Stefan Mihailescu

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Nicotine, locally administered into the dorsal raphe nucleus (DRN) of rat midbrain slices, increased the discharge rate of 70% of serotoninergic neurons, decreased it in 30% and induced reciprocal oscillatory increases in serotonin (5-hydroxytryptamine, 5-HT) and gamma-aminobutyric acid (GABA) release. All of nicotine's stimulatory effects were maximal at(More)
Several behavioral effects of nicotine are mediated by changes in serotonin (5-HT) release in brain areas that receive serotonergic afferents from the dorsal raphe nucleus (DRN). In vitro experiments have demonstrated that nicotine increases the firing activity in the majority of DRN 5-HT neurons and that DRN contains nicotinic acetylcholine receptors(More)
Previous studies showed that nicotine suppresses the ponto-geniculo-occipital (PGO) spikes of rapid eye movement (REM) sleep in cats. This effect may depend on stimulation of dorsal raphe nucleus (DRN) serotoninergic neurons that inhibit the pedunculopontine (PPT) and laterodorsal tegmental (LDT) cholinergic neurons, generators of PGO spikes. For testing(More)
Neuronal nicotinic acetylcholine receptors (nAChRs) represent a large family of ligand-gated cation channels with diverse structures and properties. In contrast to the muscular nAChRs, the physiological functions of neuronal nAChRs are not well defined to date. Behavioral studies indicate that brain nAChRs participate in complex functions such as attention,(More)
Cholinergic signaling mediated by nicotinic receptors has been associated to a large number of physiological and behavioral processes such as learning, memory, attention, food-intake and mood disorders. Although it is well established that many nicotinic actions are mediated through an increase in serotonin (5-HT) release, the physiological mechanisms by(More)
This study investigates the hypothesis that serotonin mediates certain nicotine effects, such as mood improvement and the suppression of the ponto-geniculo-occipital spikes of rapid eye movement sleep. The influence of nicotine (10-300 microM) on the firing rate of dorsal raphe neurons and on serotonin release was therefore, studied in rat midbrain slices.(More)
Very few neurons in the telencephalon have been shown to express functional postsynaptic nicotinic acetylcholine receptors (nAChRs), among them, the noradrenergic and dopaminergic neurons. However, there is no evidence for postsynaptic nAChRs on serotonergic neurons. In this study, we asked if functional nAChRs are present in serotonergic (5-HT) and(More)
The pharmacological activity of bupropion was compared between α7 nicotinic acetylcholine receptors expressed in heterologous cells and hippocampal and dorsal raphe nucleus neurons. The inhibitory activity of bupropion was studied on GH3-α7 cells by Ca2+ influx, as well as on neurons from the dorsal raphe nucleus and interneurons from the stratum radiatum(More)
The authors check the theory according to which cardiac rhythm disturbances developing after myocardial infarction or in the course of a long Q-T interval syndrome are due to stimulation of the autonomic nervous system which innervates the heart via the stellate ganglia, the tonus of the left sympathetic being predominant over the right sympathetic at(More)
Clinical studies suggest that depression facilitates alcohol abuse. Depressed individuals also have increased rates of smoking, and it has been suggested that nicotine may improve depression. It is therefore possible that nicotine may reduce alcohol use in depression. To investigate this potential relationship, we evaluated alcohol intake in an animal model(More)