5-HT7 receptors in Alzheimer's disease.

Even though the involvement of serotonin (5-hydroxytryptamine; 5-HT) and its receptors in Alzheimer's disease (AD) is widely accepted, data on the expression and the role of 5-HT7 receptors in AD is relatively limited. Therefore, the objective of the present work was to study the expression of serotonergic 5-HT7 receptors in postmortem samples of AD brains and correlate it with neurotransmitter levels, cognition and behavior. The study population consisted of clinically well-characterized and neuropathologically confirmed AD patients (n = 42) and age-matched control subjects (n = 18). Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and high-performance liquid chromatography were performed on Brodmann area (BA) 7, BA10, BA22, BA24, hippocampus, amygdala, thalamus and cerebellum to measure mRNA levels of 5-HT7 receptors (HTR7), as well as the concentrations of various monoamine neurotransmitters and their metabolites. Decreased levels of HTR7 mRNA were observed in BA10. A significant association was observed between HTR7 levels in BA10 and BEHAVE-AD cluster B (hallucinations) (rs(28) = 0.444, P < 0.05). In addition, a negative correlation was observed between HTR7 levels in BA10 and both MHPG concentrations in this brain region (rs(45) = -0.311; P < 0.05), and DOPAC levels in the amygdala (rs(42) = -0.311; P < 0.05). Quite surprisingly, no association was found between HTR7 levels and cognitive status. Altogether, this study supports the notion of the involvement of 5-HT7 receptors in psychotic symptoms in AD, suggesting the interest of testing antagonist acting at this receptor to specifically treat psychotic symptoms in this illness.

[6]-Gingerol Ameliorates Cisplatin-Induced Pica by Regulating the TPH/MAO-A/SERT/5-HT/5-HT3 Receptor System in Rats.

PURPOSE: [6]-gingerol is a bioactive compound extracted from ginger, a traditional anti-emetic herb in Chinese medicine. Previous studies have demonstrated that [6]-gingerol can ameliorate chemotherapy-induced pica in rats, although the underlying mechanism has not been elucidated. This study is designed to investigate [6]-gingerol's antiemetic mechanism focusing on the 5-hydroxytryptamine (serotonin, 5-HT) system by evaluating the synthesis, metabolism and reuptake of 5-HT, as well as the mechanism of 5-hydroxytryptamine type 3 receptor (5-HT3 receptor), in a cisplatin-induced pica model of rats. METHODS: Rats were randomly divided into control group (vehicle + saline, Con), [6]-gingerol control group (50 mg/kg [6]-gingerol + saline, G-con), ondansetron control group (2.6 mg/kg ondansetron + saline, O-con), cisplatin model group (vehicle + cisplatin, Model), ondansetron-treated group (2.6 mg/kg ondansetron + cisplatin, O-treated), high dosage of [6]-gingerol-treated group (100 mg/kg [6]-gingerol + cisplatin, GH-treated), and low dosage of [6]-gingerol-treated group (50 mg/kg [6]-gingerol + cisplatin, GL-treated). The rats were administered with [6]-gingerol, ondansetron, and vehicle (3% Tween-80) by gavage twice (7:00 AM and 7:00 PM). One hour after the first treatment (8:00 AM), rats in groups Model, O-treated, GH-treated and GL-treated were injected intraperitoneally (i.p.) with 6 mg/kg cisplatin, and the other groups were injected i.p. with saline of equal volume. The consumption of kaolin of the rats were measured. All the rats were anesthetized by i.p. injection of pentobarbital sodium at 24 h post-cisplatin. After blood samples were taken, medulla oblongata and ileum were removed. The levels of 5-HT and its metabolite 5-HIAA in ileum, medulla oblongata and serum were determined using high-performance liquid chromatography with electrochemical detection (HPLC-ECD). The mRNA expression levels of 5-HT3 receptor, tryptophan hydroxylase (TPH), monoamine oxidase A (MAO-A) and serotonin reuptake transporter (SERT) were detected by real-time PCR. The protein expression levels and distribution of 5-HT3 receptor, TPH and MAO-A in the medulla oblongata and ileum were measured by Western blotting and immunohistochemistry, respectively. RESULTS: [6]-gingerol treatment significantly reduced the kaolin ingestion and the increase in 5-HT concentration in rats induced by cisplatin. TPH, MAO-A, SERT, and 5-HT3 receptor are important in 5-HT metabolism, and cisplatin-induced alterations in the associated protein/mRNA levels were restored when treated with [6]-gingerol. CONCLUSION: This suggests that the antiemetic effect of [6]-gingerol against cisplatin-induced emesis may be due to 5-HT attenuation via modulating the TPH/MAO-A/SERT/5-HT/5-HT3 receptor system.

