Antagonist-induced increase in 5-HT1A-receptor expression in adult rat hippocampus and cortex

Cannabidiol Improves Random-Pattern Skin Flap Survival in Rats: Involvement of Cannabinoid Type-2 Receptors

BACKGROUND

 One of the major complications associated with random-pattern skin flaps is distal necrosis. Cannabidiol (CBD) has recently gained much attention as a therapeutic anti-inflammatory agent. We aimed to evaluate the efficacy of CBD on the random-pattern skin flap survival (SFS) in rats and to explore the possible involvement of cannabinoid type-2 (CB2) receptors.

METHODS

 In this controlled experimental study, we randomly divided male Wistar rats into seven study groups (six rats each). We performed a random-pattern skin flap model in each rat following pretreatment with vehicle (control) or multiple doses of CBD (0.3, 1, 5, or 10 mg/kg). In a separate group, we injected SR144528 (2 mg/kg), a high affinity and selective CB2 inverse agonist, before the most effective dose of CBD (1 mg/kg). A sham nontreated and nonoperated group was also included. Seven days after surgeries, the percentage of necrotic area (PNA) was calculated. Histopathological microscopy, CB2 expression level, and interleukin (IL)-1β and tumor necrosis factor (TNF)-α concentrations were also investigated in the flap tissue samples.

RESULTS

 A PNA of 72.7 ± 7.5 (95% confidence interval [CI]: 64.8-80.6) was captured in the control group. Following treatment with CBD 0.3, 1, 5, and 10 mg/kg, a dose-dependent effect was observed with PNAs of 51.0 ± 10.0 (95% CI: 40.5-61.5; p <0.05), 15.4 ± 5.8 (95% CI: 9.3-21.5; p <0.001), 37.1 ± 10.2 (95% CI: 26.3-47.8; p <0.001), and 46.4 ± 14.0 (95% CI: 31.7-61.1; p <0.001), respectively. Histopathologically, tissues enhanced significantly. Besides, CB2 expression surged remarkably, IL-1β and TNF-α concentrations decreased considerably after treatment with CBD of 1 mg/kg compared with the control (p <0.05 and <0.001, respectively). Administering SR144528 reversed the favorable effects of CBD of 1 mg/kg, both macroscopically and microscopically.

CONCLUSION

 Pretreatment with CBD of 1 mg/kg improved SFS considerably in rats and exerted desirable anti-inflammatory effects which were possibly mediated by CB2 receptors.

Involvement of Cannabinoid Type 2 Receptors in the Favorable Effects of Sumatriptan on the Random-Pattern Skin Flap Survival in Rats: A Novel Potential Target

INTRODUCTION

Recent investigations have indicated the potential therapeutic role of cannabinoid type 2 (CB2) receptors in various inflammatory-related disorders. However, the role of these receptors has not been studied in skin flap models to date. In this study, we aimed to evaluate the possible involvement of CB2 receptors in the anti-inflammatory effects of sumatriptan, improving the random-pattern skin flap survival in rats.

METHODS

In a controlled experimental study, 36 male Wistar rats were randomly divided into 6 study groups (n = 6 per group). Two doses of sumatriptan (0.1 and 0.3 mg/kg) were administered intraperitoneally 30 min before harvesting the flap tissue. In a separate group, SR144528 (a selective CB2 receptor inverse agonist) was injected before the most effective dose of sumatriptan to determine the possible involvement of CB2 receptors in its action. Histopathological examinations, the expression level of CB2 receptors (Western blot analysis), and IL-1β and TNF-α concentrations (ELISA) were explored in the skin flap sampled tissues.

RESULTS

Sumatriptan 0.3 mg/kg remarkably enhanced the skin flap survival in all macroscopic and microscopic investigations compared to the control group (p < 0.001). IL-1β and TNF-α levels were significantly attenuated (p < 0.001), and the expression of CB2 receptors in skin cells was amplified in rats treated with sumatriptan 0.3 mg/kg (p < 0.05) compared to the control group. However, the administration of SR144528 (2 mg/kg) nullified all the protective effects of sumatriptan 0.3 mg/kg.

