5-HT1A Receptor Levels Research Articles

Jiawei Suanzaoren decoction for the treatment of perimenopausal insomnia: clinical observation and experimental study

BackgroundTraditional Chinese medicine has a good clinical therapeutic effect on perimenopausal insomnia, Jiawei Suanzaoren Tang (JW-SZRT) has a significant therapeutic effect on people with yin deficiency and fire excess type insomnia.MethodFirstly, 80 cases of perimenopausal yin deficiency and fire excess type insomnia were included in the study. The treatment group was treated with Jiawei Suanzaoren decoction, while the control group was treated with lorazepam for 4 weeks. The study observed and compared the Pittsburgh Sleep Quality Index (PSQI), Kupperman score, Polysomnography (PSG) and sex hormone levels of two groups before and after treatment. Secondly, we also conducted network pharmacology analysis and mechanism research. We first searched public databases for the targets of the compound known tobe associated with JW-SZRT, as well as those predicted to be targets of insomnia, and then used software Cytoscape 3.7.2, GO and KEGG to identify enriched gene pathways and networks. Networks and pathways that overlapped between Insomnia-associated proteins and JW-SZRT target proteins were then used to predict candidate protein targets of JW-SZRT in insomnia. Finally, 40 rats were selected in animal experimentation and 30 perimenopausal insomnia rat models were created through ovariectomy and a modified multi-platform water environment 72-hour sleep deprivation method. The model group received normal saline, the western medicine group received lorazepam suspension, and the Chinese medicine group received Jiawei Suanzaoren decoction. The sham surgery group was given routine feeding. The sleep condition, the levels of blood hormone levels and the expression levels of 5-Hydroxytryptamine (5-HT) and Gamma-Aminobutyric Acid receptor A (GABAA) receptor in the hypothalamus were compared between groups.ResultsIn clinical observation, the sleep condition and the changes of hormone levels between the treatment group and the control group were statistically significant (P < 0.05). The results of network pharmacology indicate that in the main signaling pathways for treating insomnia, it is speculated that Jiawei Suanzaoren Tang can regulate the signaling pathway of neuroactive ligand receptor interactions by inhibiting the activation of related proteins, thereby improving sleep. Animal experiments have also shown that the JW-SZRT can significantly improve the sleep conditions of insomnia rats during perimenopause, and the expression levels of 5-HT and GABAA receptors in the hypothalamus had a significant difference between groups in animal experiments (P < 0.05).ConclusionJiawei Suanzaoren Decoction can improve the perimenopausal insomnia. The mechanism behind this improvement may be related to the regulation of Estradiol (E2), Follicle-Stimulating Hormone (FSH), and luteinizing hormone (LH) levels, as well as the mRNA expression levels of 5-HT1a, 5-HT2a, GABAARα1, and GABAARγ2 receptors in the hypothalamus.

Sleep-enhancing effect of Hongcheon-hop (Humulus lupulus L.) extract containing xanthohumol and humulone through GABAA receptor

Ethnopharmacological relevanceThe bitter resins in hops (Humulus lupulus) modulate GABA receptors, leading to central nervous system suppression, which induces sedative effects and enhances sleep. Aim of the studyThis study intends to explore the sleep-enhancing properties of Hongcheon-hop extract, a hop native to Korea, by analyzing sleep structure and its mechanisms through EEG. Materials and methodsA pentobarbital-induced sleep model was used, along with EEG analysis to study sleep architecture. The receptor binding of Hongcheon-hop extract was analyzed using GABA receptor antagonists. ResultsThe extract contained 7.44 mg/g of xanthohumol, 133.04 mg/g of α-acids including 13.74 mg/g of humulone and 84.52 mg/g of β-acids. Administration of the extracts resulted in a dose-dependent enhancement of sleep duration. Both low (100 mg/kg) and high doses (200 mg/kg) of the extract increased non-rapid eye movement (NREM) sleep by enhancing δ wave sleep, which represents deep sleep. The extract exerted its sleep-promoting effects by binding to the γ-aminobutyric acid (GABA) binding site on GABAA receptor. In an insomnia model, low dose of the extract was more effective than the same dose of GABA in enhancing sleep. Administration of the extract for 3 weeks increased the expression and protein levels of 5-HT1A receptors in addition to GABAA receptor, and also increased the content of GABA in the brain. A mixture of xanthohumol (1.49 mg) and humulone (2.75 mg) within Hongcheon-hop extract (200 mg) exhibited a sleep-enhancing effect comparable to that of the extract. ConclusionThese findings suggest that Hongcheon-hop extract, which contains xanthohumol and humulone, improves sleep quality by increasing NREM sleep through the enhancement of δ-wave sleep via GABAA receptors. Hongcheon-hop shows potential as a natural therapeutic agent for treating insomnia and enhancing sleep.

