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  • 1
    ISSN: 1432-2072
    Keywords: Key words Intracranial self-administration ; GABA ; Bicuculline ; Reward ; Ventral tegmental area ; Mouse ; Dopaminergic D2 receptors ; Sulpiride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract BALB/c mice were unilaterally implanted with a guide cannula, the tip of which was positioned 1.5 mm above the ventral tegmental area (VTA). On each day of the experimental period, a stainless steel injection cannula was inserted into the VTA in order to study the eventual self-administration of a low dose (1.5 ng/50 nl) of bicuculline, a GABAA-antagonist, using a spatial discrimination task in a Y maze. Mice rapidly discriminated between the arm enabling a micro-injection of bicuculline and the neutral arm of the maze, and robust self-administration of this GABAergic antagonist was observed. Once this self-administration response for bicuculline had been fully acquired, the systemic injection of the dopaminergic D2 antagonist sulpiride (50 mg/kg), 30 min before the test, produced a rapid extinction of the self-administration response. Moreover, if this same sulpiride pre-treatment was given during the initial acquisition period mice did not discriminate between the two arms of the Y-maze. These data demonstrate the dopamine D2 dependence of this bicuculline self-administration behavior, and confirm that GABAergic interneurons and/or inputs normally transynaptically inhibit neuronal activity in the mesocorticolimbic dopamine system.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 77 (1998), S. 551-555 
    ISSN: 1439-6327
    Keywords: Key words Oxygen uptake ; Running ; Training ; Fatigue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eight male endurance runners [mean ± (SD): age 25 (6) years; height 1.79 (0.06) m; body mass 70.5 (6.0) kg; % body fat 12.5 (3.2); maximal oxygen consumption (V˙O2max 62.9 (1.7) ml · kg−1 · min−1] performed an interval training session, preceded immediately by test 1, followed after 1 h by test 2, and after 72 h by test 3. The training session was six 800-m intervals at 1 km · h−1 below the velocity achieved at V˙O2max with 3 min of recovery between each interval. Tests 1, 2 and 3 were identical, and included collection of expired gas, measurement of ventilatory frequency (f v ), heart rate (f c), rate of perceived exertion (RPE), and blood lactate concentration ([La−]B) during the final 5 min of 15 min of running at 50% of the velocity achieved at V˙O2max (50% −V˙O2max).␣Oxygen uptake (V˙O2), ventilation (V˙ E ), and respiratory exchange ratio (R) were subsequently determined from duplicate expired gas collections. Body mass and plasma volume changes were measured preceding and immediately following the training session, and before tests 1–3. Subjects ingested water immediately following the training session, the volume of which was determined from the loss of body mass during the session. Repeated measures analysis of variance with multiple comparison (Tukey) was used to test differences between results. No significant differences in body mass or plasma volume existed between the three test stages, indicating that the differences recorded for the measured parameters could not be attributed to changes in body mass or plasma volume between tests, and that rehydration after the interval training session was successful. A significant (P 〈 0.05) increase was found from test 1 to test 2 [mean (SD)] for V˙O2 [2.128 (0.147) to 2.200 (0.140) 1 · min−1], f c [125 (17) to 132 (16) beats · min−1], and RPE [9 (2) to 11 (2)]. A significant (P 〈 0.05) decrease was found for submaximal R [0.89 (0.03) to 0.85 (0.04)]. These results suggest that alterations in V˙O2 during moderate-intensity, constant-velocity running do occur following heavy-intensity endurance running training, and that this is due to factors in addition to changed substrate metabolism towards greater fat utilisation, which could explain only 31% of the increase in V˙O2.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 79 (1999), S. 237-243 
    ISSN: 1439-6327
    Keywords: Key words Oxygen uptake ; Running ; Training ; Fatigue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Elevated oxygen uptake (V˙O2) during moderate-intensity running following a bout of interval running training has been studied previously. To further investigate this phenomenon, the V˙O2 response to high-intensity exercise was examined following a bout of interval running. Well-trained endurance runners were split into an experimental group [maximum oxygen uptake, V˙O2 max 4.73 (0.39) l · min−1] and a reliability group [V˙O2 max 4.77 (0.26) l · min−1]. The experimental group completed a training session (4 × 800 m at 1 km · h−1 below speed at V˙O2 max , with 3 min rest between each 800-m interval). Five minutes prior to, and 1 h following the training session, subjects completed 6 min 30 s of constant speed, high-intensity running designed to elicit 40% Δ (where Δ is the difference between V˙O2 at ventilatory threshold and V˙O2 max ; tests 1 and 2, respectively). The slow component of V˙O2 kinetics was quantified as the difference between the V˙O2 at 6 min and the V˙O2 at 3 min of exercise, i.e. ΔV˙O2(63). The ΔV˙O2(63) was the same in two identical conditions in the reliability group [mean (SD): 0.30 (0.10) l · min−1 vs 0.32 (0.13) l · min−1]. In the experimental group, the magnitude of the slow component of V˙O2 kinetics was increased in test 2 compared with test 1 by 24.9% [0.27 (0.14) l · min−1 vs 0.34 (0.08) l · min−1, P 〈 0.05]. The increase in ΔV˙O2(63) in the experimental group was observed in the absence of any significant change in body mass, core temperature or blood lactate concentration, either at the start or end of tests 1 or 2. It is concluded that similar mechanisms may be responsible for the slow component of V˙O2 kinetics and for the fatigue following the training session. It has been suggested previously that this mechanism may be linked primarily to changes within the active limb, with the recruitment of alternative and/or additional less efficient fibres.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Retina ; Taurine ; GABA ; Glycine ; Glutamate ; Immunocytochemistry ; Lungfish, Neoceratodus forsteri (Dipnoi)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The morphology of the retina of the Australian lungfish Neoceratodus forsteri was investigated by means of light- and electron microscopy, whilst immunocytochemical studies were performed to determine the cellular distributions of the major amino acid neurotransmitters and other amino acids. The distributions of glycine and GABA were similar to those previously described for teleost, amphibian and mammalian retinae. Labelling was abundant in amacrine cells, whilst GABA was also present in one layer of horizontal cells and some bipolar cells. Taurine was present in both rods and cones, but, unlike the mammalian or avian retina, was absent from other cellular structures, including glial elements. Unexpectedly, the photoreceptor terminals lacked an apparent content of the excitatory amino acid transmitter glutamate. The glutamate that was present in the rods and cones occupied a crescentic arc corresponding to the location of glycogen-rich paraboloids. Asparagine was also present in rods, albeit in the modified mitochondria that formed the elipsoids of the rod inner segments. Arginine, the precursor for formation of nitric oxide, was present in glial cells, and in the paraboloids of both rods and cones.
    Type of Medium: Electronic Resource
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