Fischer Strain Rats Research Articles

Host-Derived Endothelial Regeneration of Corneal Transplants in a Rat Keratoplasty Model

Background: It has been observed that formerly rejected opaque corneal transplants can regain clarity in the rat. We hypothesized that graft endothelium is regenerated by the host. Therefore, we used green fluorescent protein (GFP) transgenic rats to assess the origin of cells following keratoplasty. Methods: Allogeneic corneal transplantations were carried out between Fischer strain rats as graft donors and GFP-transgenic Lewis rats as recipients. In a second group, syngeneic transplantations were performed between GFP-negative Lewis donors and GFP-positive Lewis recipients, where endothelial-cell-free grafts after mechanical endothelial debridement were used. All grafts were followed up clinically for signs of opacity and rejection. After 6 weeks, corneal flatmounts counterstained with DAPI were analyzed by confocal microscopy. Results: Syngeneic transplantation of endothelial-cell-free grafts led to medium opacity levels without rejection and to subsequent clearing. All grafts showed a population of GFP-positive, host-derived endothelial cells on the graft after 6 weeks. In the allogeneic transplantation group, all grafts but one were rejected after a median of 17 days. While the graft that was not rejected maintained the GFP-negative transplant endothelium, all formerly rejected grafts showed GFP-positive endothelium on the transplant after 6 weeks, accompanied by clinical clearing of the graft. Conclusion: GPF positivity shows that in both a syngeneic and an allogeneic setting, the host-derived corneal endothelium can compensate for the endothelial cell loss of the graft. Following rejection, the grafts are repopulated by host-derived endothelial cells in the rat. This finding demonstrates a high regenerative capacity of the peripheral corneal endothelium in the rat, which should be considered whenever interpreting rat keratoplasty results.

T‐cell seeding: neonatal transfer of anti‐myelin basic protein T‐cell lines renders Fischer rats susceptible later in life to the active induction of experimental autoimmune encephalitis

Fischer strain rats resist active induction of experimental autoimmune encephalomyelitis (EAE) following immunization with guinea-pig myelin basic protein (MBP) in complete Freund's adjuvant (CFA). Nevertheless, we now report that an encephalitogenic CD4(+) anti-MBP T-cell line could be developed from actively immunized Fischer rats. Adoptive transfer of the activated line mediated acute EAE in adult Fischer rats, but not in 1-day-old rats. Moreover, we found that both resting and activated anti-MBP T cells injected 1 day post-natally rendered these rats susceptible later in life to the active induction of EAE by immunization with MBP/CFA. The actively induced EAE manifested the accelerated onset of a secondary, memory-type response. Resting anti-MBP T cells injected even up to 2 weeks post-natally produced no clinical signs but seeded 50-100% of the recipients for an active encephalitogenic immune response to MBP. An earlier T-cell injection (1-2 days) produced a higher incidence and stronger response. The transferred resting T cells entered the neonatal spleen and thymus and proliferated there but did not change the total anti-MBP precursor number in adults. Splenocytes harvested from rats that were injected neonatally but not exposed to MBP in vivo proliferated strongly and produced significant amounts of interferon-gamma to MBP in vitro. Similar results were observed in rats injected with resting T-cell lines reactive to ovalbumin, suggesting that the neonatal injection of resting T cells specific for a self or for a foreign antigen can seed the immune system with the potential for an enhanced effector response to that antigen later in life.

Effects of atrazine on reproductive performance in the rat.

The effects of subacute exposure to atrazine on body weight, ovarian cycling, conception rate and the size of litters in Fischer strain rats were studied. An atrazine dose of 120 mg kg-1 body wt given p.o. daily for 7 days to both female and male rats caused statistically significant loss of body weight in both sexes during the period of treatment. After the cessation of treatment the body weight of female rats remained below control body weights at least for 2 weeks. In male rats the difference in body weights narrowed with time and reached control level 5 days after the last dose. Atrazine caused a significant increase in the relative weights of pituitary and prostate. Atrazine also transiently prolonged the oestrous cycle, characterized by extended vaginal dioestrus. As a result of disturbed ovarian cycling, the rate of successful mating decreased in the first week after treatment when both sexes were exposed or exposed females were mated with an unexposed male. No similar effect was observed when only the males were exposed. The size of litters did not differ significantly between experimental groups.

