X-irradiated Rats Research Articles

Human Umbilical Cord Blood-Derived CD133+CD34+ Cells Protect Retinal Endothelial Cells and Ganglion Cells in X-Irradiated Rats through Angioprotective and Neurotrophic Factors.

Radiation retinopathy (RR) is a common complication following radiation therapy of globe, head, and neck malignancies, and is characterized by microangiopathy, neuroretinopathy, and the irreversible loss of visual function. To date, there is no effective treatment for RR. Stem cells have been clinically used to treat retinal degeneration. CD133+CD34+ cells from human umbilical cord blood (hUCB-CD133+CD34+ cells), a subpopulation of hematopoietic stem cells, were applied to determine their protective efficacy on irradiated rat retinas. After X-ray irradiation on the retinas, rats were intravitreally injected with hUCB-CD133+CD34+ cells. Transplantation of hUCB-CD133+CD34+ cells prevented retinal dysfunction 2 weeks post-operation and lasted at least 8 weeks. CD133+CD34+ cells were distributed along the retinal vessel and migrated to the ganglion cell layer. Moreover, grafted CD133+CD34+ cells reduced the apoptosis of endothelial and ganglion cells in irradiated rats and increased the number of survived CD31+ retinal endothelial cells and Brn3a+ ganglion cells at 2 and 4 weeks, respectively, post-operation. Co-culturing of CD133+CD34+ cells or supernatants with irradiated human retinal microvascular endothelial cells (hRECs) in vitro, confirmed that CD133+CD34+ cells ameliorated hREC apoptosis caused by irradiation. Mechanistically, we found that angioprotective mediators and neurotrophic factors were secreted by CD133+CD34+ cells, which might attenuate irradiation-induced injury of retinal endothelial cells and ganglion cells. hUCB-CD133+CD34+ cell transplantation, as a novel treatment, protects retinal endothelial and ganglion cells of X-irradiated rat retinas, possibly through angioprotective and neurotrophic factors.

Single neonatal irradiation induces long-term gene expression changes in the thyroid gland, which may be involved in the tumorigenesis

Exposure to ionizing radiation in childhood has been recognized as a risk factor for thyroid cancer. We previously demonstrated that neonatal X-irradiation induced specific deformation of the thyroid follicles. Here, we further analyzed this model to understand the possible relationship with thyroid carcinogenesis. Wistar rats were subjected to cervical X-irradiation at different ages of 1–8 weeks old and at different doses of 1.5–12 Gy. For tumor promotion, rats were fed with an iodine-deficient diet (IDD). In cervically X-irradiated neonatal rats, the size of thyroid follicles decreased, accompanied by an increase in the number of TUNEL-positive cells. Fas and Lgals3 mRNA levels increased, while Mct8 and Lat4 expressions decreased. The co-administration of IDD induced the proliferation and the upregulation in Lgals3 expression, resulting in thyroid adenoma development at 28 weeks post-exposure. Our data demonstrated that single neonatal X-irradiation induced continuous apoptotic activity in the thyroid with the long-term alternation in Fas, Mct8, Lat4, and Lgals3 mRNA expressions. Some of these changes were similar to those induced by IDD, suggesting that neonatal X-irradiation may partially act as a thyroid tumor promoter. These radiation-induced thyroidal changes may be enhanced by the combined treatment with IDD, resulting in the early development of thyroid adenoma.

Radioprotective Effect of Thymoquinone in X-irradiated Rats.

