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  • Amphetamine  (2)
  • Investigatory behaviour  (2)
  • Analgesia  (1)
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  • 1
    ISSN: 1432-2072
    Keywords: Psychostimulant ; Amphetamine ; Stress ; Long-term sensitization ; Social isolation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to assess the influence of experimential factors on the vulnerability of rats to develop amphetamine (AMPH)- and stressor-induced behavioral sensitization. Young male Wistar rats with previous social experience were isolated from their peers for 2 weeks. 1) The effect of this short-lasting social deprivation were: a) a reduced tendency to explore a fearful environment; b) a prolonged exploratory activity in response to a novel but little fearful environment; and c) a dose-dependent increase in the psychomotor stimulation induced by systemic AMPH injection. 2) After repeated AMPH injections (injection every other day for 10 days), isolated rats exhibited behavioral sensitization at lower doses (0.5 and 0.75 mg/kg) than those required for group-housed rats (1 mg/kg). 3) After being submitted to a repeated stressor (3, 7 or 14 footshock sessions, with 2 days between sessions), the isolated rats exhibited a greater increase in the behavioral responsivity to a subsequent AMPH challenge (1 mg/kg) than did the group-housed rats regardless of the number of stress sessions. In conclusion, these results suggest that experiential factors such as privation of contact with peers (social isolation) may make rats more vulnerable to the long-term repercussions of chronic environmental and pharmacological challenges.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Neurotensin ; Ventral mesencephalon ; Investigatory behaviour ; Motor behavior ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present experiments examined in detail the behavioral response to microinfusions of neurotensin (NT) into the ventral tegmental area (VTA), substantia nigra (SN) and hippocampus (HPC). The behavioral apparatus consisted of an eight-hole box in which investigatory and spontaneous motor behavior were recorded. Three doses (0.175, 0.5, 4.0 μg) of NT were injected into the VTA. The main effect of NT was a strong augmentation of rearing (frequency and duration) both in the periphery and center of the arena, accompanied by a small increase in locomotion and decreased grooming. NT had no effect on the strategy, organization, or duration of exploration but did augment frequency of hole visits towards the end of the session. NT injected into the SN and HPC had no effect on investigatory and spontaneous behavior with the exception of an increase in peripheral locomotion after HPC-NT injections. The results are discussed in terms of a modulatory role of endogenous NT on mesolimbic dopamine neurons.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2072
    Keywords: Amphetamine ; Apomorphine ; Dopamine ; Exploration ; Locomotor activity ; Hole-board ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present experiments, the effects of a wide range of doses of d-amphetamine and apomorphine were studied on investigatory behavior in an automated eight-hole box. Amphetamine (0.125, 0.25, 0.5, 1.0, 3.0, 5.0 mg/kg) increased frequency and total duration of responses, and decreased mean duration in a dose-dependent manner. The strategy and organization of responses, as measured by the order of hole-visits and hole-switching, were unchanged at lower doses of amphetamine but were altered at higher doses. Perseverative hole-poking was observed at the highest dose (5.0) as indicated by increased number of hole-pokes per hole-visit. Apomorphine (0.05, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 mg/kg) decreased mean duration of responses, but in contrast to amphetamine markedly diminished frequency. Locomotor activity was also measured at all doses of both drugs. Our observations indicate that these two stimulant drugs both of which increase motor activity, have markedly different effects on investigatory responses. It is likely that amphetamine increases prepotent response tendencies (i.e., hole-poking), although this does not necessarily reflect enhanced exploration. Further, the results obtained with amphetamine support predictions made by the Lyon-Robbins behavioral theory of amphetamine effects.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2072
    Keywords: Enkephalin ; Ventral mesencephalon ; Investigatory behaviour ; Motor behaviour ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mesolimbic dopamine (DA) system, originating in the ventral tegmental area and projecting to limbic forebrain regions, plays a crucial role in mediating several important aspects of behaviour. Proximal to these DA neurons are enkephalin-containing nerve fibers. In an attempt to characterize the behavioural role of enkephalinergic transmission in the VTA, the present experiment examined in detail the investigatory and motor responses to microinfusion of d-ala-met-enkephalin (DALA), a long lasting analogue of enkephalin, into the ventral tegmental area (VTA). Injections into the substantia nigra (SN) and the hippocampus (HPC) were also performed as controls for site specificity. The behavioural apparatus consisted of an eight-hole box monitored by a video camera. Four doses of DALA were injected in the VTA (0.05, 0.1, 1 and 2.5 μg/μl bilaterally in 1 μl volume) and one dose in the SN and HPC (0.1 μg/μl bilaterally in 1 μl volume). The effect of DALA injections in the VTA was characterized by an inverted U-shape dose-effect curve. The low doses (0.05 and 0.1) induced an increase in the frequency of hole visits accompanied by a decrease in the mean duration of visits, whereas the highest doses induced a decrease in hole visit frequency. Low doses of DALA had no effect on strategy or organization of exploration, whereas the high doses produced decreased switching between holes. After low doses of DALA, locomotor activity at the periphery of the testing box was not significantly affected but locomotor activity in the centre was increased. After high doses of DALA, locomotor activity in the center and at the periphery of the box were decreased. Frequency of rearing was either not affected or decreased by DALA treatment. DALA injected in the SN resulted in a small increase in frequency of hole visits and did not affect rearing and locomotor activity. DALA injection in the HPC had no effect on investigatory and spontaneous motor behaviour. The results are discussed in terms of a modulatory role of endogenous enkephalin on mesolimbic dopamine neurons.
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  • 5
    ISSN: 0196-9781
    Keywords: Analgesia ; Antiopiate activity ; Hyperesthesia ; Morphine ; NPFF ; Tail-flick test
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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