Psychedelic-Induced Serotonin 2A Receptor Downregulation Does Not Predict Swim Stress Coping in Mice

Serotoninergic psychedelics such as psilocybin have been reported to elicit a long-lasting reduction in depressive symptoms. Although the main target for serotoninergic psychedelics, serotonin type 2A receptor (5-HT2A), has been established, the possible mechanism of the antidepressant action of psychedelics remains unknown. Using the mouse forced swim test model, we examined whether the administration of the synthetic serotoninergic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) would modulate 5-HT2A receptor levels in the medial prefrontal cortex (mPFC) and revert stress-induced changes in behavior. Mice subjected to swim stress developed a passive stress-coping strategy when tested in the forced swim test 6 days later. This change in behavior was not associated with the hypothesized increase in 5-HT2A receptor-dependent head twitch behaviors or consistent changes in 5-HT2A receptor levels in the mPFC. When DOI was administered 1 day before the forced swim test, a low dose (0.2 mg/kg i.p.) unexpectedly increased immobility while a high dose (2 mg/kg i.p.) had no significant effect on immobility. Nevertheless, DOI evoked a dose-dependent decrease in 5-HT2A levels in the mPFC of mice previously exposed to swim stress. Our findings do not support the hypothesis that the downregulation of 5-HT2A receptors in the mPFC contributes to the antidepressant-like properties of serotoninergic psychedelics.

Elevated levels of serotonin 5-HT2A receptors in the orbitofrontal cortex of antisocial individuals.

Antisocial behavior (ASB) is characterized by frequent violations of the rights and properties of others, as well as aggressive conduct. While ample evidence points to a critical role of serotonin in the emotional modulation of social responses, the implication of this neurotransmitter in ASB is unclear. Here, we performed the first-ever postmortem analysis of serotonergic markers in the orbitofrontal cortex (OFC) of male subjects with ASB (n = 9). We focused on this brain region, given its well-recognized role in social response and ASB pathophysiology. Given that all individuals also had a substance use disorder (SUD) diagnosis, two age-matched control groups were used: SUD only and unaffected controls. Tissues were processed for immunoblotting analyses on eight key serotonergic targets: tryptophan hydroxylase 2 (TPH2), the rate-limiting enzyme of brain serotonin synthesis; serotonin transporter (SERT), the primary carrier for serotonin uptake; monoamine oxidase A (MAOA), the primary enzyme for serotonin catabolism; and five serotonin receptors previously shown to influence social behavior: 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2C, and 5-HT4. Our analyses documented a significant increase in 5-HT2A receptor levels in the ASB + SUD group compared to SUD-only controls. Furthermore, TPH2 levels were significantly reduced in the SUD group (including SUD only and ASB + SUD) compared to unaffected controls. No difference was detected in the expression of any other serotonergic target. These results are in keeping with previous evidence showing high 5-HT2A receptor binding in the OFC of pathologically aggressive individuals and point to this molecule as a potential target for ASB treatment.

Neonatal maternal deprivation facilitates the expression of a panic-like escape behavior in adult rats

A wealth of evidence associates disruptions of the parent-infant relationship (e.g. childhood parental loss or parental neglect) with the later appearance of panic disorder. In rodents, neonatal maternal separation and maternal deprivation (MD) are reported to increase the expression of anxiety-related defensive responses in adult animals. However, little is known about the long-term consequences of these early-life stressors in animal models of panic. We here investigated the effects of a single 24 h-episode of MD on post-natal day 11 (PND 11) in adult male Wistar rats submitted to two animal models that associate escape expression with panic attacks: the elevated T-maze and exposure to severe hypoxia (7% O2). We also investigated the involvement of serotonin (5-HT) in the observed changes. Although neonatal MD did not affect the behavioral responses measured in the elevated T-maze, it facilitated the expression of escape during hypoxia exposure, indicating a panicogenic-like effect. Pre-test administration of the 5-HT synthesis inhibitor, para-chlorophenylalanine (PCPA; 4 daily injections of 100 mg/kg) facilitated escape attempts in non-deprived animals during the hypoxia challenge, but did not interfere with the expression of this behavior in maternally-deprived rats. The levels of 5-HT1A receptors in key panic- and anxiety-associated areas, the dorsal periaqueductal gray and amygdala, respectively, were not different between previously deprived and non-deprived animals. Plasma corticosterone levels were significantly increased by hypoxia exposure, independently of the animals’ previous stress condition or PCPA administration. Therefore, MD on PND 11 predisposes the adult animal to the panic-evoking effects of severe hypoxia, a stimulus also reported to induce panic attacks in humans. The lack of PCPA effect on the pro-escape consequence of MD may be indicative that 5-HT signaling is impaired in the stressed animal.