Hormonal and metabolic profiles related to placental retention with emphasis on oxidative stress and serotonin receptors in pluriparous buffaloes.

This study was designed to investigate the hormonal and metabolic factors associated with placental retention in buffaloes with respect to the roles of oxidative stress biomarkers and serotonin receptors. Blood samples were collected at weeks 3, 2 and 1 pre-partum and at calving from 37 buffaloes; thirty normally dropped their placentae (Non-RFM group) and 7 dropped their placentae after 12 hr post-calving (RFM group). Serum progesterone (P4 ), oestradiol, cortisol, non-esterified fatty acids (NEFA), beta-hydroxybutyric acid (BHBA), antioxidant/oxidant biomarkers and mineral concentrations were assessed. Histopathology and histochemistry were implemented to detect collagen in foetal placental tissues. Immunohistochemistry for serotonin receptors in placental tissues was performed. Significant elevations in P4 , cortisol, NEFA, BHBA and oxidative biomarkers concentrations were observed in the RFM group. However, oestradiol, antioxidants and mineral concentrations were significantly lower in RFM buffaloes than Non-RFM group. Histopathological examination revealed degenerative changes and necrosis in retained placental tissue compared with that in normal placental tissues. Serotonin receptors were significantly expressed with collagen condensation in retained placental tissues. Furthermore, inferior reproductive performance was pronounced in the retained group. In conclusion, retained foetal membranes in buffaloes were associated with hormonal imbalance, metabolic perturbation, oxidative stress, serotonin receptor upregulation and markedly reduced fertility indices.

Identification, characterization, and expression analysis of a serotonin receptor involved in the reproductive process of the Pacific abalone, Haliotis discus hannai.

Serotonin receptor (5-HT) is a biogenic amine acting as a neurotransmitter and neuromodulator that mediates various aspects of reproduction and gametogenesis. The full-length nucleotide sequence of Haliotis discus hannai encodes a protein of 417 amino acids with a predicted molecular mass of 46.54 kDa and isoelectric point of 8.94. The structural profile of 5-HTHdh displayed key features of G protein-coupled receptors, including seven hydrophobic transmembrane domains, putative N-linked glycosylation sites, and several phosphorylation consensus motifs. It shares the highest homology of its amino acid sequence with the 5-HT receptor from Haliotis asinina, and to lesser extent of human 5-HT receptor. The cloned sequence possesses two cysteine residues (Cys-115 and Cys-193), which are likely to form a disulfide bond. Phylogenetic comparison with other known 5-HT receptor genes revealed that the 5-HTHdh is most closely related to the 5-HTHa receptor. The three-dimensional structure of the 5-HTHdh showed multiple alpha helices which is separated by a helix-loop-helix (HLH) structure. Quantitative PCR demonstrated that the receptor mRNA was predominantly expressed in the pleuropedal ganglion. Significant differences in the transcriptional activity of the 5-HTHdh gene were observed in the ovary at the ripening stage. An exclusive expression was detected in pleuropedal ganglion, testis, and ovary at higher effective accumulative temperature (1000 °C). In situ hybridization showed that the 5-HTHdh expressing neurosecretory cells were distributed in the cortex of the pleuropedal ganglion. Our results suggest that 5-HTHdh synthesized in the neural ganglia may be involved in oocyte maturation and spawning of H. discus hannai.

Effect of chronic corticosterone treatment on expression and distribution of serotonin 5-HT7 receptors in rat adrenal glands.

