Examination of the pathogenesis of diabetic nephropathy in OLETF rats

We conducted protein loading to examine the progression and pathogenesis of diabetic nephropathy. For this experiment, male OLETF, LETO, F344 and BN rats were used. This experiment was performed on rats between 5 and 30 weeks of age. Examination parameters included body weight, food intake, oral glucose tolerance test (OGTT), urinary protein level (UP), urinary albumin level (UA), glomerular filtration rate (GFR), kidney weights, light microscopy (LM) and electron microscopy (EM). In the protein-loaded OLETF group, the UP level was markedly increased 20 weeks or more after birth. In OLETF control group, GFR were higher than those in other strains. Glomerular hypertrophy and kidney weights were markedly increased in protein-loaded groups in OLETF rats. Thirty weeks after birth, EM showed that the number of polyethyleneimine (PEI) of the glomerular basement membrane (GBM) in protein-loaded OLETF group was significantly decreased compared to that in control group. These changes in OLETF rats were more marked in the protein-loaded group than those in the control group. LM showed that the number of exudative lesions with fibrin-cap in the protein-loaded OLETF group was significantly increased than those in control group. In OLETF rats, protein loading caused deterioration of nephropathy at 30 weeks of age. Therefore, it was demonstrated that not only blood sugar control but also protein intake factors play important roles in the deterioration of nephropathy in OLETF rats.     

Unchanged Distribution Density of Anionic Sites on the Glomerular Wall in Rats with Active Heymann Nephritis

In various kinds of glomerulonephritis, alteration of anionic charge on the glomerular basement membrane (GBM) and podocytes has been controversial for more than decade. To elucidate the relation between glomerular protein leakage and anionic sites on the glomerular wall, we examined the distribution of anionic sites on the GBM and podocytes of rats with active Heymann nephritis (AHN). Urinalysis for protein levels was conducted, and the kidneys were examined using electron microscopic cytochemistry for the assessment of anionic charge with two cationic probes. The anionic sites on podocytes were decreased in number in the AHN rats; however, the distributions of anionic sites on the GBM were similar in density to those seen in the control animals. From these results, we consider that the decrease in anionic charge density on podocytes might be attributable to protein leakage and that the charge barrier of the GBM is irrelevant to the protein leakage in AHN rats.     

Systemic and eosinophilic lesions in rats with spontaneous eosinophilia (mes rats)

The mes rat is from an inbred mutant colony of rats with spontaneous eosinophilia. In order to investigate the pathogenesis of the mes rat, the histopathology and hematology for 76 mes rats were examined at several weeks of age. Tissue eosinophilia developed at 8 weeks of age when the blood eosinophil was 500 cells per microliter or more. Subsequently, eosinophilia progressed with age, and splenic eosinophilopoiesis and erythropoiesis appeared simultaneously. Many inflammatory lesions were induced after 10 weeks of age when the blood eosinophils became 1,000 cells per microliter or more. Gastroenteritis and mesenteric lymphadenitis were seen in 44 of 47 (94%) and 31 of 47 (66%) rats, respectively, after 10 weeks of age. Aortitis that deteriorated with age was found in 19 of 39 (49%) rats after 12 weeks of age. Hepatic fibrosis was found in four rats that exhibited severe eosinophilia and anemia. These results are comparable to the features of a hypereosinophilic syndrome in humans and other animals.     

Changes in the distribution of urea in body fluids during growth]

Urea concentration in plasma, muscle, and liver fluids of Wistar rats at the age of 3, 6, and 12 weeks was determined. In rats at the age of 3 weeks urea was cumulated in liver and muscle tissue fluids, in older rats (6 and 12 weeks) in plasma fluid. According to the stated urea distribution in individual age categories, a higher urea transport from tissues to blood is considered to be in rats at the age of 6 and 12 weeks. The urea transport proved to be one of the mechanisms of facilitating better utilization of endogenous urea nitrogen in bio-synthetic processes of the nitrogen metabolism in ruminants as well as in monogastric animals.     

Auditory brainstem response (ABR) in spontaneously epileptic rats (SER) and their parent mutants.