Background:Thymoquinone, has anti-inflammatory, anti-oxidant, and cardio protection properties. This study aimed to evaluate the radioprotective effect of thymoquinone in whole body X-irradiated rats. Methods:This study conducted on 40 male adult Wistar albino rats randomized into the following groups: Group I: Control rats did not receive thymoquinone or ionizing radiation. Group II: Whole-body irradiated rats with 6 Gy of X-ray. Group III: Rats orally intubated with thymoquinone (10 mg/kg/day) for 7 days then subjected to whole-body irradiation with 6 Gy then supplemented with thymoquinone for another 7 days. Group IV: Rats orally intubated with thymoquinone (20 mg/kg/day) for 7 days then subjected to whole-body irradiation with 6 Gy then supplemented with thymoquinone (20 mg/kg/day) for another 7 days. LDH, CK-MB, ALT, AST, MDA, TAC, Catalase activity, GPX, GSR and GSH were measured. Results:Lipid peroxidation biomarker in the blood of X-irradiated rats significantly increased and accompanied by decrease in the levels of GSH, GSR, GPX, catalase as well as TAC. Moreover, exposure to IR significantly increases cardiac and liver enzymes. However, administration of TQ to X-irradiated rats with either 10 mg/kg or 20 mg/kg have the same reform effects and significantly protects rats against adverse effects of IR. Conclusion:Exposure to X-ray leads to significant changes in cellular biochemical and morphological conditions. Administration of TQ before radiation treatment significantly decreases the adverse effects of IR. TQ can improve cardiac function, decrease myocardial enzyme levels and inhibit oxidative stress.

Metformin prolongs survival rate in mice and causes increased excretion of cell-free DNA in the urine of X-irradiated rats

An antidiabetic drug metformin has anticarcinogenic and geroprotective effects and has been used in combination with radiation cancer therapy. The present work is devoted to the study of the effect of metformin on survival in mice, the frequency of micronuclei in mouse bone marrow cells and excretion of cell-free nuclear and mitochondrial DNA in the urine of X-ray-exposed rats. The survival rate and the frequency of micronuclei in mice and excretion of DNA into rat urine were determined after administration of the drug before and after irradiation of animals. The DNA content was measured by qRT-PCR. Metformin shows a radioprotective effect only when administered to mice after the radiation exposure. On the 11th day after irradiation, we observed 100% mortality in the control group; 78% of mice remained alive if metformin was given. Twenty percent of the mice in this group survived for 30 days after irradiation. Metformin has the same effect on the frequency of micronuclei; its reduction is observed, when the drug is administered to the mice after irradiation. Metformin promotes the excretion of nuclear and mitochondrial DNA with the urine of irradiated rats. The results show that metformin acts as a radiomitigation effector. Metformin promotes the active excretion of DNA of dying cells from the tissues of irradiated animals.

Low dose X-irradiation mitigates diazepam induced depression in rat brain

Depression is considered as one of the most prevalent health ailments. Various anti-depressant drugs have been used to provide succour to this ailment, but with little success and rather have resulted in many side effects. On the other hand, low dose of ionizing radiations are reported to exhibit many beneficial effects on human body by stimulating various biological processes. The present study was conducted to investigate the beneficial effects of low doses of X-rays, if any, during diazepam induced depression in rats. Female Sprague Dawley rats were segregated into four different groups viz: Normal control, Diazepam treated, X-irradiated and Diazepam + X-irradiated. Depression model was created in rats by subjecting them to diazepam treatment at a dosage of 2 mg/kg b.wt./day for 3 weeks. The skulls of animals belonging to X-irradiated and Diazepam + X-irradiated rats were X-irradiated with a single fraction of 0.5 Gy, given twice a day for 3 days, thereby delivered dose of 3 Gy. Diazepam treated animals showed significant alterations in the neurobehavior and neuro-histoarchitecture, which were improved after X-irradiation. Further, diazepam exposure significantly decreased the levels of neurotransmitters and acetylcholinesterase activity, but increased the monoamine oxidase activity in brain. Interestingly, X-rays exposure to diazepam treated rats increased the levels of neurotransmitters, acetylcholinesterase activity and decreased the monoamine oxidase activity. Further, depressed rats also showed increased oxidative stress with altered antioxidant parameters, which were normalized on X-rays exposure. The present study, suggests that low dose of ionizing radiations, shall prove to be an effective intervention and a novel therapy in controlling depression and possibly other brain related disorders.

