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  • 1
    Electronic Resource
    Electronic Resource
    Effects of morphine on different aspects of social play in juvenile rats (1995)
    Springer
    Psychopharmacology 117 (1995), S. 225-231 
    Details
    ISSN: 1432-2072
    Keywords: Social play ; Opioid ; Morphine Environment ; Social isolation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify the influence of opioids on social play, the effects of morphine on playful and non-playful social behavior in juvenile rats was investigated under different conditions. Environmental variables employed were different (dim and intense) levels of illumination during testing, familiarity to the test cage, and different periods of social isolation prior to testing. Under dim light conditions, morphine markedly increased playful social behavior, such as pinning, boxing/wrestling and following/chasing, whereas non-playful social behavior such as social exploration and contact behavior was hardly affected. This effect of morphine was independent of duration of previous isolation and dose-dependent, with a maximal effect at 1.0 mg/kg. The mechanism of this effect is interpreted as an action on the rewarding aspects of play. A dose of 0.1 mg/kg of morphine abolished the initial suppression of play induced by unfamiliarity to the test cage, without influencing total levels of play. This may be an effect of morphine on the integration of sensory stimuli. Under intense light conditions, where playful behavior was completely suppressed, morphine itself hardly affected such behavior, but decreased some aspects of non-playful social behavior. These results suggest that in juvenile rats playful and non-playful forms of social behavior are differentially regulated. In addition, opioid systems may be involved at different levels in the regulation of social play.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245191
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  • 2
    Electronic Resource
    Electronic Resource
    Cell deletion by apoptosis during regression of rat parotid sialadenosis (1995)
    Springer
    Virchows Archiv 427 (1995), S. 181-186 
    Details
    ISSN: 1432-2307
    Keywords: Isoproterenol ; Apoptosis ; Rat ; Parotid ; Sialadenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Enlargement of the rat parotid salivary glands was induced by repeated administration of isoproterenol. Mean wet weights of the treated glands increased steadily to 240% of control values. Following withdrawal of the drug, quantitative histological techniques were used to investigate the balance between hypertrophy, hyperplasia and apoptosis. The volume occupied by acinar cells relative to the total gland volume together with cytoplasmic|:|nuclear area ratios as measures of hypertrophy increased during the early experimental period. Similarly, serous acinar cell mitotic counts increased, indicating that hyperplasia had occurred. Apoptosis was demonstrated at light microscopical level to be the main mechanism for cell deletion as the glands returned to normal size and weight. The results indicate that hypertrophy and hyperplasia of serous acinar cells contribute to isoproterenol-induced sialadenosis. The experimental animal model demonstrates that these proliferative changes are completed by 48 h and thereafter are balanced by apoptosis as the glands recover their normal size and weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196524
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  • 3
    Electronic Resource
    Electronic Resource
    Peroxisomes and Hepatotoxicity (1995)
    Springer
    Comparative clinical pathology 5 (1995), S. 189-195 
    Details
    ISSN: 1433-2981
    Keywords: Cell lines ; Guinea pig ; Human ; Hypolipaemic agents ; Peroxisome proliferators ; Rat ; Species difference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Peroxisomes are ubiquitous organelles of eukaryotic cells and are present in significant amounts in hepatic liver cells. Peroxisomal enzymes contribute to several metabolic pathways including fatty acid, purine and amino acid catabolism or bile acid synthesis. The peroxisomal oxidative reactions produce hydrogen peroxide, mostly degraded by catalase which prevents oxidative stress. Moreover, peroxisomes are involved in arylderivative drug detoxification through its epoxide hydrolase activity. In rodents the exposure of cells to xenobiotic compounds such as fibrates, phthalates/adipates and chlorophenoxyacetic acid derivatives, which are used as hypolipaemic drugs, plasticizers and pesticides respectively, lead to a liver mass increase and to a high peroxisome proliferation. This latter event is due to a strong genetic activation triggered by the PPAR (peroxisome proliferator activated nuclear receptor). Human contrasts with rodent since there is no, or little, effect of the above cited compounds. In contrast, the defect of single or multiple peroxisomal functions caused by genetic disorders lead to an increase of very long chain fatty acid level, which is toxic, especially for brain and kidney. The liver response to xenobiotics of the peroxisome proliferator class may be modulated by auxiliary compounds such as hormones (e.g. thyroid hormone) or nutriments (e.g. retinoids).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368043