Histopathological changes induced by thermal exposure in the rat liver

To clarify the effects of a thermal environment on rats, histopathological changes, and temperatures in the rectum and eyes of Fischer strain rats exposed to a thermal environment of 32 degrees C for 2 days or 7 days were investigated. Thermal exposure to 32 degrees C induced elevations in rectal and ocular temperatures. The increased temperature levels persisted during the thermal exposure. Vacuolar degeneration surrounding the hepatic vein was observed in rat livers exposed to 32 degrees C for 7 days. No abnormalities were observed in other organs. These results indicate that thermal exposure to 32 degrees C induces vacuolar degeneration in hepatocytes due to the elevation of body temperature.

Sex and strain differences in the circadian rhythm fluctuation of endocrine and immune function in the rat: implications for rodent models of autoimmune disease

This study compares 24-h basal patterns of corticosterone and immunoreactivity for Lewis and Fischer (F344) strain rats. Significant differences in the circadian rhythm of plasma corticosterone were found across sex and strain. Male Lewis rats exhibited significantly lower 24-h corticosterone levels relative to female Lewis and male F344 rats. In addition, male Lewis rats were found to have higher mononuclear cell counts than female Lewis or male F344 rats, particularly in the peripheral blood and spleen compartments. Levels of CD4-bearing lymphocytes in blood, lymph node, and spleen were found to be higher in Lewis rats compared to the F344 strain over a 24-h period. In general, percentages of CD8- and major histocompatibility complex (MHC) class II-bearing lymphocytes were shown to vary over 24 h in all compartments across strains. Given that the Lewis rat has low basal levels of circulating corticosterone, and comparatively higher numbers of CD4-bearing lymphocytes, these factors may play a causative role in the known susceptibility of this strain to many experimental models of autoimmune disease.

High-fat diets stimulate transient hyperphagia whereas wet diets stimulate prolonged hyperphagia in Fischer rats

The effectiveness of several different kinds of diets in stimulating hyperphagia in Fischer strain rats was compared. Of three different high-fat diets examined, only one stimulated significant hyperphagia and stimulated weight gain; this diet was high in both fat and carbohydrate. However, this hyperphagia and increased weight gain was transient, lasting less than four weeks. A high-sucrose diet stimulated energy intake for only one week. In contrast, adding water to a high-starch diet or adding saccharin to a wet diet stimulated energy intake and weight gain for at least ten weeks. Once water or saccharin were removed from these diets, hyperphagia subsided or even turned into hypophagia, until body weights approached control levels. The degree of hyperphagia during the first week did not correlate with subsequent hyperphagia or weight gain. These results suggest that wet diets act by different mechanisms than do dry high-fat and high-sucrose diets.

Anti-adenovirus type 5 cytotoxic T lymphocytes: immunodominant epitopes are encoded by the E1A gene

Virus specific, major histocompatibility complex-restricted, cytotoxic T lymphocytes (CTL) generated in Fischer strain rats infected with human adenovirus type 5 (Ad5) were found to recognize antigenic determinants encoded within the Ad5 early region 1A (E1A) gene. Preliminary mapping studies suggest that the E1A CTL epitopes are encoded within the regions between bp 625 to 810 and 916 to 974 in the first exon of this gene. These epitope-coding regions occur within subregions of E1A that are conserved functionally, and to some extent structurally (approximately 50% sequence homology), among adenoviruses of different groups. Nevertheless, Ad5-specific CTL lysed only targets infected with adenoviruses of the same group (group C; e.g., Ad2) and not targets infected with adenoviruses of different groups (groups A, B, and E). These results suggest that virus-specific CTL may limit adenoviral dissemination by destroying virus-infected cells at an early stage in the viral replicative cycle, during E1A gene expression. Expression of other adenovirus genes does not appear to be required to target infected cells for elimination by CTL.

