Localization Of Serotonin Research Articles

Novel polymorphism in the 5′-upstream region of the human 5-HT 6 receptor gene and schizophrenia

The localization of 5-hydroxytryptamine 6 (5-HT 6) receptor in the limbic and cortical regions, and the high affinity of atypical antipsychotic drugs such as clozapine for the receptor, suggest the possible involvement of the receptor in the pathogenesis of schizophrenia. In this study, we searched systematically for polymorphisms in the 5′-upstream region of the human 5-HT 6 receptor gene. We identified a trinucleotide repeat polymorphism, (GCC) 2/3, at a nucleotide position between −1093 and −1085 bp upstream from the translation start site. Subsequent case-control association study did not demonstrate significant differences of genotype and allele frequency between 206 controls and 246 patients with schizophrenia. Our results suggest that the 5-HT 6 receptor gene polymorphism does not confer increased susceptibility to schizophrenia.

Studies on the localization of 5-hydroxytryptamine and its receptors in human placenta

The localization of 5-hydroxytryptamine (5-HT) and its receptors in human placenta was studied under light and electron microscopy using immunohistochemistry and in situ hybridization. The syncytiotrophoblast, cytotrophoblast, stromal cells and decidual cells in human placentae all appeared to be 5-HT immunoreactive. The 5-HT immunoreactive material was distributed in cytoplasm with negative nuclei. The 5-HT immunoreactive material was also found in capillary endothelium. Trophoblast cells cultured in serum-free medium also showed 5-HT immunoreactivity in the cytoplasm. Fetal white blood cells and both syncytiotrophoblast and cytotrophoblast in human placenta showed 5-HT receptor immunoreactivity and 5-HT 1A receptor mRNA hybridized signal was also detected in cytoplasm. The stromal cells and capillary endothelium in placental villi and maternal decidual cells all showed 5-HT receptor immunoreactivity in cytoplasm. The small flattened vesicles and large dense cored vesicles within trophoblast cells showed electron-dense 5-HT receptor immunoreactivity using immunoelectron microscopy. These results suggest that human placenta may not only produce 5-HT but also be a 5-HT target organ, and that 5-HT may not only play roles in placental development and pregnancy maintenance by paracrine and autocrine interactions but may also take part in regulating fetal development.

Antibodies as molecular probes in neurobiology. Identification of chemically defined neurons and synapses in tissues and tissue cultures.

Immunocytochemical localization of 5-hydroxytryptamine (5-HT) in the nervous system and aggregate tissue cultures was performed employing an antibody to 6-OH-1,2,3,4-tetrahydro-beta-carboline. A number of immunochemical and biochemical tests with the antigen and the antibody and some procedural changes in the methodology applied for immunolocalization revealed the anti-5-HT-like affinity of the antibody, if applied in paraformaldehyde-fixed tissues. Studies in the hypothalamus, striatum, brainstem, spinal cord, and pineal gland show the complexities of the serotoninergic system. Ultrastructural immunocytochemistry with the preembedding technique reveals that 5-HT synapses are of the asymmetric type. The presynaptic element contains clear, round, small vesicles, with some large dense-core vesicles. The contacts are made with the somata and primary, secondary dendrites or with spines of non-5-HT neurons. Presynaptic dendrites are found in the n. raphe dorsalis, contacting non-5-HT dendrites. Double immunocytochemical methods demonstrated contacts of 5-HT fibers on enkephalin containing neurons of the spinal trigeminal nucleus and on somatostatin containing neurons of the medullary reticular formation. In vitro studies of cultured mesencephalic neurons were performed with the method of aggregating cultures. Such development of a miniature organized nerve tissue was followed up to 35 d in culture. Organization of the neuropil and synaptogenesis was studied using standard electron microscopy. The differentiation of neurons and astrocytes was studied using antibodies to 5-HT and GFAP. Serotonin immunoreactivity could be observed in neuronal bodies and processes at light microscope level as early as the fourth day of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Gland cells in the tentacles of the jellyfish Cyanea lamarcki reactive with an antibody against 5-hydroxytryptamine

A light- and electron-microscopic immunocytochemical study on the localization of 5-hydroxytryptamine in Cyanea lamarcki revealed a reaction product in the epidermal gland cells surrounding the nematocyst clusters. The closely related scyphozoan medusa Cyanea capillata lacked a reaction product in the similar mucus-producing gland cells. Earlier conflicting views on the presence and localization of 5-hydroxytryptamine in coelenterates can thus be due to large species differences. It can be stated that 5-hydroxytryptamine is lacking in the venom of Cyanea.

Immunocytochemistry on the localization of 5-hydroxytryptamine in monkey and rabbit taste buds.

Immuno-electron microscopy with the protein A-gold method demonstrated immunoreactive gold particles against 5-hydroxytryptamine localized in cored vesicles aggregating around presynaptic terminals of the gustatory cells in monkey and rabbit taste buds. The positive reactions were also found in the intragemmal and subepithelial nerve fibers. The role of these cored vesicles in taste transduction is still uncertain but the data strongly suggest that they may participate in a serotonergic modulation of a cholinergic synaptic transmission from the gustatory cells to the nerve endings.

