Characterization of the analgesic and anti-inflammatory activities of ketorolac and its enantiomers in the rat. (17/64177)

The marked analgesic efficacy of ketorolac in humans, relative to other nonsteroidal anti-inflammatory drugs (NSAIDs), has lead to speculation as to whether additional non-NSAID mechanism(s) contribute to its analgesic actions. To evaluate this possibility, we characterized (R,S)-ketorolac's pharmacological properties in vivo and in vitro using the nonselective cyclooxygenase (COX) inhibitors [indomethacin (INDO) and diclofenac sodium (DS)] as well as the selective COX-2 inhibitor, celecoxib, as references. The potency of racemic (R,S)-ketorolac was similar in tests of acetic acid-induced writhing, carrageenan-induced paw hyperalgesia, and carrageenan-induced edema formation in rats; ID50 values = 0.24, 0. 29, and 0.08 mg/kg, respectively. (R,S)-ketorolac's actions were stereospecific, with (S)-ketorolac possessing the biological activity of the racemate in the above tests. The analgesic potencies for (R,S)-, (S)-, and (R)-ketorolac, INDO, and DS were highly correlated with their anti-inflammatory potencies, suggesting a common mechanism. (R,S)-ketorolac was significantly more potent than INDO or DS in vivo. Neither difference in relative potency of COX inhibition for (R,S)-ketorolac over INDO and DS nor activity of (S)-ketorolac at a number of other enzymes, channels, or receptors could account for the differences in observed potency. The distribution coefficient for (R,S)-ketorolac was approximately 30-fold less than for DS or INDO, indicating that (R,S)-ketorolac is much less lipophilic than these NSAIDs. Therefore, the physicochemical and pharmacokinetics properties of (R,S)-ketorolac may optimize the concentrations of (S)-ketorolac at its biological target(s), resulting in greater efficacy and potency in vivo.  (+info)

Effect of riluzole on the neurological and neuropathological changes in an animal model of cardiac arrest-induced movement disorder. (18/64177)

Posthypoxic myoclonus and seizures precipitate as secondary neurological consequences in ischemic/hypoxic insults of the central nervous system. Neuronal hyperexcitation may be due to excessive activation of glutamatergic neurotransmission, an effect that has been shown to follow ischemic/hypoxic events. Therefore, riluzole, an anticonvulsant that inhibits the release of glutamate by stabilizing the inactivated state of activated voltage-sensitive sodium channels, was tested for its antimyoclonic and neuroprotective properties in the cardiac arrest-induced animal model of posthypoxic myoclonus. Riluzole (4-12 mg/kg i.p.) dose-dependently attenuated the audiogenic seizures and action myoclonus seen in this animal model. Histological examination using Nissl staining and the novel Fluoro-Jade histochemistry in cardiac-arrested animals showed an extensive neuronal degeneration in the hippocampus and cerebellum. Riluzole treatment almost completely prevented the neuronal degeneration in these brain areas. The neuroprotective effect was more pronounced in hippocampal pyramidal neurons and cerebellar Purkinje cells. These effects were seen at therapeutically relevant doses of riluzole, and the animals tolerated the treatment well. These findings indicate that the pathogenesis of posthypoxic myoclonus and seizure may involve excessive activation of glutamate neurotransmission, and that riluzole may serve as an effective pharmacological agent with neuroprotective potential for the treatment of neurological conditions associated with cardiac arrest in humans.  (+info)

Recovery following relief of unilateral ureteral obstruction in the neonatal rat. (19/64177)