Induction of lymphokine-activated killer cells from rat thymocytes using recombinant human interleukin-2.

Using a 4-h 51Cr release assay, we observed that thymocytes from Fischer strain rats incubated with recombinant human interleukin-2 (rhIL-2) developed cytotoxicity to YAC-1 lymphoma, 9L-glioma, and B-16 melanoma cells (effector/target ratio = 25/1). Induction of the lymphokine-activated killer (LAK) cells was as follows: (1) when 5 x 10(6)/ml thymocytes were cultured with various concentrations of rhIL-2 (50, 125, 250, 500, or 1,000 units/ml) for 4 days, no cell proliferation was observed at any concentration. However, the LAK cells showed significant cytotoxicity toward all tumor cells at more than 50 units/ml. (2) When 5 x 10(6)/ml thymocytes were cultured for 1 to 6 days with 250 units/ml of rhIL-2, the harvested cell count decreased markedly after the 2nd day. The cytotoxicity of all the tumor cells became significant after the 2nd day, with peak activity on the 4th day. In rat splenocytes, on the other hand, the LAK cells could not be identified because rat splenocytes developed nonspecific cytotoxicity in medium containing fetal calf serum without adding rhIL-2.

Blood coagulation abnormalities in Fischer strain rats bearing tumors

This study reports an unusual subpopulation of rats bearing transplanted tumors approximately 50% of the total and apparently unrelated to the presence of metastases, that exhibited shortened bleeding times despite reduced platelet numbers and/or fibrinogen levels. The remaining rats exhibited the expected inverse relationships between bleeding time and platelet numbers and/or fibrinogen level. Tumors were hepatomas and squamous cell carcinomas initially induced in the Fischer strain of rats and carried by passage through tissue culture or syngenic recipient animals.

Fetal intestinal transplants in syngeneic rats: a developmental model of intestinal immunity.

We conducted a longitudinal study of the development of lymphoid tissue in fetal small intestine transplanted to a subcutaneous site in adult syngeneic Fischer strain rats. Fetal jejunoileal segments obtained between 18 and 21 days of gestation were transplanted to a dorsal subcutaneous site on syngeneic adult rats. Three weeks later, intestinal segments greater than 2.5 cm in length were found in 70% of recipients. Each week for 6 wk post-transplantation, a full-thickness biopsy was obtained for histologic and immunohistologic examination. At the time of transplantation, fetal rat intestine did not display Peyer's patches, intraepithelial lymphocytes, lymphoid follicles, or IgA-containing plasma cells. These lymphoid structures reached adult levels by 4 wk after transplantation, and the sequence of development of the lymphoid structures in the transplants appeared to match the postnatal development of normal small intestine. After immunizing the in situ intestine or the transplanted fetal intestine with cholera toxin, the number of cells producing specific antibodies to the immunogen increased significantly in intestinal transplants and in situ intestine. In contrast, few if any cells synthesizing antibodies to cholera toxin developed in the transplants after i.p. immunization. This study suggests that fetal intestinal transplants behave as part of the mucosal immune system. This model may provide useful approaches to studying the development of mucosal immunity.

Functional capacity of solid tissue transplants in the brain: evidence for immunological privilege.