Localization of 5-hydroxytryptamine and protein (s) in the secretion granules of the rudimentary photoreceptor cells in the pineal ofLacerta

In order to localize 5-hydroxytryptamine (5-HT) stores, the pineal organ of Lacerta was examined by electron microscopy following argentaffin and chromaffin reactions. The results obtained with these ultracytochemical reactions were correlated with those obtained previously using the Falck and Hillarp method and electron microscopic radioautography. The secretion granules (diameter: 60-340 nm) of the secretory rudimentary photoreceptor (SRP) cells are the locus of the argentaffin and chromaffin reactions. The reactivity of the granules disappeared after p-CPA or reserpine administration and increased after nialamide injection. From the previous and present results it can be concluded that 5-HT in the pineal organ of Lacerta is stored in the secretion granules of SRP cells and coexists with a proteinaceous and/or possibly a glycoproteinaceous component. Whether this secretion is neurohormonal in nature is still not clear.

ラット脳内の5-Hydroxytryptamine neuronの分布とThiopental sodium投与後の変化に関する蛍光組織化学的研究

The localization of 5-hydroxytryptamine (5-HT) neurons in the rat brain was studied by the fluorescence histochemical method of Falck and Hillarp. A model experiment and tissue experiment were used to measure the characteristics of wave length of 5-HT fluorophor and we decided 420 mmu for excitation maxima and 520 mmu for emission maxima. The 5-HT neurons both in frontal and sagittal sections of the brain from reserpine-nialamide-treated rats were observed fluorohistochemically. The brain was divided into 5 portions; medulla oblonga, pons, midbrain, diencephalon and telencephalon. In frontal sections, from B1 to B8 cell groups were localized in raphe nuclei, in the region of 200 mu width on both sides from the central plane, excluding most of B2 cells and cells of B9 group which were situated on both side apart from the central plane. Microphotographs taken from about 34 areas of a sagittal section were composed to determine the interrelationship between B cell groups of 5-HT neurons. The frontal sections untreated with reserpine-nialamide showed a faint fluorescence of 5-HT neurons, however, after the administration of thiopental sodium 80 mg/kg i.p. the fluorescence of 5-HT neurons was increased in intensity and the observable cells were increased in number, especially in the B7 cell group. The yellow fluorescence of 5-HT nerve terminals in nuc suprachiasmaticus in the sagittal section was increased in intensity and varicosities of the terminals were readily observed. These results verified the increase of 5-HT in 5-HT neurons after the administration of thiopental and suggest that the 5-HT neuron may play a role in the mechanism of the central action of a thiopental.

The localization of 5-hydroxytryptamine in chromaffin cells of the leech body wall.

AbstractThe present study is an analysis of the sites of uptake of radioactive 5‐HT into the leech body wall. Two sites of uptake are noted: (1) the axons and nerve terminals containing large dense core vesicles and (2) the type I cells of the vasofibrous tissue. Both of these cell types are chromaffin cells in that they contain vesicles or granules with cores that reduce dichromate salts. Chemicla analysis indicates that most of the radioactivity in the body wall at the time of sacrifice is 5‐HT. Thus, these two cell types acquire 5‐HT when it is present in the extracellular environment and presumably store it in the cores of the vesicles of granules that characterize these cells. This acquisition of 5‐HT may be an impotrant method of inactivation for 5‐HT.In addition, the fine structure of the vasofibrous tissues is described here for the first time. There are two types of cells in the vasofibrous tissue, rather than one as previously thought, and the electorn microscope clearly shows that the fibrils of vasofibrous tissue are not pigmented capillaries.

The localization of 5-hydroxytryptamine in turtle ( Pseudymys scripta elegans) blood, its presence and uptake

1. 1. Turtle whole blood contains a range of 0·23-1·32 μg. 5-hydroxytryptamine (5-HT) per ml. in 5 animals as determined by spectrophotofluorometric methods. 2. 2. The 5-HT is located, by Falck formaldehyde fluorescence methods, in the basophil instead of the ecpected thrombocyte. 3. 3. A combination of scintillation counting experiments, Falck formaldehyde fluorescence, and autoradiography demonstrates that 5-HT is taken up by the basophil against a concentration gradient. 4. 4. Cold inhibits this uptake by 74–80 per cent. 5. 5. Dinitrophenol and sodium fluoride at final concentrations of 10 −3 M do not inhibit uptake.

Histochemical and experimental studies of 5-hydroxytryptamine in pineal organs of teleosts (Salmo gairdneri and Atherinopsis californiensis).

Abstract Occurrence and localization of 5-hydroxytryptamine (5-HT) in pineals of rainbow trout ( Salmo gairdneri ) and jacksmelt ( Atherinopsis californiensis ) were investigated by means of the fluorescence histochemical procedure perfected by Hillarp and Falck. All fish were kept in a 14-hr/day photoperiod and were experimentally injected and autopsied either during the night or during the day. Although little if any 5-HT-specific fluorescence was seen in control (saline-injected) fish pineals, others injected with either or both 5-hydroxytryptophan (5-HTP) and iproniazid (a monoamine oxidase inhibitor) did show such fluorescence. Active uptake by the fish pineals of 5-HTP and synthesis of 5-HT appear likely. Differences in results according to time of treatment and autopsy were not detectable.