Cotton rats (Sigmodon hispidus) with a high prevalence of hydrocephalus without clinical symptoms.

Normal-pressure hydrocephalus (NPH) is a condition in which the ventricle is enlarged without elevated cerebrospinal fluid pressure, and it generally develops in later life and progresses slowly. A complete animal model that mimics human idiopathic NPH has not yet been established, and the onset mechanisms and detailed pathomechanisms of NPH are not fully understood. Here, we demonstrate a high spontaneous prevalence (34.6%) of hydrocephalus without clinical symptoms in inbred cotton rats (Sigmodon hispidus). In all 46 hydrocephalic cotton rats, the severity was mild or moderate and not severe. The dilation was limited to the lateral ventricles, and none of the hemorrhage, ventriculitis, meningitis, or tumor formation was found in hydrocephalic cotton rats. These findings indicate that the type of hydrocephalus in cotton rats is similar to that of communicating idiopathic NPH. Histopathological examinations revealed that the inner granular and pyramidal layers (layers IV and V) of the neocortex became thinner in hydrocephalic brains. A small number of pyramidal cells were positive for Fluoro-Jade C (a degenerating neuron marker) and ionized calcium-binding adaptor molecule 1 (Iba1)-immunoreactive microglia were in contact with the degenerating neurons in the hydrocephalic neocortex, suggesting that hydrocephalic cotton rats are more or less impaired projections from the neocortex. This study highlights cotton rats as a candidate for novel models to elucidate the pathomechanism of idiopathic NPH. Additionally, cotton rats have some noticeable systemic pathological phenotypes, such as chronic kidney disease and metabolic disorders. Thus, this model might also be useful for researching the comorbidities of NPH to other diseases.

Novel polychrome staining distinguishing osteochondral tissue and bone cells in decalcified paraffin sections.

The bone is a dynamic and metabolically active organ in which growth and resorption of the osteochondral matrix is orchestrated by osteoblasts and osteoclasts. For decalcified paraffin-embedded specimens, decalcifying agents alter the staining intensity, and excess decalcification interferes with bone staining. Robust bone staining methods independent of the decalcification conditions and animal species are lacking. In this study, we have developed a novel polychrome staining method, named JFRL staining, which stains the components of osteochondral tissue in different colors. With this staining we could visualize the hyaline cartilage as blue by alcian blue, osteoid as red by picrosirius red, and mineralized bone as green by picro-light green SF or picro-naphthol green B and easily distinguished osteoblasts, osteocytes, and osteoclasts. In mineralized bone, this staining revealed the obvious lamellar structures and woven bone. Notably, this staining was independent of the decalcification conditions and experimental animal species examined. To verify the usefulness of JFRL staining, we observed cotton rat tail which has shorter length and shows a false autotomy. The caudal vertebrae were normally developed via endochondral ossification without a fracture plane. At 6 months of age, the number of chondrocytes declined and the hypertrophic zone was absent at the epiphyseal plate, which might reflect the shorter tail. In conclusion, JFRL staining is the first method to simultaneously distinguish osteochondral matrix and bone cells in one section regardless of decalcifying conditions. This robust staining will provide new information for a wide number of biomedical fields, including bone development, physiology, and pathology.

Cotton rat (Sigmodon hispidus) develops metabolic disorders associated with visceral adipose inflammation and fatty pancreas without obesity.

Obesity induces metabolic disorders such as type 2 diabetes, hypertension, and cardiovascular diseases and has become a global health concern. Recent studies imply that fat accumulation in nonadipose tissue correlates with metabolic disorders. However, there are no suitable animal models to evaluate this phenomenon. This study investigated the characteristics of metabolic disorders found in cotton rat (Sigmodon hispidus). Blood biochemical examinations revealed that cotton rats, predominantly males, developed hyperinsulinemia, hyperglycemia, and dyslipidemia when fed a normal diet. The islets increased in size through ß-cell hyperplasia, which was associated with serum insulin level in both sexes, strongly indicating insulin resistance. In male cotton rats, oxidative stress was observed in ß cells, and macrophage infiltration into the visceral white adipose tissue was reported, both of which were associated with serum insulin level without visceral obesity. In contrast, female cotton rats developed hyperinsulinemia without histopathological changes that were reported in males. Adipocytes were found to be accumulated in the pancreas but not in the liver of both sexes during aging. Pancreatic fat accumulation was associated with the serum insulin level only in females. Taken together, cotton rats developed metabolic disorders associated with visceral fat inflammation in the absence of obesity. In addition, pancreatic ectopic fat may also be related to the early stages of these conditions. Thus, the cotton rat may serve as a novel and useful model for metabolic disorders characterized by visceral adipose inflammation and ectopic fat accumulation in the pancreas without obesity.