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  • 4
    Electronic Resource
    Electronic Resource
    Haematology and clinical chemistry in rats: Comparison of different blood collection sites (1996)
    Springer
    Comparative clinical pathology 6 (1996), S. 160-166 
    Details
    ISSN: 1433-2981
    Keywords: Clinical chemistry ; Haematology ; Rat ; Sampling technique(s)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Blood samples from male and female rats were collected from four different sampling sites by the same technicians and analysed by the same procedures. The sampling sites were the abdominal aorta, orbital venous plexus, dorsal anastomotic orbital vein and sublingual vein. Values obtained in blood samples collected from peripheral sites were compared to those from the abdominal aorta, a sampling site which is normally unaffected by the sampling technique. There were significant differences in haematological parameters, particularly in leucocyte counts which were higher in samples collected from the peripheral sites than in those withdrawn from the central one. No significant changes were observed in coagulation parameters. A significant increase in clinical chemistry parameters related to soft tissue damage, namely creatinine kinase, lactate dehydrogenase, hydroxybutyrate dehydrogenase and aspartate aminotransferase, was seen in samples collected from both orbital sites. From this study it can be concluded that haematological and biochemical values obtained from rats in toxicological studies using different sampling sites are reliable both in males and females, provided that they are compared to values obtained from the same site in untreated controls. Sampling from the orbital plexus proved to be the least invasive method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368460
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  • 5
    Electronic Resource
    Electronic Resource
    Repeated administration of a selective dopamine D2 receptor agonist to 6-OHDA — lesioned rats does not affect the survival and outgrowth of intrastriatal fetal mesencephalic grafts (1995)
    Springer
    Experimental brain research 107 (1995), S. 52-58 
    Details
    ISSN: 1432-1106
    Keywords: Transplantation ; Dopamine D2 receptor ; Image analysis ; Tyrosine hydroxylase immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of the present study was to investigate the effects of chronic activation of dopamine D2 receptors on the development of grafted fetal rat mesencephalic dopaminergic neurons. Therefore, unilaterally 6-hydroxydopamine — lesioned rats received intrastriatal mesencephalic cell suspension grafts and were subsequently chronically treated with the selective dopamine D2 receptor agonist LY 171555 (Quinpirole). After treatment for 6 consecutive weeks, the rats were processed for tyrosine-hydroxylase immunocytochemistry to assess the survival and outgrowth from grafted dopaminergic neurons. Morphological analysis revealed that, like the volume and morphology of the graft, neither the number nor the cell area of grafted dopaminergic neurons was significantly different between vehicle- and LY 171555-treated animals. To obtain a quantitative estimate of the graft-derived dopaminergic reinnervation, a computerized image analysis system was used. Using this procedure, which was based on the densitometric measurement of tyrosine hydroxylase immunoreactivity in the area adjacent to the grafted tissue, it was found that the extent of graft-derived outgrowth also appeared to be un-affected upon chronic treatment with LY 171555. It is concluded that long-term concurrent administration of a dopamine D2 receptor agonist for 6 consecutive weeks does not impair the survival and outgrowth of grafted rat fetal mesencephalic dopaminergic neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228016
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  • 6
    Electronic Resource
    Electronic Resource
    The role of the ascending 5-hydroxytryptaminergic pathways in timing behaviour: further observations with the interval bisection task (1995)
