Cortical sponge kidneys induced in rats by alloxan

Acute alloxan toxicity causes granulomatous tubulointerstitial nephritis with severe mineralization

Alloxan had been recognized as having a direct nephrotoxic effect different from its diabetogenic action. We encountered previously unreported granulomatous tubulointerstitial nephritis with severe luminal and interstitial mineralization in one diabetic rat after one week of alloxan administration. Histopathologically, many dilated and occluded proximal and distal tubules were segmentally observed in the cortex and outer medulla. The tubular lumen contained minerals and cell debris. Tubular epithelial cells were degenerated and piled up, and they protruded into the lumen, where they enveloped minerals. Mineralization was observed mainly in the tubular lumen, and to some extent in the subepithelium and interstitium. The mineralization beneath the tubular epithelium was often continuous from the subepithelium to the interstitium. In these lesions, the tubular basement membrane was disrupted by mineralization, and a granuloma with multinuclear foreign-body giant cells was formed in the interstitial areas.

Acute alloxan renal toxicity in the rat initially causes degeneration of thick ascending limbs of Henle

Alloxan (AL) is a material well-known to induce diabetes. Prior to inducing a prolonged diabetic state, AL causes acute tubulointerstitial nephritis. However, the precise primary target site and mechanism of its nephrotoxicity remain unclear. The objective of this study was to evaluate the morphological characteristics relevant to acute renal toxicity following AL administration. Rats were intravenously treated with AL. Eight hours after AL treatment, aquaporin 1-negative and Na/K pump-positive thick ascending limbs of Henle (TAL) were degenerated in the outer medulla. These tubular lesions progressed from the outer medulla to the cortex. At day 2 after AL treatment, the lesions reached a peak, then both proximal and distal tubules also showed degeneration and necrosis, and tubular regeneration was seen in TAL. Immunohistochemically, damaged tubular epithelium included slightly enlarged prohibitin-positive granules, but it expressed no GLUT2, which is an AL transporter. Ultrastructurally, cytoplasmic and mitochondrial swelling was detected in degenerated cells of TAL. These findings suggest that AL initially causes degeneration of TAL, and induces mitochondrial and cellular damage in the tubular epithelium without involving GLUT2.

A new diabetes model induced by neonatal alloxan treatment in rats

Rats treated with streptozotocin (STZ) during the neonatal period have been used as a model of non-insulin-dependent diabetes mellitus. The present study was designed to produce another diabetes model by substituting alloxan for STZ. Male Sprague-Dawley rats of 2, 4 or 6 days of age were injected intraperitoneally with 200 mg/kg of alloxan monohydrate after 16 h fast. Control rats received vehicle alone at 6 days of age. Non-fasting plasma glucose levels in alloxan-treated rats significantly increased after 8 weeks as compared with control, as the age of alloxan treatment advanced (6.6 +/- 0.2 (S.E.M.) mM in control, 8.3 +/- 0.3 mM in 2 days, P < 0.05, 9.8 +/- 0.9 mM in 4 days, P < 0.05, 17.1 +/- 3.5 mM in 6 days, P < 0.05). For the long-term observation, alloxan-treated rats were divided into mild and severe diabetes groups. Hyperglycemia persisted in both groups until 52 weeks (6.5 +/- 0.1 mM in control, 10.3 +/- 0.7 mM in mild diabetes group, 25.3 +/- 3.6 mM in severe group), but significant albuminuria developed only in severe diabetes group. The diabetogenicity of alloxan rapidly increased during the neonatal period, and the neonatal alloxan diabetes model may be useful for studying chronic diabetic complications.

A new gastric juice peptide, BPC. An overview of the stomach-stress-organoprotection hypothesis and beneficial effects of BPC