Hepatic Nrf2 expression is altered by quercetin supplementation in X-irradiated rats

Whole-body irradiation has been associated with liver function alterations. Ionizing radiation exposure increases oxidative stress and antioxidants can activate transcription of antioxidant target genes. In the present study, modifications of the liver antioxidant system were evaluated at 7 and 30 days following sub-lethal whole-body X-irradiation in male Wistar rats, which were intragastrically supplemented with quercetin or control solvent for 4 days prior to and 6 days following irradiation. Animal groups were as follows: CS, control, solvent-supplemented; CQ, control, quercetin-supplemented; RS, irradiated, solvent-supplemented; and RQ, irradiated, quercetin-supplemented. After 7 days, liver tissue from RS animals demonstrated marked hydropic panlobular degeneration with Mallory bodies in ballooning hepatocytes. These changes were mostly reversed in RQ rats. Lipid peroxidation in addition to copper/zinc superoxide dismutase (Cu/Zn-SOD), nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) protein expression levels were all increased by X-irradiation, but significantly decreased by quercetin supplementation. Catalase (CAT) and quinone oxidoreductase 1 (NQO1) expression levels remained high in irradiated rats regardless of quercetin supplementation. After 30 days, the liver from RS animals had small portal infiltrates and diffuse cytoplasmic vacuolization, with reduced lipid peroxidation and reduced expression levels of CAT, NQO1, Nrf2 and Keap1, but consistently elevated Cu/Zn-SOD expression. RQ animals indicated reduced expression levels of Nrf2 and Keap1 30 days after irradiation. The present study demonstrated a quercetin-induced reduction of the oxidative stress-associated increase in Nrf2 expression that may be useful for preventing cancer cell survival in response to ionizing radiation exposure.

Evaluation of the potential protective effects of ad libitum black grape juice against liver oxidative damage in whole-body acute X-irradiated rats

Aims The aim of this study was to evaluate the potential protective effects of ad libitum black grape ( Vitis labrusca) juice against liver oxidative damage in whole-body acute X-irradiated rats. Main methods Animals were fed ad libitum and drank voluntarily black grape juice or placebo (isocaloric glucose and fructose solution) for 6 days before and 15 days following a 6 Gy X-irradiation from a 200 kV machine. Key findings Irradiated animals receiving placebo showed a significant increase in the concentration of thiobarbituric acid-reactive substances (TBARS), a marker of lipid peroxidation, as well as a significant decrease in both Cu/Zn superoxide dismutase (Cu/ZnSOD) and glutathione peroxidase (GPx) activity and reduced glutathione concentration (GSH). Black grape juice supplementation resulted in a reversal of lipid peroxidation, Cu/ZnSOD activity, and GSH concentration, towards values not significantly differing from those in non-irradiated, placebo-supplemented rats. Poly(ADP-ribose) polymerase (PARP-1) and Cu/ZnSOD changes in protein expression were observed for irradiated rats. No change in p53 expression or DNA fragmentation was found. Significance Ad libitum black grape juice intake is able to restore the liver primary antioxidant system against adverse effects due to whole-body acute X-irradiation in rats after 15 days post-irradiation. The results support using antioxidant supplements as a preventive tool against radiation-induced harm.

The effect of prenatal X-irradiation on the developing cerebral cortex of rats. II: A quantitative assessment of glial cells in the somatosensory cortex

The developing central nervous system is known to be highly vulnerable to X-irradiation. Although glial cells are involved in various brain functions, knowledge on the effects of X-irradiation on glial cells is limited. Therefore, the purpose of the present study was to evaluate the effects of prenatal X-irradiation on glial cells. Pregnant Wistar rats were exposed to X-irradiation at a dose of 1.0Gy on day 15 of gestation. Their offspring were examined at 7 weeks of age. The forebrain weight of X-irradiated rats was significantly lower than that of the age-matched controls. Histological quantification with stereology of the somatosensory cortex (SC) revealed no significant difference in the numerical density of glial cells between the X-irradiated and control rats. However, the glial cells in the X-irradiated animals had significantly larger nuclear size. We had previously reported that a similar X-irradiation paradigm resulted in no significant change in the numerical density of neurons in the SC. According to the results of the present study, there were no significant differences in the glial cell-to-neuron ratios between the X-irradiated and control animals. Taken together, it is speculated that prenatal X-irradiation has an equal effects on the numerical densities of glial cells and neurons.