    Springer
    Psychopharmacology 120 (1995), S. 213-219 
    Details
    ISSN: 1432-2072
    Keywords: 5-hydroxytryptamine ; 5,7-Dihydroxytryptamine ; Operant behaviour ; Timing ; Interval bisection procedure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This experiment examined the effect of destroying the 5-hydroxytryptaminergic (5HTergic) pathways on rats' ability to discriminate between two durations. Rats received injections of 5,7-dihydroxytryptamine into the median and dorsal raphe nuclei or sham lesions. They were trained to press lever A following a 2-s presentation of a light and lever B following an 8-s presentation of the light. For some rats, the levers were inserted into the chamber immediately after stimulus presentation (“no-poke-requirement”); for others, the levers were not inserted until a flap covering the food tray positioned midway between the levers had been depressed (“poke-requirement”). When stable performance was attained, “probe” trials were introduced in which the light was presented for intermediate durations. Logistic functions were derived relating percent choice of lever B to log stimulus duration. Under the “no-poke-requirement” condition, the bisection point (duration yielding 50% choice of lever B) was shorter in the lesioned rats than in the control rats. Under the “poke-requirement” condition, this effect of the lesion was attenuated. There was no effect of the lesion on the Weber fraction under either condition. The levels of 5HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered. It is proposed that rats may attain accurate timing under the interval bisection task by moving from one lever to the other during stimulus presentation; this movement may be facilitated by destruction of the 5HTergic pathways. Accurate timing is still possible when this movement is suppressed by the introduction of a “poke requirement”; however, in this case timing is not affected by 5HT depletion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246196
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  • 7
    Electronic Resource
    Electronic Resource
    Differential effects of ketamine on gating of auditory evoked potentials and prepulse inhibition in rats (1999)
    Springer
    Psychopharmacology 142 (1999), S. 9-17 
    Details
    ISSN: 1432-2072
    Keywords: Key words NMDA (N-methyl-D-aspartate) ; Schizophrenia ; Prepulse inhibition (PPI) ; Sensory gating ; P50 ; Auditory evoked potentials (AEP) ; Ketamine ; d-Amphetamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Schizophrenic patients suffer from deficits in information processing. Patients show both a decrease in P50 gating [assessed in the conditioning-testing (C-T) paradigm] and prepulse inhibition (PPI), two paradigms that assess gating. These two paradigms might have a related underlying neural substrate. Gating, as measured in both the C-T paradigm (the gating of a component of the auditory evoked potential (AEP)], and PPI can easily be measured in animals as well as in humans. This offers the opportunity to model these information processing paradigms in animals in order to investigate the effects of neurotransmitter manipulations in the brain. In order to validate the animal model for disturbances in AEP gating, d-amphetamine (0.5 and 1 mg/kg, IP) was administered. Gating of an AEP component was changed due to injection of d-amphetamine (1 mg/kg) in the same way as seen in schizophrenic patients: both the amplitude to the conditioning click and the gating were significantly reduced. Next, the effect of the N-methyl-D-aspartate (NMDA) antagonist ketamine (2.5 and 10 mg/kg, IP) was investigated to assess its effects in the two gating paradigms. It was found that ketamine (10 mg/kg) did not affect gating as measured with components of the AEP. However, ketamine (10 mg/kg) disrupted PPI of the startle response to the extent that prepulse facilitation occurred. Firstly, it is concluded that AEP gating was disrupted by d-amphetamine and not by ketamine. Secondly, PPI and the C-T paradigm reflect distinct inhibitory sensory processes, since both paradigms are differentially influenced by ketamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050856
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  • 8
    Electronic Resource
    Electronic Resource
    Motivational properties of buprenorphine as assessed by place and taste conditioning in rats (1997)
    Springer
    Psychopharmacology 130 (1997), S. 104-108 
    Details
    ISSN: 1432-2072
