Impact of Serotonergic 5HT1A and 5HT2A Receptor Activation on the Respiratory Response to Hypercapnia in a Rat Model of Parkinson's Disease.

In Parkinson's disease (PD), along with typical motor dysfunction, abnormal breathing is present; the cause of which is not well understood. The study aimed to analyze the effects of stimulation of the serotonergic system with 5-HT1A and 5-HT2A agonists in a model of PD induced by injection of 6-hydroxydopamine (6-OHDA). To model PD, bilateral injection of 6-OHDA into both striata was performed in male Wistar rats. Respiratory disturbances in response to 7% hypercapnia (CO2 in O2) in the plethysmographic chamber before and after stimulation of the serotonergic system and the incidence of apnea were studied in awake rats 5 weeks after 6-OHDA or vehicle injection. Administration of 6-OHDA reduced the concentration of serotonin (5-HT), dopamine (DA) and norepinephrine (NA) in the striatum and the level of 5-HT in the brainstem of treated rats, which have been associated with decreased basal ventilation, impaired respiratory response to 7% CO2 and increased incidence of apnea compared to Sham-operated rats. Intraperitoneal (i.p.) injection of the 5-HT1AR agonist 8-OH-DPAT and 5-HT2AR agonist NBOH-2C-CN increased breathing during normocapnia and hypercapnia in both groups of rats. However, it restored reactivity to hypercapnia in 6-OHDA group to the level present in Sham rats. Another 5-HT2AR agonist TCB-2 was only effective in increasing normocapnic ventilation in 6-OHDA rats. Both the serotonergic agonists 8-OH-DPAT and NBOH-2C-CN had stronger stimulatory effects on respiration in PD rats, compensating for deficits in basal ventilation and hypercapnic respiration. We conclude that serotonergic stimulation may have a positive effect on respiratory impairments that occur in PD.

Establishing an OCD Model in BALB/c Mice Using RU24969: A Molecular and Behavioural Study of Optimal Dose Selection.

Obsessive-compulsive disorder (OCD) is a disabling disease characterized by distressing obsessions and repetitive compulsions. The etiology of OCD is poorly known, and mouse modeling allows to clarify the genetic and neurochemical basis of this disorder and to investigate potential treatments. This study evaluates the impact of the 5-HT1B agonist RU24969 on the induction of OCD-like behaviours in female BALB/c mice (n = 30), distributed across five groups receiving varying doses of RU24969. Behavioural assessments, including marble test, tail suspension test, sucrose preference test, forced swim test, and nestlet shredding test, were conducted. Gene expression and protein quantitation of Gabra1 and serotonin transporter in mouse brain were also performed. Marble-burying behaviour increased significantly at high doses of RU24969 (15-20 mg/kg). The forced swimming test consistently showed elevated values at the same high concentrations, compared to the control. Altered reward-seeking behaviour was indicated by the sucrose preference test, notably at 15 and 20 mg/kg doses of RU24969. Nestlet shredding results did not show statistical significance among the tested animal groups. Gene expression analysis revealed reduced Gabra1 expression with increasing doses of RU, while serotonin transporter was not related to varying doses of RU24969. Western blotting corroborated these trends. The results underscore complex interactions between the serotonin system, GABAergic signaling, and OCD-relevant behaviours and suggest the use of intraperitoneal injection of 15 mg/kg of RU24969 to induce OCD-like behaviour in BALB/c mouse models.

Healthcare resource utilization and associated costs among patients with migraine in Finland: A retrospective register-based study.