Sensitized stress-induced corticosterone (CORT) secretion in chronically stressed rats involves 5-HT7 receptor activation. The effect of 14-day chronic CORT and vehicle (VEH) administration on 5-HT7 receptor expression in adrenal glands, adrenal 5-HT content, and adrenocorticotropic hormone and CORT secretion was analysed. On day 15, VEH- and CORT-treated animals were perfused or decapitated without stress exposure (0 min) or after 10 and 30 min of restraint for collection of trunk blood and tissues. 5-HT7 receptor-like immunoreactivity (5-HT7R-LI), 5-HT7 receptor protein, and mRNA levels were determined by immunohistochemistry, Western blot, and reverse transcription polymerase chain reaction assays, respectively; 5-HT levels and hormones were quantified using HPLC and ELISA kits, respectively. An undisturbed control group was included for most experimental comparisons. Chronic CORT strongly increased 5-HT7R-LI in the outer adrenal cortex, as well as 5-HT7 receptor protein and mRNA in whole adrenal glands; adrenal 5-HT content also increased in these animals. Decreased adrenocorticotropic hormone and CORT secretion at 30 min of restraint occurred in CORT-treated rats. The results support the notion that chronic stress-induced increase of adrenocortical 5-HT7 receptors and adrenal 5-HT content is a glucocorticoid-dependent phenomenon; the development of magnified stress-induced 5-HT7 receptor-mediated CORT responses in chronically stressed animals nevertheless likely involves additional mechanisms.

MiRNA-29a modulates visceral hyperalgesia in irritable bowel syndrome by targeting HTR7.

Some patients with irritable bowel syndrome (IBS) have visceral hypersensitivity, which contributes to their abdominal pain. miRNA-29 was detected to be significantly upregulated in colonic tissues of patients with IBS. However, it is unknown whether miRNA-29a is involved in the visceral hypersensitivity pathogenesis of IBS. This study aimed to investigate whether miRNA-29a participates in visceral hypersensitivity in IBS. We investigated miRNA-29a in intestinal biopsies collected during endoscopy of patients with IBS (n = 10) and healthy volunteers (control) (n = 10). In addition, a water avoidance stress (WAS)-induced visceral hypersensitivity IBS mouse model was established. The abdominal withdrawal reflex (AWR) scores of mice in response to colorectal distention were used to assess visceral sensitivity. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was used to measure miRNA-29a levels. Immunofluorescence, RT-qPCR and western blot were used to measure 5-HT7 receptor (HTR7) levels. Bioinformatic analysis and luciferase reporter assays were used to detect the direct relationship between miRNA-29a and HTR7. Finally, alterations in the levels of HTR7 and miRNA-29a were measured in the human intestinal epithelial cell line NCM460 after transfection with miRNA-29a inhibitor or mimic. Intestinal tissues from patients with IBS and WAS-induced IBS mice had increased levels of miRNA-29a, but reduced levels of HTR7. MiRNA-29a knockout resulted in overexpression of HTR7 and attenuated visceral hyperalgesia in WAS-induced IBS mice. HTR7 was a direct target of miRNA-29a. Based on analyses of intestinal tissue samples from patients with IBS and WAS-induced miRNA-29a-/- mice, miRNA-29a plays a role in the visceral hyperalgesia pathogenesis of IBS, probably through regulating HTR7 expression.

The Leptin, Dopamine and Serotonin Receptors in Hypothalamic POMC-Neurons of Normal and Obese Rodents.

The pro-opiomelanocortin (POMC)-expressing neurons of the hypothalamic arcuate nucleus (ARC) are involved in the control of food intake and metabolic processes. It is assumed that, in addition to leptin, the activity of these neurons is regulated by serotonin and dopamine, but only subtype 2C serotonin receptors (5-HT2CR) was identified earlier on the POMC-neurons. The aim of this work was a comparative study of the localization and number of leptin receptors (LepR), types 1 and 2 dopamine receptors (D1R, D2R), 5-HT1BR and 5-HT2CR on the POMC-neurons and the expression of the genes encoding them in the ARC of the normal and diet-induced obese (DIO) rodents and the agouti mice (A y /a) with the melanocortin obesity. As shown by immunohistochemistry (IHC), all the studied receptors were located on the POMC-immunopositive neurons, and their IHC-content was in agreement with the expression of their genes. In DIO rats the number of D1R and D2R in the POMC-neurons and their expression in the ARC were reduced. In DIO mice the number of D1R and D2R did not change, while the number of LepR and 5-HT2CR was increased, although to a small extent. In the POMC-neurons of agouti mice the number of LepR, D2R, 5-HT1BR and 5-HT2CR was increased, and the D1R number was reduced. Thus, our data demonstrates for the first time the localization of different types of the serotonin and dopamine receptors on the POMC-neurons and a specific pattern of the changes of their number and expression in the DIO and melanocortin obesity.

New Trends and Current Status of Positron-Emission Tomography and Single-Photon-Emission Computerized Tomography Radioligands for Neuronal Serotonin Receptors and Serotonin Transporter.