CONCLUSION

We discovered that CB2 receptors play a crucial role in the favorable effects of sumatriptan on skin flap survival as a novel mechanism of action. So, targeting these receptors seems to be a dependable method in skin flap surgeries to ensure its survival and prevent tissue necrosis. Further experimental and clinical investigations are needed to ensure the safe clinical application of this method.

Caulerpin Mitigates Helicobacter pylori-Induced Inflammation via Formyl Peptide Receptors

The identification of novel strategies to control Helicobacter pylori (Hp)-associated chronic inflammation is, at present, a considerable challenge. Here, we attempt to combat this issue by modulating the innate immune response, targeting formyl peptide receptors (FPRs), G-protein coupled receptors that play key roles in both the regulation and the resolution of the innate inflammatory response. Specifically, we investigated, in vitro, whether Caulerpin—a bis-indole alkaloid isolated from algae of the genus Caulerpa—could act as a molecular antagonist scaffold of FPRs. We showed that Caulerpin significantly reduces the immune response against Hp culture filtrate, by reverting the FPR2-related signaling cascade and thus counteracting the inflammatory reaction triggered by Hp peptide Hp(2–20). Our study suggests Caulerpin to be a promising therapeutic or adjuvant agent for the attenuation of inflammation triggered by Hp infection, as well as its related adverse clinical outcomes.

Serotonin modulation of hippocampal functions: From anatomy to neurotherapeutics

The hippocampal region receives a dense serotoninergic innervation originating from both medial and dorsal raphe nuclei. This innervation regulates hippocampal activity through the activation of distinct receptor families that are expressed in excitatory and inhibitory neurons, terminals of several afferent neurotransmitter systems, and glial cells. Preclinical and clinical studies indicate that hippocampal dysfunctions are involved in learning and memory deficits, dementia, Alzheimer's disease, epilepsy and mood disorders such as anxiety, depression and post-traumatic syndrome disorder, whereas the hippocampus participates also in the therapeutic mechanisms of numerous medicines. Not surprisingly, several drugs acting via 5-HT mechanisms are efficacious to some extent in some diseases and the link between 5-HT and the hippocampus although clear remains difficult to untangle. For this reason, we review reported data concerning the distribution and the functional roles of the 5-HT receptors in the hippocampal region in health and disease. The impact of the 5-HT systems on the hippocampal function is such that the research of new 5-HT mechanisms and drugs is still very active. It concerns notably drugs acting at the 5-HT_1A,_2A,_2C,_4,6 receptor subtypes, in addition to the already existing drugs including the selective serotonin reuptake inhibitors.

Ivermectin Increases Random-Pattern Skin Flap Survival in Rats: The Novel Role of GABAergic System

BACKGROUND

Ivermectin (IVM) was first used as an antiparasitic agent; however, the role of this drug evolved into a broad spectrum. Many mechanisms have been proposed, including interaction with the GABAergic system. Considering the presence of GABA receptor in the skin tissue and its role in ischemia-reperfusion I/R injury, we aimed to evaluate the effect of IVM through GABA receptors on random-pattern skin flap survival.

METHODS

Sixty Wistar male rats were used. Multiple doses of IVM (0.01, 0.05, 0.2, and 0.5 mg/kg) were injected intraperitoneally before the surgery. Baclofen (selective GABAB agonist) and bicuculline (selective GABAA antagonist) were administered in combination with IVM to assess the role of the GABAergic system. Histopathological evaluations, immunohistochemical staining, quantitative assessment of IL-1β and TNFα, and the expression of GABAA α1 subunit and GABAB R1 receptors were evaluated in the skin tissue.