Postnatal development of auditory brainstem response (ABR) in spontaneously epileptic rats (SER; zi/zi, tm/tm), a double mutant, their parent mutants, tremor rats (tm/tm) and zitter rats (zi/zi), and Kyo:Wistar rats (control), was studied by repeated ABR recordings from 2 to 13 weeks of age. In tremor rats and Kyo:Wistar rats at 2 weeks of age, ABR pattern was almost the same and 2 or 3 waves were identified. However, no further development in ABR was observed in tremor rats and prolongation of latency and lowering of amplitude were marked. Only wave I with prolonged latency and lowered amplitude was recognized in zitter rats, SER and SER-N (zitter phenotype without epilepsy; zi/zi, tm/+ or zi/zi, +/+). ABR pattern was almost the same from 2 to 13 weeks of age in them. Electrocochleography revealed delay of N1 latency of compound action potential in SER. Vacuolation was observed in the cochlear nuclei and the brainstem of tremor rats and SER from 3 weeks of age in histopathological examination. The organ of Corti and cochlear nerve of tremor rats and SER exhibited no remarkable histopathological findings. The deafness in SER and its parent mutants was considered to occur as a result of impairment of inner ear, cochlear nerve and brainstem as well.     

Age- and sex-related changes in susceptibility of Wistar rats to Strongyloides venezuelensis infection

The effects of host age and sex on susceptibility to Strongyloides venezuelensis in Wistar rats were examined by counting larvae recovered from the lungs of animals 3 days after infection. The susceptibility of female rats to S. venezuelensis rapidly decreased with age and elevated estrogen. Resistance in female rats inoculated at 6 and 10 weeks of age was nine and twenty-fold higher, respectively than that in the youngest group (3 weeks). In contrast, the susceptibility of male animals was lowest in the youngest group, then increased with age and elevated testosterone. Sex differences in susceptibility were not evident in the youngest group, but became apparent with age.     

High susceptibility to zymbal gland and intestinal carcinogenesis in diabetic Otsuka long-evans Tokushima Fatty rats

Diabetes mellitus (DM) and obesity are believed to be risk factors for colorectal cancer in humans. In experiment 1, male nondiabetic Long-Evans Tokushima Otsuka (LETO) rats and Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model animal of type 2 DM, were whole-body X-irradiated (4 Gy) at 6 and 8 weeks of age and euthanized at 78 weeks of age (n=15, respectively). The incidences of small intestine adenocarcinoma in LETO and OLETF rats were 0% and 30%, respectively. In experiment 2, male LETO and OLETF rats (n=24, respectively) were given s.c. injections of 15 mg/kg azoxymethane (AOM) once weekly for 3 weeks and euthanized at 36 weeks of age. The incidences of Zymbal gland tumors in LETO and OLETF rats were 0% and 67%, respectively (P<0.001), whereas those of small intestine adenocarcinoma were 0% and 43% (P<0.001) and those of cecum/colon adenocarcinoma were 46% and 79% (P<0.05), respectively. Fatty change of hepatocytes was common in OLETF rats (63%) but not in LETO rats. Serum triglyceride and free fatty acid levels in OLETF rats were significantly higher than in LETO rats at sacrifice, whereas serum insulin levels in OLETF rats were very diverse. These data suggest that hyperlipidemia plays a significant role in high susceptibility to lower intestinal tract carcinogenesis in OLETF rats; this strain is susceptible to AOM-induced Zymbal gland carcinogenesis.     

Bovine Haematological Values during Fattening with Possible Implications for Muscle Growth

Haemoglobin concentration (Hb), haematocrit (PCV) and mean corpuscular haemoglobin concentration (MCHC) were determined as indicators of oxygen-carrying capacity in 25 Simmental bulls during intensive fattening. Their possible relations to muscle growth were also investigated. The animals were the progeny of two sires. Blood samples were taken at 6, 9, 12 and 15 months of age. After slaughter, the right thoracic rib cut (7–9) was dissected into the longissimus dorsi muscle (LD), other muscles (OM) and total muscles (TM) (LD+OM). There was a significant increase in the mean PCV and Hb values during fattening. The PCV and Hb values were significantly correlated with the tissue share of OM or TM only at 12 and 15 months of age. LD muscle share was not significantly correlated with any of the parameters at any fattening time. It would appear from these results that muscle growth proceeds in two phases. The first is until the age of 12 months and the other from then to maturity.     