BACKGROUND: Obstructive nephropathy is a primary cause of renal insufficiency in infants and children. This study was designed to distinguish the reversible and irreversible cellular consequences of temporary unilateral ureteral obstruction (UUO) on the developing kidney. METHODS: Rats were subjected to UUO or sham operation in the first 48 hours of life, and the obstruction was removed five days later (or was left in place). Kidneys were removed for study 14 or 28 days later. In additional groups, kidneys were removed at the end of five days of obstruction. Immunoreactive distribution of renin was determined in arterioles, and the distribution of epidermal growth factor, transforming growth factor-beta1, clusterin, vimentin, and alpha-smooth muscle actin was determined in tubules and/or interstitium. The number of glomeruli, glomerular maturation, tubular atrophy, and interstitial collagen deposition was determined by morphometry. Renal cellular proliferation and apoptosis were measured by proliferating cell nuclear antigen and the TdT uridine-nick-end-label technique, respectively. The glomerular filtration rate was measured by inulin clearance. RESULTS: Renal microvascular renin maintained a fetal distribution with persistent UUO; this was partially reversed by the relief of obstruction. Although glomerular maturation was also delayed and glomerular volume was reduced by UUO, the relief of obstruction prevented the reduction in glomerular volume. Although relief of obstruction did not reverse a 40% reduction in the number of nephrons, the glomerular filtration rate of the postobstructed kidney was normal. The relief of obstruction did not improve tubular cell proliferation and only partially reduced apoptosis induced by UUO. This was associated with a persistent reduction in the tubular epidermal growth factor. In addition, the relief of obstruction reduced but did not normalize tubular expression of transforming growth factor-beta1, clusterin, and vimentin, all of which are evidence of persistent tubular injury. The relief of obstruction significantly reduced interstitial fibrosis and expression of alpha-smooth muscle actin by interstitial fibroblasts, but not to normal levels. CONCLUSIONS: The relief of obstruction in the neonatal rat attenuates, but does not reverse, renal vascular, glomerular, tubular, and interstitial injury resulting from five days of UUO. Hyperfiltration by remaining nephrons and residual tubulointerstitial injury in the postobstructed kidney are likely to lead to deterioration of renal function later in life.  (+info)

22-oxacalcitriol suppresses secondary hyperparathyroidism without inducing low bone turnover in dogs with renal failure. (20/64177)

BACKGROUND: Calcitriol therapy suppresses serum levels of parathyroid hormone (PTH) in patients with renal failure but has several drawbacks, including hypercalcemia and/or marked suppression of bone turnover, which may lead to adynamic bone disease. A new vitamin D analogue, 22-oxacalcitriol (OCT), has been shown to have promising characteristics. This study was undertaken to determine the effects of OCT on serum PTH levels and bone turnover in states of normal or impaired renal function. METHODS: Sixty dogs were either nephrectomized (Nx, N = 38) or sham-operated (Sham, N = 22). The animals received supplemental phosphate to enhance PTH secretion. Fourteen weeks after the start of phosphate supplementation, half of the Nx and Sham dogs received doses of OCT (three times per week); the other half were given vehicle for 60 weeks. Thereafter, the treatment modalities for a subset of animals were crossed over for an additional eight months. Biochemical and hormonal indices of calcium and bone metabolism were measured throughout the study, and bone biopsies were done at baseline, 60 weeks after OCT or vehicle treatment, and at the end of the crossover period. RESULTS: In Nx dogs, OCT significantly decreased serum PTH levels soon after the induction of renal insufficiency. In long-standing secondary hyperparathyroidism, OCT (0.03 microg/kg) stabilized serum PTH levels during the first months. Serum PTH levels rose thereafter, but the rise was less pronounced compared with baseline than the rise seen in Nx control. These effects were accompanied by episodes of hypercalcemia and hyperphosphatemia. In animals with normal renal function, OCT induced a transient decrease in serum PTH levels at a dose of 0.1 microg/kg, which was not sustained with lowering of the doses. In Nx dogs, OCT reversed abnormal bone formation, such as woven osteoid and fibrosis, but did not significantly alter the level of bone turnover. In addition, OCT improved mineralization lag time, (that is, the rate at which osteoid mineralizes) in both Nx and Sham dogs. CONCLUSIONS: These results indicate that even though OCT does not completely prevent the occurrence of hypercalcemia in experimental dogs with renal insufficiency, it may be of use in the management of secondary hyperparathyroidism because it does not induce low bone turnover and, therefore, does not increase the risk of adynamic bone disease.  (+info)

Up-regulation of glomerular extracellular matrix and transforming growth factor-beta expression in RF/J mice. (21/64177)