Mouse chromosome 2 harbors genetic determinants of resistance to podocyte injury and renal tubulointerstitial fibrosis.

BACKGROUND: Tensin2 deficiency results in alterations in podocytes and subsequent glomerular and tubulointerstitial injuries. However, this pathology is critically dependent on genetic background. While the Tensin2-deficient podocytes of resistant murine strains, including C57BL/6J mice, remain almost intact, susceptible murine strains with Tensin2 deficency, including ICGN mice, develop chronic kidney disease following alterations in the podocyte foot processes. In a previous study, genome-wide linkage analysis was utilized to identify the quantitative trait loci associated with the disease phenotypes on mouse chromosome 2. This study investigated the disease phenotypes of chromosome 2 consomic and subcongenic strains. RESULTS: ICGN consomic mice introgressed with chromosome 2 from the C57BL/6J mouse were generated and found to exhibit milder renal failure than that in ICGN mice. We developed 6 subcongenic strains that carry C57BL/6J-derived chromosomal segments from the consomic strain. One showed significantly milder albuminuria, another showed significantly milder tubulointerstitial injury, and the both showed significantly milder glomerular injury. CONCLUSIONS: These data indicate that mouse chromosome 2 harbors two major genes associated with the severities of nephropathy induced by Tensin2 deficiency. The proximal region on chromosome 2 contributes to the resistance to tubulointerstitial fibrosis. In contrast, the distal region on chromosome 2 contributes to the resistance to podocyte injury. This study would be helpful to discover the biological mechanism underlying the renal injury, and may lead to the identification of therapeutic targets.

Usefulness of an anesthetic mixture of medetomidine, midazolam, and butorphanol in cotton rats (Sigmodn hispidus).

Tne cotton rat (Sigmodon hispidus) is a laboratory rodent used for studying human infectious diseases. However, a lack of suitable anesthetic agents inconveniences the use of cotton rats in surgical manipulation. This study demonstrated that subcutaneous injection of the mixture of medetomidine, midazolam, and butorphanol (0.15, 2.0, and 2.5 mg/kg, respectively), which is a suitable anesthetic agents for mice and rats, produced an anesthetic duration of more than 50 min in cotton rats. We also demonstrated that 0.15 mg/kg of atipamezole, an antagonist of medetomidine, produced a quick recovery from anesthesia in cotton rats. This indicated that the anesthetic mixture of medetomidine, midazolam, and butorphanol, functioned as a useful and effective anesthetic for short-term surgery in cotton rats.

Genetic background strongly influences the severity of glomerulosclerosis in mice.

The ICGN mouse strain is a glomerulosclerosis (GS) model that shows characteristic proteinuria, podocyte morphological abnormalities and increased extracellular matrix accumulation in the glomeruli, which are the final common pathology associated with a variety of kidney diseases leading to end-stage renal failure. Previously, we performed a quantitative trait locus (QTL) analysis to identify the causative genes for GS in ICGN mice and found the deletion mutation of the tensin2 (Tns2) gene that creates both a premature stop codon and dramatically decreases mRNA expression levels within the region of the major QTL (this mutation was designated Tns2(nep)). The severity of GS varies considerably in humans and other animals, indicating the influence of several genes controlling the disease phenotype. In this study, to identify the modifier/resistant gene(s) for GS, we produced congenic strains carrying the Tns2(nep) mutation on the C57BL/6J (B6) genetic background and analyzed GS severity. Interestingly, the B6 congenic mice exhibited milder phenotypes than the ICGN strain mice. The results suggest that B6 mice have a modifier(s) of GS resistance. Therefore, identification of the modifier loci in B6 mice will provide important new information regarding gene interactions controlling GS.