Plasma Profiles of Glucose, Insulin and Lipids in the Male WBN/Kob-Lepr(fa) Rat, a New Model of Type 2 Diabetes with Obesity

Plasma profiles of glucose, insulin and lipids were examined in the male WBN/Kob-Lepr(fa) (fa/fa) rat, a new model of type 2 diabetes (T2D), in comparison with age-matched original male WBN/Kob (lean) rats. The fa/fa rats developed hypertriglycemia, obesity and hyperglycemia from 5, 7, and 9 weeks of age, respectively. Plasma insulin levels in fa/fa rats were significantly higher than those in lean rats at 5 weeks of age, but after 11 weeks of age gradually declined to the levels in lean rats. HOMA-IR, a measure of insulin resistance status, showed that fa/fa rats had insulin resistance. The fa/fa rat has the potential to become an important animal model of T2D with obesity.     

Intake and digestion of wethers fed with dwarf elephant grass hay with or without the inclusion of peanut hay

The aim of this study was to evaluate the effect of the inclusion of peanut (Arachis pintoi cv. Amarillo) hay in diets based on dwarf elephant grass (DEG, Pennisetum purpureum Schum cv. Kurumi) hay of different regrowth ages on forage intake and digestibility in wether lambs. The experimental treatments consisted of DEG hay with an interval of regrowth of 30 or 45 days offered as the only feed or in mixture with peanut hay (300 g/kg of total dry matter (DM)), which were tested in eight Texel?×?Suffolk crossbred wethers in a replicated 4?×?4 Latin square experiment. Both organic matter (OM) and digestible OM intakes were higher (P?<?0.05) in animals receiving the legume forage. Total apparent OM digestibility was higher (P?<?0.05) at an increased grass regrowth age. Ruminal OM digestibility increased (P?<?0.05) with legume inclusion and at a higher grass regrowth age. The nitrogen (N) intake was higher (P?<?0.05) in legume treatments and lower (P?<?0.05) as the grass regrowth age increased, but retention of N was not affected by treatments. Duodenal flow of both, non-ammonia N and microbial N, were not affected by legume inclusion and were lower (P?<?0.05) as grass regrowth age increased. The efficiency of rumen microbial protein synthesis (ERMPS) was negatively affected (P?<?0.05) by legume inclusion and was lower (P?<?0.05) as the grass regrowth age increased. Supplementation of dwarf elephant grass hay cut at the vegetative stage with peanut legume hay improves nutritional supply to wethers due to an increase in the forage intake.     

The effect of age of host in resistance expressed at the gut level in rats infected with Fasciola hepatica

The development of oral and intraperitoneal infections with Fasciola hepatica in young and old rats showed that the gut was involved in the expression of age resistance. The role of the gut was assessed by comparison of the number of flukes recovered 4 and 10 weeks after oral or intraperitoneal infection of 2-, 6-, 15-, and 35-week-old male Wistar rats and 6- and 15-week-old male DA rats with encysted metacarcariae of F. hepatica.Rats of both strains behaved similarly in their response to F. hepatica infection. For both routes of infection the number of flukes recovered decreased as host age increased. In 22- and 6-week-old rats equal numbers of flukes were recovered at 4 and 10 weeks after oral or intraperitoneal infection. In 15-week-old rats, fluke burdens 4 weeks after infection were significantly greater following intraperitoneal infection than oral infection. A significant loss of flukes from the intraperitoneal infection of 15-week-old Wistar rats occured between 4 and 10 weeks after infection. In 35-week-old Wistar rats there was no significant effect for route or age of infection.As intraperitoneal infection (to by-pass rejection at the gut level) only partially eliminates the age response, additional age related mechanism(s), able to reject flukes at some time after they have entered the peritoneal cavity, must be operative in the peritoneal cavity and/or the liver.     