The critical role of serotonin (5-hydroxytryptamine; 5-HT) and its receptors (5-HTRs) in the pathophysiology of diverse neuropsychiatric and neurodegenerative disorders render them attractive diagnostic and therapeutic targets for brain disorders. Therefore, the in vivo assessment of binding of 5-HT receptor ligands under a multitude of physiologic and pathologic scenarios may support more-accurate identification of disease and its progression and the patient's response to therapy as well as the screening of novel therapeutic strategies. The present Review aims to focus on the current status of radioligands used for positron-emission tomography (PET) and single-photon-emission computerized tomography (SPECT) imaging of human brain serotonin receptors. We further elaborate upon and emphasize the attributes that qualify a radioligand for theranostics on the basis of its frequency of use in clinics, its benefit to risk assessment in humans, and its continuous evolution, along with the major limitations.

Cyproheptadine exhibits antitumor activity in urothelial carcinoma cells by targeting GSK3ß to suppress mTOR and ß-catenin signaling pathways.

Cyproheptadine, a serotonin antagonist, has recently been reported to function as a novel therapeutic agent by inhibiting PI3K/AKT signaling in several human cancers. However, the therapeutic effect of cyproheptadine in urothelial carcinoma (UC) has never been explored. In this study, we determined the effect of cyproheptadine on the growth of five human UC cell lines and an in vivo xenograft model. The results showed that cyproheptadine exerted an inhibitory effect on the proliferation of UC cells both in vitro and in vivo. Cyproheptadine also induced cell cycle arrest in the G1 phase, subsequently followed by apoptosis and necrosis. The underlying mechanisms of cell cycle arrest were associated with the reduction of c-Myc, induction of p21 and p27, and the stabilization of Rb expression. In addition, the suppression of the GSK3ß/TSC2/mTOR pathway and deregulation of the GSK3ß/ß-catenin signaling were observed in cyproheptadine-treated UC cells. Furthermore, cyproheptadine-induced apoptosis was associated with ANGPTL4 expression followed by activation of caspase3 and PARP in UC cells. Our experimental results provide evidence that cyproheptadine is a suitable therapeutic agent for the treatment of UC.

Distribution of serotonin receptor 5-HT6 mRNA in rat neuronal subpopulations: A double in situ hybridization study.

The 5-HT6 receptor (5-HT6R) is almost exclusively expressed in the brain and has emerged as a promising target for cognitive disorders, including Alzheimer's disease. In the present study, we have determined the cell types on which the 5-HT6R is expressed by colocalizing 5-HT6R mRNA with that of a range of neuronal and interneuronal markers in the rat brain. Here, we show that 5-HT6R mRNA was expressed at high levels in medium spiny neurons in caudate putamen and in nucleus accumbens, as well as in the olfactory tubercle. Striatal 5-HT6R mRNA was colocalized with both dopamine D1 and D2 receptor mRNA. 5-HT6R mRNA was moderately expressed in the hippocampus and throughout cortical regions in glutamatergic neurons coexpressing vGluT1. A subset of GAD67-positive GABAergic interneurons (approximately 15%) expressed 5-HT6R mRNA in the cortex and hippocampus, the majority of which belonged to the 5-HT3a receptor (5-HT3aR)-expressing subpopulation. In contrast, 5-HT6R mRNA was only expressed to a minor extent in the parvalbumin and somatostatin subpopulations. A subset of calbindin- and calretinin-positive GABAergic interneurons expressed 5-HT6R mRNA while only a very minor fraction of VIP or NPY interneurons in forebrain structures expressed 5-HT6R mRNA. Serotonergic, dopaminergic or cholinergic neurons did not express 5-HT6R mRNA. These data indicate that the 5-HT6R is located on GABAergic and glutamatergic principal neurons, and on a subset of interneurons mainly belonging to the 5-HT3aR subgroup suggesting that the 5-HT6R is positioned to regulate the balance between excitatory and inhibitory signaling in the brain. These data provide new insights into the mechanisms of 5-HT6R signaling.

Characterization of the Distance Relationship Between Localized Serotonin Receptors and Glia Cells on Fluorescence Microscopy Images of Brain Tissue.