The capacity of the mammalian brain to support the physiological function of allografts was assessed in parathyroidectomized Fischer strain rats bearing either isografts or immunogenic DA allografts of parathyroid glands implanted in their cerebral cortices. Established isografts and allografts survived indefinitely in the brain, maintaining normal serum calcium levels, with equal numbers of spontaneous failures (18-21%) in each group. Similarly, both MHC-compatible and incompatible skin allografts survived and were 'functional' at 40-50 days postgrafting as assessed by: continued formation of keratin; the presence of differentiated hair follicles and sebaceous glands; and frequent mitotic figures. No serum alloantibodies were induced by either MHC-incompatible parathyroid glands or skin in this site. However, both types of allografts were promptly rejected or failed to become established in the brains of specifically presensitized hosts. Furthermore, when Fischer hosts with long-established intracerebral DA parathyroid grafts received orthotopic DA skin grafts, their parathyroid grafts were rejected along with first-set rejection of the skin grafts. The tempo of this cellular immune response and the primary alloantibody response that accompanied it indicate that although the intracerebral grafts failed to induce detectable host sensitization or suppression, they remained susceptible to immune effectors. Thus, by using strongly immunogenic, adult tissues, we have established that the rat cerebral cortex is an immunologically privileged site, and the privilege is not dependent on lack of graft immunogenicity or alterations in host responsiveness. Furthermore, Ia+ (possible antigen-presenting) cells were rare in the cortical parenchyma sites used for transplantation though numerous in the choroid plexus of the ventricles and in certain areas of white matter. Therefore, privilege probably reflects deficient graft antigen presentation related to the paucity of Ia+ cells as well as to the brain's poor lymphatic drainage.

Hymenolepis nana: Maturation in an immunosuppressed unnatural rat host

When eggs of the dwarf tapeworm Hymenolepis nana, cycled exclusively and directly through mice for more than 10 years, were inoculated into previously uninfected inbred Fischer (F344) strain rats, they failed to mature in the rat intestinal lumen. Eggs of H. nana inoculated into the rat developed normally into cysticercoids (cysts) in the intestinal tissue, but thereafter failed to mature in the lumen except when the host was treated with cortisone acetate from the day of cyst maturation. The Fischer rat initially given eggs of H. nana became completely immune to egg challenge within 2 days of egg inoculation; no cysts derived from challenge eggs were found in the immunized rat. Immunosuppression, assessed by the success of cyst recovery in the tissue 4 days after egg challenge, had no promotive effect on the recovery of adult worms derived from eggs initially inoculated. Rats initially given eggs and immunosuppressed by cyclophosphamide or antithymocyte serum did not harbor any adult worms. Cortisone acetate treatment which was sufficient for eggs inoculated to mature (a total of 75 or even 200 mg, from Day 5 of egg inoculation) had no effects of immunosuppression, whereas cortisone acetate treatment which was sufficient for immunosuppression (a total of 150 mg from Day -2, two days prior to the initial egg inoculation) induced some adult formation as well. In addition, when mouse-derived cysts were inoculated into the rat instead of eggs, they also failed completely to mature even when the rat was treated with cyclophosphamide or antithimocyte serum. However, when the rat was treated with cortisone acetate from the day of cyst inoculation, the cysts developed into adult worms. Therefore, these results indicate that the Fischer rat clearly differs in its susceptibility to the tissue phase of egg inoculation and to the lumen phase of cyst inoculation of H. nana, and strongly suggest that the failure of maturation of H. nana in the unnatural host Fischer rat is not attributed to innate and/ or acquired immunity of the rat but to other nonimmunological mechanisms.

Effect of protein nutrition throughout gestation and lactation on growth, morbidity and life span of rat progeny.