Reproductive performance of rats supplemented with L-carnitine

It has been shown previously that supplementation of sows with l-carnitine increases their reproduction performance. The current study was carried out to investigate if feeding of l-carnitine also affects the reproduction performance of rats. Thirty female rats at 4 weeks of age were divided into two groups. The rats were fed diets with or without l-carnitine (1 g/kg diet) over a period of 34 weeks. After 8 weeks of feeding, the female rats were mated the first time. Two more reproductive cycles followed, with 3-week intervals in between. Body weight development of the females was similar in both groups during the whole experimental period. Number of pregnancies and number of total rat pups, pups born alive and stillborn pups were not influenced by l-carnitine. There was also no influence of dietary l-carnitine on the body weight of individual pups and the litter weights at birth. Weight development of litters differed between both groups on several days, but no uniform effect of l-carnitine was observed. Body weight development of weaned rats fed a commercial diet was different between both groups, but only in one reproduction cycle. In conclusion, this study shows that l-carnitine supplementation does not improve the reproductive performance of rats.     

Unilateral degeneration of retina and optic nerve in Fischer-344 rats

Unilateral degeneration of the retina and optic nerve was observed among Fischer-344 (F-344) rats fed a semi-purified synthetic feed. Further studies were conducted using standard cereal-based and synthetic diets. Beginning at 4 weeks of age, all experimental rats (169 F-344 rats) were fed various diets and were examined for morphologic and functional changes in the retina and optic nerve. No ocular lesions were observed in any F-344 rats prior to 21 weeks of age, whether fed a synthetic diet or a standard diet; however, approximately 16% (13/86) of the F-344 rats examined between 57 and 64 weeks of age developed unilateral degeneration of the retina and optic nerve. On the other hand, the F-344 rats fed the synthetic diet developed the degenerative lesions by 30 weeks of age, while the F-344 rats fed the standard diet did not develop lesions over this shorter time period. Degenerative changes of the affected retinas and optic nerves were closely related with functional abnormalities evaluated by electroretinogram and visual evoked potentials. In contrast with the F-344 rats, Long-Evans rats that were fed either the synthetic or standard diet up to the age of 68 weeks (77 rats) did not develop the ocular lesions. There was no apparent relationship of the development of the lesions with dietary modification, toxicity or trauma; thus, these observations appear to indicate that spontaneous unilateral degeneration of the retina and optic nerve occurs in F-344 rats and that these ocular lesions may be accelerated by the feeding of certain semi-purified synthetic diets.     

Developmental hormonal profiles in rdw rats with congenital hypothyroidism accompanying increased testicular size and infertility in adulthood

Congenital hypothyroid mutant male rdw rats have enlarged testes in adulthood with dwarfism accompanied by infertility. To explain how rdw rats acquire enlarged testes in adulthood, we compared age-matched normal (N) rats at various developmental stages for blood levels of hormones, thyroxine (T4), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T), and investigated whether T4 therapy (rdw+T4) from 3 weeks of age (w) until adulthood could induce recovery of fertility in rdw rats, as well as how rdw+T4 affected hormonal patterns. Testes weights of rdw rats were higher than those of N rats at 19 w in adulthood though it was low during development. Serum T4 values in rdw rats were markedly lower than those in N rats but steadily increased up to 19 w. The serum FSH values in rdw rats were lower than those in N rats at all ages, and neither serum LH nor T value was significantly different at any age. The testes weight of rdw+T4 rats was significantly higher than that of N rats at 13 w with recovered growth, and was higher than that of rdw rats at 19 w. When they were mated with proestrous females after 16 w, all females became pregnant and gave birth to a normal number of pups. The T4 and FSH values of rdw+T4 rats were significantly higher than those in rdw rats, but similar to those in N rats in adulthood. The results suggest that even low levels of circulating thyroid hormone (TH) in rdw rats stimulate the development of their testes, probably through Sertoli cells, resulting in the enlarged adult testes without fertility, and that a sufficient circulating TH level from the immature stage plays a pivotal role in restoring mating activity, probably through FSH-mediated action towards adulthood.     