We here present two new methods for the characterization of fluorescent localization microscopy images obtained from immunostained brain tissue sections. Direct stochastic optical reconstruction microscopy images of 5-HT1A serotonin receptors and glial fibrillary acidic proteins in healthy cryopreserved brain tissues are analyzed. In detail, we here present two image processing methods for characterizing differences in receptor distribution on glial cells and their distribution on neural cells: One variant relies on skeleton extraction and adaptive thresholding, the other on k-means based discrete layer segmentation. Experimental results show that both methods can be applied for distinguishing classes of images with respect to serotonin receptor distribution. Quantification of nanoscopic changes in relative protein expression on particular cell types can be used to analyze degeneration in tissues caused by diseases or medical treatment.

Preparation and biodistribution of 1-((2-methoxyphenyl) piperazine)ferrocenecarboxamide labeled with technetium-99m as a potential brain receptor imaging agent.

The goal of this study is to develop a novel brain receptor imaging agent. This study reports the synthesis, characterization and the biological evaluation of 1-((2-methoxyphenyl) piperazine)ferrocenecarboxamide labeled with technetium-99 m ((99m)Tc-MP). The (99m)Tc-MP was obtained quickly (radiolabelling time < 5 min), in 90% yield. The (99m)Tc-complex, characterized by HPLC (20-50% ACN of 0 at 5 min then 50% ACN of 5 at 17 min to finally with 50 at 20% ACN of 17 at 20 min), is stable, neutral and lipophilic enough to cross the blood-brain barrier which was confirmed by octanol/water partition coefficient (LogP = 1.82). In vivo biodistribution indicated that this complex had exceptional brain uptake (2.47% ID/g at 5 min and 0.75% ID/g at 60 min). The distribution of the activity at 15 min post-injection in various rat brain regions showed a higher accumulation in the hippocampus area. After blocking with 8-hydroxy-2-(dipropylamino) tetralin, the uptake of hippocampus was decreased significantly from 0.87% ID/g to 0.21% ID/g at 15 min p.i., while the cerebellum had no significant decrease. The new (99m)Tc-cyclopentadienyltricarbonyl technetium complex reported here showed promising biological results, making it an interesting starting point for the development of a new (99m)Tc-complex as brain receptor imaging agent.

Evaluation of 3-Ethyl-3-(phenylpiperazinylbutyl)oxindoles as PET Ligands for the Serotonin 5-HT7 Receptor: Synthesis, Pharmacology, Radiolabeling, and in Vivo Brain Imaging in Pigs.

We have investigated several oxindole derivatives in the pursuit of a 5-HT7 receptor PET ligand. Herein the synthesis, chiral separation, and pharmacological profiling of two possible PET candidates toward a wide selection of CNS-targets are detailed. Subsequent (11)C-labeling and in vivo evaluation in Danish landrace pigs showed that both ligands displayed high brain uptake. However, neither of the radioligands could be displaced by the 5-HT7 receptor selective inverse agonist SB-269970.

Spatial cluster analysis of nanoscopically mapped serotonin receptors for classification of fixed brain tissue.

We present a cluster spatial analysis method using nanoscopic dSTORM images to determine changes in protein cluster distributions within brain tissue. Such methods are suitable to investigate human brain tissue and will help to achieve a deeper understanding of brain disease along with aiding drug development. Human brain tissue samples are usually treated postmortem via standard fixation protocols, which are established in clinical laboratories. Therefore, our localization microscopy-based method was adapted to characterize protein density and protein cluster localization in samples fixed using different protocols followed by common fluorescent immunohistochemistry techniques. The localization microscopy allows nanoscopic mapping of serotonin 5-HT1A receptor groups within a two-dimensional image of a brain tissue slice. These nanoscopically mapped proteins can be confined to clusters by applying the proposed statistical spatial analysis. Selected features of such clusters were subsequently used to characterize and classify the tissue. Samples were obtained from different types of patients, fixed with different preparation methods, and finally stored in a human tissue bank. To verify the proposed method, samples of a cryopreserved healthy brain have been compared with epitope-retrieved and paraffin-fixed tissues. Furthermore, samples of healthy brain tissues were compared with data obtained from patients suffering from mental illnesses (e.g., major depressive disorder). Our work demonstrates the applicability of localization microscopy and image analysis methods for comparison and classification of human brain tissues at a nanoscopic level. Furthermore, the presented workflow marks a unique technological advance in the characterization of protein distributions in brain tissue sections.

Expression and localization of serotonin receptors in human breast cancer.