Thirteen Fischer strain rats were divided randomly into 3 groups soon after became pregnant and fed a 10%, 18%, or 36% casein diet throughout pregnancy and lactation. At weaning, female pups from the dams were divided into 3 further groups which were fed throughout life 10%, 18%, or 36% casein diet. The animals were weighed regularly and given a full autopsy after death. DNA was determined in the cerebrum and cerebellum of progeny at 7, 15 and 50 weeks of age respectively. The level of protein intake of the dams did not affect the litter-size, but did affect the body weight of pups at weaning. When fed a high protein diet after weaning, pups from dams fed a low protein diet weighed less throughout life than those from dams fed a high protein diet. A similar effect of protein intake was observed on the tail length. Pups of dams fed a low protein diet ate a larger amount of diet per unit body weight after weaning than those of dams fed at a high level of protein. Pups at 7, 15, and 50 weeks of age respectively from dams fed 10% casein diet had a lighter cerebrum and cerebellum than pups of the same ages from dams fed respectively 18% and 36% casein diet. They also had less total DNA in the cerebrum and cerebellum than the latter. At the ages of 1 and 2 years respectively, the survival rates of rats fed the same diet as their mothers tended to be greater than those of rats fed diet different from that of their mothers. They also tended to live longer than the latter: 4 of 60 rats lived for over 1,000 days, and 3 of these were fed the same diet as that of their mothers. Lesions observed at death did not differ in different groups. However, the incidence of lesions of the kidney and the number of tumors seemed to be greater in groups fed a high protein diet.

Pharmacological studies on Perillae Herba. I. Neuropharmacological action of water extract and perillaldehyde (author's transl)

Neuropharmacological actions of the water extract of Perillae Herba, and perillaldehyde which is one of the main components of the essential oil of this crude drug, were examined. In ddY strain mice, a dose of 4g/kg, p.o. of the water extract and 100mg/kg, p.o. of perillaldehyde exerted a significant prolongation of sleeping time induced by the administration of hexobarbital Na but did not show any effects on the body temperature and the rotating rod performance. On the laryngeal reflex in cats, the water extract and perillaldehyde exerted a clear inhibitory effect, and such inhibitory effects were also observed on the excitable membranes by using an isolated snail's neuron and frog's sciatic nerve fibers. With the continuous administration of the water extract or perillaldehyde, only the water extract showed a depressive effect on the spontaneous locomoter activity in Fischer strain rats. These results suggest that the water extract of Perillae Herba and perillaldehyde have a depressive action on the central nervous system.

Behavioral characteristics of F344/DuCrj (Fischer) strain rats: spontaneous motor activity and acquisition of conditioned avoidance responses (author's transl)

In order to study the behavioral characteristics of F344/DuCrj (Fischer) strain rats, male rats of this strain were compared with those of the Wistar strain regarding both spontaneous motor activity and the processes of acquisition of conditioned avoidance responses under two types of avoidance situations, namely the Sidman (continuous) avoidance schedule and the discriminated (discrete) avoidance schedule with an escape contingency. It was found on the first point that the Fischer strain rats displayed higher activity than the Wistar strain rats under a 12 : 12 hr light-dark situation. On the second point, strain differences were observed in the processes of acquisition of the avoidance responses. Here, in the early stage of the training, the Fischer strain rats received many shocks than the Wistar strain rats under the Sidman avoidance situation, while the wistar strain rats showed a lower avoidance rate than the Fischer strain rats under the discriminated avoidance situation. However, in the final stages of the training, no marked difference was observed in the results between the two strains. The present results suggest that the Fischer strain rats may show behavioral characteristics those differ from the Wistar strain rats.

Effects of the co-mutagen norharman in rats

Studies were made on the acute and subacute toxic effects of the co-mutagen norharman when given orally to male Fischer strain rats. Animals were given diets containing 1500 ppm of norharman for 28 days, and 3 or 6 animals were killed for examination on days 0, 1, 3, 7, 14, 21, and 28. During norharman administration, the body weight and food and water intakes of the rats gradually decreased, the kidney weight increased significantly and blood urea nitrogen also increased. Norharman caused segmental coagulative necrosis of the tubular epithelium of the kidney, which increased in severity and extent with the period of treatment, but glomerular changes were negligible. In the testis, the germinal epithelium showed decreased spermatogenic activity after day 7. Norharman had no detectable effects on other organs.