Migraine is a common chronic brain disorder, characterized by recurring and often disabling attacks of severe headache, with additional symptoms such as photophobia, phonophobia and nausea. Migraine affects especially the working age population. The objective of this retrospective observational register-based study was to analyze the use of healthcare services and associated costs in Finnish migraine patients. Study was based on aggregate data from January 1st, 2020, to December 31st, 2021, from the Finnish Institute for Health and Welfare's national registries. Patients were grouped into nine patient groups according to medication prescriptions and diagnoses. Healthcare resource utilization in specialty, primary, and occupational healthcare was assessed and analyzed separately for all-cause and migraine related healthcare contacts from a one-year period. The total number of patients was 175 711, and most (45%) of the patients belonged to a group that had used only one triptan. Migraine related total healthcare resource utilization was greater for patients that had used two or more triptans compared to those that had used only one. The patients with three or more preventive medications had the highest total migraine related healthcare resource utilization of the studied patient cohorts. Of the total annual healthcare costs 11.5% (50.6 million €) was associated to be migraine related costs. Total per patient per year healthcare costs were highest with patients that had used three or more preventive medications (5 626 €) and lowest in those with only one triptan (2 257 €). Our findings are in line with the recent European Headache Federation consensus statement regarding the unmet need in patients who have had inadequate response to two or more triptans. When assessing the patient access and cost-effectiveness of novel treatments for the treatment of migraine within different healthcare systems, a holistic analysis of the current disease burden along with potential gains for patients and healthcare service providers are essential information in guiding decision-making.

The 5-HT1B and 5-HT1D agonists in acute migraine therapy: Ergotamine, dihydroergotamine, and the triptans.

The advent of the triptans revolutionized acute migraine treatment. The older migraine-specific drugs, the ergot alkaloids (ergotamine and dihydroergotamine), also relieve migraine attacks through agonism at the 5-HT1B and 5-HT1D receptors, but the triptans have much greater specificity for these receptors. Unlike the ergot alkaloids, the triptans do not activate many other receptor types, and therefore are much better tolerated. This reduction in side effects greatly enhanced their clinical utility as it allowed a far greater proportion of patients to take a full therapeutic dose. As a result, the clinical use of ergotamine is minimal today, although dihydroergotamine still has a significant clinical role. There is extensive evidence that the seven triptans available today, sumatriptan, zolmitriptan, rizatriptan, eletriptan, naratriptan, almotriptan, and frovatriptan, are effective in the acute treatment of migraine. Available formulations include oral tablets, orally dissolving tablets, subcutaneous injections, nasal sprays, and in some countries, rectal suppositories. For optimal benefit, therapy needs to be individualized for a given patient both regarding the triptan chosen and the formulation. This chapter discusses the ergot alkaloids and the triptans, including mechanism of action, evidence for efficacy, clinical use, and adverse effects.

5-HT1F agonists.

5-Hydroxytryptamine (HT)/serotonin receptor agonism has been a long-recognized property of triptan medications, and more recently, the study and development of medications with selective binding to the 1F receptor subtype have been explored. While the exact mechanism contributing to decreased symptoms of an acute migraine attack remains unclear, selective 5-HT1F agonists have demonstrated clinical efficacy with lasmiditan as the only approved medication from this class to date. Lasmiditan lacks vasoconstrictive properties, giving it utility in specific patient populations in whom triptans should be avoided. Availability, central nervous system (CNS) side effects, and 8-hour driving restriction may affect its clinical use.

5-HT1A receptors within the intermediate lateral septum modulate stress vulnerability in male mice.

Chronic stress is a major risk factor for psychiatric disorders. However, certain individuals may be at higher risk due to greater stress susceptibility. Elucidating the neurobiology of stress resilience and susceptibility may facilitate the development of novel strategies to prevent and treat stress-related disorders such as depression. Mounting evidence suggests that the serotonin (5-HT) system is a major regulator of stress sensitivity. In this study, we assessed the functions of 5-HT1A and 5-HT2A receptors within the lateral septum (LS) in regulating stress vulnerability. Among a group of male mice exposed to chronic social defeat stress (CSDS), 47.2% were classified as stress-susceptible, and these mice employed more passive coping strategies during the defeat and exhibited more severe anxiety- and depression-like behaviors during the following behavioral tests. These stress-susceptible mice also exhibited elevated neuronal activity in the LS as evidenced by greater c-Fos expression, greater activity of 5-HT neurons in both the dorsal and median raphe nucleus, and downregulated expression of the 5-HT1A receptor in the intermediate LS (LSi). Finally, we found the stress-induced social withdrawal symptoms could be rapidly relieved by LSi administration of 8-OH-DPAT, a 5-HT1A receptor agonist. These results indicate that 5-HT1A receptors within the LSi play an important role in stress vulnerability in mice. Therefore, modulation of stress vulnerable via 5-HT1A receptor activation in the LSi is a potential strategy to treat stress-related psychiatric disorders.