    Keywords: Key words Buprenorphine ; Drug abuse ; Place preference ; Taste aversion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Buprenorphine, a mixed agonist-antagonist opioid with considerable analgesic activity, is currently indicated as a therapeutic agent with low abuse potential. Nevertheless, buprenorphine abuse has been recently reported from some countries. Thus the present experiments were performed to characterize further the motivational properties of buprenorphine in rats. Rewarding and aversive effects were assessed by place preference and taste aversion conditioning, respectively. It was found that buprenorphine (0.025, 0.050, 0.100 mg/kg SC) causes a significant increase in the amount of time spent on the conditioned side, but no significant decrease in saccharin consumption. Therefore buprenorphine data are not consistent with the general finding that psychoactive drugs cause rewarding and aversive effects within a similar dose range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050216
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of desipramine and fluvoxamine on timing behaviour investigated with the fixed-interval peak procedure and the interval bisection task (1996)
    Springer
    Psychopharmacology 125 (1996), S. 274-284 
    Details
    ISSN: 1432-2072
    Keywords: Antidepressants ; Desipramine ; Fluvoxamine ; Timing ; Fixed-interval peak procedure ; Interval bisection task ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute treatment with antidepressant drugs is known to increase the mean interresponse time (IRT) in the IRT 〉72-s schedule of reinforcement. In order to examine the possibility that this effect may reflect an action of the antidepressants on timing processes, we tested the effects of two antidepressants, desipramine and fluvoxamine, on behaviour maintained under two other timing schedules in rats. In the fixed-interval peak procedure (fixed-interval 30-s), acute treatment with desipramine (8 mg kg−1) reduced response rate, whereas acute treatment with fluvoxamine (8 mg kg−1) increased it. Neither drug significantly altered the time to attainment of peak response rate or the Weber fraction. In the interval bisection task (standard durations 2 s and 8 s), the bisection point was not significantly altered by acute treatment with either drug. Chronic treatment with desipramine (8 mg kg−1 b.d.) had no effect on any of the indices of timing under either schedule. Chronic treatment with fluvoxamine (8 mg kg−1 b.d.) reduced the time to attainment of peak response rate but had no effect on the Weber fraction under the fixed-interval peak procedure, and did not alter the bisection point or Weber fraction under the interval bisection procedure. The failure of desipramine and fluvoxamine to increase the time to peak response rate or the bisection point at doses that significantly altered operant response rate suggests that the effect of these drugs on IRT schedule performance is unlikely to reflect an interaction with timing processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247339
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  • 10
    Electronic Resource
    Electronic Resource
    Mast cell-mediated induction of ICAM-1, VCAM-1 and E-selectin in endothelial cells in vitro: constitutive release of inducing mediators but no effect of degranulation (1997)
    Springer
    Pflügers Archiv 435 (1997), S. 137-144 
    Details
    ISSN: 1432-2013
    Keywords: Key words Mast cells ; Endothelial cells ; Cell adhesion molecules ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Mast cell (MC)-mediated induction of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and of E-selectin was studied in cultures of rat heart endothelial cells (EC) and human umbilical vein EC (HUVEC) respectively. MC induced VCAM-1 and E-selectin, but hardly any ICAM-1 in EC. Induction was not dependent on MC degranulation, but seemed to be provoked by constitutively released substances, other than histamine, from MC. Co-incubation of MC and EC, allowing for direct contact between the two cell types, was more potent in induction than MC co-incubated separately from EC using a permeable membrane. MC were less potent in induction than exogenous added cytokines or LPS. Induction of cell adhesion molecules in rat heart EC was MC-specific, since EC incubations with either rat cardiomyocytes or heart fibroblasts had no effect. The data show that rat MC, independent of degranulation, secrete mediators relevant for the induction of a specific set of EC adhesion molecules in vitro. This suggests a (supportive) role for MC in cell-adhesion molecule induction in the endothelium in settings of early or mild inflammation. The results are discussed in the context of inflammatory processes in the heart in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050493
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