Oxytocin inhibits hindpaw hyperalgesia induced by orofacial inflammation combined with stress.

Oxytocin (OT) is recognized as a critical neuropeptide in pain-related disorders. Chronic pain caused by the comorbidity of temporomandibular disorder (TMD) and fibromyalgia syndrome (FMS) is common, but whether OT plays an analgesic role in the comorbidity of TMD and FMS is unknown. Female rats with masseter muscle inflammation combined with 3-day forced swim (FS) stress developed somatic hypersensitivity, which modeled the comorbidity of TMD and FMS. Using this model, the effects of spinal OT administration on mechanical allodynia and thermal hyperalgesia in hindpaws were examined. Furthermore, the protein levels of OT receptors and 5-HT2A receptors in the L4–L5 spinal dorsal horn were analyzed by Western blot. The OT receptor antagonist atosiban and 5-HT2A receptor antagonist ritanserin were intrathecally injected prior to OT injection in the separate groups. Intrathecal injection of 0.125 μg and 0.5 μg OT attenuated the hindpaw hyperalgesia. The expression of OT receptors and 5-HT2A receptors in the L4–L5 spinal dorsal horn significantly increased following intrathecal injection of 0.5 μg OT. Intrathecal administration of either the OT receptor antagonist atosiban or 5-HT2A receptor antagonist ritanserin blocked the analgesic effect of OT. These results suggest that OT may inhibit hindpaw hyperalgesia evoked by orofacial inflammation combined with stress through OT receptors and/or 5-HT2A receptors, thus providing a therapeutic prospect for drugs targeting the OT system and for patients with comorbidity of TMD and FMS.

Influence of 5-HT2A receptor function on anxiety-like behavior induced by a combination treatment with doxorubicin and cyclophosphamide in rats.

Anxiety-like behavior induced by a combination of doxorubicin and cyclophosphamide may be mediated by serotonin (5-HT)2A receptor hyperactivity. The anxiolytic effects of fluoxetine may be inhibited by this combination. The present study examined the mechanisms underlying anxiety-like behavior induced by the combination doxorubicin and cyclophosphamide in rats. Anxiety-like behavior was induced during a light-dark test by the doxorubicin and cyclophosphamide treatment (once a week for 2weeks). 5-HT2A receptor and 5-HT2A receptor-mediated extracellular signal-related kinase (ERK)1/2 levels were measured using Western blotting. 5-HT reuptake activity in fluoxetine-treated rats was also examined using microdialysis. ( ±)-1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane, a 5-HT2A receptor agonist, induced anxiety-like behavior. The fluoxetine treatment increased extracellular 5-HT concentrations in the hippocampus of vehicle- and doxorubicin and cyclophosphamide-treated rats. 5-HT transporter levels in the hippocampus were not affected by chemotherapy. The doxorubicin and cyclophosphamide treatment did not alter 5-HT2A receptor levels in the frontal cortex. However, chemotherapy increased 5-HT2A receptor-mediated ERK1/2 phosphorylation levels significantly more than the vehicle treatment. The present results suggest that anxiety-like behavior induced by the combination of doxorubicin and cyclophosphamide is mediated by 5-HT2A receptor hyperactivity without an increase in 5-HT2A receptor levels in rats.

Abstract P352: An Antiplatelet Agent Sarpogrelate Suppresses Pressure Overload-induced Development Of Heart Failure In A 5-ht 2a Receptor-independent Manner

Purpose: The cost of new drug development is increasing year by year, and drug repositioning is being used as a strategy to develop new treatments at low-cost. We used a library of approved drugs to screen for compounds that suppress cardiomyocyte hypertrophy, and identified as a candidate the antiplatelet drug sarpogrelate, a selective serotonin-2A (5-HT 2A ) receptor antagonist. In this study, we examined the effect of sarpogrelate on cultured cardiomyocyte hypertrophy and development of heart failure. Methods & Results: First, primary cultured cardiomyocytes were treated with 1 μM sarpogrelate and then stimulated with various hypertrophic stimuli (30 μM phenylephrine (PE), 0.1 μM angiotensin II and 0.1 μM endothelin 1). The results of immunofluorescence staining with anti-MHC antibody showed that sarpogrelate significantly suppressed cardiomyocyte hypertrophy induced by each stimulus. Western blotting and qPCR analysis showed that the mRNA and protein levels of 5-HT 2A receptor did not change by PE, and sarpogrelate significantly suppressed PE-induced phosphorylation of ERK1/2 and GATA4. Next, C57BL/6j male mice were subjected to a transverse aortic constriction (TAC) and sham operation. One day after the operation, the mice were randomly divided into 3 groups: sarpogrelate at 1 mg/kg or 5 mg/kg, and vehicle as a control. Daily oral administration was repeated for 8 weeks. Echocardiographic analysis showed that 5 mg/kg sarpogrelate significantly prevented a TAC-induced increase in posterior left ventricular wall thickness and a decrease in fractional shortening at 8 weeks after the operation. Five mg/kg sarpogrelate also suppressed TAC-induced increase in HW/BW ratio, cross-sectional areas, perivascular fibrosis, and mRNA levels of ANF and BNP. Moreover, the western blotting analysis showed that 5 mg/kg sarpogrelate significantly suppressed TAC-induced phosphorylation of ERK1/2. Conclusions: These results indicate that sarpogrelate significantly suppresses cardiomyocyte hypertrophy and the development of heart failure via at least, in part, by inhibition of ERK1/2-GATA4 pathway. These findings suggest that sarpogrelate may be an effective agent for heart failure therapy.