Amelioration of anemia in the ICGN mouse, a renal anemia model, with a subcutaneous bolus injection of erythropoietin adsorbed to hydroxyapatite matrix.

The recombinant human erythropoietin (rhEPO) is used for the treatment of patients with renal anemia. However, rhEPO should be administered subcutaneously or intravenously three times a week. The repetitive injections of rhEPO result in burdens to patients. To resolve this problem, we investigated the sustaining release methods using an rhEPO-hydroxyapatite (HAp) made by spray-drying technique as the drug delivery system. Two types of rhEPO-HAp formulations were prepared; zinc (Zn) formulation and Zn and poly-L-lactic acid (PLA) formulation. These formulations were examined in genetically anemic model, ICGN (ICR-derived glomerulonephritis) mice. According to in vivo release test of rhEPO from HAp in ICGN mice, elevated plasma concentration of rhEPO could be maintained for more than 7 days. These mice showed the amelioration of anemia for more than 3 weeks post-administration without causing any side effect. In conclusion, Zn or Zn/PLA formulation of HAp was considered to be one of the useful carriers of rhEPO for long-term improvement of anemia.

Sustained efficacy of erythropoietin with a hydroxyapatite carrier administered in mice.

For chronic kidney disease patients with renal anemia, recombinant human erythropoietin (rHuEPO) is a very effective drug; however, the treatment regime is troublesome, requiring multiple administrations each week. In the present study, we examined the efficiency of hydroxyapatite (HAp) as a drug delivery carrier for the sustained release of erythropoietin (EPO) to reduce the frequency of administration. Spray-dried HAp microparticles, formed from zinc-containing HAp (Zn-HAp) and Zn-HAp calcined at 400 degrees C, were used as carriers of EPO, and five Zn-HAp formulation samples incorporating EPO were prepared; no formulation, poly-L-lactic acid (PLA) formulation, zinc (Zn) formulation, Zn/PLA formulation, and calcined/Zn/PLA formulation. ICR mice were administered these samples or commercial rHuEPO (Epogin) as a control from dorsal neck subcutaneous, and hematological and histopathological analyses, including enzyme-linked immunosorbent assay for plasma EPO concentration, were performed. An increase in the blood EPO level was detected on days 3 and 8 post-administration. Peak hematopoiesis was delayed and higher hematological values were obtained on day 14 post-administration with no serious adverse reactions compared with the control. The Zn/PLA formulation sample was found to be most effective in reducing the initial peak while sustaining the delayed release of EPO. In conclusion, the Zn-HAp formulation samples were considered to be useful carriers for the sustained release of EPO, and the Zn/PLA formulation appears to be the most effective of five Zn-HAp formulation samples in sustaining EPO release.

Slc:Wistar/ST rats develop unilateral thyroid dysgenesis: A novel animal model of thyroid hemiagenesis.

Developmental anomalies of the thyroid gland lead to congenital malformations such as thyroglossal duct cysts and thyroid dysgenesis. However, the pathogenesis of thyroid dysgenesis remains unclear due to the lack of suitable animal models. This study demonstrated that Slc:Wistar/ST rats frequently developed unilateral thyroid dysgenesis, including hemiagenesis, characterized by the absence of one lobe. In Wistar/ST rats, each thyroid lobe was frequently different in size, and approximately 27% and 20% of the rats presented with hemihypoplasia and hemiagenesis of the thyroid gland, respectively. Dysgenesis was predominant on the left side in both sexes, without sex differences. At a young age, thyroid hemiagenesis did not alter body weight. In rats of both sexes with thyroid hemiagenesis, plasma total triiodothyronine and total triiodothyronine levels remained unchanged while plasma thyroid-stimulating hormone levels were significantly elevated in young rats. The remaining thyroid lobes increased in weight, but the follicular epithelial cells appeared normal in terms of their height and proliferating activities. On the side of thyroid dysgenesis, the parathyroid glands were normally localized and were situated at the same location as the contralateral glands. The ultimobranchial body remnants were localized at the level of the thyroid gland along with the cranial thyroid artery and vein, forming cell clusters or cystic structures and containing calcitonin-positive C-cells. In conclusion, Wistar/ST rats developed unilateral thyroid dysgenesis and may be novel and useful animal models for thyroid hemiagenesis in humans and for morphogenesis of pharyngeal pouch-derived organs.