Functional Recovery in a Friedreich's Ataxia Mouse Model by Frataxin Gene Transfer Using an HSV-1 Amplicon Vector

Functional Recovery in a Friedreich's Ataxia Mouse Model by Frataxin Gene Transfer Using an HSV-1 Amplicon Vector

Parathyroid hormone (PTH) and hematopoiesis: New support for some old observations

Forty-seven years ago, the parathyroid hormone (PTH) in one injection of Lilly's old bovine parathyroid extract, PTE, was found to greatly increase the 30-day survival of heavily X-irradiated rats when given from 18 h before to as long as 3 h after irradiation but no later. This was the first indication that PTH might stimulate hematopoiesis. Recent studies have confirmed the relation between PTH and hematopoiesis by showing that hPTH-(1-34)OH increases the size of the hematopoietic stem cell pool in mice. The peptide operates through a cyclic AMP-mediated burst of Jagged 1 production in osteoblastic cells lining the stem cells' niches on trabecular bone surfaces. The osteoblastic cells' Jagged 1 increases the hematopoietic stem cell pool by activating Notch receptors on attached stem cells. PTH-triggered cyclic AMP signals also directly stimulate the proliferation of the hematopoietic stem cells. However, the single PTH injection in the early experiments using PTE probably increased the survival of irradiated rats mainly by preventing the damaged hematopoietic progenitors from irreversibly initiating self-destructive apoptogenesis during the first 5 h after irradiation. It has also been shown that several daily injections of hPTH-(1-34)OH enable lethally irradiated mice to survive by stimulating the growth of transplanted normal bone marrow cells. If the osteogenic PTHs currently entering or on the verge of entering the market for treating osteoporosis can also drive hematopoiesis in humans as well as rodents, they could be potent tools for reducing the damage inflicted on bone marrow by cytotoxic cancer chemotherapeutic drugs and ionizing radiation.

Expression of matrix metalloproteinases and tissue inhibitor metalloproteinases increases in X-irradiated rat ileum despite the disappearance of CD8a T cells

To investigate their expression and activity in the rat ileum after exposure to ionizing radiation along with that of the cellular effectors and molecular mediators involved in the regulation of MMPs. Rats were exposed to a single 10-Gy dose of X-rays delivered to the abdomen. A combination of methods, such as zymography, immunohistochemistry and real time reverse transcriptase-polymerase chain reaction, were used to localize and quantify MMPs and the molecules involved in MMP activating and inhibitory pathways (plasmin/plasminogen, TIMPs), CD8+, as well as inflammatory (interleukin (IL)-1beta, IL-8, tumor necrosis factor-alpha, TNF-alpha) and fibrogenic mediators (transforming growth factor-beta1-3) within ileal tissue at 1, 3, and 7 d after irradiation. A marked increase in MMP-2 and -14 mRNA and protein levels associated with an increased activity of MMP-2 was observed in irradiated ileal tissue. MMP-2 and -14 expression was mainly observed in inflammatory, epithelial, and mesenchymal cells, whereas a slight increase in MMP-3 expression was detected in the few infiltrating macrophages at d 1 after irradiation. Conversely, MMP-1, -7, and -9 mRNA levels were not found to be affected by abdominal irradiation. Irradiation was found to induce disappearance of CD8+ cells. Furthermore, we have observed that TNF-alpha and IL-1beta protein levels increased 6 h after irradiation, whereas those of IL-8 only increased after 3 d and was concomitant with neutrophil infiltration. In addition, the expressions of molecules involved in MMP activating and inhibitory pathways (urokinase-type plasminogen activator and tissue-type plasminogen activator; TIMP-1, TIMP-2, and plasminogen activator-inhibitor-1) were found to be increased after abdominal irradiation. This study showed that abdominal irradiation induces an acute remodeling of the ileum associated with an increased expression of MMPs and TIMPs that do not involve CD8+ T cells but involve mesenchymal and epithelial cells, although to a lesser extent, and probably even soluble inflammatory and fibrogenic mediators.

