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  • 1975-1979  (5)
  • 1970-1974  (5)
  • 1960-1964
  • Symbiotes  (4)
  • d-Amphetamine  (4)
  • Amphetamine  (2)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 62 (1979), S. 193-200 
    ISSN: 1432-2072
    Keywords: Rotational behavior ; Hallucinogens ; Serotonergic-dopaminergic interactions ; LSD ; Mescaline ; Methysergide ; Cyproheptadine ; p-Chlorophenylalanine ; Amphetamine ; Scopolamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract LSD, mescaline, and MDMT (5-methoxy-N,N-dimethyltryptamine) in normal rats induced dose-dependent rotation (circling behavior), which was consistent in direction from week to week (1 week separating hallucinogen administration). The direction of LSD-induced rotation for individual animals was the same as amphetamine-induced, but not apomorphine-induced, rotation. Of the three postsynaptic serotonin antagonists (methysergide, cyproheptadine, and 2-bromo-LSD) tested, only methysergide induced rotation; this rotation was consistent in direction from week to week, and was in the same direction as LSD-induced rotation. l-LSD induced weak rotation and was approximately six times less potent than d-LSD. p-Chlorophenylalanine pretreatment increased the sensitivity to LSD, whereas α-methyl-p-tyrosine pretreatment blocked LSD-induced rotation. Simultaneous administration of LSD and amphetamine induced rotation significantly greater than amphetamine alone; a similar effect was observed with LSD plus scopolamine. However, apomorphine plus LSD induced rotation similar in magnitude to apomorphine alone. These results suggest that the mechanism by which hallucinogens induce rotation is consistent with an inhibitory action on the serotonin-containing midbrain raphe neurons. The inhibition of raphe neuronal firing could disinhibit nigrostriatal activity (possibly at the level of the substantia nigra). Methysergide-induced rotation could result from partial antagonism of postsynaptic serotonin receptors in the substantia nigra or striatum. The dopaminergic properties of LSD may attenuate rotation resulting from disinhibition of nigrostriatal activity by interacting with presynaptic nigrostriatal dopamine autoreceptors.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 22 (1971), S. 396-402 
    ISSN: 1432-2072
    Keywords: d-Amphetamine ; Lever Pressing ; Food and Water Intake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two experiments were conducted to examine the behavioral effects of low doses of d-amphetamine in rats. In contrast to previous studies showing depression of fixed-ratio 30 lever pressing by doses of d-amphetamine greater than 0.5 mg/kg, lower doses of the drug were found to facilitate such lever pressing. A low dose (0.05 mg/kg) of d-amphetamine was also found to enhance the amount of prandial drinking following food deprivation. These results indicated that the dose-response curve for d-amphetamine is generally non-monotonic and usually in the shape of an inverted U.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 28 (1973), S. 363-371 
    ISSN: 1432-2072
    Keywords: d-Amphetamine ; Frontal Cortex ; Tolerance ; Self-Administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract When offered a solution of d-amphetamine sulphate (0.025 mg/ml) in place of water, normal rats initially drank more drug solution per day than previously consumed water. The drug solution quickly became aversive to normal rats as daily intake decreased. Tolerance to the anorexic effect of d-amphetamine paralleled the decrease in daily drug intake. Rats with bilateral lesions of frontal cortex initially consumed as much drug solution and as much food as normal rats. Although frontal rats' daily intake of drug solution also decreased, an aversion never developed. Tolerance to d-amphetamine's anorexic effect took much longer to occur in frontal rats. The results indicated possible roles for both cumulative drug effects and conditioning factors in the response to chronic d-amphetamine use. A possible mechanism by which frontal cortical lesions interfered with chronic changes was suggested.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 21 (1971), S. 353-360 
    ISSN: 1432-2072
    Keywords: Amphetamine ; Learning ; Situational Determinants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Water-rewarded spatial discrimination learning was studied in rats injected with either d-amphetamine sulphate or physiological saline 15 min prior to the first of two training sessions. The effect of a light which functioned as a reward and/or as a distraction in the testing situation was examined. Amphetamine was found to facilitate learning by enhancing the reward value of light onset and also to impair learning by enhancing the distraction of light onset. The effects of amphetamine were found to interact with the duration of water deprivation preceding the first training session. Factors responsible for the controversy concerning amphetamine's influence on learning were implicated.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2072