The aim of this study was to examine the expression of serotonin receptors in patients with breast cancer and to explore their utility as diagnostic and prognostic markers. Immunohistochemical analysis was performed to examine the expression of serotonin (5-HT) receptor subtypes 1A, 1B, 2B and 4 in a tissue microarray containing tumor specimens from 102 patients. Statistical analysis was performed to correlate the expression of these proteins with regard to clinical parameters. We found that all four serotonin receptors (5-HTRs) exhibited different expression patterns in breast cancer specimens. In general strong staining for 5-HTR1A was observed on the membrane of cancer cells but it was detected only in the cytoplasm of non-malignant cells. 5-HTR1B and 5-HTR2B were predominantly expressed in the cytoplasm of breast cancer cells, while 5-HTR4 was exclusively found in the nucleus of malignant and non-malignant cells. Correlation analysis revealed a significant correlation of 5-HTR2B with estrogen receptor-α (ER-α) and 5-HTR4 with ER-α and progesterone (PR). In conclusion, the different expression patterns and subcellular localization of 5-HTRs in breast cancer may reflect their role in breast cancer progression.

G protein-coupled receptor heterodimerization in the brain.

G protein-coupled receptors (GPCRs) play critical roles in cellular processes and signaling and have been shown to form heteromers with diverge biochemical and/or pharmacological activities that are different from those of the corresponding monomers or homomers. However, despite extensive experimental results supporting the formation of GPCR heteromers in heterologous systems, the existence of such receptor heterocomplexes in the brain remains largely unknown, mostly because of the lack of appropriate methodology. Herein, we describe the in situ proximity ligation assay procedure underlining its high selectivity and sensitivity to image GPCR heteromers with confocal microscopy in brain sections. We describe here how the assay is performed and discuss advantages and disadvantages of this method compared with other available techniques.

[Role of brain 5-HT7 receptors as a functional molecule involved in the development of stress adaptation].

A growing body of evidence suggests that the brain serotonin (5-HT) nervous system is an important component related to the etiology as well as the treatment of stress-related psychiatric disorders. Molecular cloning studies have revealed the existence of 14 different genes, each encoding a distinct 5-HT receptor subtype. The 5-HT7 receptor is the most recently identified member of the 5-HT receptor subtypes, and the physiological role of this receptor is still unknown. Recently, either selective agonists or antagonists for 5-HT7 receptors, as well as 5-HT7 receptor knockout mice, have been developed, and these have recently been used as the experimental tools for determining the actual function of 5-HT7 receptors. The first half of the present article introduces the reports that have examined the role of the 5-HT7 receptor on emotional regulation. On the other hand, it has been indicated that the ability to adapt to stress is an important defensive function of a living body, and impairment of this ability may contribute to some stress-related disorders. Thus, the examination of brain mechanisms involved in stress adaptation could help to pave the way for new therapeutic strategies for stress-related psychiatric disorders. The second half of the present article introduces our recent studies focusing on the relationship between brain 5-HT7 receptors and the mechanisms of stress adaptation.

Normative database of the serotonergic system in healthy subjects using multi-tracer PET.

The highly diverse serotonergic system with at least 16 different receptor subtypes is implicated in the pathophysiology of most neuropsychiatric disorders including affective and anxiety disorders, obsessive compulsive disorder, post-traumatic stress disorder, eating disorders, sleep disturbance, attention deficit/hyperactivity disorder, drug addiction, suicidal behavior, schizophrenia, Alzheimer, etc. Alterations of the interplay between various pre- and postsynaptic receptor subtypes might be involved in the pathogenesis of these disorders. However, there is a lack of comprehensive in vivo values using standardized procedures. In the current PET study we quantified 3 receptor subtypes, including the major inhibitory (5-HT(1A) and 5-HT(1B)) and excitatory (5-HT(2A)) receptors, and the transporter (5-HTT) in the brain of healthy human subjects to provide a database of standard values. PET scans were performed on 95 healthy subjects (age=28.0 ± 6.9 years; 59% males) using the selective radioligands [carbonyl-(11)C]WAY-100635, [(11)C]P943, [(18)F]altanserin and [(11)C]DASB, respectively. A standard template in MNI stereotactic space served for region of interest delineation. This template follows two anatomical parcellation schemes: 1) Brodmann areas including 41 regions and 2) AAL (automated anatomical labeling) including 52 regions. Standard values (mean, SD, and range) for each receptor and region are presented. Mean cortical and subcortical binding potential (BP) values were in good agreement with previously published human in vivo and post-mortem data. By means of linear equations, PET binding potentials were translated to post-mortem binding (provided in pmol/g), yielding 5.89 pmol/g (5-HT(1A)), 23.5 pmol/g (5-HT(1B)), 31.44 pmol/g (5-HT(2A)), and 11.33 pmol/g (5-HTT) being equivalent to the BP of 1, respectively. Furthermore, we computed individual voxel-wise maps with BP values and generated average tracer-specific whole-brain binding maps. This knowledge might improve our interpretation of the alterations taking place in the serotonergic system during neuropsychiatric disorders.