Risk of Stroke and Myocardial Infarction Among Initiators of Triptans.

Importance: Triptans are contraindicated in patients with ischemic heart disease or previous myocardial infarction, and caution is advised when prescribing these drugs to patients with vascular risk factors. However, controlled observational studies have either shown no association or an apparent lower risk, possibly owing to a channeling of triptans to individuals at low risk of cardiovascular outcomes, and it remains unclear whether avoiding triptan treatment for these patients is meaningful. Objective: To establish whether an association between triptans and ischemic events could be demonstrated using a self-controlled design because this type of design is robust to the previously mentioned type of confounding. Design, Setting, and Participants: All people in nationwide Danish registries who were initiating triptans and all the ischemic events that they experienced were identified. A case-crossover design was used to estimate odds ratios (OR) for associations between first-ever triptan use and ischemic outcomes, comparing triptan exposure in the 2-week period up to the event with four 2-week reference periods. Data were obtained for the period January 1995 to August 2022. Included from the population of Denmark were individuals redeeming a prescription for any triptan and experiencing at least 1 of 3 predefined ischemic outcomes. No one was excluded. Exposure: Initiation of any triptan. Main Outcomes and Measures: Acute myocardial infarction, ischemic stroke, or nonspecified stroke. Results: Identified were a total of 429 612 individuals (median [IQR] age, 38 [28-48] years; 325 687 female [75.8%]) who redeemed a first prescription for a triptan in the study period. Of these patients, 11 (0.003%) had a myocardial infarction with the first triptan prescription in either a focal or referent window (odds ratio [OR], 3.3; 95% CI, 1.0-10.9), 18 (0.004%) had ischemic stroke (OR, 3.2; 95% CI, 1.3-8.1), and 35 (0.008%) had ischemic/nonspecified stroke (OR, 3.0; 95% CI, 1.5-5.9). Case patients had a median age of approximately 60 years and had a high-risk cardiovascular profile. Conclusions and Relevance: Results of this case-crossover study suggest that triptan initiation was associated with higher risk of ischemic stroke and myocardial infarction. For the individual patient with low background cardiovascular risk, the risk of an ischemic event after triptan initiation was very low.

Serotonergic and Adrenergic Neuroreceptor Manipulation Ameliorates Core Symptoms of ADHD through Modulating Dopaminergic Receptors in Spontaneously Hypertensive Rats.

The core symptoms of attention deficit hyperactivity disorder (ADHD) are due to the hypofunction of the brain's adrenergic (NE) and dopamine (DA) systems. Drugs that enhance DA and NE neurotransmission in the brain by blocking their transporters or receptors are the current therapeutic strategies. Of late, the emerging results point out the serotonergic (5-HT) system, which indirectly modulates the DA activity in reducing the core symptoms of ADHD. On this basis, second-generation antipsychotics, which utilize 5-HT receptors, were prescribed to children with ADHD. However, it is not clear how serotonergic receptors modulate the DA activity to minimize the symptoms of ADHD. The present study investigates the efficacy of serotonergic and alpha-2 adrenergic receptor manipulation in tackling the core symptoms of ADHD and how it affects the DA neuroreceptors in the brain regions involved in ADHD. Fifteen-day-old male spontaneously hypertensive rats (SHRs) received 5-HT1A agonist (ipsapirone) or 5-HT2A antagonist (MDL 100907) (i.p.) or alpha-2 agonist (GFC) from postnatal days 15 to 42 along with age-matched Wistar Kyoto rats (WKY) (n = 8 in each group). ADHD-like behaviors were assessed using a battery of behavioral tests during postnatal days 44 to 65. After the behavioral tests, rat brains were processed to estimate the density of 5-HT1A, 5-HT2A, DA-D1, and DA-D2 neuroreceptors in the prefrontal cortex, the striatum, and the substantia nigra. All three neuroreceptor manipulations were able to minimize the core symptoms of ADHD in SHRs. The positive effect was mainly associated with the upregulation of 5-HT2A receptors in all three areas investigated, while 5-HT1A was in the prefrontal cortex and the substantia nigra. Further, the DA-D1 receptor expression was downregulated by all three neuroreceptor manipulations except for alpha-2 adrenergic receptor agonists in the striatum and 5-HT2A antagonists in the substantia nigra. The DA-D2 expression was upregulated in the striatum while downregulated in the prefrontal cortex and the substantia nigra. In this animal model study, the 5-HT1A agonist or 5-HT2A antagonist monotherapies were able to curtail the ADHD symptoms by differential expression of DA receptors in different regions of the brain.

