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  • 1980-1984  (3)
  • 1975-1979  (1)
  • Aluminum  (2)
  • Concurrent schedules  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Concurrent etonitazene and water intake in rats: Role of taste, olfaction, and auditory stimuli (1979)
    Springer
    Psychopharmacology 64 (1979), S. 1-7 
    Details
    ISSN: 1432-2072
    Keywords: Etonitazene ; Etonitazene reinforcement ; Concurrent schedules ; Choice procedures ; Rats ; Taste ; Olfaction ; Auditory stimuli ; Discriminative stimuli ; Conditioned reinforcers ; Fixed-ratio schedules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Etonitazene and water were concurrently available to four rats during daily 1 h sessions in operant conditioning chambers equipped with two levers and two liquid dippers. A food-induced training procedure was used whereby etonitazene drinking was rapidly established by presenting rats with gradually increased drug concentrations with their daily food ration. When food was subsequently removed from the session and given post-session, etonitazene responding persisted. The rats were subsequently trained on fixed-ratio (FR) schedules with concurrent access to etonitazene and water. The number of dipper presentations compared with etonitazene concentrations (0.078–10.0 μg/ml) resulted in a typical inverted U-shaped function while etonitazene intake (μg/kg) increased directly with concentration. After drinking large quantities of etonitazene the rats showed ataxia, hyper-activity, and stereotypy. Extinction tests demonstrated that rats could discriminate between etonitazene and water on the basis of one dipper full of each liquid; the amount of etonitazene in one dipper was 0.0078 μg. Further tests showed that this discrimination was based on taste or immediate post-ingestional feedback rather than olfactory cues. An auditory stimulus was presented concurrently with responses on the drug lever; however, there was no difference in responding for the drug in the presence or absence of this stimulus except at the lowest concentration. After the extinction tests, when the lowest drug concentration was again available with concurrent water, responding was substantially higher in the presence of stimulus associated with availability of etonitazene. The results extend previous work on oral narcotic intake to a lever-press concurrent choice procedure which is sensitive to reinforcing effects of the drug at low concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427336
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of feeding conditions on drug-reinforced behavior: Maintenance at reduced body weight versus availability of food (1980)
    Springer
    Psychopharmacology 68 (1980), S. 121-124 
    Details
    ISSN: 1432-2072
    Keywords: Etonitazene reinforcement ; Oral selfadministration ; Food deprivation ; Food access ; Concurrent schedules ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent research has shown that food deprivation increases drug self-administration in rats and rhesus monkeys. The purpose of the present study was to examine two variables related to this food-deprivation effect: maintenance of rats at reduced body weights and the absence of food. Etonitazene HCl was established as a reinforcer orally for 12 rats according to procedures previously used in experiments reported by this laboratory. Lever-pressing behavior was maintained under fixed-ratio (FR) schedules during daily 1-h sessions by etonitazene or water, which were available either concurrently or on alternating days. In the first experiment, six rats were maintained at 75% of their free-feeding weights. The effect of presenting the daily food allotment at 23, 4, 2, 1, or 0 h before their daily drug or water self-administration session was studied. When the rats were fed 23, 4, or 2 h before the session, etonitazene dipper presentations were at maximum levels and were substantially higher than for water. When the rats were fed during (0) or 1 h before the session, the number of etonitazene dipper presentations was lower, but it exceeded those for water. Under conditions of complete food satiation (0 h deprived-100% body weight), etonitazene and water dipper presentations were both low, and there were no differences between them. In the second experiment, six rats maintained at 75% of their free-feeding weights were trained to respond for etonitazene or water on alternating days. When they were subsequently food satiated (100% body weight), drug- and water-maintained behavior decreased to low levels. These rats were then deprived of food for 4 or 16 h before their daily 1-h session, and responding did not increase. Body weight did not decrease below 100%. These results suggest that maintenance at reduced body weight rather than the absence of food is the determinant of increased rates of drug-reinforced behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432128
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of aluminum on normal and uremic rats: Tissue distribution, vitamin D metabolites, and quantitative bone histology (1983)
    Springer
    Calcified tissue international 35 (1983), S. 344-351 
    Details
    ISSN: 1432-0827
    Keywords: Aluminum ; Tissue distribution ; Bone histomorphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of intraperitoneal aluminum chloride (1.5 mg aluminum/kg/day for 9 weeks) were studied in normal and uremic rats. Parameters measured included tissue aluminum, serum vitamin D metabolites, and quantitative bone histology. Aluminum administration increased tissue concentrations of this metal in uremic and nonuremic animals. Bone aluminum concentrations were higher in uremic rats (121 ± 27 mg/kg compared to 47 ± 4), whereas liver values were higher in the nonuremic group (175 ± 47 mg/kg compared to 100 ± 36). Serum concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D were reduced in uremia, but aluminum was without apparent effect on any vitamin D metabolite. Aluminum, in the doses administered, caused no skeletal changes in nonuremic animals. Some uremic, non-aluminum-treated rats developed osteomalacia and marrow fibrosis. However, osteomalacia was more severe and the osteoclast count was higher in the uremic, aluminum-treated rats. In this group of animals the mineral apposition rate was reduced at the metaphyseal endosteum but increased at the periosteum, indicating different control mechanisms at the two sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405056
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of aluminum and parathyroid hormone on osteoblasts and bone mineralization in chronic renal failure (1984)
    Springer
    Calcified tissue international 36 (1984), S. 133-138 
    Details
    ISSN: 1432-0827
    Keywords: Aluminum ; Parathyroid hormone ; Bone ; Renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone aluminum, quantitative bone histology, and plasma parathyroid hormone (PTH) were compared in 29 patients undergoing chronic hemodialysis. Histologic techniques included double tetracycline labeling and histochemical identification of osteoclasts and osteoblasts. Bone aluminum was measured chemically by flameless atomic absorption spectrophotometry, and histochemically. When measured chemically, the bone aluminum was 67±46 (SD) mg/kg dry weight (normal 2.4±1.2 mg/kg); histochemically, aluminum was present at 2.9±4.4% of trabecular surface. The biochemical and histochemical results agreed well (r=0.80,P〈0.001). No double tetracycline labels were seen at the mineralization front where aluminum was deposited, indicating cessation of mineralization at these sites. The osteoblast surface correlated positively with plasma PTH (r=0.67,P〈0.001) and negatively with bone aluminum level (r=−0.42,P〈0.05). Multiple linear regression showed a correlation of aluminum with osteoblasts additional to that of PTH, consistent with a direct effect of aluminum in depressing osteoblast numbers. Though a relationship between PTH and chemically determined bone aluminum level could not be demonstrated, there was a negative correlation between osteoclast count and aluminum, and the nine patients with severe hyperparathyroid bone disease had lower chemically determined aluminum levels than the other patients. These results suggest that aluminum (a) directly inhibits mineralization, (b) is associated with decreased PTH activity and hence osteoblast numbers, and (c) directly reduces osteoblast numbers. In addition to inducing severe, resistant osteomalacia, aluminum appears to contribute to the mild osteomalacia commonly seen in renal failure, characterized by extensive thin osteoid and low tetracycline and osteoblast surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405308
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    Paper (German National Licenses)
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