Inhibitory and activatory effects of dopamine on neurons in slices of the compact zone of theSubstantia nigra of rats
Autor: | V. D. Gerasimov, D. P. Artemenko |
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Rok vydání: | 1996 |
Předmět: |
medicine.medical_specialty
Physiology General Neuroscience Dopaminergic Biology Inhibitory postsynaptic potential Cell biology Electrophysiology Dopamine receptor D1 medicine.anatomical_structure Endocrinology nervous system Dopamine Internal medicine Dopamine receptor D2 Excitatory postsynaptic potential medicine Neuron medicine.drug |
Zdroj: | Neurophysiology. 27:214-221 |
ISSN: | 1573-9007 0090-2977 |
DOI: | 10.1007/bf01053336 |
Popis: | Effects of dopamine on the background spike activity of functionally (according to their electrophysiological characteristics) identified dopaminergic (DA) or non-dopaminergic (non-DA) neurons of the compact zone of thesubstantia nigra were studied on slices of the midbrain of adult rats. In the majority of DA neurons, dopamine suppressed the background activity in a dose-dependent manner. Sensitivity of these cells to dopamine varied within a wide range: IC50, the concentration providing the 50% maximum effect, equalled from 3 to 3,000 µM in different units. A part of DA neurons responded to dopamine with an increase in their activity. Mixed responses, in which an initial suppression of impulsation was replaced by a slow-developing activation, was observed in some neurons. Non-DA neurons usually responded to dopamine by an enhancement of impulsation; yet, the cells with inhibitory or mixed responses similar to those of DA neurons could be found in this population as well. Sensitivity of non-DA neurons to dopamine was about the same as that of DA-cells, without the dependence on the direction of responses. S(−)-suipiride, a blocker of D2 receptors, decreased the inhibitory component of all tested responses to dopamine both in DA and non-DA neurons and evoked no changes in the excitatory component. At the same time, R(+)-SCH 23390 HC1, a blocker of D1 receptors, suppressed the activatory component of responses with no effect on the inhibitory component. We conclude that both types of DA receptors, D2 and D1 receptors, can be present on the DA and non-DA neurons. Dopamine, influencing these receptors, suppresses or facilitates, respectively, the spike activity of these cells. The relative amount of such receptors is the main factor determining the pattern and dynamics of the integral response to dopamine application. The possible functional role of the presence of both D1 and D2 receptors on the membrane of a single neuron is discussed. |
Databáze: | OpenAIRE |
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