Biomedical subjects

F Stratta

Publications and source records attributed to F Stratta.

22 records · Page 2Linked to original sources

PubMed1991

Nomifensine but not amantadine increases dopamine-induced responses on rat substantia nigra zona compacta neurons.

Responses of substantia nigra zona compacta neurons to nomifensine and amantadine were studied with intracellular recording techniques (current and voltage clamp) in in vitro slice preparation of rat mesencephalon. The application of nomifensine (1-10 microM) slightly hyperpolarized the cells and inhibited action potential discharge that occurs spontaneously. In voltage-clamp experiments (-50, -60 mV, holding potential) an outward current was observed. The membrane responses to exogenously-applied dopamine were potentiated by the concomitant superfusion of nomifensine. The effects of nomifensine were antagonized by (-)-sulpiride (1 microM), a D2 receptor antagonist. By contrast, the superfusion of amantadine (1-30 microM) on substantia nigra zona compacta cells was ineffective on firing rate, membrane potential or on sensitivity to exogenous dopamine. In the presence of high doses (300 microM to 1 mM) of amantadine a depolarization and an increase in firing activity was observed. While our results provide electrophysiological evidence for an inhibition of the dopamine uptake system by nomifensine, they do not support a dopaminergic mechanism for the actions of amantadine in the substantia nigra zona compacta.

Amantadine↗

PubMed1991

GABA depolarizes neurons in the rat striatum: an in vivo study.

GABA, applied by iontophoresis to striatal neurons of the rat in an in vivo preparation, depolarized the membrane potential and decreased the input resistance in a dose-dependent manner. The null potential of the GABA depolarization was about -50 mV. In addition, a fading of the GABA-induced response was observed for prolonged and relatively high amino acid application. We conclude that GABA has a depolarizing effect on striatal cells. This is in line with recent in vitro works describing a depolarizing effect of GABA in the rat neostriatum.

Animals↗

PubMed1991

Electrophysiological effects of amineptine on neurones of the rat substantia nigra pars compacta: evidence for an inhibition of the dopamine uptake system.

1. Intracellular recordings were made from substantia nigra pars compacta neurones of the rat maintained in vitro in order to study the effects of the tricyclic antidepressant drug, amineptine. 2. Amineptine hydrochloride (1-30 microM) decreased spontaneous firing and slightly hyperpolarized the membrane potential. In neurones voltage-clamped at -50 or -60 mV, amineptine produced an outward membrane current. These actions were concentration-dependent and were completely antagonized by (-)-sulpiride. 3. The amineptine-induced hyperpolarization was resistant to tetrodotoxin (1 microM) but it was abolished in 0 mM Ca2+ (plus 13 mM MgCl2) solutions. 4. Amineptine (300 nM-30 microM) and cocaine (10-30 microM) increased the amplitude and duration of responses to exogenously applied dopamine. The effects of dopamine were potentiated about 5 fold by 10 microM amineptine; this potentiation persisted in calcium-free solutions. 5. Cocaine (10 microM) had no additional effect on the dopamine-induced responses in the presence of amineptine (30 microM). Amineptine (10 microM) produced no detectable effects in the presence of cocaine (30 microM). 6. It is concluded that amineptine acts as a dopamine uptake blocker in slices of rat substantia nigra.

Animals↗

PubMedDate not supplied

Electrophysiological evidence for the presence of ionotropic and metabotropic excitatory amino acid receptors on dopaminergic neurons of the rat mesencephalon: an in vitro study.

The actions of the ionotropic and metabotropic excitatory amino acid agonists AMPA, quisqualate, kainate, NMDA and trans-ACDP were studied by means of intracellular electrophysiological recordings from dopaminergic neurons of rat mesencephalon in brain slices. It was observed that all these agents evoked an inward current in cells which were voltage-clamped near the resting potential (-50, -60 mV). The membrane responses produced by AMPA, kainate and quisqualate were associated with an increase of the apparent input conductance while the responses induced by NMDA and trans-ACDP were associated with a decrease in the apparent input conductance. Therefore, stimulation of ionotropic and metabotropic amino acid receptors activates inward currents in the dopaminergic cells by different mechanisms.

Animals↗