RESULTS

IVM 0.05 mg/kg could significantly increase flap survival compared with the control group (P < 0.001). Subeffective dose of baclofen (0.1 mg/kg) had synergistic effect with the subeffective dose of IVM (0.01 mg/kg) (P < 0.001), whereas bicuculline 1 mg/kg reversed the effect of IVM (0.05 mg/kg) (P < 0.001). IVM 0.05 mg/kg could also decrease the IL-1β and TNFα levels and increase the expression of GABAA α1 subunit and GABAB R1 receptors in the flap tissue compared with the control group.

CONCLUSIONS

IVM could improve skin flap survival, probably mediated by the GABAergic pathway. Both GABAA and GABAB receptors are involved in this process. This finding may repurpose the use of old drug, "Ivermectin."

Cannabidiol Acts at 5-HT1A Receptors in the Human Brain: Relevance for Treating Temporal Lobe Epilepsy

Experimental evidence indicates that cannabidiol (CBD) induces anxiolytic and antiepileptic effects through the activation of 5-HT_1A receptors. These receptors are coupled to G_i/o proteins and induce inhibitory effects. At present, the interaction of CBD with 5-HT_1A receptors in the human brain is unknown. The aim of this study focused on evaluating the interaction between CBD and 5-HT_1A receptors in cell membranes obtained from the hippocampus and temporal neocortex of autopsies and patients with drug-resistant mesial temporal lobe epilepsy (DR-MTLE). Cell membranes were isolated from the hippocampus and temporal neocortex of a group of patients with DR-MTLE who were submitted to epilepsy surgery (n = 11) and from a group of autopsies (n = 11). The [³H]-8-OH-DPAT binding assay was used to determine the pharmacological interaction of CBD with 5-HT_1A receptors. The [³⁵S]-GTPγS assay was used to investigate the CBD-induced activation of G_i/o proteins through its action on 5-HT_1A receptors.The CBD affinity (pK _i) for 5-HT_1A receptors was similar for autopsies and patients with DR-MTLE (hippocampus: 4.29 and 4.47, respectively; temporal neocortex: 4.67 and 4.74, respectively). Concerning the [³⁵S]-GTPγS assay, no statistically significant changes were observed for both hippocampal and neocortical tissue (p > 0.05) at low CBD concentrations (1 pM to 10 μM). In contrast, at high concentrations (100 μM), CBD reduced the constitutive activity of G_i/o proteins of autopsies and DR-MTLE patients (hippocampus: 39.2% and 39.6%, respectively; temporal neocortex: 35.2% and 24.4%, respectively). These changes were partially reversed in the presence of WAY-100635, an antagonist of 5-HT_1A receptors, in the autopsy group (hippocampus, 59.8%, p < 0.0001; temporal neocortex, 71.5%, p < 0.0001) and the group of patients with DR-MTLE (hippocampus, 53.7%, p < 0.0001; temporal neocortex, 68.5%, p < 0.001). Our results show that CBD interacts with human 5-HT_1A receptors of the hippocampus and temporal neocortex. At low concentrations, the effect of CBD upon G_i/o protein activation is limited. However, at high concentrations, CBD acts as an inverse agonist of 5-HT_1A receptors. This effect could modify neuronal excitation and epileptic seizures in patients with DR-MTLE.

The effect of aryl hydrocarbon receptor ligands on gentamicin-induced nephrotoxicity in rats

Polycyclic aromatic hydrocarbons (PAHs)/aryl hydrocarbon receptor (AhR) regulate the expression of target genes, including drug transporter genes which harbor xenobiotic response element (XRE) in their promoter regions. Thus, PAHs/AhR could alter the toxicokinetic profile of many nephrotoxic drugs, including aminoglycosides. In the current study, we investigated the expression and localization of AhR and megalin in rat kidney. Furthermore, we investigated whether AhR and its ligands could modulate the expression of megalin and consequently the gentamicin-induced nephrotoxicity (GN) in rats. Both megalin and AhR receptors are expressed in the proximal tubules of the rat kidney. Treatment with AhR agonist benzo(a)pyrene aggravated GN as indicated by a significant increase in serum creatinine, BUN, KIM1, NAGL, CD-86, and urinary albumin/creatinine ratio. On the other hand, treatment with AhR antagonist resveratrol ameliorated GN as manifested by a pronounced decrease in the aforementioned parameters. The effects of AhR ligands on GN were associated with altered expression of megalin receptor.

