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: 1435-1463
    Keywords: Catalepsy ; haloperidol ; locomotion ; reserpine ; α-methyl-ptyrosine ; rotation ; substantia nigra lesion ; amantadine ; memantine ; MK-801 ; NMDA receptor antagonism ; plasma levels ; brain levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Amantadine (25, 50, 100 mg/kg), memantine (5, 10, 20 mg/kg) and MK-801 (0.05, 0.1, 0.2 mg/kg), all having NMDA channel blocking properties, were compared in three tests used for screening of antiparkinsonian agents in rats, namely: haloperidol-induced catalepsy, locomotor activity in monoamine depleted rats and rotation in rats with a unilateral substantia nigra lesion. Additionally, plasma levels of amantadine and memantine were assessed to gain an insight into the concentration ranges achieved at behaviorally active doses. Amantadine and (+)-MK-801 produced dosedependent inhibition of haloperidol-induced catalepsy while memantine was less efficacious producing clear-cut anticataleptic action at a dose of 10 mg/kg only but failing at 20 mg/kg due to myorelaxant activity. All agents attenuated sedation in monoamine depleted rats with amantadine being the least and MK-801 being the most effective. The same rank order of efficacy was seen in inducing ipsilateral rotations in rats after a substantia nigra lesion. On the basis of the present study and published data, it can be assumed that the doses of amantadine, memantine and MK-801 showing antiparkinsonian-like activity in animals result in plasma levels leading to NMDA antagonism. However, in the haloperidol-induced catalepsy test the efficacy of amantadine was higher than memantine, while the opposite was true for rotation and reserpine-induced sedation indicating pharmacodynamic differences between both agents.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1435-1463
    Keywords: Keywords: Dopamine ; memantine ; microdialysis ; pharmacokinetics ; pre-frontal cortex.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. Memantine is an uncompetitive N-methyl-D-aspartate receptor antagonist which blocks the NMDA receptor with moderate-affinity in a use- and voltage dependent manner. In clinical practice it is used chronically in the treatment of dementia and does not induce psychotomimetic effects as, high affinity, uncompetitive antagonists. Thus, it was of interest to determine dopamine (DA) and metabolite (DOPAC – dihydroxyphenylacetic acid and HVA – homovanillic acid) concentrations in the prefrontal cortex (PFC) in response to 14 days administration of memantine (20 mg/kg/day). It was previously determined that in rats this treatment induces sensitization to the locomotor effect and tolerance to the learning impairing properties of high doses of memantine. Acute administration of memantine (20 mg/kg, ip) did not affect dopamine levels in the PFC. It did however increase DA metabolite (DOPAC and HVA) concentrations. Administration of memantine (20 mg/kg/day) for 14 days before the acute challenge only slightly changed memantine's effect on PFC neurochemistry even though pharmacokinetic tolerance was observed. When memantine was administered to the sham group, which had been repeatedly treated with Hypnorm (including neuroleptic), an increase in PFC dopamine and metabolite content was seen. In accordance with the fact that memantine does not possess psychotomimetic activity at therapeutically relevant doses, these experiments showed that it does not affect the prefrontal cortex dopamine levels.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1435-1463
    Keywords: Keywords: Amantadine ; dopamine D2 receptor ; memantine ; (+)MK-801 ; muscarinic receptor ; NMDA receptor ; receptor autoradiography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. Behavioral changes have previously been reported following administrations of uncompetitive NMDA receptor antagonists memantine, amantadine and MK-801 for 14 days, at the doses that produce plasma levels comparable to those seen in patients (20, 100 and 0.31 mg/kg/day respectively). Using the same doses, the effect on receptor binding (autoradiography) was studied in rats. [3H]MK-801 binding was increased in the dentate gyrus and CA3 region of the hippocampus (35.2 and 24.3% respectively) following 3 days S.C. infusion of memantine by ALZET minipumps. One daily injection of memantine for 14 days, increased [3H]MK-801 binding in the frontal cortex by 40.3%. The same treatment with amantadine did increase [3H]raclopride binding to dopamine D2 receptors by 13.5%. None of these treatments changed the expression of muscarinic receptors. It is concluded that subchronic blockade of the NMDA receptor by uncompetitive antagonists at moderate (therapeutically-relevant) doses induced only minor changes in NMDA and dopamine D2 receptor expression.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 98 (1994), S. 57-67 
    ISSN: 1435-1463
    Keywords: Locomotion ; Parkinson's model ; reserpine ; α-methyl-p-tyrosine ; memantine ; amantadine ; L-deprenyl ; bromocriptine ; L-DOPA ; synergism ; rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Some treatments used for Parkinson's disease attenuate locomotor depression in rats treated with reserpine and α-methyl-p-tyrosine. In the present study memantine (2.5, 5.0mg/kg), amantadine (10, 20mg/kg) (both uncompetitive NMDA antagonists), and L-deprenyl (1.0, 5.0 mg/kg; MAO-B inhibitor) were tested for possible synergistic interactions with the dopamine agonists: bromocriptine (2.5, 5.0mg/kg) and L-DOPA (50, 100mg/kg, + benserazide, 100 mg/kg). At higher doses, memantine (10 mg/kg), amantadine (40 mg/kg), bromocriptine (5 and 10mg/kg) and L-DOPA (100, 200mg/kg) but not L-deprenyl (up to 10 mg/kg) produced a pronounced increase in locomotor activity when given alone. The combination of memantine, amantadine and L-deprenyl with bromocriptine did not result in synergism of action and, at best, an additive effect was seen. On the other hand the combination of these agents with L-DOPA produced a pronounced synergistic effect. Hence, the clinical observation that coadministration of L-DOPA with either memantine or amantadine results in enhancement of their action is also reflected in an animal model of Parkinson's disease. Such a combination therapy should allow the use of lower doses of both drugs which may reduce the occurrence of side effects and may also be predicted to have additional benefits related to the neuroprotective properties of memantine, amantadine, and L-deprenyl.
    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...