MRNA Levels of MAOA and 5-HT 2 A Receptor in Patients With Pathological Internet Use: Correlations With Comorbid Symptoms.

Objective: Uncontrolled internet use may lead to the emergence of pathological internet use (PIU). PIU has become a global public health concern that can cause a range of psychotic symptoms, including anxiety, depression, and impulse control disorder. To date, we know very little about the principal biological factors related to PIU. Monoamine oxidase type A (MAOA) and serotonin (5-HT) 5-HT2A receptor (5-HT2AR) play critical roles in the development of behavioural and drug addictions. Thus, the aim of this study was to measure the relative expression of mRNA of MAOA and 5-HT2AR in peripheral blood mononuclear cells (PBMCs) of patients with PIU and to determine the correlations between these biological indicators and the comorbid symptoms of patients with PIU.Methods: In this study, the mRNA of MAOA and 5-HT2AR was detected using real-time PCR in PBMCs of the patients with PIU (n = 24) and healthy controls (HCs, n = 25). The relationship between the mRNA levels of MAOA and 5-HT2AR and clinical symptoms in patients with PIU was further investigated.Results: MAOA mRNA in PBMCs was significantly upregulated in patients with PIU compared with that in HCs. mRNA levels of 5-HT2AR were not found to differ significantly between HCs and patients with PIU. Correlation analyses further revealed a significant positive correlation between the relative expression of MAOA mRNA in PBMCs of patients with PIU and the Young's Internet Addiction Test and Self-Rating Depression Scale scores.Conclusion: The present study revealed upregulated expression of MAOA mRNA in patients with PIU and an association between the expression of MAOA mRNA and clinical symptoms of PIU, suggesting that the neurobiological changes may be similar between PIU and substance addiction. Additionally, this study demonstrated a potential association between comorbid symptoms and mRNA levels of MAOA.

423 - Visual Hallucinations in Parkinson Disease and Dementia with Lewy Bodies: a review

Visual Hallucinations (VH) are a common psychiatric symptom of Parkinson’s Disease (PD) and Dementia with Lewy Bodies (DLB). According to the Perception-Attention Deficits Model, VH stem from impaired perceptual (bottom-up), including dorsal (DVS) and ventral visual streams (VVS), and attentional (top-down) processes, with a persistent Default Mode Network (DMN) activity and a dysfunctional imbalance of Dorsal (DAN) and Ventral Attentional Networks (VAN).We review the literature on the neurobiological underpinnings of VH in DLB and PD, concerning overlapping and different mechanisms.In DLB hallucinators, PET-scan findings of disconnection between higher and primary visual areas and dysfunctional recruitment of the VVS, corroborate other imaging and neuropathologic studies which document inferior longitudinal fasciculus damage and increased temporal lobe Lewy body (LB) pathology. The alteration of network topography is more pronounced in the DAN and DMN. The involvement of anterior cortical regions, clustering around attentional networks, is demonstrated in neuropathologic, volumetric and perfusion studies. VH severity closely correlates with anterior cingulate cortex and inferior temporal cortex hypoperfusion, structural changes in the DVS (superior parietal gyrus and precuneus) and increased diffusivity of the right thalamic projections to parieto-occipital cortices. Thalamocortical dysfunction alongside decreased cholinergic activity in reticular nucleus, which receive projections from the nucleus basalis of Meynert, seems to play a crucial role.Both DLB and demented PD hallucinators have more frontal cortical atrophy, yet greater in DLB, supporting top-down mechanisms.Regarding PD hallucinators, findings of cortical atrophy in inferior parietal lobule, cuneus, lingual lobule, and precentral gyrus correlated with hallucination scores. However, some studies did not evidence volumetric cortical differences between hallucinators and non-hallucinators. Moreover, LB are not necessarily present in hallucinators, suggesting other neuropathologic mechanisms in the genesis of VH, namely altered neurochemical circuitry. Volume loss in pedunculopontine nucleus and right-thalamus support the hypothesis of a dysfunctional cholinergic brainstem control of the cortex. PET-scan studies discovered higher 5-HT2A receptor levels in the inferolateral temporal and prefrontal cortices. A greater nigrostriatal impairment is documented in the right-caudate of hallucinators. Therefore, VH may arise from an inability to activate DAN (in which caudate is involved) and consequent faulty visuo-perceptual processing by DMN and VAN.