Thymus satureioides and Origanum majorana essential oils improve the quality of Beni Arouss buck semen during storage at 4°C

This study aims to investigate the effects of essential oils (EOs), extracted from Thymus satureioides (TS) and Origanum majorana (OM), on Beni Arouss buck semen quality stored in skimmed milk at 4°C. EOs were extracted by hydro-distillation, and the chemical compounds were determined. Ejaculates were collected from six Beni Arouss bucks, once a week for 10 weeks, and they were pooled, divided into five equal aliquots and diluted to 400 × 10⁶ sperm/ml with skimmed milk supplemented with 0.01% of OM EO, 0.01% of TS EO, 0.05% of OM EO and 0.05% of TS EO. Non-supplemented skimmed milk was considered as a control. Semen motility, kinematic parameters, viability, abnormality, membrane integrity and lipid peroxidation were evaluated at 0, 4, 8, 24, 28, 32 and 48 hr of liquid storage at 4°C. The main EO components were carvacrol (31.7%), thymol (28.0%) and borneol (14.4%) for TS, and terpinene-4-ol (31.2%), γ-terpinene (17.4%) and α-terpinene (12.7%) for OM. The results highlighted a dose-dependent effect of TS and OM EOs on all semen quality parameters. 0.01% of both EOs had a beneficial effect on the sperm preservation stored at 4°C compared with control (p < .05) excepted for the straight-line velocity. The 0.05% EO addition had harmful effects during storage particularly for TS EO. In conclusion, 0.01% of TS and OM EOs are recommended to improve the Beni Arouss buck semen preservation at 4°C.     

Influence of cholesterol administration and aging on the development of pulmonary foam cells in F344 rats

The influence of experimentally induced hyperlipidemia and aging on the development of pulmonary foam cells (PFCs) was examined in Fischer 344 rats. The male and female rats were administered orally with cholesterol at a dosage level of 1000 mg/kg/day for 30 days from 6 to 10 weeks or from 33 to 37 weeks of age. The control rats received the vehicle only in the same manner. Plasma levels of total cholesterol, phospholipid, triglyceride (TG), beta-lipoprotein (beta-LP) and calcium in both control and cholesterol-administered groups were higher at 37 weeks than at 10 weeks of age. Plasma beta-LP and TG levels in the treated groups were significantly higher or tended to be higher than those of the controls at 10 and 37 weeks of age. Males of the treated group showed the highest level of beta-LP at 37 weeks of age, positively correlated with the highest incidence of PFCs. PFCs developed singly or in a small cluster in peribronchial and subpleural regions. PFCs had an abundant cytoplasm filled with many fine vacuoles containing neutral lipid and cholesterol. PFCs stained with PAS and reacted immunohistochemically with both anti-rat monocytes/macrophages monoclonal antibody and anti-lysozyme antibody. Moderately swollen macrophages with a foamy appearance were detected in perivascular connective tissues of the lungs and they were considered to represent an initial stage of the development of PFCs. These observations suggest that hyperlipidemic conditions, particularly hyper beta-lipoproteinemia, resulting from cholesterol administration or aging may be involved in the development of PFCs in rats.     

Blood pressure characteristics of female spontaneously diabetic Torii-Lepr(fa) rats

Blood pressure in female SDT-fa/fa rats was periodically investigated at ages 8, 16, and 24 weeks. Furthermore, an insulin therapy was performed for 5 weeks in the female rats at age 11 weeks, and the change of blood pressure was examined. In addition to obesity, hyperglycemia, hyperinsulinemia, and hyperlipidemia, hyperleptinemia and increased urinary angiotensinogen level were observed during the experimental period. Blood pressure was elevated at ages 8 and 16 weeks, but that at 24 weeks was comparable to that in Sprague-Dawley (SD) rats. Heart rate was decreased from age 8 to 24 weeks. Insulin therapy induced good glycemic control and improvement of hyperlipidemia, but the blood pressure was not reduced. Blood pressure in female SDT-fa/fa rats was elevated temporarily. The blood pressure was not decreased by insulin treatment. SDT-fa/fa rat is a useful model to investigate the relation between diabetes mellitus and hypertension.     

