlled conditions at the Research Institute for Animal Science in Biochemistry and Toxicology (RIAS). We investigated the growth kinetics and population dynamics of the laboratory colony within a Styrofoam-based maintenance box (SBMB) containing chicks. PRM propagation was tracked over 28 days, with mites collected every seven days. The average bulk weight of the mites in the trap increased from 4.3 ± 1.2 mg on day 7 to 201.4 ± 56.5 mg on day 28, despite seasonal variations, indicating optimal conditions for population growth. The collected mites spanned various blood-feeding developmental stages such as protonymph, deutonymph, and adult stages, enabling comprehensive assessments of molting and egg-laying efficiency. Our findings confirm that the laboratory colony of PRM can be stably maintained, providing a reliable source of PRMs for further experimental research aimed at advancing control strategies against this pervasive pest.

This study aims to clarify influences of the short-term carbohydrate (CHO) restriction on plasma cells in chicken cecal tonsil (CT) using immunohistochemical and morphometrical techniques. Healthy male layer chickens were randomly divided into the control and three experimental groups. The three experimental groups were fed with diets containing 50%, 25%, and 0% CHO of that in the control diet, respectively. Following the experimental period for 7 days, CTs were collected from each chicken. Immunohistochemistry was performed to detect immunoglobulin (Ig) A, G and M. The density of IgA-immunoreactive cells was significantly lower in the lymphoid follicles (LFs) and diffuse lymphoid tissues (DLTs) in CTs of the 0% group compared to those of the other groups. There was a positive correlation between daily CHO intake and the density of IgA-immunoreactive cells in the DLTs and LFs. The density of IgM-immunoreactive cells was significantly decreased as daily CHO intake decreased, and there was a positive correlation between these two factors in both DLTs and LFs. The density of IgG-immunoreactive cells was significantly lower in DLTs of the 0% group than those in the control and 50% groups. The density of IgG-immunoreactive cells was significantly decreased with a decrease in daily CHO intake in DLT but not in LF. These findings demonstrated that dietary CHO had a significant effect on the density of plasma cells in the CTs exhibiting a declining trend with a decrease of ingested CHO volume.