Slc:Hartley guinea pigs frequently possess duplication of the caudal vena cava.

The formation of the caudal vena cava is a complex process involving development, regression, and anastomosis. In mammals, the normal caudal vena cava runs to the right side of the abdominal aorta, while duplication of the caudal vena cava has been identified as a congenital abnormality in both companion animals and humans. The present study demonstrates that Slc:Hartley guinea pigs frequently possess asymptomatic duplicated caudal vena cava. The prevalence was 30% and 24% for males and females, respectively, with no sex-related differences. In accordance with Saad et al. (2012)'s criteria, duplicated caudal vena cava were classified into two distinct variations. The dominant variation was a complete duplication without iliac anastomosis where the left caudal vena cava continued from the left common iliac vein and joined the left renal vein; the left renal vein ran to the right to join the right caudal vena cava. The alternative variation was an incomplete duplication where the left caudal vena cava joined the right infrarenal caudal vena cava at a more cranial point than in normal cases; the renal segment was unchanged. Iliac anastomosis was not found in any cases. Duplicated caudal vena cava neither affected the body weight nor the kidney weight. In conclusion, Slc:Hartley guinea pigs frequently possess asymptomatic duplicated caudal vena cava in the absence of iliac anastomosis and appear to be a novel and useful animal model for duplicated caudal vena cava in animals and humans.

Restricted localization of ultimobranchial body remnants and parafollicular cells in the one-humped camel (Camelus dromedarius).

Parafollicular cells (C-cells) exist within the thyroid glands and display different distributions within the glands among mammalian species. In the one-humped camel (Camelus dromedarius), localization of the C-cells remains under debate. We herein investigated appearance of C-cells and the remnants of the ultimobranchial body, origin of C-cells, in the thyroid glands of one-humped camels. Macroscopically, a white mass was present at one-third the length from the cranial end of the thyroid glands where the cranial thyroid artery entered. In addition, large fossae were frequently found adjacent to the white mass. Histologically, the mass was mainly composed of connective tissues, thyroid follicles, and two types of cell clusters: one was composed of cells with clear cytoplasm and the other was composed of non-keratinized epidermoid cells. The mass and the fossae contained p63-positive cells, indicating that they consisted of ultimobranchial body remnants. Calcitonin was expressed in cells with clear cytoplasm, which were localized just beneath the fossae and in the cell clusters of the white mass. C-cells also resided in both subfollicular and interfollicular spaces adjacent to the white mass, but gradually decreased toward the periphery. C-cells tended to display round shapes in the ultimobranchial body remnants and subfollicular spaces, and spindle shapes in interfollicular spaces. In conclusion, we demonstrated that the ultimobranchial body remnants were limited to the region around the entrance of cranial thyroid artery and vein, and C-cells were mainly concentrated within and around the ultimobranchial body remnants.

Cotton rats (Sigmodon hispidus) possess pharyngeal pouch remnants originating from different primordia.

Pharyngeal pouches in mammals develop into specific derivatives. If the differentiation of the pharyngeal pouches is anomalous, their remnants can result in cysts, sinuses, and fistulae in the differentiated organs or around the neck. In the present study, we found several pharyngeal pouch remnants, such as cystic structures in thymus and parathyroid gland and fossulae extended from the piriform fossa, in the inbred cotton rats maintained at Hokkaido Institute of Public Health (HIS/Hiph) and University of Miyazaki (HIS/Mz). In HIS/Hiph, the fossulae extended from the apex of the piriform fossa into the thyroid glands and were lined with stratified squamous and cuboidal epithelium. Calcitonin-positive C-cells were present within their epithelium in HIS/Hiph. In contrast, the fossulae of HIS/Mz ran outside the thyroid glands toward the parathyroid glands; they were lined with columnar ciliated epithelium and a few goblet cells, but had no C-cells, which was consistent with the cystic structures in the thymus and the parathyroid gland. These results indicated that the fossulae were a remnant of the ultimobranchial body in HIS/Hiph and of the thymopharyngeal duct in HIS/Mz. Thus, the fossulae of the piriform fossa resembled the piriform sinus fistula in human. In conclusion, cotton rats frequently possessed pharyngeal pouch remnants, including the piriform sinus fistula, and therefore, might serve as a novel model to elucidate the mechanisms of pharyngeal pouch development.