Age-related pathophysiological changes in rats with unilateral renal agenesis

Affected rats of the unilateral urogenital anomalies (UUA) strain show renal agenesis restricted to the left side. To determine whether unilateral renal agenesis is a risk factor for the progression of renal insufficiency, we studied age-related pathophysiological alterations in affected rats. Although body growth and food intake were normal, polydipsia and polyuria with low specific gravity were present at 10 weeks and deteriorated further with age. Blood hemoglobin concentrations were normal, though there was slight erythropenia with increased MCV and MCH. Although hypoalbuminemia, hypercholesterolemia, azotemia, and hypermagnesemia were manifested after age 20 weeks, neither hyperphosphatemia nor hypocalcemia was observed. Plasma Cre and UN concentrations gradually increased with age. Cre clearance was almost normal, whereas fractional UN excretion was consistently lower than normal. Proteinuria increased with age, and albumin was the major leakage protein. In addition to cortical lesions, dilated tubules, cast formation, and interstitial fibrosis were observed in the renal medulla of 50 week-old affected rats. Renal weight was increased 1.7-fold and glomerular number 1.2-fold compared with normal rats. These findings show that the remaining kidney in UUA rats is involved not only in compensatory reactions but experiences pathophysiological alterations associated with progressive renal insufficiency.     

Age Difference in Morphology and Immunohistology inthe Thymus and Spleen in Crl:CD (SD) Rats

We investigated chronological changes in immunohistochemical phenotyping in the thymus and spleen in Crl:CD rats up to the age of about one year. In the thymus, T cells increased markedly from 3 to 4 weeks of age. Proliferating cells also increased markedly at these points. B cells tended towards an increase with age. In the spleen, white pulp increased until 9 weeks of age and remained fairly stable thereafter. In the periarteriolar lymphoid sheath and marginal zone, T cells gradually increased until 9 weeks of age and became almost flat thereafter. In the lymph follicle, T cells increased with age. B cells tended towards an increase with age in all areas of the spleen. It was concluded that development of the thymus was most marked from 3 to 4 weeks of age and that both the thymus and spleen had matured by 9 weeks of age.     

Gallbladder Mucocele: Variables Associated with Outcome and the Utility of Ultrasonography to Identify Gallbladder Rupture in 219 Dogs (2007–2016)

Background

Gallbladder mucocele (GBM) is an increasingly recognized extrahepatic biliary disease in dogs.

Objectives

To investigate cases of GBM and identify variables associated with survival and the sensitivity and specificity of ultrasonography to identify gallbladder rupture.

Animals

Two hundred and nineteen client‐owned dogs with GBM.

Methods

Multicenter, retrospective study of dogs with GBM, presented from January 2007 to November 2016 to 6 academic veterinary hospitals in the United States. Interrogation of hospital databases identified all cases with the inclusion criteria of a gross and histopathologic diagnosis of GBM after cholecystectomy and intraoperative bacteriologic cultures of at least 1 of the following: gallbladder wall, gallbladder contents, or abdominal effusion.

Results

Two hundred and nineteen dogs fulfilled the inclusion criteria. Dogs with GBM and gallbladder rupture with bile peritonitis at the time of surgery were 2.7 times more likely to die than dogs without gallbladder rupture and bile peritonitis (P = 0.001; 95% confidence interval [CI], 1.50–4.68; n = 41). No significant associations were identified between survival and positive bacteriologic cultures, antibiotic administration, or time (days) from ultrasonographic identification of GBM to the time of surgery. The sensitivity, specificity, positive, and negative likelihood ratios for ultrasonographic identification of gallbladder rupture were 56.1% (95% CI, 39.9–71.2), 91.7% (95% CI, 85.3–95.6), 6.74, and 0.44, respectively.

Conclusion and Clinical Importance

Dogs in our study with GBM and intraoperative evidence of gallbladder rupture and bile peritonitis had a significantly higher risk of death. Additionally, abdominal ultrasonography had low sensitivity for identification of gallbladder rupture.