Increased behavioral and neuronal responses to a hallucinogenic drug after adolescent toluene exposure in mice: Effects of antipsychotic treatment

Toluene has been characterized as a non-classical hallucinogen drug through activation of 5-HT2A receptors and antagonism of NMDA receptors. It remains unclear whether psychotic symptoms after long-term and intense toluene exposure are associated with abnormalities in 5-HT2A receptor function. The present study examined whether the responses to a hallucinogenic 5-HT2A receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) were altered in a mouse model of toluene psychosis. Male NMRI mice were subchronically treated with toluene during adolescence. Reciprocal social interaction test and novel object recognition test were conducted to confirm the persistent behavioral deficits in adulthood. Subsequently, DOI-induced head twitch, c-Fos and Egr-2 expression, field potentials in the medial prefrontal cortex (mPFC), and the levels of 5-HT2A, 5-HT1A and mGlu2 receptors in the mPFC were monitored. Toluene exposure during adolescence produced social and memory impairments and enhanced DOI–induced behavioral, molecular and electrophysiological responses, but did not change the levels of 5-HT2A, 5-HT1A or mGlu2 receptors in the mPFC. Moreover, the effects of haloperidol and risperidone on the behavioral deficits and hyper-responsiveness to DOI after adolescent toluene exposure were compared. When administered after adolescent toluene exposure, risperidone could reverse social withdrawal, cognitive impairment and hypersensitivity to DOI, whereas haloperidol was only beneficial for social withdrawal. These findings suggest that increased functionality of 5-HT2A receptors may play a critical role in solvent-induced psychosis and recommend the antipsychotics with more selective 5-HT2A receptor antagonism as the first-line treatment for solvent-induced psychosis.

Influence of Experimental Autoimmune Prostatitis on Sexual Function and the Anti-inflammatory Efficacy of Celecoxib in a Rat Model.

Experimental autoimmune prostatitis (EAP) is a well-established model induced by an autoimmune response to prostate antigen. The symptomatic, pathological, and immunological characteristics of EAP animals are highly consistent with human chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), which makes EAP an ideal model for this disease. Here, we investigate the influence of EAP on male rat sexual function and the efficacy of anti-inflammatory therapy with celecoxib. EAP rat models were established using male Wistar rats. Rats were randomly assigned to a normal control group, an EAP model group, or an EAP model with celecoxib treatment group (celecoxib group). Behavioral changes, sexual behavioral changes, and erectile function were estimated using an open-field test, a sucrose consumption test, mating experiments, and by intracavernous pressure/mean arterial pressure ratio (ICP/MAP). Histological changes in the prostate were observed by HE staining, and the serum inflammatory factors IL-1β and TNF-α levels were measured by enzyme-linked immunosorbent assay. In addition, serotonin (5-hydroxytryptamine, 5-HT), 5-HT1A receptor, 5-HT2C receptor, and serotonin transporter (SERT) expression levels in the hippocampus and spinal cord (T13–L1, L5–S2) were examined by immunohistochemistry and western blot analysis. Results showed that EAP rats exhibited characteristics of depression, decreased sexual drive, premature ejaculation, and increased threshold of penile erection. Moreover, all these changes were effectively alleviated by celecoxib. Significant increases in prostatic interstitial infiltration by inflammatory cells and in serum IL-1β and TNF-α levels were observed in EAP rats, and these were partially reduced by celecoxib. Additionally, the expression pattern of serotonin system regulators in the hippocampus and spinal cord were altered in EAP model rats, including a decrease in 5-HT levels and an increase in 5-HT1A receptor levels. In conclusion, autoimmune prostatitis impaired rat sexual function, and this was effectively prevented by anti-inflammatory therapy with celecoxib. Moreover, a serotonin system disorder in the central nervous system was likely mediated via inflammation in EAP rats.