Morphologic and Biologic Correlation of Hyperplastic and Neoplastic Renal Lesions Occurring in Buffalo and Fischer Strain Rats Ingesting N-4-(4'-Fluorobiphenyl)Acetamide

Hyperplastic and neoplastic lesions of the kidney induced in inbred Buffalo and Fisher strain rats with 0.04% N-4-(4'-fluorobiphenyl) acetamide were transplanted s.c. to rats of the same strain. Hyperplastic renal lesions ("areas" or nodules) did not survive and grow. Carcinomas of the kidney grew and killed the animals. Growth was related to the size and the degree of differentiation of the carcinoma. It is concluded that the histologic pattern of hyperplastic and neoplastic lesions of the kidney can be correlated with the results obtained on transplantation.

Factors inflencing tolerance to the effects of Δ9-THC on a conditioned avoidance response

Male, Fischer strain rats were resistant to the impairing effects of Δ 9-THC (15–60 mg/kg, IG) on performance of a conditioned pole-climb avoidance response (CAR) after daily subacute pretreatment for 4 or 6 days. A single administration of 20 mg/kg Δ 9-THC independent of the performance test did not attenuate the subsequent impairment caused by Δ 9-THC when tested 1–6 days later; however, administration 2 hr before each test attenuated the effect on subsequent tests given at intervals of 1–5 weeks. Similarly, subacute treatment with 20 mg/kg Δ 9-THC for 4 days independent of the performance test attenuated the impairment caused by Δ 9-THC during tests given to separate groups of rats 1 or 6, but not 14 days later. However, when the tests for tolerance were conducted repeatedly in the same rats, the attenuation appeared to persist for intervals up to 5 weeks. The results are discussed in terms of metabolic, functional and compensatory (behavioral) tolerance.

HUMORAL ANTIBODY RESPONSE IN RAT RENAL ALLOTRANSPLANTATIO,N1

Female inbred Fischer (F344) rats were grafted with kidneys from female BN rats. Humoral antibodies in some of the recipients were demonstrated as early as 3 days after transplantation: (1) antibodies bound to the graft were detected by mixed agglutination tests with graft sections and erythrocytes of the donor as indicator cells; (2) lytic and agglutinating antibodies against donor strain erythrocytes were demonstrated in the recipients' sera by hemolysis in agar gel and dextran hemagglutination tests; and (3) similar antibodies secreted by a significant number of cells were detected in the recipients' spleens by plaque assay. The antibody response of the recipients was directed against a single antigen, designated N, which was shown to be present on erythrocytes of 57% of Fischer strain rats and was shared by erythrocytes of all rat strains tested (BN, Lewis, Wistar, ACI, MAXX, and Buffalo). The N antigen did not seem to belong to any known rat histocompatibility antigen system. Segregation of the gene coding for this antigen within the Fischer strain would indicate residual genetic heterogeneity. Evidence was presented that this antigen is present not only on erythrocytes, but also on other cells including splenocytes.

SKIN GRAFTS IN NUDE MICE

Nude mice of each of the three genetic backgrounds BALB/c, C3H, and C57/BL readily accept skin heterotransplants from inbred Fischer strain rats and other rat strains. Second set transplants from the same donors are also readily accepted. In all instances graft take was uneventful, and the final appearance of grafts was as in normal animals of the donor strain. This event contrasts strongly with that observed in similar nude mice receiving allotransplants. Allograft take was delayed, and although ultimate acceptance was virtually 100 per cent, many grafts evidenced endogenous damage occurring during the acceptance process. This damage was manifested by tufted irregular hair growth in many cases, and by bare atrophic, though vital, areas of graft skin. Also strikingly contrasting were the findings that allografting in nude mice excited no cytotoxic antibody response, while cytotoxic antibody titres in serum of nude mice receiving heterotransplants were moderate to high. Thymus grafting confers capacity for heterograft rejxsection.