Ovarian mast cells migrate toward ovary-fimbria connection in neonatal MRL/MpJ mice.

MRL/MpJ mice have abundant ovarian mast cells (MCs) as compared with other strains at postnatal day 0 (P0); however, they sharply decrease after birth. These ovarian MCs, particularly beneath the ovarian surface epithelium (SE), which express mucosal MC (MMC) marker, might participate in early follicular development. This study investigated the changes in spatiotemporal distribution of MCs in the perinatal MRL/MpJ mouse ovaries. At P0 to P7, the MCs were densely localized to the ovary, especially their caudomedial region around the ovary-fimbria connection. The neonatal ovarian MCs showed intermediate characteristics of MMC and connective tissue MC (CTMC), and the latter phenotype became evident with aging. However, the expression ratio of the MMC to CTMC marker increased from P0 to P4 in the MRL/MpJ mouse ovary. Similarly, the ratio of MCs facing SE to total MC number increased with aging, although the number of ovarian MCs decreased, indicating the relative increase in MMC phenotypes in the early neonatal ovary. Neither proliferating nor apoptotic MCs were found in the MRL/MpJ mouse ovaries. The parenchymal cells surrounding MCs at ovary-fimbria connection showed similar molecular expression patterns (E-cadherin+/Foxl2-/Gata4+) as that of the ovarian surface epithelial cells. At P2, around the ovary-fimbria connection, c-kit- immature oocytes formed clusters called nests, and some MCs localized adjacent to c-kit- oocytes within the nests. These results indicated that in postnatal MRL/MpJ mice, ovarian MCs changed their distribution by migrating toward the parenchymal cells composing ovary-fimbria connection, which possessed similar characteristics to the ovarian surface epithelium. Thus, we elucidated the spatiotemporal alterations of the ovarian MCs in MRL/MpJ mice, and suggested their importance during the early follicular development by migrating toward the ovary-fimbria connection. MRL/MpJ mice would be useful to elucidate the relationship between neonatal immunity and reproductive systems.

Effects of a mixture of medetomidine, midazolam and butorphanol on anesthesia and blood biochemistry and the antagonizing action of atipamezole in hamsters.

Syrian golden hamsters (Mesocricetus auratus) are useful laboratory rodents for studying human infectious diseases, metabolic diseases and cancer. In other rodents, such as mice and rats, a mixture of medetomidine, midazolam and butorphanol functions as a useful anesthetic, although it alters some blood biochemical parameters. In this study, we examined the effects of this mixture on anesthesia and blood biochemical parameters, and the action of atipamezole, a medetomidine antagonist, in hamsters. Intramuscular injection of a mixture of medetomidine, midazolam and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, had a short induction time (within 5 min) and produced an anesthetic duration of approximately 100 min in hamsters. We also demonstrated that 0.15 mg/kg of atipamezole, corresponding to the same dose as medetomidine, made hamsters recover quickly from anesthesia. The anesthetic agent markedly altered metabolic parameters, such as plasma glucose and insulin; however, 0.15 mg/kg of atipamezole returned these levels to normal range within approximately 10 min after the injection. The anesthetic also slightly altered mineral levels, such as plasma inorganic phosphorus, calcium and sodium; the latter two were also improved by atipamezole. Our results indicated that the mixture of medetomidine, midazolam, and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, functioned as an effective anesthetic, and atipamezole was useful for antagonizing both anesthesia and biochemical alteration in hamsters.

Genetic background-dependent diversity in renal failure caused by the tensin2 gene deficiency in the mouse.

