This study investigates the diabetes-induced lesions in liver and kidney and in addition the possible side effects of the diabetogenic substance streptozotocin (SR) on these organs in non-diabetic animals. 5-week-old female Wistar rats were injected 65 or 130 mg SR/kg body mass. Some animals of the drug group did not become hyperglycemic; thus it was possible to separate the drug effect from the diabetic influence on liver and kidney. In serum investigations some metabolic changes concerning the activities of the liver enzymes aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and the concentrations of urea and creatinine up to 30 days after drug application were studied. SR in hyperglycemic animals causes a time and dose dependent rise in all investigated parameters. Also in normoglycemic rats a significant increase in alkaline phosphatase and in creatinine was observed after 10 days. After 21 and 30 days there were no differences compared to untreated control rats, whereas elevated levels were observed in the hyperglycemic rats. Thus our results support the view of a short damaging effect of SR on liver and kidney without inducing a diabetic state; in hyperglycemic rats the damaging effect is more pronounced.
Methods for the determination of the red cell isoenzymes 6-PGD and acP by means of agarosegel thinlayer electrophoresis are referred. Using these relatively simple techniques, results can be obtained after at least two hours. The quality of separation in both systems is higher than that obtained after starch gel electrophoresis.
The quantitative distribution of the different structural elements on the surface of the motoneurons (MN) in the spinal cord of the frog was studied in thin sections and freeze-fracture replicas. In particular, the different synaptic types and their distribution on the MN soma and dendrites are described. In thin sections three types of synapses were discerned: the S-type with spherical vesicles, the F-type with flattened vesicles, and finally the C-type synapse with spherical vesicles and a subsynaptic cistern. The synaptic covering at the MN surface as determined by thin sections is about 36%. In freeze-fracture replicas were observed boutons with and without gap junctions, and C-type boutons. When using the latter technique the synaptic covering was found to be 43%. With both techniques special attention was paied to the morphology of the C-type bouton and both the subsynaptic and extrasynaptic cisterns. The soma membrane over the sub- and extrasynaptic cisterns reveals characteristic and very similar morphological features with respect to both the distribution and size of the membrane particles. the possible functions of the two cisternal types are discussed.
The uptake of utilizable dietary energy (DE) as affected by diet (containing 3 or 50% (w/w)fat), body mass (BM) and age was investigated in male Wistar rats. In comparing heavy-weight animals fed the high-fat diet (HFD) with light-weight animals fed the low-fat diet (LFD) (differences in BM up to 60%), it was found that the uptakes of DE calculated on animal were significantly higher (up to 55%) in the HFD animals than in the LFD animals; but there were no significant differences when the uptakes of DE were calculated on 100 g BM. Thus, the LFD rats (the diet of which contained a high proportion of protein (70% (w/w)) exhibited no reduced uptakes of utilizable DE as compared to HFD rats. Of the heavy-weight LFD animals and the light-weight HFD animals which showed virtually no differences in BM, the HFD animals take up more utilizable DE (per animal or per 100 g BM) than the LFD animals. This difference, which amounts to 60%, is statistically significant. The comparison of the uptakes of DE/animal/100 g BM by light-weight rats with those by heavy-weight rats fed the same diet showed that the uptakes by the heavy-weight animals were in most cases significantly greater. Consequently, the greater BM of the heavy-weight animals of the respective diet groups must be attributed to more efficient utilization of feed. This is also indicated by the fact that the light-weight HFD animals excret more fat in the faeces than the heavy-weight animals. The amount of fat excreted by the HFD animals is some 10-fold greater than that excreted by the LFD animals. However, when the amount of excreted fat is expressed in % of ingested dietary fat, the fat excretion is of the same order of magnitude on both diets.
The influence of a single i.v. injection of 75 or 175 mg N-nitrosomethylurea (NMU)/kg into Wistar rats on plasma glucose, i.p. glucose tolerance, plasma insulin and glucagon, glucose stimulated insulin secretion and release as well as on the biosynthesis of insulin in isolated pancreatic islets have been investigated at set intervals between the 3rd day and the 6th week post injectionem. At the end of the experimental period all NMU-treated animals were alive but had significantly reduced body mass. All animals remained normoglycemic even after the glucose load. 3 days after drug application plasma insulin decreased only insignificantly in the 175 mg NMU-group, whereas plasma glucagon was significantly reduced in both drug-groups; after 3 and 6 weeks the reduction of plasma glucagon was still about 30 percent. In isolated islets the glucose stimulated insulin secretion, the percent stimulation of insulin release and insulin biosynthesis were significantly decreased.
Es werden folgende Möglichkeiten zur tierexperimentellen Erzeugung von Fettsucht bei Versuchstieren beschrieben: Fettsucht durch Fettdiät, Hyperphagie durch Insulin, Periactinol, cerebrale ventrikuläre Infusion von Phlorrhizin oder Injektion von 4‐Nitrochinolin‐1‐oxid, Goldthioglucose, Bipiperidyl Senf, mechanische Schädigung des Hypothalamus sowie Verfettung nach ACTH sezernierenden Tumortransplantaten. Von diesen Fettsuchtformen dürfte die Erzeugung durch fetthaltiges Futter mit Rücksicht auf die gegenwärtig übliche Fehlernährung der Industriegesellschaft den meisten Fällen von Fettsucht beim Menschen am nächsten kommen. Daher sollten Vergleichsuntersuchungen zunächst an diesem Modell durchgeführt werden. Mit sehr viel geringerer Wahrscheinlichkeit dürften genetische Schäden, die ggfs. zentral durch Hyperphagie oder peripher durch Stoffwechselanomalie charakterisiert sind oder auch Intoxikationen mit besonderer Auswirkung auf den Hypothalamus zum Auftreten von Fettsuchtformen führen. Für diese Formen wären die genetischen Varianten und Goldthioglucose‐Tiere repräsentativ. Von besonderer Bedeutung ist aber auch die hormonale Regulation des Fettstoffwechsels mit ihren sehr differenzierten Auswirkungen auf verschiedene Körperpartien, z. B. Morbus Cushing. Für solche hormonale Dysregulation haben wir Vertreter in der ACTH‐Fettsucht und in der insulinbedingten Hyperphagie aufgewiesen. Für erste Untersuchungen dürften auch diese Modelle geeignet sein.
The distribution of 125I-thyroxine (% dose/g tissue; tissue/plasma radioactivity ratio) was investigated in different tissues of 28-week-old obese Wistar rats. Obesity was induced by high-fat diet (HFD) and confirmed by carcass analysis; in heavy obese animals the relative and absolute fat content is increased twofold and threefold, respectively, compared to control rats fed on a low-fat diet (LFD). Heavy HFD rats exhibit diminished 125I-T4 distribution in the "slow pool" (fat tissue, muscle) and unchanged values in the "fast pool" (liver, kidney) in comparison with LFD rats with low body weight. The differences in distribution presented here are not caused by the diet per se, but they are the consequence of the obesity of the animal, because no differences in the 125I-T4 distribution were found in the 125I-T4 between HFD and LFD rats with relatively equal body weight and body composition. The reduced T4 distribution in the fat tissue of obese rats is discussed in connection with possibly decreased lipolysis in this tissue and possible causal participation in the beginning of obesity.
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