Antagonists for serotonin receptors ameliorate rhabdomyolysis induced by 25D-NBOMe, a psychoactive designer drug

N-Benzyl-substituted phenethylamines (NBOMes) are psychoactive drugs, which induce various symptoms like serotonin syndrome, even at low doses. Recently, we reported the first lethal case of a designer drug, 2-(4-bromo-2, 5-dimethoxyphenyl)-NBOMe (25B-NBOMe) intoxication with severe rhabdomyolysis, evaluated by clinical, pathological, and toxicological analyses. We also confirmed that 25B-NBOMe can induce rhabdomyolysis using a zebrafish model. To further elucidate pathomechanism of NBOMes-induced rhabdomyolysis, we treated zebrafish with a similar designer drug, 2-(4-methyl-2, 5-dimethoxyphenyl)-NBOMe (25D-NBOMe). Zebrafish treated with a designer drug, 25D-NBOMe, were examined survival rate and were analyzed skeletal muscle degeneration by birefringence. They were also analyzed expression levels of 5-HT2A and 5-HT2C receptors and ryanodine receptor. The 25D-NBOMe-treated fish showed decreased survival rate and skeletal muscle degeneration detected by birefringence mimicking to those of 25B-NBOMe-treated fish. We revealed that 25D-NBOMe induced up-regulation of the expression of 5-HT2A and 5-HT2C receptors, and rhabdomyolysis was inhibited by the 5-HT2A receptor antagonist, aripiprazole and 5-HT2C receptor antagonist, SB242084. Moreover, ryanodine receptor expression was up-regulated in 25D-NBOMe-treated fish as compared to that of untreated fish, and the up-regulated expression of ryanodine receptor in 25D-NBOMe-treated fish was improved with co-treatment aripiprazole and SB242084. Our findings suggest that multiple 5-HT receptors have important roles in NBOMes-induced rhabdomyolysis together with other serotonin-related symptoms. Zebrafish is a highly useful model for therapeutic studies of rhabdomyolysis induced by psychoactive designer drugs.

Expression Analysis of Serotonin Receptors, Serotonin Transporter and l-Amino Acid Decarboxylase in the Mouse Sphenopalatine Ganglion by RT-PCR, Northern Blot Analysis and In Situ Hybridization

The sphenopalatine ganglion (SPG) is a gathering of the cell bodies of parasympathetic fibers that dominate the nasal gland, lacrimal gland and cerebral blood vessels. The SPG controls nasal secretions, tears, and the dilation of cerebral blood vessels. However, it is unclear how serotonin regulates SPG functions. In this study, we investigated the expression of genes involved in the serotonergic system in the mouse SPG. We examined the mRNA expression levels of 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT2C, 5-HT3A, 5-HT3B, 5-HT4, 5-HT5A, 5-HT5B, 5-HT6 and 5-HT7 receptors, as well as serotonin transporter, tryptophan hydroxylases 1 and 2, and L-amino acid decarboxylase (AADC) by RT-PCR. It revealed that the 5-HT3A and 5-HT3B ionotropic receptors and AADC were likely to be highly expressed in the SPG, as measured by RT-PCR. We next performed in situ hybridization on the SPG to examine the expression of these three genes at the cellular level after validating the specificity of each cRNA probe by northern blotting. The 5-HT3A receptor, 5-HT3B receptor, and AADC were expressed in 96.5% ± 1.0%, 29.7% ± 10.7%, and 57.4% ± 2.9% of neuronal cell bodies in the SPG, respectively, indicating that the 5-HT3A receptor was virtually expressed in all SPG neurons. Our results on the expression of these critical serotonin system genes in the parasympathetic SPG provide insight into the pathogenetics of rhinitis, conjunctivitis and headache. Furthermore, our findings suggest that targeting the 5-HT3A receptor might have therapeutic potential in the treatment of these ailments.

The role of serotonin and serotonin 2A receptor in the anxiety due to traumatic brain injury in immature rats

Objective: The aim of this study is to investigate the relationship between anxiety due to traumatic brain injury (TBI) and prefrontal cortex serotonin (5-HT) and 5-HT2A receptor in immature rats. Methods: Seven days old rats were subjected to traumatic brain injury model. They were divided into five groups. 1-Sham; 2-TBI group; 3-TBI followed by 14 days of administration of essitalopram (selective serotonin reuptake inhibitors; SSRI) (10 mg/kg) group (TBI+SSRI); 4-TBI and cyproheptadine (nonspecific serotonin receptor antagonist; A) (5 mg/kg) given by gastric gavage one hour prior to behavioral tests (TBI+A); 5-TBI followed by 14 days of essitalopram (SSRI) and cyproheptadine (A) given 1 hour prior to behavioral tests (TBI+SSRI+A). Elevated T-maze test and open field test applied to all groups and then blood corticosterone, prefrontal cortex tissue 5-HT and 5-HT2A receptor quantities measured. Prefrontal cortex neuron density histologically evaluated. Results: In the TBI group, the time spent in the peripheral cells, the time spent in the elevated T-maze closed arms, and serum corticosterone levels found to increase as a result of anxiety. Neuronal density decreased in prefrontal cortex. SSRI treatment reduced the time spent on the closed arms in the elevated T-maze test. SSRI decreased serum corticosterone levels and increased neuronal density. Tissue serotonin levels decreased in all groups exposure to TBI compared to sham group. 5-HT2A receptor levels were higher in the TBI and A group. Conclusion: SSRIs showed anxiolytic effect for anxiety, secondary to TBI in immature rats.