Tensin2 (Tns2) is thought to be a component of the cytoskeletal structures linking actin filaments with focal adhesions and is known to play a role as an intracellular signal transduction mediator through integrin in podocytes, although the mechanism by which it functions remains unclear. A Tns2-null mutation (nph) leads to massive albuminuria following podocyte foot process effacement in the ICGN mice, the origin of the mutation, and the DBA/2J (D2) mice, but not in the C57BL/6J (B6) mice or 129(+Ter)/SvJcl (129T) mice. Elucidating the reasons for these differences in diverse genetic backgrounds could help in unraveling Tns2 function in podocytes. We produced congenic mice in which Tns2(nph) was introgressed into a FVB/NJ background (FVB-Tns2(nph)), and evaluated the progression of kidney disease. FVB-Tns2(nph) mice developed albuminuria, renal fibrosis and renal anemia as seen in ICGN mice. The FVB-Tns2(nph) mice demonstrated podocyte foot process alteration under an electron microscope by as early as 4 weeks of age. This revealed that FVB strain is susceptible to Tns2-deficiency.

Quantitative trait Loci for resistance to the congenital nephropathy in tensin 2-deficient mice.

The ICR-derived glomerulonephritis (ICGN) mouse is a chronic kidney disease (CKD) model that is characterized histologically by glomerulosclerosis, vascular sclerosis and tubulointerstitial fibrosis, and clinically by proteinuria and anemia, which are common symptoms and pathological changes associated with a variety of kidney diseases. Previously, we performed a quantitative trait locus (QTL) analysis to identify the causative genes for proteinuria in ICGN mice, and found a deletion mutation of the tensin 2 gene (Tns2nph, MGI no: 2447990). Interestingly, the congenic strain carrying the Tns2nph mutation on a C57BL/6J (B6) genetic background exhibited milder phenotypes than did ICGN mice, indicating the presence of several modifier genes controlling the disease phenotype. In this study, to identify the modifier/resistant loci for CKD progression in Tns2-deficient mice, we performed QTL analysis using backcross progenies from susceptible ICGN and resistant B6 mice. We identified a significant locus on chromosome (Chr) 2 (LOD = 5.36; 31 cM) and two suggestive loci on Chrs 10 (LOD = 2.27; 64 cM) and X (LOD = 2.65; 67 cM) with linkage to the severity of tubulointerstitial injury. One significant locus on Chr 13 (LOD = 3.49; approximately 14 cM) and one suggestive locus on Chr 2 (LOD = 2.41; 51 cM) were identified as QTLs for the severity of glomerulosclerosis. Suggestive locus in BUN was also detected in the same Chr 2 region (LOD = 2.34; 51 cM). A locus on Chr 2 (36 cM) was significantly linked with HGB (LOD = 4.47) and HCT (LOD = 3.58). Four novel epistatic loci controlling either HGB or tubulointerstitial injury were discovered. Further genetic analysis should lead to identification of CKD modifier gene(s), aiding early diagnosis and providing novel approaches to the discovery of drugs for the treatment and possible prevention of kidney disease.

Genomic analysis of the appearance of ovarian mast cells in neonatal MRL/MpJ mice.

In MRL/MpJ mice, ovarian mast cells (OMCs) are more abundant than in other mouse strains, and tend to distribute beneath the ovarian surface epithelium at birth. This study investigated the factors regulating the appearance of neonatal OMCs in progeny of the cross between MRL/MpJ and C57BL/6N strains. F1 neonates had less than half the number of OMCs than MRL/MpJ. Interestingly, MRLB6F1 had more neonatal OMCs than B6MRLF1, although they were distributed over comparable areas. Furthermore, in MRL/MpJ fetuses for which parturition was delayed until embryonic day 21.5, the number of OMCs was significantly higher than in age-matched controls at postnatal day 2. These results suggest that the number of OMCs was influenced by the environmental factors during pregnancy. Quantitative trait locus analysis using N2 backcross progeny revealed two significant loci on chromosome 8: D8Mit343-D8Mit312 for the number of OMCs and D8Mit86-D8Mit89 for their distribution, designated as mast cell in the ovary of MRL/MpJ 1 (mcom1) and mcom2, respectively. Among MC migration-associated genes, ovarian expression of chemokine (C-C motif) ligand 17 at mcom1 locus was significantly higher in MRL/MpJ than in C57BL/6N, and positively correlated with the expression of OMC marker genes. These results indicate that the appearance of neonatal OMCs in MRL/MpJ is controlled by environmental factors and filial genetic factors, and that the abundance and distribution of OMCs are regulated by independent filial genetic elements.

