Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-2072
    Keywords: Neuropeptide Y ; Anxiolysis ; Conflict model ; Alpha-adrenergic ; Idazoxan ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of intracerebroventircular (ICV), neuropeptide Y (NPY) (0.2–5.0 nmol) and its C-terminal 13–36 amino acid (AA) fragment (0.4–2.0 nmol) have been examined with respect to anxiolytic properties in two rat anxiety models, Montgomery's conflict test (MT), and Vogel's drinking conflict test (VT). In the MT, 1.0 and 5.0 nmol NPY abolished the normal preference for the closed arms of the maze. At 5.0 nmol, the total number of entries made into both closed and open arms was decreased by 50%. In the VT, both 0.2 and 1.0 nmol NPY markedly increased the number of shocks accepted. The effect of 5.0 nmol NPY was less pronounced. In control experiments, NPY (0.2 nmol) did not affect pain sensitivity or thirst. Pretreatment with the selective alpha2-adrenergic receptor antagonist idazoxan, at a dose which by itself did not affect behaviour (2.0 mg/kg), antagonized the effect of 1.0 nmol NPY in the VT. NPY 13-36 was without significant effect in both models. The results suggest that NPY exerts anxiolytic-like effects, and that these effects are mediated through an interaction with noradrenergic systems. Higher doses of NPY produce sedation and ataxia, which decrease overall activity in the MT, and interfere with the ability fully to express behaviourally the anxiolytic-like effect in the VT. The findings are discussed in relation to the noradrenaline hypothesis of anxiety, and to observations indicating involvement of NPY in the pathophysiology of major depression.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2072
    Keywords: Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Dopamine ; Serotonin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The β-adrenoceptor antagonist as well as serotonin 5-HT1 receptor antagonist, (−)alprenolol, was found to potentiate the disrupting effect of the non-competitive NMDA receptor antagonist, dizocilpine, on prepulse inhibition (PPI) of the acoustic startle response (ASR) in the rat. The facilitating effect of dizocilpine on ASR amplitude was also potentiated by (−)alprenolol. (−)Alprenolol by itself did not affect either of these measures. These effects did not seem to be related to the unselective β-adrenoceptor antagonist property of (−)alprenolol, since combined pretreatment with the β1- and β2-adrenoceptor antagonists, metoprolol and ICI 118551, did not alter the effects of dizocilpine on startle behaviour. However, a serotonergic influence was suggested by the fact that a facilitating effect of dizocilpine on ASR amplitude was also obtained by pretreatment with the 5-HT precursor, L-5-HTP, in benserazide-pretreated rats. Furthermore, pretreatment with the 5-HT2 selective receptor antagonist, MDL 100907, significantly reduced the (−)alprenolol-induced potentiation of the effects of dizocilpine on startle behaviour, while the 5-HT3 selective receptor antagonist, ondansetron, failed to do that. Finally, the (−)alprenolol-induced potentiation of the effects of dizocilpine was significantly reduced by pretreatment with the atypical antipsychotic, clozapine, and by the potential antipsychotic and selective dopamine D2 receptor antagonist, raclopride. This study suggests that altered 5-HT activity may influence the effects of psychotomimetic drugs such as dizocilpine on sensorimotor function, and this observation may have implications for the pharmacological treatment of schizophrenia in humans.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-2072
    Keywords: Benzodiazepines ; Brain reward systems ; Dependence-producing drugs ; Diazepam ; Dopamine ; Locomotor activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is well known that benzodiazepines produce dependence in humans and locomotor stimulation in experimental animals. In this study the possible involvement of catecholamines in the diazepam-induced locomotor stimulation in mice were investigated. Diazepam was found to have a biphasic effect; increasing locomotor activity at a low dose (0.25 mg/kg), while decreasing it at higher doses (〉0.5 mg/kg). The locomotor stimulating effect of diazepam was effectively blocked by pretreatment with the benzodiazepine receptor antagonist flumazenil, as well as with the catecholamine synthesis inhibitor α-methyltyrosine and the dopamine receptor antagonists haloperidol, spiperone and SCH 23390. Taken together, these data indicate that the locomotor stimulating effect observed after low doses of diazepam is due to activation of brain dopaminergic systems involved in locomotor activity. The observations are discussed in relation to the hypothesis that dependence-producing drugs activate specific brain reward systems.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-2072
