Search results for "NAPS"
showing 10 items of 302 documents
Affinity and efficacy of racemic, (+)-, and (−)-methacholine in muscarinic inhibition of [3H]-noradrenaline release
1985
The right postganglionic sympathetic nerves of rat isolated perfused hearts (previously loaded with [3H]-noradrenaline) were stimulated electrically with 10 trains of 10 pulses at 10 Hz. The inhibition by methacholine of stimulation-evoked [3H]-noradrenaline overflow into the perfusate (determined in the presence of corticosterone, desipramine, phentolamine, and propranolol) was taken as a measure for activation of presynaptic muscarinic receptors. The evoked [3H]-noradrenaline overflow was inhibited by (+)-, racemic, and (-)-methacholine in a reversible and concentration-dependent manner. The concentration causing 50% inhibition (IC50) was 0.1, 0.26, and 65 microM, respectively, resulting …
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…
Depletion of polysialic acid from neural cell adhesion molecule (PSA-NCAM) increases CA3 dendritic arborization and increases vulnerability to excito…
2012
Chronic immobilization stress (CIS) shortens apical dendritic trees of CA3 pyramidal neurons in the hippocampus of the male rat, and dendritic length may be a determinant of vulnerability to stress. Expression of the polysialylated form of neural cell adhesion molecule (PSA-NCAM) in the hippocampal formation is increased by stress, while PSA removal by Endo-neuraminidase-N (endo-N) is known to cause the mossy fibers to defasciculate and synapse ectopically in their CA3 target area. We show here that enzymatic removal of PSA produced a remarkable expansion of dendritic arbors of CA3 pyramidal neurons, with a lesser effect in CA1. This expansion eclipsed the CIS-induced shortening of CA3 dend…
The atypical dopamine transport inhibitor, JHW 007, prevents amphetamine-induced sensitization and synaptic reorganization within the nucleus accumbe…
2013
Benztropine (BZT) analogs, a family of agents with high affinity for the dopamine transporter have been postulated as potential treatments in stimulant abuse due to their ability to attenuate a wide range of effects evoked by psychomotor stimulants such as cocaine and amphetamine (AMPH). Repeating administration of drugs, including stimulants, can result in behavioral sensitization, a progressive increase in their psychomotor activating effects. We examined in mice the sensitizing effects and the neuroplasticity changes elicited by chronic AMPH exposure, and the modulation of these effects by the BZT derivative and atypical dopamine uptake inhibitor, JHW007, a candidate medication for stimu…
Role of calcineurin in Ca2+-induced release of catecholamines and neuropeptides
1998
Neurotransmission requires rapid docking, fusion, and recycling of neurotransmitter vesicles. Several of the proteins involved in this complex Ca2+-regulated mechanism have been identified as substrates for protein kinases and phosphatases, e.g., the synapsins, synaptotagmin, rabphilin3A, synaptobrevin, munc18, MARCKS, dynamin I, and B-50/GAP-43. So far most attention has focused on the role of kinases in the release processes, but recent evidence indicates that phosphatases may be as important. Therefore, we investigated the role of the Ca2+/calmodulin-dependent protein phosphatase calcineurin in exocytosis and subsequent vesicle recycling. Calcineurin-neutralizing antibodies, which blocke…
Mouse photoreceptor synaptic ribbons lose and regain material in response to illumination changes
2004
Abstract Chemical synapses equipped with ribbons are tonically active, high-output synapses. The ribbons may play a role in the trafficking of synaptic vesicles. Recent findings in retinal rod cells of BALB/c mice indicate that ribbons are large and smooth in the dark phase, and, due to the formation and release of protrusions, small during the light phase. As a consequence of these changes, ribbons may traffick fewer vesicles in the light than in the dark phases. The aim of the present study was to find out whether the above ribbon changes in this mouse strain are strictly illumination-dependent and which signalling processes may be involved. Here, we show that ribbons form protrusions and…
Characterization of a population of tyrosine hydroxylase-containing interneurons in the external plexiform layer of the rat olfactory bulb
2012
The olfactory bulb (OB) of mammals contains the major endogenous dopamine-producing system in the forebrain. The vast majority of dopaminergic neurons consists of juxtaglomerular cells, which innervate the olfactory glomeruli and modulate the entrance of sensory information to the OB. Although dopaminergic juxtaglomerular cells have been widely investigated, the presence of dopaminergic interneurons other than juxtaglomerular cells has been largely unexplored. In this study, we analyze a population of tyrosine hydroxylase (TH)-containing interneurons located in the external plexiform layer (EPL) of the rat OB. These interneurons are GABAergic and morphologically heterogeneous. They have an …
USH3A transcripts encode clarin-1, a four-transmembrane-domain protein with a possible role in sensory synapses.
2002
Usher syndrome type 3 (USH3) is an autosomal recessive disorder characterised by the association of post-lingual progressive hearing loss, progressive visual loss due to retinitis pigmentosa and variable presence of vestibular dysfunction. Because the previously defined transcripts do not account for all USH3 cases, we performed further analysis and revealed the presence of additional exons embedded in longer human and mouse USH3A transcripts and three novel USH3A mutations. Expression of Ush3a transcripts was localised by whole mount in situ hybridisation to cochlear hair cells and spiral ganglion cells. The full length USH3A transcript encodes clarin-1, a four-transmembrane-domain protein…
Ultrastructural observations on the central innervation of the guinea-pig pineal gland.
1981
In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between h…