The possibility that the stomach, affected by general stress, might initiate a counter-response has not until recently been considered in theories of stress. We suggest that the stomach, as the most sensitive part of the gastrointestinal tract and the largest neuroendocrine organ in the body, is crucial for the initiation of a full stress response against all noxious stress pathology. The end result would be a strong protection of all organs invaded by 'stress'. Consistent with this assumption, this coping response is best explained in terms of 'organoprotection'. Endogenous organoprotectors (eg prostaglandins, somatostatin, dopamine) are proposed as mediators. Such an endogenous counteraction could even be afforded by their suitable application. A new gastric juice peptide, M(r) 40,000, named BPC, was recently isolated. Herein, a 15 amino acid fragment (BPC 157), thought to be essential for its activity, has been fully characterized and investigated. As has been demonstrated for many organoprotective agents using different models of various tissue lesions, despite the poorly understood final mechanism, practically all organ systems appear to benefit from BPC activity. These effects have been achieved in many species using very low dosages (mostly microgram and ng/kg range) after ip, ig, and intramucosal (local) application. The effect was apparent already after one application. Long lasting activity was also demonstrated. BPC was highly effective when applied simultaneously with noxious agents or in already pathological, as well as chronical, conditions. Therefore, it seems that BPC treatment does not share any of the so far known limitations for 'conventional organoprotectors'. No influence on different basal parameters and no toxicity were observed. These findings provide a breakthrough in stress theory. BPC, as a possible endogenous free radical scavenger and organoprotection mediator, could be a useful prototype of a new class of drugs, organoprotective agents.

The effect of alloxan, and alloxan-induced diabetes on the kidney

Alloxan is known to induce diabetic renal changes as well as causing nephrotoxic alterations. However, no ultrastructural study has been performed to differentiate diabetic verses toxic affects of alloxan to the tubule and/or glomerulus. Therefore the present study used the "protected" kidney model to prevent one kidney from being exposed to the alloxan while allowing the other to receive the drug immediately. In all experimental animals the right renal hilum was gently occluded for 5 minutes and then released. This was performed prior to the injection of alloxan. Subsequently, the left renal hilum was occluded at the time of, and for 5 minutes after, alloxan administration (40 mg/kg i.v.). The experimental rats were divided into three groups: untreated diabetics, diabetics treated with protamine-zinc-insulin, and alloxan-treated rats that failed to become diabetic. Three groups of controls were included: one group received an equal volume of saline diluent as the experimental rats but no clamping of either renal hilum; another group received the saline and had the left renal hilum occluded for 5 minutes; and a third group had both the right and left renal hila occluded. All animals were followed and sacrificed after 9 weeks. Endogenous creatinine clearance did not change among groups. Alloxan-treated nondiabetic rats displayed marked interstitial nephritis in unprotected kidneys, while protected kidneys were normal. The diabetic state resulted in mesangial proliferation and focal glomerular basement membrane thickening as well as glomerular capillary endothelial abnormalities and visceral epithelial foot-process fusion. The endothelial changes consisted of focal areas showing a reduction in the size of endothelial fenestrae. All glomerular changes were ameliorated by insulin treatment. We conclude: 1) alloxan per se is distinctly nephrotoxic; and 2) the glomerular endothelium and epithelium are involved early in the course of experimental diabetes.

Renal transplantation in diabetes mellitus in rats

Immunoglobulins and complement are deposited in the glomerular mesangium of rats with progressive glomerulosclerosis secondary to chemically induced diabetes mellitus. Isotransplantation of a kidney from a rat diabetic for 6 mo into a normal recipient results within 2 mo in the disappearance of IgG, IgM, and beta(1)C from the mesangium and arrest or reversal of the light microscopic glomerular lesions. Kidneys isotransplanted from normal donors into diabetic rats developed mesangial matrix thickening and deposition of IgG, IgM) and beta(1)C in the mesangium. No glomerular changes occur upon transplantation of a normal kidney into a normal rat. These findings indicate that diabetic glomerular changes in the rat are reversible and are secondary to the diabetic state rather than to the inducing agent.

Experimental diabetic ketoacidosis. Sequential changes of metabolic intermediates in blood, liver, cerebrospinal fluid and brain after acute insulin deprivation in the streptozotocin-diabetic rat

Male rats rendered diabetic by the intravenous injection of streptozotocin (150mg/kg) were treated with a long-acting insulin for 1 week, then allowed to develop ketoacidosis. By using sampling techniques designed to avoid the use of anaesthesia and extended anoxic periods, sequential measurements of metabolic intermediates were made in blood, liver, cerebrospinal fluid and brain at 24h intervals after the last insulin injection. Measurements in blood and liver suggested a rapid increase in hepatic glycogenolysis and gluconeogenesis and peripheral-depot lipolysis between 24 and 48h after the last insulin injection, whereas blood and liver ketone-body and triglyceride concentrations rose more slowly. The changing metabolic patterns occurring with increasing time of insulin deprivation stress the importance of sequential compared with static measurements in experimental diabetes. Data are presented for brain metabolic intermediates in diabetic ketoacidosis, and support recent evidence that glucose plays a less important role in brain oxidative metabolism in ketotic states.