Altered synaptic activities in cultures of neocortical neurons from prenatally X-irradiated rats

Prenatal X-irradiation can induce severe microcephaly in the brains of offspring. The possible alteration of neuronal synapse formation was examined in such X-irradiated rats with microcephaly using the whole-cell current clamp technique. The total number of neocortical cells from prenatally (E16) X-irradiated rats decreased to 16% of the control value, while the ratio of GABA-positive/MAP2-positive neurons increased 2.2-fold. Neocortical neurons from E17 normal rat fetuses cultured on monolayers of astrocytes for 7–10 days exhibited synchronized synaptically-driven rhythmic depolarizing potentials (RDPs). Neocortical neurons from prenatally (E15 or E16) X-irradiated rats also exhibited synchronized RDPs, however, their amplitude and the number of spikes decreased. These results suggest that, although neurons which survive in X-irradiated rats can form synapses, inhibitory inputs are predominant over excitatory inputs. It is possible that not only acute neuronal loss induced by X-irradiation but also increased inhibitory inputs in neocortex give rise to subsequent neurological disorders in X-irradiated rats.

Secretion of saliva in X-irradiated rat submandibular glands.

The mechanism of radiation-induced dysfunction in rat submandibular glands was investigated at the cellular level. After X irradiation (single dose, 15 Gy), a vacuolation in the acinar cells or an enlargement of the acinar lumen was observed as a typical morphological change for 2 weeks. As observed using a video-enhanced contrast differential interference contrast (VEC-DIC) microscope, exocytosis and shrinkage of the acinar cells induced by application of pilocarpine (100 microM) were markedly suppressed for 5 days and then recovered to 80% of the control levels. Using an immunohistochemical method, no significant change was observed in amylase distribution, but a marked loss of aquaporin 5 was found in the acinar cells after the irradiation. The extent and time course of pilocarpine-induced mobilization of intracellular Ca(2+) did not change after the irradiation. We conclude that radiation-induced dysfunction in the salivary glands is due to an impairment of exocytosis and a reduction of water secretion. The loss of aquaporin 5 and possibly other membrane-fusion proteins in acinar cells may be the major mechanism underlying such a dysfunction.

Cevimeline hydrochloride hydrate (Saligren capsule 30 mg): a review of its pharmacological profiles and clinical potential in xerostomia

Cevimeline hydrochloride hydrate is a muscarinic receptor agonist with a chemical structure of a quinuclidine. Intraduodenal administration of cevimeline hydrochloride hydrate dose-dependently increased salivary secretion in normal mice and rats, two strains of autoimmune disease mice, and X-irradiated rats. The clinical efficacy of the cevimeline hydrochlide hydrate at 30 mg t.i.d. during 4 weeks has been demonstrated in double blind comparative study with placebo. In addition, its treatments in 52 weeks have increased salivary flow and improved subjective and objective symptoms of patients with xerostomia in Sjögren's syndrome.

A proteomic approach to rapidly elucidate oligodendrocyte-associated proteins expressed in the myelinating rat optic nerve.

The lack of cDNA libraries derived from myelinating oligodendrocytes has hampered attempts to identify proteins associated with myelination during normal development or with remyelination after insult or disease. We, therefore, established a new method to elucidate such proteins by coupling the techniques of X-irradiation, two-dimensional (2-D) gel electrophoresis, and mass spectrometry. Specifically, 2-D gel protein profiles of normal optic nerves were compared with those of X-irradiated rat optic nerves, which were absent of oligodendrocytes, to elucidate oligodendrocyte-associated proteins. The subsequent identification of these oligodendrocyte-associated proteins was accomplished by mass spectrometry. The results presented in this paper demonstrate the potential of the X-irradiated optic nerve model system combined with proteomic techniques to rapidly elucidate oligodendrocyte-associated proteins expressed in vivo.