    Keywords: Rotation ; d-Amphetamine ; Apomorphine ; Scopolamine ; L-Dopa ; Haloperidol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Normal unoperated rats were tested for rotation (i.e., circling behavior) in a spherical “rotometer” and dose-response relationships were generated using d-amphetamine, apomorphine, L-Dopa, haloperidol, and scopolamine. The rotation induced by amphetamine was significantly antagonized by alphamethyl-p-tyrosine and haloperidol, but not by diethyl-dithiocarbamate. The rotation elicited by apomorphine was unaffected by alpha-methyl-p-tyrosine. Rotation was not necessarily in the same direction with high and low doses of amphetamine, or amphetamine and apomorphine administered a week apart from each other. Dopaminergic-cholinergic interactions were evident, since pilocarpine antagonized amphetamine-induced rotation whereas scopolamine did not; scopolamine elicited rotation in the same direction as that induced by amphetamine. Left and right striatal dopamine and tel-diencephalic norepinephrine levels were determined in rats injected with various doses of amphetamine and tested for rotation. There were significant bilateral differences in striatal dopamine which were related to the direction of rotation. Since amphetamine was found to be equally distributed to the two sides of the brain, the difference in striatal dopamine appeared to be the neurochemical substrate for rotation in normal rats. These results suggest that normal rats have asymmetrical levels of striatal dopamine as well as an asymmetrical complement of striatal dopamine receptors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 36 (1974), S. 109-115 
    ISSN: 1432-2072
    Keywords: Frontal Cortical Ablations ; d-Amphetamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats trained to bar-press on a FI 15 sec schedule for water reinforcement were administered various doses of d-amphetamine (0.25–4.0 mg/kg) both before and 6–8 weeks after bilateral ablation of frontal cortex. Preoperatively, low doses (e.g. 0.25–0.5 mg/kg) of (d-amphetamine increased responding and high doses (e.g. 2.0–4.0 mg/kg) of d-amphetamine depressed responding. Postoperatively, frontal rats showed larger facilitatory effects in response to low doses of d-amphet-amine but lesser depressant effects in response to high doses of d-amphetamine; the whole dose-response curve was generally shifted higher by the frontal lesions. These results indicate that frontal lesions differentially influence mechanisms mediating two different actions of d-amphetamine.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: Cholesterol ; Symbiotes ; Aphids ; Digitonin ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphid primary symbiotes have previously been shown to synthesize cholesterol in vitro. Two electron microscopic techniques were used here to determine whether the symbiotes also synthesize cholesterol in vivo and whether this cholesterol is made available to the aphid. We also inquired into a possible role of secondary symbiotes in cholesterol biosynthesis. Treatment of aphids with digitonin resulted in significant alteration of ultrastructural sites in primary and secondary symbiote membranes. We concluded that these sites are areas of high cholesterol concentration in the symbiotes. Electron microscopic autoradiography with 3H-mevalonate precursor indicated that both primary and secondary symbiotes synthesize cholesterol; in both cases, the majority of grains were associated with the symbiote membranes. While the frequency of grains on the symbiotes remained constant, irrespective of incubation time in labelled media, the frequency of grains over surrounding tissues increased exponentially as the time of incubation was increased from 30 min to 8 h, indicating that symbiote cholesterol is transported to other tissues. High voltage electron microscopic autoradiography permitted thick section autoradiography, reducing the time of emulsion exposure from 54 days (thin section) to 12 days (0.5 μm sections).
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: OsO4 ; Cholesterol ; Symbiotes ; Aphids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the pea-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 148 (1974), S. 287-300 
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Antibiotics ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of penicillin and chlortetracyline HCl on the fine structure of the intracellular symbiotes of the pea aphid were studied in an attempt to remove the symbiote population. High penicillin concentrations, 1% and 0.1%, caused symbiote breakdown but were toxic and/or repellent to the aphids; at 0.1% specific effects were observed on the symbiotes' cell walls. After the use of 0.01% penicillin in the aphid diet, the symbiotes had abnormal cell walls and were abnormally dilated; however, symbiote division and transmission from one aphid generation to the next seemed unaffected and the aphids appeared normal. Aphids fed 0.1% chlortetracycline failed to reproduce. After 7 days, their symbiotes were found to break down at a high rate but aphid mitochondria were also adversely affected at this stage. Following 0.002% chlortetracycline, the aphids produced aposymbiotic progeny with apparently normal mitochondrial populations; these larvae failed to develop.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 159 (1975), S. 351-367 
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Vesicles ; Organelles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A detailed investigation into the ultrastructure of the pea aphid mycetocytes and their contained symbiotes and organelles was carried out with the transmission electron microscope. The most striking observation was the presence of small vesicles in the space between the primary symbiote cell wall and membrane envelope (outer membrane space). The vesicles appear to form by a budding process at the outer cell wall layer. Subsequently, the vesicles, we suggest, may move out into the mycetocyte cytoplasm via a similar budding of the membrane envelope. The Golgi apparatus was found to be an important structural component of the primary mycetocyte; it is continuous with the rough endoplasmic reticulum and the latter, in turn, appears to be closely connected to the primary symbiote membrane envelope. This may be of functional significance. A number of other organelles not previously described in mycetocytes were found, including transparent vacuoles, granular bodies, multivesicular bodies and microfilaments. The chemical composition of the various vesicles and organelles is unknown at present.
    Type of Medium: Electronic Resource
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