Excitatory and inhibitory effects of dopamine on neuronal activity of the caudate nucleus neurons in vitro |
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| Affiliation: | 1. Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville TN 37232, USA;2. Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville TN 37232, USA;3. Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA;4. Kennedy Center for Research on Human Development, Vanderbilt University School of Medicine, Nashville, TN 37232, USA;5. Curriculum in Neuroscience, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA;6. Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA;7. Department of Pharmacology, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA;1. Department of Neurologic Surgery, Mayo Clinic, Rochester, MN;2. Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN;3. Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN;4. School of Medicine, Heidelberg University, Neuenheimer Feld, Bergheim, Germany;1. Graduate School of Science and Engineering, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe, Kyoto, 610-0321, Japan;2. Surface and Material Science Laboratory, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma, Nara, 630-0192, Japan;3. Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan |
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| Abstract: | ![]()
Effects of dopamine on the rat caudate nucleus neurons were examined in a slice preparation using an intracellular recording technique. Perfusion of the bath with a low concentration (1 μM) of dopamine produced a depolarization concomitant with an increase in the spontaneous firing and the number of action potentials evoked by a depolarizing pulse applied into the cells. In contrast, higher concentrations (100–500 μM) of dopamine inhibited the spontaneous and current-induced firings without apparent effects on the resting membrane potential. In addition, during application of a high concentration (100 μM) of dopamine there was a marked elevation of the threshold potential of the action potential elicited by a higher depolarizing current. Simultaneous application of haloperidol (0.5–5 μM) antagonized both excitatory and inhibitory effects induced by the low and high concentrations of dopamine, respectively. In addition, the excitatory effect induced by a low concentration (1 μM) of dopamine was antagonized by domperidone (0.5 μM), a selective D2 receptor antagonist, while the inhibitory effect by a high concentration (100 μM) was blocked by SCH 23390, a selective D1 receptor antagonist. These results strongly suggest that the postsynaptic sites of caudate nucleus neurons have at least two subtypes of dopamine receptors (D1 and D2 receptors) that mediate inhibitory and excitatory responses of the neuron to dopamine, respectively. |
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