Beneficial effect of 5-HT1b/1d agonist on Parkinson's disease by modulating glutamate and reducing deposition of α-synuclein.

The given investigation examined the neuroprotection role of 5-HT1b/1d agonist in reserpine induced Parkinson's disease (PD) in male Wistar rats. PD was induced in rats by reserpine at 5 mg/kg ip for 3 days and thereafter the rats were provided with the following treatments for 4 days, zolmitriptan (ZLM) group (30 mg/kg ip); STD group (levodopa + carbidopa, 200 + 5 mg/kg ip); ZLM + GA group (zolmitriptan, 30 mg/kg ip and glutamic acid, 1.5 mg/kg); ZLM + DX group (zolmitriptan, 30 mg/kg ip and dextromethorphan, 20 mg/kg ip). All the groups were then assessed for cognitive and motor functions at the end of the protocol. Moreover, oxidative stress parameters and histopathological changes were observed in rats of all treatment groups. Deposition of α-synuclein in the brain tissue was observed by silver staining. Data of this investigation revealed that motor and cognitive functions were improved in the ZLM-treated group compared with the negative control group, which was observed to be reversed in ZLM + GA group. Treatment with ZLM ameliorated oxidative stress and histopathological changes in the brain tissue of PD rats. Further, ZLM reduced the deposition of α-synuclein in PD rats, which reversed in ZLM + GA-treated group. This study concludes by stating that 5-HT1b/1d agonist can prevent neurodegeneration and reduce oxidative stress in PD rats. The probable underlying mechanism of such an effect of 5-HT1b/1d agonist could be by regulating the deposition of α-synuclein and reducing the expression of NMDA receptor.

Triptan non-response in specialized headache care: cross-sectional data from the DMKG Headache Registry.

BACKGROUND: Triptans are effective for many migraine patients, but some do not experience adequate efficacy and tolerability. The European Headache Federation (EHF) has proposed that patients with lack of efficacy and/or tolerability of ≥ 2 triptans ('triptan resistance') could be considered eligible for treatment with the novel medications from the ditan and gepant groups. There is little data on the frequency of 'triptan resistance'. METHODS: We used patient self-report data from the German Migraine and Headache Society (DMKG) Headache Registry to assess triptan response and triptan efficacy and/or tolerability failure. RESULTS: A total of 2284 adult migraine patients (females: 85.4%, age: 39.4 ± 12.8 years) were included. 42.5% (n = 970) had failed ≥ 1 triptan, 13.1% (n = 300) had failed ≥ 2 triptans (meeting the EHF definition of 'triptan resistance'), and 3.9% (n = 88) had failed ≥ 3 triptans. Compared to triptan responders (current use, no failure, n = 597), triptan non-responders had significantly more severe migraine (higher frequency (p < 0.001), intensity (p < 0.05), and disability (p < 0.001)), that further increased with the level of triptan failure. Responders rates were highest for nasal and oral zolmitriptan, oral eletriptan and subcutaneous sumatriptan. CONCLUSION: In the present setting (specialized headache care in Germany), 13.1% of the patients had failed ≥ 2 triptans. Triptan failure was associated with increased migraine severity and disability, emphasizing the importance of establishing an effective and tolerable acute migraine medication. Acute treatment optimization might include switching to one of the triptans with the highest responder rates and/or to a different acute medication class. TRIAL REGISTRATION: The DMKG Headache Registry is registered with the German Clinical Trials Register (DRKS 00021081).