BACKGROUND: RF/J mice were first reported as a murine model of spontaneous glomerulosclerosis by Gude and Lupton in 1960, but the precise histologic characteristics and immunopathological background of this mouse have not been investigated further. METHODS: Measurements of serum levels of immunoglobulins, anti-single strand DNA (anti-ss-DNA) antibody, complement (C3), and circulating immune complex (IC) were performed. Analyses of glomerular histological and immunopathological lesions in association with the detection of mRNA expression of collagen IV, TGF-beta, matrix protein turnover related enzymes, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2) and platelet-derived growth factor (PDGF) were also performed in young (10-week-old) and elderly (60-week-old) RF/J mice with age-matched BALB/C mice as the controls. RESULTS: High levels of serum IgA and IgG from as early as 20 weeks of age were noted in the RF/J mice. Serum anti-ss-DNA antibody of aged RF/J mice increased up to 23% of that of aged MRL-lpr/lpr mice, and serum C3 concentration significantly decreased with age, reaching lower levels than that of BALB/c mice. IgA-IC levels were significantly high compared to BALB/C mice both in the early and late stages of life, whereas IgG-IC levels were high only in mice younger than 20 weeks. Semiquantitative and quantitative analyzes of renal histopathological findings revealed significantly marked and age-related mesangial matrix expansion in RF/J mice, with increasing frequency of global glomerular sclerosis and tubulointerstitial damage. On the other hand, although precise measurements of glomerular cell numbers also showed an apparent augmentation in both young and old RF/J mice compared to BALB/C mice, glomerular cellularity decreased with age in RF/J mice. Immunohistochemical study revealed massive immunoglobulin deposition from a young age in association with significantly higher accumulation of matrix proteins, such as types I and IV collagen and laminin from the early stage of life. In addition, in these glomeruli, transforming growth factor-beta1 (TGF-beta1) was highly expressed both in young and old mice. The mRNA expression of MMP-2 was up-regulated only in the early stage of life. Although PDGF mRNA of RF/J mice was significantly up-regulated in the early stage of life, the differences between the mice disappeared in the late stage of life. CONCLUSIONS: These findings suggest that in RF/J mice, an immunopathological background inducing high serum immunoglobulin and IC levels from the early stage of life is closely related to mesangioproliferative glomerular lesions mediated by PDGF, and that development of massive extracellular matrix accumulation in glomeruli was induced by up-regulated expression of TGF-beta with inappropriate regulation of protein turnover-related enzyme production.  (+info)

Blocking angiotensin II ameliorates proteinuria and glomerular lesions in progressive mesangioproliferative glomerulonephritis. (22/64177)

BACKGROUND: The renin-angiotensin system is thought to be involved in the progression of glomerulonephritis (GN) into end-stage renal failure (ESRF) because of the observed renoprotective effects of angiotensin-converting enzyme inhibitors (ACEIs). However, ACEIs have pharmacological effects other than ACE inhibition that may help lower blood pressure and preserve glomerular structure. We previously reported a new animal model of progressive glomerulosclerosis induced by a single intravenous injection of an anti-Thy-1 monoclonal antibody, MoAb 1-22-3, in uninephrectomized rats. Using this new model of progressive GN, we examined the hypothesis that ACEIs prevent the progression to ESRF by modulating the effects of angiotensin II (Ang II) on the production of transforming growth factor-beta (TGF-beta) and extracellular matrix components. METHODS: We studied the effect of an ACEI (cilazapril) and an Ang II type 1 receptor antagonist (candesartan) on the clinical features and morphological lesions in the rat model previously reported. After 10 weeks of treatment with equihypotensive doses of cilazapril, cilazapril plus Hoe 140 (a bradykinin receptor B2 antagonist), candesartan, and hydralazine, we examined systolic blood pressure, urinary protein excretion, creatinine clearance, the glomerulosclerosis index, and the tubulointerstitial lesion index. We performed a semiquantitative evaluation of glomerular immunostaining for TGF-beta and collagen types I and III by immunofluorescence study and of these cortical mRNA levels by Northern blot analysis. RESULTS: Untreated rats developed massive proteinuria, renal dysfunction, and severe glomerular and tubulointerstitial injury, whereas uninephrectomized control rats did not. There was a significant increase in the levels of glomerular protein and cortical mRNA for TGF-beta and collagen types I and III in untreated rats. Cilazapril and candesartan prevented massive proteinuria, increased creatinine clearance, and ameliorated glomerular and tubulointerstitial injury. These drugs also reduced levels of glomerular protein and cortical mRNA for TGF-beta and collagen types I and III. Hoe 140 failed to blunt the renoprotective effect of cilazapril. Hydralazine did not exhibit a renoprotective effect. CONCLUSION: These results indicate that ACEIs prevent the progression to ESRF by modulating the effects of Ang II via Ang II type 1 receptor on the production of TGF-beta and collagen types I and III, as well as on intrarenal hemodynamics, but not by either increasing bradykinin activity or reducing blood pressure in this rat model of mesangial proliferative GN.  (+info)

Proteinuria induces tubular cell turnover: A potential mechanism for tubular atrophy. (23/64177)