Evaluation of canine 2D cell cultures as models of myxomatous mitral valve degeneration

The utility of cells cultured from the mitral valve as models of myxomatous diseases needs to be properly validated. In this study valve interstitial cells (VICs) and valve endothelial cells (VECs) were cultured from normal and diseased canine mitral valves in 2% (v/v) or 10% FBS media, in the presence of TGFβ1, 2 and 3, the TGFβ RI kinase inhibitor SB431542 and TGFβ neutralising antibodies, 5HT and the 5HT2RB antagonist LY272015. Cultures were examined by morphology, transcriptomic profiling, protein expression of the cell specific markers αSMA and SM22α (VICs), and CD31 (VECs), deposition of proteoglycans (PG), the PG versican, and the TGFβs themselves. VECs derived from normal valves were CD31+/αSMA-, but those from diseased valves were αSMA+, indicating endothelial-to-mesenchymal (EndoMT) transition had occurred. The TGFβs induced EndoMT in normal VECs, and this was abolished by SB431542, with significant changes in αSMA, CD31 and HAS2 expression (P<0.05). Normal VICs cultured in 10% FBS media were αSMA+ (activated myofibroblast (disease) phenotype), but were αSMA- when grown in 2% FBS. VICs from diseased dogs were αSMA+ in 2% FBS (retention of the activated myofibroblast disease phenotype), with significantly increased TGFβ1 expression (P<0.05) compared to normal cells. Treatment of normal and diseased VICs with the TGFβs significantly increased expression of αSMA, SM22α, versican, the TGFβs themselves, and deposition of PGs (P<0.05), with TGFβ1 being the most potent activator. These effects were either abolished or markedly reduced by SB431542 and a pan-TGFβ neutralizing antibody (P<0.05). SB431542 also markedly reduced αSMA expression in VICs from diseased valves, but 5HT and LY272015 had no effect on VIC phenotype. Transcriptomic profiling identified clear differences in gene expression for the different conditions and treatments that partially matched that seen in native diseased valve tissue, including changes in expression of ACTA2 (αSMA), 5HTR2B, TAGLN (SM22α) and MYH10 (SMemb), gene ontology terms and canonical signalling pathways. Normal and diseased VICs and normal VECs from canine mitral valves can be successfully grown in culture with retention of phenotype, which can be manipulated using TGFβ1 and the TGFβ RI kinase inhibitor SB431542. This optimized cell system can now be used to model MMVD to elucidate disease mechanisms and identify key regulators of disease progression.

5-HTR2A and 5-HTR3A but not 5-HTR1A antagonism impairs the cross-modal reactivation of deprived visual cortex in adulthood