Does Eradication of Helicobacter Pylori Reverse Atrophic Gastritis or Intestinal Metaplasia? : Data from Japan

In Japan, more reports showing improvement of atrophy or IM after eradication have appeared than reports showing no change. Many authors take biopsy specimens from the lesser and greater curvatures of the antrum and body and incisura angularis and make a histologic assessment using the standardized Updated Sydney System. Sampling errors should be taken into account, however. Interobserver agreement is poor in grading of atrophy. Apart from these problems, it seems almost certain that some patients show improvement or regression of atrophy or IM after eradication. Takizawa et al, evaluating many gastritis specimens, observed that antral IM might regress after eradication in the antral mucosa, where some pyloric glands remained under IM because pyloric glands and IM shared the proliferative zone, and that body IM replacing total fundic glands might hardly regress (T. Takizawa, MD, personal communication). Suto et al showed in an animal model that pseudopyloric glands differentiated into chief and parietal cells. Watanabe et al examined the influence of gastric pH on IM in x-irradiated rats and showed that increased acid secretion was associated with partial disappearance of IM without Paneth cells. Because gastric acid secretion of hypochlorhydric patients with body-predominant gastritis increased into normal range 1 to 6 months after eradication, it is possible that IM may regress in human subjects whose acid-secreting capacity recovers after eradication. The point of no return at which eradication leads to regression of atrophy and IM is not known. It is unknown how long IM takes to regress after eradication. There may be some differences in the characteristics between patients with and without improvement. Factors other than H. pylori (e.g., environmental factors) also should be investigated.

Olivocerebellar Climbing Fibers in the Granuloprival Cerebellum: Morphological Study of Individual Axonal Projections in the X-Irradiated Rat

Elimination of cerebellar granule cells early during postnatal development produces abnormal neural organization that retains immature characteristics in the adult, including innervation of each Purkinje cell by multiple climbing fibers from the inferior olive. To elucidate mechanisms underlying development of the olivocerebellar projection, we studied light-microscopic morphology of single olivocerebellar axons labeled with biotinylated dextran amine in adult rats rendered agranular by a single postnatal X-irradiation. Each reconstructed olivocerebellar axon gave off approximately 12 climbing fibers, approximately twice as many as in normal rats. Terminal arborizations of climbing fibers made irregular tufts in most areas, whereas they were arranged vertically in a few mildly affected areas. Each climbing fiber terminal arborization innervated only part of the dendritic arbor of a Purkinje cell, and multiple climbing fibers innervated a single Purkinje cell. These climbing fibers originated either from the same olivocerebellar axon (pseudomultiple innervation) or from distinct axons (true multiple innervation). Abundant non-climbing fiber thin collaterals projected to all cortical layers. Although the longitudinal pattern of the zonal olivocerebellar projection was generally observed, lateral branching, including bilateral projections, was relatively frequent. These results suggest that the granule cell-parallel fiber system induces several important features of olivocerebellar projection: (1) organization of the climbing fiber terminal arborization tightly surrounding Purkinje cell dendrites, (2) elimination of pseudo- and true multiple innervations establishing one-to-one innervation, (3) retraction of non-climbing fiber thin collaterals from the molecular layer, and (4) probable refinement of the longitudinal projection domains by removing aberrant transverse branches.

Prenatal X-irradiation increases GFAP- and calbindin D28k-immunoreactivity in the medial subdivision of the nucleus of solitary tract in the rat

Glial fibrillary acidic protein- (GFAP) and calbindin D28k-immunoreactivity (IR) were investigated in the medial subdivision of the nucleus of the solitary tract (mNST) of prenatally X-irradiated rats. Pregnant rats were exposed to a single whole-body X-irradiation on day 11 or 16 of gestation at a dose of 1.3 Gy. The offspring were killed at 7–14 days of age for the immunohistochemical observations. Rat pups showed strong GFAP-IR at the level rostral to the obex when receiving X-rays on day 11 of gestation, with hypertrophy of astrocyte cell bodies and cytoplasmic processes, but weak GFAP-IR when receiving X-rays on day 16 of gestation. Calbindin D28k-IR was stronger in the animals receiving X-rays on day 11 or 16 of gestation compared to that in the control animals. In the present study, the increase of GFAP- and calbindin D28k-IR cells in the mNST might indicate that adaptative mechanisms are taking place to preserve integrated nervous system function and possibly, to provide neuroprotection.