Efecto de la restricción física: sobre el papel de los receptores 5-HT1A en la proliferación linfocitaria / Effect of phisical restraints: the role of the 5-HT1A in lymphocyte proliferation

El estrés afecta el sistema inmunológico, sin embargo, no hay reportes sobre receptores de serotonina en linfocitos. Se estudiaron los receptores 5-HT1A y la proliferación linfocitaria de ratas macho adultas luego de restricción física. Fueron colocadas en cajas de Plexiglass durante 5 horas diarias por 1, 3 ó 5 días. Se extrajo sangre cardíaca, se aislaron los linfocitos por gradiente de densidades y adhesión al plástico; se cultivaron con el agonista 8-hidroxi-di-n-propil-aminotetralina(8-OH-DPAT) ó el antagonista N-(2-(4-(2-metoxifenil)-1-piperazinetil)-N-(2-piridinil) ciclohexanocarboxamida (WAY-100635) de los receptores 5-HT1A y del mitógeno concanavalina A. La proliferación se midió con sales de tetrazolio. La 8-OH-DPAT no afectó la proliferación. El WAY-100635 disminuyó la proliferación. La restricción física aumentó la sensibilidad al efecto del WAY-100635, lo cual podría deberse a cambios en la expresión o a una modulación funcional de los receptores por efecto del estrés, como se ha reportado previamente en cerebro de rata.

Stress affects the immune system, however, little is known about the effects on specific modifications of lymphocytes serotonin receptors. The effects of restraint stress on the role of 5-HT1A receptors in lymphocyte proliferation were evaluated in male adult rats. They were placed in Plexiglass boxes, during 5 daily hours for 1, 3 or 5 consecutive days. Next day a blood sample was obtained by cardiac punction. Lymphocytes were isolated by density gradient and adhesionto plastic. They were cultured with agonist 8-hydroxy-di-n-propyl-aminotetralin (8-OH-DPAT) or antagonist N-(2-(4-(2-methoxyphenyl)-1-piperazinyl) ethyl)-N-(2-pyridiyl) cyclohexanecarboxamide (WAY-100635) of 5-HT1A receptors and the mitogen concanavalin A. Proliferation was measured by tetrazolium salts. 8-OH-DPAT did not modify cell proliferation; WAY-100635 diminished it. Restraint stress increased the susceptibility to effect of WAY-100635. These results suggest changes in the expression or functional modulation of 5-HT1A receptors in lymphocytes by stress, similar to previous reports on serotonergic system in rat brain.

The serotonergic anatomy of the developing human medulla oblongata: implications for pediatric disorders of homeostasis.

The caudal serotonergic (5-HT) system is a critical component of a medullary "homeostatic network" that regulates protective responses to metabolic stressors such as hypoxia, hypercapnia, and hyperthermia. We define anatomically the caudal 5-HT system in the human medulla as 5-HT neuronal cell bodies located in the raphé (raphé obscurus, raphé magnus, and raphé pallidus), extra-raphé (gigantocellularis, paragigantocellularis lateralis, intermediate reticular zone, lateral reticular nucleus, and nucleus subtrigeminalis), and ventral surface (arcuate nucleus). These 5-HT neurons are adjacent to all of the respiratory- and autonomic-related nuclei in the medulla where they are positioned to modulate directly the responses of these effector nuclei. In the following review, we highlight the topography and development of the caudal 5-HT system in the human fetus and infant, and its inter-relationships with nicotinic, GABAergic, and cytokine receptors. We also summarize pediatric disorders in early life which we term "developmental serotonopathies" of the caudal (as well as rostral) 5-HT domain and which are associated with homeostatic imbalances. The delineation of the development and organization of the human caudal 5-HT system provides the critical foundation for the neuropathologic elucidation of its disorders directly in the human brain.