Relationship between numerous mast cells and early follicular development in neonatal MRL/MpJ mouse ovaries.

In the neonatal mouse ovary, clusters of oocytes called nests break into smaller cysts and subsequently form individual follicles. During this period, we found numerous mast cells in the ovary of MRL/MpJ mice and investigated their appearance and morphology with follicular development. The ovarian mast cells, which were already present at postnatal day 0, tended to localize adjacent to the surface epithelium. Among 11 different mouse strains, MRL/MpJ mice possessed the greatest number of ovarian mast cells. Ovarian mast cells were also found in DBA/1, BALB/c, NZW, and DBA/2 mice but rarely in C57BL/6, NZB, AKR, C3H/He, CBA, and ICR mice. The ovarian mast cells expressed connective tissue mast cell markers, although mast cells around the surface epithelium also expressed a mucosal mast cell marker in MRL/MpJ mice. Some ovarian mast cells migrated into the oocyte nests and directly contacted the compressed and degenerated oocytes. In MRL/MpJ mice, the number of oocytes in the nest was significantly lower than in the other strains, and the number of oocytes showed a positive correlation with the number of ovarian mast cells. The gene expression of a mast cell marker also correlated with the expression of an oocyte nest marker, suggesting a link between the appearance of ovarian ? 4mast cells and early follicular development. Furthermore, the expression of follicle developmental markers was significantly higher in MRL/MpJ mice than in C57BL/6 mice. These results indicate that the appearance of ovarian mast cells is a unique phenotype of neonatal MRL/MpJ mice, and that ovarian mast cells participate in early follicular development, especially nest breakdown.

The 129 genetic background affects susceptibility to glomerulosclerosis in tensin2-deficient mice.

The ICGN mouse strain is a glomerulosclerosis (GS) model that shows significant proteinuria, podocyte morphological abnormalities and increased extracellular matrix accumulation in the glomeruli, which represent the final common pathology associated with a variety of kidney diseases leading to end-stage renal failure. Previously, we demonstrated that GS in ICGN mice can be attributed to the deletion mutation of the tensin2 (Tns2) gene (Tns2(nep)). Further, the C57BL/6J (B6) mouse is resistant to GS caused by this mutation. 129/Sv is also a popular strain; however, its susceptibility to GS has not been defined. Thus, to determine whether 129/Sv is resistant or susceptible to GS, we produced a congenic strain carrying Tns2(nep) on the 129(+Ter)/Sv (129T) background. 129T congenic mice (129T-Tns2(nep)) did not exhibit albuminuria, renal anemia, increases in BUN, or any severe pathological changes until at least 16 weeks of age. These results indicate that 129T is resistant to GS. Although their usage in biomedical studies is already widespread, 129/Sv mice may afford a late-onset and unique strain applicable to kidney disease research.

Distinct distribution of the tensin family in the mouse kidney and small intestine.

Tensin family members are cytoplasmic proteins that are localized to the integrin-mediated cell-basement membrane junctions and implicated in cytoskeletal organization, cell migration, and proliferation. The mammalian genome contains four paralogs, Tns1, Tns2, Tns3, and Tns4. Murine mutations in the Tns1 and Tns2 genes cause polycystic kidney disease and glomerular sclerosis, respectively, and Tns3-null mice exhibit an impaired intestinal epithelial development. However, the knowledge concerning the localization of each tensin is still fragmentary. In this study, the cellular and subcellular distributions of tensin members were defined and compared with each other. RT-PCR analysis indicated that Tns2 and Tns3 were more abundant in isolated glomeruli and that Tns1 was highly expressed in areas other than the glomeruli, but no Tns4 expression was observed in the kidney. All tensin members were detected in the small intestine. Immunohistochemical staining revealed that Tns1 was predominantly localized to the mesangium of glomeruli and renal tubules. In contrast, Tns2 and Tns3 were highly expressed in the podocytes and the partial collecting system. In the small intestine, Tns2 and Tns3 were highly expressed in crypt and villous epithelial cells. Furthermore, we found that Tns3 was colocalized with TJ protein ZO-1 in renal tubules. These results indicate distinct differences in the cellular expression of Tns1, Tns2, and Tns3, and suggest that they may be able to function independently of each other in the kidney and the small intestine.