GM1 ganglioside treatment protects against long-term neurotoxic effects of neonatal X-irradiation on cerebellar cortex cytoarchitecture and motor function

Exposure of neonatal rats to a 5 Gy dose of X-irradiation induces permanent abnormalities in cerebellar cortex cytoarchitecture (disarrangement of Purkinje cells, reduction of thickness of granular cortex) and neurochemistry (late increase in noradrenaline levels), and motor function (ataxic gait). The neuroprotective effects of gangliosides have been demonstrated using a variety of CNS injuries, including mechanical, electrolytic, neurotoxic, ischemic, and surgical lesions. Here, we evaluated whether systemically administered GM1 ganglioside protects against the long-term CNS abnormalities induced by a single exposure to ionizing radiation in the early post-natal period. Thus, neonatal rats were exposed to 5 Gy X-irradiation, and subcutaneously injected with one dose (30 mg/kg weight) of GM1 on h after exposure followed by three daily doses. Both at post-natal days 30 and 90, gait and cerebellar cytoarchitecture in X-irradiated rats were significantly impaired when compared to age-matched controls. By contrast, both at post-natal days 30 and 90, gait in X-irradiated rats that were treated with GM1 was not significantly different from that in non-irradiated animals. Furthermore, at post-natal day 90, cerebellar cytoarchitecture was still well preserved in GM1-treated, X-irradiated animals. GM1 failed to modify the radiation-induced increase in cerebellar noradrenaline levels. Present data indicate that exogenous GM1, repeatedly administered after neonatal X-irradiation, produces a long-term radioprotection, demonstrated at both cytoarchitectural and motor levels.

INFECTIOUS TOLERANCE IN RENAL ALLOGRAFTS: TH2 CYTOKINES AND INDUCTION OF "PROTECTIVE" GENES WHICH INHIBIT NF-??B ACTIVATION

672 CD4 mAb therapy generates donor-specific, regulatory T cells in heart allograft recipients (LBNF1->LEW) which upon transfer induce acceptance of LBNF1 cardiac allografts. Moreover, long-surviving cardiac allografts in recipients tolerized in this "infectious" manner were free of chronic rejection. We hypothesized absence of chronic rejection might involve induction of protective genes, e.g. hemoxygenase (HO-1), A20 and bcl family members which, in vitro, block activation of NF-κB in endothelial cells(EC). To test this, adoptive transfer of cells from tolerant cardiac allograft recipients into x-irradiated rats was performed and the latter were challenged with test renal isografts or allografts, followed by immunohistologic analysis of grafts at day 12 (adoptive transfer vs. irradiated controls) and day 45 (adoptive transfer). Irradiation alone did not prevent a mixed humoral and cellular response, with graft rejection by day 10 (n=4/ group). However, adoptive transfer of cells from tolerized recipients gave permanent renal engraftment and normal renal function(>100 days). Comparison of gene expression within renal allografts by quantitative image analysis (basal expression in isografts = 1 optical unit, mean ± SD), including detection of nuclear localizing sequence (NLS) of NF-κ showed:- FigureGene Expression in Renal Allografts (relative optical units)Thus, cell transfer in a renal allograft model suppressed Th1 cytokines and NF-κB activation at day 12, but not IL-4, IL-10 or HO-1 induction. By day 45, there was a marked Th2 predominance with EC expression of HO-1 and A20, and ongoing suppression of NFκB. These data suggest expression of protective genes may be instrumental to avoidance of transplant arteriosclerosis in the context of infectious tolerance and alloimmunity.