Patterns of anti-CGRP mAbs use and variation of triptan consumption following treatment initiation: A descriptive drug utilization study in the Tuscany region, Italy.

OBJECTIVE: To describe the pattern of anti-calcitonin gene-related peptide monoclonal antibodies (anti-CGRP mAbs) utilization in the Tuscany region, Italy, and the variation of triptan consumption after treatment initiation. BACKGROUND: Given the recent commercialization of anti-CGRP mAbs as migraine preventive medications, real-world evidence on their patterns of utilization and their impact on migraine abortive medication use is still limited. METHODS: A retrospective, descriptive, cohort study on the real-world utilization of anti-CGRP mAbs was performed using the population-based regional administrative database of Tuscany. Patients with ≥1 anti-CGRP mAb dispensing (namely erenumab, galcanezumab, fremanezumab) between April 1, 2019, and September 30, 2021, were identified. The first dispensing was the cohort entry (CE). New users (NUs) were patients with no anti-CGRP mAb dispensing before CE. Kaplan-Meier (KM) curves were plotted to describe the cumulative probability of remaining with the initial anti-CGRP mAb during a 15-month follow-up period as a measure of treatment persistence. Among NUs with ≥2 triptan dispensings during the 6 months before CE (i.e., baseline), the mean monthly number of triptan dosage units dispensed was measured in five consecutive follow-up time windows (months 1-3, 4-6, 7-9, 10-12, 13-15) and the difference from the baseline was calculated. RESULTS: A total of 624 NUs (erenumab = 295, galcanezumab = 223, fremanezumab = 106) were identified, of whom 188 (78%) were women. Mean age was 49.2 years (standard deviation [SD] = 12.6). The survival to discontinuation at 6, 12, and 15 months was about 69%, 48%, and 6%, respectively. The survival to switch was about 6% at 15 months. The observed variation of triptan consumption at 3/6/9/12/15 months and the corresponding SD was -4.4 [8.2]/-5.2 [9.0]/-5.5 [9.2]/-5.4 [9.2]/-4.5 [10.0], respectively. CONCLUSION: Patient demographics reflect the place of these medications in therapy. Overall, findings seem to indicate a favorable tolerability and effectiveness profile. Further studies are warranted to better establish the long-term comparative effectiveness, safety, and cost effectiveness of anti-CGRP mAbs compared to other preventive medications.

Non-CGRP Antagonist/Non-Triptan Options for Migraine Disease Treatment: Clinical Considerations.

PURPOSE OF REVIEW: Although the association between CGRP and migraine disease is well-known and studied, therapies can target other pathways to minimize migraine symptoms. It is important to understand the role of these medications as options for migraine treatment and the varied mechanisms by which symptoms can be addressed. In the present investigation, the role of non-CGRP antagonist/non-triptan options for migraine disease therapy is reviewed, including NSAIDs, ß-blockers, calcium channel blockers, antidepressants, and antiepileptics. Pharmacologic therapies for both acute symptoms and prophylaxis are evaluated, and their adverse effects are compared. RECENT FINDINGS: At present, the Food and Drug Association has approved the beta-blockers propranolol and timolol and the anti-epileptic drugs topiramate and divalproex sodium for migraine prevention. Clinicians have other options for evidence-based treatment of episodic migraine attacks. Treatment decisions should consider contraindications, the effectiveness of alternatives, and potential side effects. NSAIDs are effective for the acute treatment of migraine exacerbations with caution for adverse effects such as gastrointestinal upset and renal symptoms. Beta-blockers are effective for migraine attack prophylaxis but are associated with dizziness and fatigue and are contraindicated in patients with certain co-morbidities, including asthma, congestive heart failure, and abnormal cardiac rhythms. Calcium channel blockers do not show enough evidence to be recommended as migraine attack prophylactic therapy. The anti-epileptic drugs topiramate and divalproex sodium and antidepressants venlafaxine and amitriptyline are effective for migraine exacerbation prophylaxis but have associated side effects. The decision for pharmacologic management should ultimately be made following consideration of risk vs. benefit and discussion between patient and physician.