021 Potential role of 5-HT serotonin system in the rat spinal cord of premature ejaculation with category III prostatitis

To explore the mechanism of premature ejaculation in rat with category III prostatitis, or chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). We establish rat model of experimental autoimmune prostatitis (EAP) by subcutaneous multiple point's injection of male prostate gland extract emulsified in an equal volume of Freund’s adjuvant at the 0 and 21th day. The behavioral change and the sexual behavior was investigated. Then, We took out the hippocampus tissue, T13-L2 and L5- S2 spinal cord tissue after perfusion, and detected the levels of 5-HT, 5-HT1A receptor, 5-HT2C receptor and SERT in these tissues by immunohistochemical staining. The levels of 5-HT, 5-HT1A receptor, 5-HT2C receptor and SERT in the remaining rats were detected by Western Blot. The EAP model was built successfully. Serum IL- 1β and TNF-α± levels in the model were significantly higher than control (p<0.01). In the copulatory test, compared with normal control group, mount frequency (MF), intromission frequency (IF) and ejaculation frequency (EF) in the model group were significantly decreased (p <0.05); mount latency (ML), intromission latency (IL) and postejaculatory interval (PEI) in the model group were significantly shortened(p <0.05); ejaculation latency (EL) in the model group was significantly significantly prolonged (p <0.05). In hippocampus tissue, 5-HT levels in the model were significantly lower than normal (p<0.05), whereas 5-HT1A, 5-HT2C and SERT levels in the model were significantly higher than normal (p<0.05). In T13-L2 spinal cord tissue, 5-HT levels in the model were significantly lower (p<0.05), 5-HT1A receptor levels in the model were significantly increased (p<0.05). In L5-S2 spinal cord tissues, 5-HT levels in the model were significantly lower (p<0.05), while the 5-HT1A, 5-HT2C and SERT levels in the model increased slightly, but the differences in 5-HT1A, 5-HT2C and SERT levels between the two group were statistically significant (p<0.05).

Diabetes Mellitus Induces Hyperreactivity of 5-Hydroxytryptamine (5-HT)-Induced Constriction in Human Internal Thoracic Artery and Is Associated with Increase in the Membrane Protein Level of 5-HT&lt;sub&gt;2A&lt;/sub&gt; Receptor

Studies indicate that 5-hydroxytryptamine (5-HT) released from activated platelets in coronary artery bypass grafting (CABG) induces 5-HT2A receptor-mediated graft spasm. We previously reported that 5-HT-induced constriction of human endothelium-denuded saphenous vein (SV) was significantly augmented in patients with diabetes mellitus (DM) than in patients without DM (non-DM), without changes in the levels of the membrane-bound 5-HT2A receptor of their smooth muscle cells. Although the internal thoracic artery (ITA) is the key graft conduit for CABG, the effect of DM on the ITA graft spasm is still unclear. Therefore, in this study, we investigated the effect of DM on 5-HT-induced vasoconstriction and the level of membrane-bound 5-HT2A receptor in ITA grafts. 5-HT-induced constriction of the isolated human endothelial-denuded ITA was significantly higher in patients with DM than in patients without DM. In addition, the level of the 5-HT2A receptor in the membrane fraction of human ITA smooth muscle cells was significantly higher in patients with DM than in those without DM. These results demonstrate that DM is a risk factor for CABG in both venous and arterial conduits, and that it differentially affects the level of the membrane-bound 5-HT2A receptor in the venous and arterial smooth muscle cells.

Yokukansan, a traditional Japanese herbal medicine, enhances the anxiolytic effect of fluvoxamine and reduces cortical 5-HT2A receptor expression in mice