Visual cortical areas show enhanced tactile responses in blind individuals, resulting in improved behavioral performance. Induction of unilateral vision loss in adult mice, by monocular enucleation (ME), is a validated model for such cross-modal brain plasticity. A delayed whisker-driven take-over of the medial monocular zone of the visual cortex is preceded by so-called unimodal plasticity, involving the potentiation of the spared-eye inputs in the binocular cortical territory. Full reactivation of the sensory-deprived contralateral visual cortex is accomplished by 7 weeks post-injury. Serotonin (5-HT) is known to modulate sensory information processing and integration, but its impact on cortical reorganization after sensory loss, remains largely unexplored. To address this issue, we assessed the involvement of 5-HT in ME-induced cross-modal plasticity and the 5-HT receptor (5-HTR) subtype used. We first focused on establishing the impact of ME on the total 5-HT concentration measured in the visual cortex and in the somatosensory barrel field. Next, the changes in expression as a function of post-ME recovery time of the monoamine transporter 2 (vMAT2), which loads 5-HT into presynaptic vesicles, and of the 5-HTR_1A and 5-HTR_3A were assessed, in order to link these temporal expression profiles to the different types of cortical plasticity induced by ME. In order to accurately pinpoint which 5-HTR exactly mediates ME-induced cross-modal plasticity, we pharmacologically antagonized the 5-HTR_1A, 5-HTR_2A and 5-HTR_3A subtypes. This study reveals brain region-specific alterations in total 5-HT concentration, time-dependent modulations in vMAT2, 5-HTR_1A and 5-HTR_3A protein expression and 5-HTR antagonist-specific effects on the post-ME plasticity phenomena. Together, our results confirm a role for 5-HTR_1A in the early phase of binocular visual cortex plasticity and suggest an involvement of 5-HTR_2A and 5-HTR_3A but not 5-HTR_1A during the late cross-modal recruitment of the medial monocular visual cortex. These insights contribute to the general understanding of 5-HT function in cortical plasticity and may encourage the search for improved rehabilitation strategies to compensate for sensory loss.

Cartography of 5-HT1A and 5-HT2A Receptor Subtypes in Prefrontal Cortex and Its Projections

Since the development of chemical neuroanatomical tools in the 1960s, a tremendous wealth of information has been generated on the anatomical components of the serotonergic system, at the microscopic level in the brain including the prefrontal cortex (PFC). The PFC receives a widespread distribution of serotonin (5-hydroxytryptamine, 5-HT) terminals from the median and dorsal raphe nuclei. 5-HT receptors were first visualized using radioligand autoradiography in the late 1980s and early 1990s and showed, in contrast to 5-HT innervation, a differential distribution of binding sites associated with different 5-HT receptor subtypes. Due to the cloning of the different 5-HT receptor subtype genes in the late 1980s and early 1990s, it was possible, using in situ hybridization histochemistry, to localize cells expressing mRNA for these receptors. Double in situ hybridization histochemistry and immunohistochemistry allowed for the chemical characterization of the phenotype of cells expressing 5-HT receptors. Tract tracing technology allowed a detailed cartography of the neuronal connections of PFC and other brain areas. Based on these data, maps have been constructed that reflect our current understanding of the different circuits where 5-HT receptors can modulate the electrophysiological, pharmacological, and behavioral functions of the PFC. We will review current knowledge regarding the cellular localization of 5-HT1A and 5-HT2A receptors in mammalian PFC and their possible functions in the neuronal circuits of the PFC. We will discuss data generated in our laboratory as well as in others, focusing on localization in the pyramidal and GABAergic neuronal cell populations in different mammalian species using molecular neuroanatomy and on the connections with other brain regions.

Development of brainstem 5-HT1A receptor-binding sites in serotonin-deficient mice

The sudden infant death syndrome is associated with a reduction in brainstem serotonin 5-hydroxytryptamine (5-HT) and 5-HT(1A) receptor binding, yet it is unknown if and how these findings are linked. In this study, we used quantitative tissue autoradiography to determine if post-natal development of brainstem 5-HT(1A) receptors is altered in two mouse models where the development of 5-HT neurons is defective, the Lmx1b(f/f/p) , and the Pet-1⁻/⁻ mouse. 5-HT(1A) receptor agonist-binding sites were examined in both 5-HT-source nuclei (autoreceptors) and in sites that receive 5-HT innervation (heteroreceptors). In control mice between post-natal day (P) 3 and 10, 5-HT(1A) receptor binding increased in several brainstem sites; by P25, there were region-specific increases and decreases, refining the overall binding pattern. In the Lmx1b(f/f/p) and Pet-1⁻/⁻ mice, 5-HT(1A)-autoreceptor binding was significantly lower than in control mice at P3, and remained low at P10 and P25. In contrast, 5-HT(1A) heteroreceptor levels were comparable between control and 5-HT-deficient mice. These data define the post-natal development of 5-HT(1A)-receptor binding in the mouse brainstem. Furthermore, the data suggest that 5-HT(1A)-heteroreceptor deficits detected in sudden infant death syndrome are not a direct consequence of a 5-HT neuron dysfunction nor reduced brain 5-HT levels. To elucidate the developmental relationship between serotonin (5-HT) levels and 5-HT(1A) receptors in the brainstem, we examined 5-HT(1A) binding in two 5-HT-deficient mouse models. In nuclei containing 5-HT neurons, 5-HT(1A) binding was decreased (autoreceptors), while binding was maintained in projection sites (heteroreceptors). Thus, brainstem 5-HT(1A)-heteroreceptor-binding sites do not appear developmentally sensitive to reduced brain 5-HT levels.

