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  • 1
    Electronic Resource
    Electronic Resource
    Naloxone effects on sucrose-motivated behavior (1996)
    Springer
    Psychopharmacology 126 (1996), S. 110-114 
    Details
    ISSN: 1432-2072
    Keywords: Motivation ; Naloxone ; Opioids ; Sucrose ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The opioid system plays an important role in feeding. In general, opioid agonists typically increase feeding and opioid antagonists decrease feeding in nonfood restricted animals. In food restricted animals the effects of these drugs are substantially reduced. Opioid antagonists have shown a marked effectiveness at reducing consumption of sweet foods. Explanations for this robust effect have typically focused on drug induced changes in taste, taste perception, or palatability. The current study relates the effects of the opioid antagonist naloxone on motivation to obtain different sucrose concentrations to the drug's effects on unrestricted sucrose solution consumption. Changes in motivation to respond were assessed under a progressive ratio reinforcement schedule (PR) which required increased response cost for each successive unit of sucrose solution. Motivation, as measured by the PR, increased as sucrose concentration increased and naloxone produced a dose-dependent decrease in motivation to respond for a given sucrose concentration. Thus, the effectiveness of naloxone was indirectly related to strength of the sucrose concentration. Under unrestricted access to sucrose solutions, naloxone reduced consumption greatest under the higher concentrations. The data suggest at least part of naloxone's effects on sweet tasting food may be mediated through endogenous opioid reward systems that are reflected in measures of motivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246345
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of neuropeptide Y, insulin, 2-deoxyglucose, and food deprivation on food-motivated behavior (1995)
    Springer
    Psychopharmacology 120 (1995), S. 267-271 
    Details
    ISSN: 1432-2072
    Keywords: Neuropeptide Y ; Insulin ; 2-Deoxyglucose ; Food deprivation ; Motivation ; Reinforcer efficacy ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The current study demonstrates the ability of neuropeptide Y (NPY) to increase break points under a progressive ratio 1 (PR1) reinforcement schedule. An initial response resulted in delivery of a food reinforcer (45 mg pellet) under the PR1, and an additional response was required foreach successive reinforcer. The break point, the number of responses emitted to obtain the last reinforcer, is considered a measure of reinforcing efficacy or motivational strength of the food reinforcer. NPY (0.3–10 µg) significantly increased break point to levels comparable to those produced by 36–48 h of food deprivation. Although insulin (3–8 U/kg) and 2-deoxyglucose (150–250 mg/kg) also increased food intake, neither increased break points to levels produced by NPY or food deprivation. These data suggest that NPY may change the value of food in ways that cannot be accounted for by changes in insulin, glucose levels or intracellular glucoprivation. These results emphasize that simply measuring the amount of freely available food eaten is not a fully adequate measure of the strength of the feeding behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311173
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Cells transformed by a wide variety of agents express higher abundance levels of some cellular RNA species (1982)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 19 (1982), S. 259-265 
    Details
    ISSN: 0730-2312
    Keywords: cytoplasmic RNA ; messenger RNA ; 3T3 cells ; C3HEF ; SV40 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A cDNA-cloned library was prepared from mRNA synthesized by SV40-transformed mouse cells. Eleven cDNA clones were selected based on their ability to hybridize higher levels of mRNA in SV40-transformed 3T3 cells than in 3T3 cells. These cDNA clones were employed to screen the steady-state levels of cytoplasmic RNAs in a wide variety of viral (SV40, polyoma, adenovirus, and Rous sarcoma virus) and nonviral (methylcholanthrene, embryonal carcinoma) transformed cell lines. Two of the cDNA clones - A17 and 104 - detected greater than 40-100-fold higher levels of mRNA in all the transformed cell lines tested when compared to nontransformed cells (3T3, C3HEF). The levels of mRNA complementary to these two cDNAs were regulated in a temperature-sensitive fashion (87-100-fold) in both SV40tsA- and RSV ts-src-transformed murine cell lines. These two cDNA clones detected greater than 100-fold, higher levels of complementary RNA derived from SV40 tumor tissue than in normal mouse liver. RNA species complementary to cDNA clones A17 or 104 were not detected in either actively growing nontransformed cells or in serum-stimulated 3T3 cells. The abundance levels of mRNAs detected by these two cDNA clones appear to be regulated 100-fold or greater by the transformed state, independent of the transforming agent. The higher levels of these RNA species detected in transformed mouse cells appear not to be solely regulated by the state of growth of nontransformed cells.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240190307
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    Paper (German National Licenses)
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