Abstract
The mechanism by which dopamine (DA) decreases the amplitude of the EPSP-IPSP sequences evoked by cortical stimulation was investigated by means of electrophysiological and biochemical methods. Intracellular recordings indicate that DA decreases the amplitude of the excitatory and inhibitory events by reducing the increase in membrane conductance measured at the peaks of the EPSP-IPSP. The non-synaptic input resistance was not modified. In addition the catecholamine (+50/+200nA balanced current) was shown to decrease the action of glutamate (−30−80nA balanced current) and GABA (+40/+100nA balanced current) when iontophoretically applied. These observations suggest that DA interferes with the excitatory (glutamatergic) and inhibitory (GABAergic) transmission at the postsynaptic site in striatal neurons. However, the depression of cellular excitability elicited by DA could not be ascribed only to its interaction with synaptic transmission at the postsynaptic level. In fact the catecholamine also inhibited spike frequency driven by depolarizing pulses and decreased the depolarization-induced release of glutamate at the presynaptic site, as shown by biochemical experiments with striatal synaptosomal preparations. A neuromodulatory role of DA in the depression of the excitability of striatal neurons by presynaptic and postsynaptic mechanisms is suggested.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.