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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 68 (1987), S. 153-170 
    ISSN: 1435-1463
    Keywords: Dopamine ; sexual behavior ; LY163502 ; autoreceptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of selective D2-dopaminergic receptor stimulation with LY163502 on male rat copulatory behavior were evaluated. LY163502 (25 ng/kg to 25Μg/kg s. c.) produced increases in the percentage of sexually inactive rats displaying mounting behavior and ejaculating during the test period. Within this same dose range, LY163502 administration induced an increase in the percentage of non-ejaculator rats that were capable of ejaculation. These findings are viewed as evidence that LY163502 can initiate sexual behavior and lower the threshold for ejaculation. The effects of LY163502 were further evaluated in rats that were capable of ejaculation during the test period. LY163502 (25 ng/kg to 25Μg/kg s. c. or p. o.) induced significant reductions in ejaculatory latency. These effects were blocked by prior treatment with centrally active dopaminergic antagonists, RO 22-1319 and sulpiride, but not with a peripherally active antagonist, domperidone. LY163502 administration was also found to inhibit sexual behavior in low doses of 25 pg/kg −10 ng/kg s. c. and in a much larger dose of 25 mg/kg s. c. These inhibitory effects are viewed as behavioral manifestations of selective dopaminergic autoreceptor activation with low doses and as the disruption of sexual behavior by induction of intense stereotypic behavior with high doses.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: ATPase ; Plasma membrane ; Pyrophosphatase ; Ricinus (solute transport) ; Sucrose transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A highly enriched plasma membrane fraction has been isolated from dark-grown cotyledons ofRicinus communis by phase partitioning. This is demonstrated by the properties of the associated ATPase: high vanadate sensitivity, azide and nitrate insensitivity, sharp pH optimum around 6.5, and high specificity for ATP as substrate. The upper plasma membrane fraction also contained a pyrophosphatase activity, normally considered to be located on the tonoplast or Golgi membranes, which showed a specific activity higher than that in the lower phase. Sucrose gradient centrifugation of both microsomal and upper phase fractions showed a comigration of some pyrophosphatase activity with the plasma membrane fraction. Sucrose uptake changes with development inRicinus cotyledons. The ATPase activity in the upper (plasma membrane) phase also varied in a similar way with development, whereas activity in the lower phase showed little change. Pyrophosphatase activity in the upper phase also increased with development but did not show a peak and fall as seen for sucrose uptake and ATPase. The possibility that changes in plasma membrane ATPase may contribute to changes in sucrose uptake capacity and the possible cellular origin and physiological significance of the pyrophosphatase activity are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 91 (1987), S. 96-100 
    ISSN: 1432-2072
    Keywords: Lordotic behavior ; Dopamine ; D2 receptors ; LY163502 ; Autoreceptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of LY163502, a highly selective D2 dopaminergic agonist, on the lordotic response of ovariectomized, estrogen-treated rats were evaluated. LY163502, administered subcutaneously or orally, produced a significantly greater lordotic response than vehicle. LY175877 [the opposite (+) enantiomer] was found to be inactive. The effects of subcutaneous administered LY163502 were abolished by prior treatment with dopaminergic receptor antagonists such as haloperidol orcis-flupenthixol. These studies are supportive of the view that LY163502 can initiate and potentiate female sexual behavior by stimulating D2 type dopaminergic receptors. In contrast to the enhancement of lordotic response that was observed in nonreceptive female rats, LY163502 was found to have suppressive effects on lordotic response frequency of receptive (estrogen-progesterone-treated) female rats. Reductions in lordotic responding occurred in two dose ranges, above and below the dose range found to potentiate lordotic response. The maximal suppressive effect at the low dose range was observed at 250 pg/kg, SC. This reduction in lordotic responding was proposed to be associated with a selective dopaminergic autoreceptor activation, leading to a diminished dopamine release and expression of a dopamine-mediated behavior (i.e., lordotic response). The reduction of lordotic responding that was observed at higher doses (25 μg/kg-25 mg/kg) was associated with an induction of stereotypic behavior that may have disrupted the sexual response pattern.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 165 (1991), S. 27-36 
    ISSN: 1615-6102
    Keywords: ATPase ; Cerium ; Cytochemistry ; Fixation ; Zea mays roots ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cytochemical localization of ATPase activity has been investigated in maize root cells using both lead and cerium-based capture methods. With both methods, staining at the plasma membrane was observed in all cells of the root, although the precipitate obtained with cerium was more uniform and granular than that with lead. Controls using no substrate or no magnesium, β-glycerophosphate to replace ATP, vanadate or boiled tissue generally showed little or no staining. However, biochemical studies on purified plasma membrane fractions showed that ATPase activity was markedly inhibited by fixation, particularly by glutaraldehyde, and also by lead and cerium ions. Non-enzymic hydrolysis of ATP by cerium was greater than that by lead. The value and limitations of these procedures for the localization of plasma membrane H+-ATPase activity are summarized in relation to previous criticisms of these methods.
    Type of Medium: Electronic Resource
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