Multi-omic analyses of triptan-treated migraine attacks gives insight into molecular mechanisms.

Migraine is a common, polygenic disorder that is characterized by moderate to severe headache attacks. Migraine attacks are commonly treated with triptans, i.e. serotonin receptor agonists. However, triptans are effective in ~ 60% of the population, and the mechanisms of triptans are debated. Here, we aim to expose the mechanisms of triptan using metabolomics and transcriptomics in spontaneous migraine attacks. We collected temporal multi-omics profiles on 24 migraine patients, using samples collected at a migraine attack, 2 h after treatment with a triptan, when headache-free, and after a cold-pressor test. Differential metabolomic analysis was performed to find metabolites associated with treatment. Their effect was further investigated using correlation analysis and a machine learning approach. We found three differential metabolites: cortisol, sumatriptan and glutamine. The change in sumatriptan levels correlated with a change in GNAI1 and VIPR2 gene expression, both known to regulate cAMP levels. Furthermore, we found fatty acid oxidation to be affected, a mechanism known to be involved in migraine but not previously found in relation to triptans. In conclusion, using an integrative approach we find evidence for a role of glutamine, cAMP regulation, and fatty acid oxidation in the molecular mechanisms of migraine and/or the effect of triptans.

Opposing effects of 5-HT1A receptor agonist buspirone on supraspinal abdominal pain transmission in normal and visceral hypersensitive rats.

The serotonergic 5-HT1A receptors are implicated in the central mechanisms of visceral pain, but their role in these processes is controversial. Considering existing evidences for organic inflammation-triggered neuroplastic changes in the brain serotonergic circuitry, the ambiguous contribution of 5-HT1A receptors to supraspinal control of visceral pain in normal and post-inflammatory conditions can be assumed. In this study performed on male Wistar rats, we used microelectrode recording of the caudal ventrolateral medulla (CVLM) neuron responses to colorectal distension (CRD) and electromyography recording of CRD-evoked visceromotor reactions (VMRs) to evaluate post-colitis changes in the effects of 5-HT1A agonist buspirone on supraspinal visceral nociceptive transmission. In rats recovered from trinitrobenzene sulfonic acid colitis, the CRD-induced CVLM neuronal excitation and VMRs were increased compared with those in healthy animals, revealing post-inflammatory intestinal hypersensitivity. Intravenous buspirone (2 and 4 mg/kg) under urethane anesthesia dose-dependently suppressed CVLM excitatory neuron responses to noxious CRD in healthy rats, but caused dose-independent increase in the already enhanced nociceptive activation of CVLM neurons in post-colitis animals, losing also its normally occurring faciliatory effect on CRD-evoked inhibitory medullary neurotransmission and suppressive action on hemodynamic reactions to CRD. In line with this, subcutaneous injection of buspirone (2 mg/kg) in conscious rats, which attenuated CRD-induced VMRs in controls, further increased VMRs in hypersensitive animals. The data obtained indicate a shift from anti- to pronociceptive contribution of 5-HT1A-dependent mechanisms to supraspinal transmission of visceral nociception in intestinal hypersensitivity conditions, arguing for the disutility of buspirone and possibly other 5-HT1A agonists for relieving post-inflammatory abdominal pain.

The 5-HT1A receptor biased agonists, NLX-204 and NLX-101, display ketamine-like RAAD and anti-TRD activities in rat CMS models.