Increased serotonin-1A (5-HT1A) autoreceptor expression and reduced raphe serotonin levels in deformed epidermal autoregulatory factor-1 (Deaf-1) gene knock-out mice

Altered regulation of the serotonin-1A (5-HT1A) receptor gene is implicated in major depression and mood disorders. The functional human 5-HT1A C(-1019)G promoter polymorphism (rs6295), which prevents the binding of Deaf-1/NUDR leading to dysregulation of the receptor, has been associated with major depression. In cell models Deaf-1 displays dual activity, repressing 5-HT1A autoreceptor expression in serotonergic raphe cells while enhancing postsynaptic 5-HT1A heteroreceptor expression in nonserotonergic neurons. A functional Deaf-1 binding site on the mouse 5-HT1A promoter was recognized by Deaf-1 in vitro and in vivo and mediated dual activity of Deaf-1 on 5-HT1A gene transcription. To address regulation by Deaf-1 in vivo, Deaf-1 knock-out mice bred to a C57BL/6 background were compared with wild-type siblings for changes in 5-HT1A RNA and protein by quantitative RT-PCR, in situ hybridization, and immunofluorescence. In the dorsal raphe, Deaf-1 knock-out mice displayed increased 5-HT1A mRNA, protein, and 5-HT1A-positive cell counts but reduced 5-HT levels, whereas other serotonergic markers, such as tryptophan hydroxylase (TPH)- or 5-HT-positive cells and TPH2 RNA levels, were unchanged. By contrast, 5-HT1A mRNA and 5-HT1A-positive cells were reduced in the frontal cortex of Deaf-1-null mice, with no significant change in hippocampal 5-HT1A RNA, protein, or cell counts. The region-specific alterations of brain 5-HT1A gene expression and reduced raphe 5-HT content in Deaf-1(-/-) mice indicate the importance of Deaf-1 in regulation of 5-HT1A gene expression and provide insight into the role of the 5-HT1A G(-1019) allele in reducing serotonergic neurotransmission by derepression of 5-HT1A autoreceptors.

Region-specific regulation of 5-HT1A receptor expression by Pet-1-dependent mechanisms in vivo

Serotonin (5-hydroxytryptamine, 5-HT) neurotransmission is negatively regulated by 5-HT1A autoreceptors on raphe neurons, and is implicated in mood disorders. Pet-1/FEV is an ETS transcription factor expressed exclusively in serotonergic neurons and is essential for serotonergic differentiation, although its regulation of 5-HT receptors has not yet been studied. Here, we show by electrophoretic mobility shift assay that recombinant human Pet-1/FEV binds directly to multiple Pet-1 elements of the human 5-HT1A receptor promoter to enhance its transcriptional activity. In luciferase reporter assays, mutational analysis indicated that while several sites contribute, the Pet-1 site at -1406 bp had the greatest effect on 5-HT1A promoter activity. To address the effect of Pet-1 on 5-HT1A receptor regulation in vivo, we compared the expression of 5-HT1A receptor RNA and protein in Pet-1 null and wild-type littermate mice. In the raphe nuclei of Pet-1-/- mice tryptophan hydroxylase 2 (TPH2) RNA, and 5-HT and TPH immunostaining were greatly reduced, indicating a deficit in 5-HT production. Raphe 5-HT1A RNA and protein levels were also reduced in Pet-1-deficient mice, consistent with an absence of Pet-1-mediated transcriptional enhancement of 5-HT1A autoreceptors in serotonergic neurons. Interestingly, 5-HT1A receptor expression was up-regulated in the hippocampus, but down-regulated in the striatum and cortex. These data indicate that, in addition to transcriptional regulation by Pet-1 in raphe neurons, 5-HT1A receptor expression is regulated indirectly by alterations in 5-HT neurotransmission in a region-specific manner that together may contribute to the aggressive/anxiety phenotype observed in Pet-1 null mice.