Ethnopharmacological relevanceYokukansan is a traditional Japanese herbal medicine that has been approved in Japan as a remedy for neurosis, insomnia, and irritability in children. It has also been reported to improve behavioral and psychological symptoms in patients with various forms of dementia. Aim of the studyTo evaluate the usefulness of co-treatment with an antidepressant and an herbal medicine in the psychiatric field, the current study examined the effect of yokukansan on the anxiolytic-like effect of fluvoxamine in mice. Materials and methodsThe anxiolytic-like effect in mice was estimated by the contextual fear conditioning paradigm. Contextual fear conditioning consisted of two sessions, i.e., day 1 for the conditioning session and day 2 for the test session. The expression levels of 5-HT1A and 5-HT2A receptor in the mouse brain regions were quantified by western blot analysis. ResultsA single administration of fluvoxamine (5–20 mg/kg, i.p.) before the test session dose-dependently and significantly suppressed freezing behavior in mice. In the combination study, a sub-effective dose of fluvoxamine (5 mg/kg, i.p.) significantly suppressed freezing behavior in mice that had been repeatedly pretreated with yokukansan (0.3 and 1 g/kg, p.o.) once a day for 6 days after the conditioning session. Western blot analysis revealed that the expression level of 5-HT2A receptor was specifically decreased in the prefrontal cortex of mice that had been administered yokukansan and fluvoxamine. Furthermore, microinjection of the 5-HT2A receptor antagonist ketanserin (5 nmol/mouse) into the prefrontal cortex significantly suppressed freezing behavior. ConclusionThe present findings indicate that repeated treatment with yokukansan synergistically enhances the anxiolytic-like effect of fluvoxamine in the contextual fear conditioning paradigm in mice in conjunction with a decrease in 5-HT2A receptor-mediated signaling in the prefrontal cortex. Therefore, combination therapy with fluvoxamine and yokukansan may be beneficial for the treatment of anxiety disorders.

The importance of small polar radiometabolites in molecular neuroimaging: A PET study with [11C]Cimbi-36 labeled in two positions

[11C]Cimbi-36, a 5-HT2A receptor agonist PET radioligand, contains three methoxy groups amenable to [11C]-labeling. In pigs, [11C]Cimbi-36 yields a polar (M1) and a less polar (M2) radiometabolite fraction, while changing the labeling to [11C]Cimbi-36_5 yields only the M1 fraction. We investigate whether changing the labeling position of [11C]Cimbi-36 eliminates M2 in humans, and if this changes the signal-to-background ratio. Six healthy volunteers each underwent two dynamic PET scans; after injection of [11C]Cimbi-36, both the M1 and M2 fraction appeared in plasma, whereas only the M1 appeared after [11C]Cimbi-36_5 injection. [11C]Cimbi-36_5 generated higher uptake than [11C]Cimbi-36 in both neocortex and cerebellum. With the simplified reference tissue model mean neocortical non-displaceable binding potential for [11C]Cimbi-36 was 1.38 ± 0.07, whereas for [11C]Cimbi-36_5, it was 1.18 ± 0.14. This significant difference can be explained by higher non-displaceable binding caused by demethylation products in the M1 fraction such as [11C]formaldehyde and/or [11C]carbon dioxide/bicarbonate. Although often considered without any impact on binding measures, we show that small polar radiometabolites can substantially decrease the signal-to-background ratio of PET radioligands for neuroimaging. Further, we find that [11C]Cimbi-36 has a better signal-to-background ratio than [11C]Cimbi-36_5, and thus will be more sensitive to changes in 5-HT2A receptor levels in the brain.

Deficient striatal adaptation in aminergic and glutamatergic neurotransmission is associated with tardive dyskinesia in non-human primates exposed to antipsychotic drugs

Tardive dyskinesia (TD) is a potentially disabling condition encompassing all delayed, persistent, and often irreversible abnormal involuntary movements arising in a fraction of subjects during long-term exposure to centrally acting dopamine receptor-blocking agents such as antipsychotic drugs and metoclopramide. However, the pathogenesis of TD has proved complex and remains elusive. To investigate the mechanism underlying the development of TD, we have chronically exposed 17 Cebus apella monkeys to typical (11) or atypical (6) antipsychotic drugs. Six additional monkeys were used as controls. Using autoradiography, Western blot and in situ hybridization techniques, we compared neurochemical components of the dopamine, serotonin, and glutamate neurotransmitter systems modulating striatal activity in monkeys chronically exposed to haloperidol and clozapine. Five (5) out of 11 monkeys treated with haloperidol develop TD, whereas none of the monkeys treated with clozapine develop TD. Haloperidol treatment significantly upregulated the levels of serotonin 5-HT2A receptor, NR2A-containing NMDA receptors, and tyrosine hydroxylase contents in the monkey putamen, whereas clozapine regulated putamen NMDA receptor levels and tyrosine hydroxylase contents, and 5-HT2A and dopamine transporter outside the putamen. Comparisons of neurochemical alterations between dyskinetic and non dyskinetic animals within the haloperidol-treated group indicate that modulations of 5-HT2A, metabotropic glutamate type 5, NR2A- and NR2B-containing NMDA receptors, and vesicular monoamine transporter type 2 levels were restricted to the non dyskinetic group. The foregoing results suggest that TD is associated with complex deficient adaptation in aminergic and glutamatergic neurotransmission in the striatum of non-human primates chronically exposed to antipsychotic drugs.