OBJECTIVES: NLX-101 and NLX-204 are highly selective serotonin 5-HT1A 'biased' agonists, displaying potent and efficacious antidepressant-like activity upon acute administration in models such as the forced swim test. METHODS: we compared the effects of repeated administration of NLX-101, NLX-204 and ketamine in the chronic mild stress (CMS) model of depression, considered to have high translational potential, on sucrose consumption (anhedonia measure), novel object recognition (NOR; working memory measure) and elevated plus maze (EPM; anxiety measure) in male Wistar and Wistar-Kyoto rats (the latter being resistant to classical antidepressants). RESULTS: in Wistar rats, NLX-204 and NLX-101 (0.08-0.16 mg/kg i.p.), like ketamine (10 mg/kg i.p.) dose-dependently reversed CMS-induced sucrose intake deficit from treatment Day 1, with nearly full reversal observed at the higher dose at Days 8 and 15. These effects persisted for 3 weeks following treatment cessation. In the NOR test, both doses of NLX-101/NLX-204, and ketamine, rescued the deficit in discrimination index caused by CMS on Days 3 and 17; all three compounds increased time spent in open arms (EPM) but only NLX-204 achieved statistical significance on Days 2 and 16. In Wistar-Kyoto rats, all 3 compounds were also active in the sucrose test and, to a lesser extent, in the NOR and EPM. In non-stressed rats (both strains), the three compounds produced no significant effects in all tests. CONCLUSIONS: these observations further strengthen the hypothesis that biased agonism at 5-HT1A receptors constitutes a promising strategy to achieve rapid-acting/sustained antidepressant effects combined with activity against TRD, in addition to providing beneficial effects against memory deficit and anxiety in depressed patients.

The Serotonin 1A (5-HT1A) Receptor as a Pharmacological Target in Depression.

Clinical depression is a common, debilitating and heterogenous disorder. Existing treatments for depression are inadequate for a significant minority of patients and new approaches are urgently needed. A wealth of evidence implicates the serotonin 1A (5-HT1A) receptor in the pathophysiology of depression. Stimulation of the 5-HT1A receptor is an existing therapeutic target for treating depression and anxiety, using drugs such as buspirone and tandospirone. However, activation of 5-HT1A raphe autoreceptors has also been suggested to be responsible for the delay in the therapeutic action of conventional antidepressants such as selective serotonin reuptake inhibitors (SSRIs). This narrative review provides a brief overview of the 5-HT1A receptor, the evidence implicating it in depression and in the effects of conventional antidepressant treatment. We highlight that pre- and post-synaptic 5-HT1A receptors may have divergent roles in the pathophysiology and treatment of depression. To date, developing this understanding to progress therapeutic discovery has been limited, partly due to a paucity of specific pharmacological probes suitable for use in humans. The development of 5-HT1A 'biased agonism', using compounds such as NLX-101, offers the opportunity to further elucidate the roles of pre- and post-synaptic 5-HT1A receptors. We describe how experimental medicine approaches can be helpful in profiling the effects of 5-HT1A receptor modulation on the different clinical domains of depression, and outline some potential neurocognitive models that could be used to test the effects of 5-HT1A biased agonists.

[Anxiolytics: Appropriate Use of Benzodiazepine Receptor Agonists].

Anxiolytics are a class of drugs that include benzodiazepine receptor agonists and serotonin 1A receptor partial agonists. Although benzodiazepine receptor agonists have anxiolytic, sedative-hypnotic, muscle relaxant, and anticonvulsant effects, their use should be carefully monitored due to their potential for paradoxical reactions, withdrawal symptoms, and dependence. On the other hand, serotonin 1A receptor partial agonists have a slower onset, and their use also presents challenges. In clinical practice, having a thorough understanding of the various types of anxiolytics and their unique features is crucial.

5-HT1A agonists for levodopa-induced dyskinesia in Parkinson's disease.

Levodopa is the most effective agent for treating the symptoms of Parkinson's disease (PD). However, levodopa-induced dyskinesia remains a significant complication that manifests after few years of treatment, for which therapeutic options remain limited. Several agonists of the serotonin type 1A (5-HT1A) receptor with varying levels of efficacy and interaction at other sites, have been tested in the clinic. Clinical trials testing 5-HT1A agonists have yielded inconsistent results in alleviating dyskinesia, especially that the antidyskinetic benefit observed was often accompanied by an adverse effect on motor function. In this article, we summarize and analyze the various clinical trials performed with 5-HT1A agonists in PD patients with dyskinesia and offer perspectives on the future of this class of agents in PD.

