Search results for "Serotonin"
showing 10 items of 414 documents
Motoneurons of the stapedius muscle in the guinea pig middle ear: Afferent and efferent transmitters
2008
The objective of the present study was to identify efferent and afferent transmitters of motoneurons of the stapedius muscle of the middle ear in order to gain more insight into the neuronal regulation of the muscle. To identify motoneurons, we injected the fluorescent neuronal tracer Fluorogold (FG) into the muscle after preparation of the middle ear in adult guinea pigs. Upon terminal uptake and retrograde neuronal transport, we observed FG in neurons located medial and ventral to the nucleus of the facial nerve ipsilateral to the injection site. Immunohistochemical studies of these motoneurons showed that the majority contains calcitonin gene-related peptide. Our data further demonstrate…
Vomeronasal inputs to the rodent ventral striatum.
2008
Vertebrates sense chemical signals through the olfactory and vomeronasal systems. In squamate reptiles, which possess the largest vomeronasal system of all vertebrates, the accessory olfactory bulb projects to the nucleus sphericus, which in turn projects to a portion of the ventral striatum known as olfactostriatum. Characteristically, the olfactostriatum is innervated by neuropeptide Y, tyrosine hydroxylase and serotonin immunoreactive fibers. In this study, the possibility that a structure similar to the reptilian olfactostriatum might be present in the mammalian brain has been investigated. Injections of dextran-amines have been aimed at the posteromedial cortical amygdaloid nucleus (th…
L-type calcium channel activity in human atrial myocytes as influenced by 5-HT.
1993
5-Hydroxytryptamine (10 mumol/l; 5-HT) exerted a positive inotropic effect associated with an increase in the Ca2+ current (ICa) in the human right atrium. For detailed analysis, L-type Ca2+ channel currents were recorded from cell-attached patches using 100 mmol/l Ba2+ as charge carrier. Ca2+ channel activity was identified, first, by burst-like inwardly directed currents and, second, by the appearance of long channel openings promoted by Bay K 8644 (1 mumol/l) upon repetitive depolarizations from -80 to 0 mV. The unitary conductance of the Ca2+ channel amounted to 25.8 pS. During superfusion with 5-HT, ensemble averaged (mean) current was enhanced by about 60%. The increase in mean curren…
Effect of chronic citalopram on serotonin-related and stress-regulated genes in the dorsal raphe nucleus of the rat
2007
Using a model of depression in which chronic social stress induces depressive-like symptoms, we investigated effects of the selective serotonin-reuptake inhibitor (SSRI) citalopram on gene expression in the dorsal raphe nucleus of male rats. Expression of tryptophan hydroxylase (TPH) protein was found to be upregulated by the stress and normalized by citalopram, while mRNAs for genes TPH 1 and 2 were differentially affected. Citalopram had no effect on serotonin transporter mRNA but reduced serotonin-1A autoreceptor mRNA in stressed animals. The SSRI prevented the stress-induced upregulation of mRNA for CREB binding protein, synaptic vesicle glycoprotein 2b and the glial N-myc downstream-re…
Influence of melatonin and serotonin on the number of rat pineal ?synaptic? ribbons and spherules in vitro
1985
Previous studies have shown that the "synaptic" ribbons (SR) and spherules (SS) of the mammalian pineal gland may respond differently under physiological and various experimental conditions. The aim of the present study was to gain insight into the mechanisms that may be responsible for the numerical changes of these organelles during a 24-h cycle. As the possibility exists that the structures are influenced by substances synthesized within the pinealocyte, rat pineal glands were cultured with and without added melatonin or serotonin, using an experimental protocol such that the addition of melatonin and serotonin mimicks the circadian changes of the respective substances within the pineal.…
p-Chlorophenylalanine treatment depresses the number of synaptic ribbon profiles in the rat pineal gland, but does not abolish their day-night rhythm
1995
It is largely unknown as to how the day/night rhythm of pineal synaptic ribbon number is regulated. Transcriptional events related to the nocturnal formation of new synaptic ribbons occur early in the morning, when pineal serotonin levels begin to increase. The present study was carried out in order to elucidate as to how altered serotonin levels affect the day/night changes in the number of synaptic ribbon profiles. To this end, male Sprague-Dawley rats received a single dose of p-chlorophenylalanine (pCPA, 300 mg/kg body weight, 72 hours before sacrifice), which depresses tryptophan hydroxylase activity and hence pineal serotonin levels. Control animals received saline injections. Experim…
Central serotonin depletion modulates the behavioural, endocrine and physiological responses to repeated social stress and subsequent c-fos expressio…
1999
Abstract Intraspecific confrontation has been used to study effect of depleting central serotonin on the adaptation of male rats to repeated social stress (social defeat). Four groups of adult male rats were used (serotonin depletion/sham: stressed; serotonin depletion/sham: non-stressed). Central serotonin was reduced (by 59–97%) by a single infusion of the neurotoxin 5,7-dihydroxtryptamine (150 μg) into the cerebral ventricles; levels of dopamine and noradrenaline were unaltered (rats received appropriate uptake blockers prior to neurotoxic infusions). Sham-operated animals received solute only. Rats were then either exposed daily for 10 days to a second larger aggressive male in the latt…
Neurotransmitter receptor density changes in Pitx3ak mice – A model relevant to Parkinson’s disease
2014
Abstract Parkinson’s disease (PD) is the second most common neurodegenerative disorder, characterized by alterations of nigrostriatal dopaminergic neurotransmission. Compared to the wealth of data on the impairment of the dopamine system, relatively limited evidence is available concerning the role of major non-dopaminergic neurotransmitter systems in PD. Therefore, we comprehensively investigated the density and distribution of neurotransmitter receptors for glutamate, GABA, acetylcholine, adrenaline, serotonin, dopamine and adenosine in brains of homozygous aphakia mice being characterized by mutations affecting the Pitx3 gene. This genetic model exhibits crucial hallmarks of PD on the ne…
Diabetes-induced changes in endothelial mechanisms implicated in rabbit carotid arterial response to 5-hydroxytryptamine
2000
Abstract The influence of diabetes on endothelial mechanisms implicated in the response of isolated rabbit carotid arteries to 5-hydroxytryptamine (5- HT ) was studied. 5-HT induced a concentration–dependent contraction that was potentiated in arteries from diabetic rabbits with respect to that in arteries from control rabbits. Endothelium removal potentiated 5-HT contractions in arteries from both control and diabetic rabbits but increased the maximum effect only in arteries from diabetic rabbits. Incubation of arterial segments with N G -nitro- l -arginine ( l- NA) enhanced the contractile response to 5-HT. This l -NA enhancement was greater in arteries from diabetic rabbits than in arter…
Behavioral deficits induced by lead exposure are accompanied by serotonergic and cholinergic alterations in the prefrontal cortex
2013
The effects of long-term lead (Pb) exposure producing a blood Pb concentration of lower than 20 μg/dL, i.e. below that associated with overt neurological deficits in occupationally exposed individuals, was studied in adult rats. In order to assess gender differences, we performed parallel behavioral experiments in male and female rats. Exposure to Pb acetate (50 ppm in drinking water) for 6 months induced motor and cognitive alterations, however these effects were gender- and task-dependent. Chronic lead exposure impaired spatial learning assessed in the Morris water maze test (MWM) in both genders, whereas it only induced hyperactivity in the open field and impaired motor coordination in t…