Icariin attenuates chronic mild stress-induced dysregulation of the LHPA stress circuit in rats

Chronic mild stress (CMS) is suggested to develop dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) stress circuit. Icariin, a major constituent of flavonoids isolated from Epimedium brevicornum, has been previously confirmed to rescue the HPA axis abnormalities in animal models of depression. However, antidepressant treatment of icariin on corticotropin-releasing factor (CRF) system within the LHPA stress circuit and its interaction with serotonergic receptor are still seldom studied in CMS model of animals. The present study further investigated the effects of CMS procedure and subsequent icariin treatment on mRNA and protein levels of CRF, CRF receptor 1 (CRFR1) and CRF binding protein (CRFBP), as well as sucrose intake in rats. Moreover, the levels of cyclic adenosine 3',5'-monophosphate (cAMP) response element binding protein (CREB), glucocorticoid receptor (GR) and 5-hydroxytryptamine 1A receptor (5-HTR1A) in hypothalamus, hippocampus and frontal cortex were simultaneously evaluated for their participations in CRF system in this model. We found that CMS procedure significantly increased CRF expression levels in the brain regions, and decreased GR and 5-HTR1A in hippocampus and frontal cortex, with sucrose intake reduction representing the hedonic deficit in rats. Icariin restored these alterations in CMS rats. These results confirmed the hypothesis that icariin exerted antidepressant-like effect via its regulation of central CRF system. And hippocampus was suggested as an important neural area controlling the LHPA stress circuit in icariin-treated CMS rats. These findings for the first time proved that the potential molecular mechanism of antidepressant action of icariin was targeted on the interaction of the LHPA stress circuit and serotonergic function in CMS rats.

Classification of 5-HT(1A) receptor ligands on the basis of their binding affinities by using PSO-Adaboost-SVM

In the present work, the support vector machine (SVM) and Adaboost-SVM have been used to develop a classification model as a potential screening mechanism for a novel series of 5-HT_1A selective ligands. Each compound is represented by calculated structural descriptors that encode topological features. The particle swarm optimization (PSO) and the stepwise multiple linear regression (Stepwise-MLR) methods have been used to search descriptor space and select the descriptors which are responsible for the inhibitory activity of these compounds. The model containing seven descriptors found by Adaboost-SVM, has showed better predictive capability than the other models. The total accuracy in prediction for the training and test set is 100.0% and 95.0% for PSO-Adaboost-SVM, 99.1% and 92.5% for PSO-SVM, 99.1% and 82.5% for Stepwise-MLR-Adaboost-SVM, 99.1% and 77.5% for Stepwise-MLR-SVM, respectively. The results indicate that Adaboost-SVM can be used as a useful modeling tool for QSAR studies.

Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs

In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77-79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n=8) and d42 pigs (n=8), using (3)H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of (3)H-8-OH-DPAT (5-HT(1A) receptor agonist) or of (3)H-ketanserin (5-HT(2A) receptor antagonist) to any brain region studied. In d12 pigs, 5-HT(1A) receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT(2A) receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT(1A) receptor mRNA data were 70-79% correlated with binding data but no correlation was found for 5-HT(2A) data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.