    Keywords: Key words Acoustic startle response ; Prepulse inhibition ; Schizophrenia ; Sensitisation ; Amphetamine ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Male Sprague-Dawley rats were repeatedly treated with amphetamine (AMP, 1 mg/kg, SC) at 3- day intervals for 15 days and tested for prepulse inhibition of acoustic startle after each treatment. This treatment regimen induced sensitisation in the animals as evidenced by a progressive increase in the disruptive effect of AMP on prepulse inhibition. Persistent changes in brain function was indicated, since an increase in disruptive effect was observed in sensitised animals also after a 22-day-long drug- and test-free period. The development of sensitisation was blocked by pretreatment with haloperidol (HPD, 0.1 mg/kg, SC), which suggests that sensitisation to the disruptive effect of AMP was dependent on dopamine (DA) D2 receptor activation. Furthermore, the development of sensitisation was blocked by adrenalectomy, which suggests that sensitisation was dependent also on circulating adrenal hormones. Increased DA-ergic activity has been implicated in the pathophysiology of schizophrenia and AMP-induced sensitisation to the neuronal functions that modulate prepulse inhibition may be an experimental model to investigate this hypothesis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-2072
    Keywords: Key words Acoustic startle response ; Prepulse inhibition ; Sensorimotor gating ; Schizophrenia ; Medial geniculate body ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prepulse inhibition of acoustic startle is the normal reduction in startle response to an intense auditory stimulus when this stimulus is immediately preceded by a weaker prestimulus. Previous studies have shown that several neuroanatomical structures and pathways in the brain are involved in the modulation of prepulse inhibition. In the present study, the functional importance of the medial geniculate body (MG) in the modulation of prepulse inhibition was investigated. To this end, in vivo brain microdialysis probes were used to infuse drugs locally into the MG of awake, freely moving rats simultaneously with startle response and prepulse inhibition measurements in the same animals. Intrageniculate infusion of the sodium channel blocker, tetrodotoxin, significantly reduced prepulse inhibition without affecting baseline startle amplitude. A similar effect was obtained after intrageniculate infusion of the GABAB receptor agonist, baclofen. In addition, intrageniculate infusion of muscimol, an agonist at the GABAA receptor complex, reduced prepulse inhibition, although this effect was obtained at a higher concentration of the drug compared to that of baclofen. These studies suggest that the MG is involved in the modulation of prepulse inhibition and that auditory signals relayed via the MG may be subjected to inhibitory control at this level, involving GABA neurotransmission.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-2072
    Keywords: Ethanol ; Tolerance ; Hypothermia ; DOPAC ; HVA ; Rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The development of tolerance to the behavioral and biochemical effects of ethanol was studied. Rats were made tolerant to ethanol by the administration of daily ethanol injections (3 g/kg, IP) for 7 and 28 days. Tolerance developed both to the behavioral (hypothermic, sedative) and biochemical (accumulation of dopamine metabolites in various brain areas) actions of ethanol. However, it was found that this tolerance to both the behavioral and biochemical effects of ethanol was no longer present when previously ethanol-tolerant animals were moved from their home environment and given a challenge dose of ethanol (2.5 g/kg; IP) in a new, unfamiliar environment. Our findings confirm that ethanol tolerance cannot be explained on the basis of a singular neurochemical event. The development of ethanol tolerance is due to a complex interaction between environmental, learning, and biochemical factors.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-2072
    Keywords: Key words Nicotine ; Behavioral sensitization ; Locomotor activity ; Elevated plus-maze ; Serotonin ; Citalopram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study investigated the effects of repeated nicotine treatment on locomotor activity and behavioral inhibition, and the influence of citalopram on the behavioral effects obtained. Male rats received daily subcutaneous injections of vehicle + vehicle (veh + veh), citalopram (5.0 mg/kg) + vehicle (cit + veh), vehicle + nicotine (1.0 mg/kg; veh + nic) or citalopram+nicotine (cit + nic). Acutely, nicotine stimulated locomotor activity, and repeated daily nicotine injections sensitized veh+nic rats to the nicotine-induced locomotor stimulation after 5, 10 and 15 treatment days, whereas in cit+nic rats, the enhancement of nicotine-induced locomotion was suppressed. However, when challenged with nicotine after citalopram withdrawal (−36 h), the cit + nic treated animals were also observed to be sensitized. In the elevated plus-maze, repeated nicotine treatment produced behavioral disinhibition, measured as an increase of time spent in and entries made into open arms (%), and chronic citalopram treatment attenuated the expression of behavioral disinhibition. Moreover, the degree of nicotine sensitization correlated to the behavioral disinhibition observed. In summary, these findings suggest that behavioral sensitization to nicotine is associated with behavioral disinhibition and that chronic citalopram treatment counteracts the expression of both phenomena. Since citalopram is a highly selective serotonin reuptake inhibitor, the effects of citalopram may be due to a facilitation of serotonin neurotransmission caused by the chronic citalopram treatment.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...