After prolonged treatment with levodopa, patients with Parkinson's disease might start to experience abnormal involuntary movements, called 'dyskinesias'. These abnormal movements may be difficult to cope with since they can occur for several hours during the day and can hamper the quality of life. A potential approach to reduce the severity of dyskinesia, which has been the focus of extensive research, consists of stimulating a target inside the brain called the 5-HT_1A receptor. Several drugs harbouring this mechanism of action have been tested in clinical studies. Here, we provide an overview of these clinical studies and discuss their results.

Defining migraine days, based on longitudinal E-diary data.

BACKGROUND: There is a need for standardization of the definition of a migraine day for clinical and research purposes. METHODS: We prospectively compared different definitions of a migraine day with E-diary data of n = 1494 patients with migraine. We used a baseline definition based on migraine characteristics with a duration of ≥4 hours OR triptan intake (independently from its effect) OR (visual) aura lasting 5-60 minutes. RESULTS: Of all migraine days defined by triptan intake only, 66.2% had a duration <4 hours. Adjusting the headache duration criterion to ≥30 minutes led to a decrease in days defined by triptan intake only and resulted in a 5.4% increase in total migraine days (equals 0.45 migraine day increase in monthly migraine days). These additional migraine days had a median duration of 2.5 hours. CONCLUSION: We propose to define a migraine day as follows: 1) (a) headache duration ≥30 minutes; (b) matching ≥2 of four characteristics: unilateral, pulsating, moderate to severe pain, aggravation by or causing avoidance of routine physical activity; and (c) during headache ≥1 of the following: nausea and/or vomiting, photophobia and phonophobia or 2) (visual) aura duration 5-60 minutes or 3) a day with headache for which acute migraine-specific medication is used irrespective of its effect.

Vortioxetine improved negative and cognitive symptoms of schizophrenia in subchronic MK-801 model in rats.

Schizophrenia is a devastating psychiatric disorder with complex symptoms and neurobiology. Serotonergic dysregulation is known to contribute to the pathogenesis of schizophrenia although dopaminergic and glutamatergic systems are thought to have central roles in neurobiology. No significant success can be achieved in the treatment of negative and cognitive symptoms while positive symptoms can be significantly reduced with current pharmacotherapy. Vortioxetine is a new multimodal antidepressant with 5-HT1A agonism, 5-HT1B partial agonism, 5-HT3, 5-HT7, and 5-HT1D antagonism, and serotonin reuptake inhibition. A limited number of studies suggest its therapeutic effect on the negative and cognitive symptoms of schizophrenia. Therefore, we investigated the potential beneficial effects of vortioxetine on behavioral and molecular deficits in the MK-801 model of schizophrenia in rats. Female Wistar albino rats (10-12 weeks) were grouped as saline, MK-801 (0.2 mg/kg), MK-801 + vortioxetine (2.5 mg/kg), MK-801 + vortioxetine (5 mg/kg), MK-801 + vortioxetine (10 mg/kg), MK-801 + risperidone (0.3 mg/kg), MK-801 + haloperidol (1 mg/kg) (n = 8 in each group). MK-801 has been daily administered (i.p.) for 14 days. Vortioxetine and antipsychotic treatments were injected for 21 days after a washout period of MK-801 and locomotor activity (LA), social interaction (SI), novel object recognition (NOR), Y-maze and prepulse inhibition (PPI) tests were performed at the 16-20th days of treatments, respectively. ELISA test was conducted to evaluate molecular analyses. MK-801 decreased PPI (%), social behaviors, and discrimination index in NOR and alternation (%) in the Y-maze test. In NOR and Y-maze tests, especially vortioxetine 5 and 10 mg/kg increased discrimination index and alternation (%) compared to MK-801. In addition, vortioxetine administration increased social behaviors. Moreover, MK-801 decreased GAD67 and parvalbumin levels while vortioxetine increased these protein levels compared to MK-801. Herein, we first suggested a potential therapeutic effect of vortioxetine, a new multimodal antidepressant, on negative and cognitive symptoms and neurobiological deficits including GAD67 and parvalbumin low expression in the MK-801 model in rats. It would be beneficial to confirm our results in different rodent models and to shed light on the possible mechanisms underlying these effects.