BACKGROUND: Proteinuria and tubular atrophy have both been closely linked with progressive renal failure. We hypothesized that apoptosis may be induced by tubular cell exposure to heavy proteinuria, potentially leading to tubular atrophy. Apoptosis was studied in a rat model of "pure" proteinuria, which does not induce renal impairment, namely protein-overload proteinuria. METHODS: Adult female Lewis rats underwent intraperitoneal injection of 2 g of bovine serum albumin (BSA, N = 16) or sham saline injections (controls, N = 8) daily for seven days. Apoptosis was assessed at day 7 in tissue sections using in situ end labeling (ISEL) and electron microscopy. ISEL-positive nuclei (apoptotic particles) were counted in blinded fashion using image analysis with NIH Image. Cell proliferation was assessed by detection of mRNA for histone by in situ hybridization, followed by counting of positive cells using NIH Image. RESULTS: Animals injected with saline showed very low levels of apoptosis on image analysis. BSA-injected rats had heavy proteinuria and showed both cortical and medullary apoptosis on ISEL. This was predominantly seen in the tubules and, to a lesser extent, in the interstitial compartment. Overall, the animals injected with BSA showed a significant 30-fold increase in the number of cortical apoptotic particles. Electron microscopy of tubular cells in a BSA-injected animal showed a progression of ultrastructural changes consistent with tubular cell apoptosis. The BSA-injected animals also displayed a significant increase in proximal tubular cell proliferation. This increased proliferation was less marked than the degree of apoptosis. CONCLUSION: Protein-overload proteinuria in rats induces tubular cell apoptosis. This effect is only partially balanced by proliferation and potentially provides a direct mechanism whereby heavy proteinuria can induce tubular atrophy and progressive renal failure.  (+info)

Mycophenolate mofetil prevents the progressive renal failure induced by 5/6 renal ablation in rats. (24/64177)

BACKGROUND: Extensive renal ablation is associated with progressive sclerosis of the remnant kidney. Because lymphocytes and monocytes accumulate in the remnant kidney, it is likely that they play a role in the renal scarring. Therefore, we treated rats with 5/6 nephrectomy (5/6Nx) with mycophenolate mofetil (MMF), a drug that has an antiproliferative effect and that suppresses the expression of intercellular adhesion molecules. METHODS: Sprague-Dawley rats with 5/6Nx received MMF (30 mg. kg-1. day-1 by daily gastric gavage, N = 15) or vehicle (N = 16). Ten additional rats were sham operated. All rats were fed a 30% protein diet. Body weight, serum creatinine, and urinary protein excretion were determined weekly. Lipid peroxidation, as a measure of oxidative stress observed by urinary malondialdehyde determinations, was performed every two weeks. Histologic studies were done in the remnant kidney four weeks (9 rats from the vehicle-treated group, 7 rats from the MMF group, and 5 sham-operated rats) and eight weeks after surgery (the remaining rats). Glomerular volume, sclerosis in glomeruli (segmental and global) and interstitium (semiquantitative scale), infiltrating lymphocytes and macrophages (CD43- and ED1-positive cells), and expression of adhesion molecules (CD54, CD18, and CD11b) were analyzed. RESULTS: MMF treatment prevented the progressive increment in serum creatinine and the proteinuria observed in the 5/6 nephrectomized rats during the eight weeks of observation (P < 0.01). Weight gain was comparable in the MMF-treated and sham-operated rats, whereas weight gain was decreased in untreated 5/6 nephrectomized rats. Excretion of malondialdehyde increased after surgery but returned sooner to control levels in the MMF-treated rats. Increments in glomerular size and mean arterial blood pressure induced by renal ablation were not modified by MMF treatment. Eight weeks after surgery, segmental sclerosis was present in 48.4 +/- 8.35% (+/- sd) glomeruli in the vehicle-treated group versus 25 +/- 10.5% in the MMF-treated group (P < 0.001). Interstitial fibrosis was reduced significantly with MMF treatment (P < 0.001). Infiltration with CD43- and ED1-positive cells in glomeruli and interstitium was two to five times lower in MMF-treated rats (P < 0.01). Expression of adhesion molecules CD18 and CD11b was similarly reduced. CONCLUSION: MMF ameliorates the progressive renal damage in the remnant kidney after 5/6Nx. This effect is associated with a reduction in the infiltration of lymphocytes and monocytes, whereas glomerular hypertrophy and systemic hypertension are unchanged.  (+info)