To better understand mechanisms of serotonin- (5-HT) mediated vasorelaxation, isolated lateral saphenous veins from cattle were assessed for vasoactivity using myography in response to increasing concentrations of 5-HT or selective 5-HT receptor agonists. Vessels were pre-contracted with 1 × 10-4 M phenylephrine and exposed to increasing concentrations of 5-HT or 5-HT receptor agonists that were selective for 5-HT1B, 5-HT2B, 5-HT4, and 5-HT7. Vasoactive response data were normalized as a percentage of the maximum contractile response induced by the phenylephrine pre-contraction. At 1 × 10-7 M 5-HT, a relaxation was observed with an 88.7% decrease (p < 0.01) from the phenylephrine maximum. At 1 × 10-4 M 5-HT, a contraction was observed with a 165% increase (p < 0.01) from the phenylephrine maximum. Increasing concentrations of agonists selective for 5-HT2B, 5-HT4, or 5-HT7 resulted in a 27%, 92%, or 44% (p < 0.01) decrease from the phenylephrine maximum, respectively. Of these 5-HT receptor agonists, the selective 5-HT4 receptor agonist resulted in the greatest potency (-log EC50) value (6.30) compared with 5-HT2B and 5-HT7 receptor agonists (4.21 and 4.66, respectively). To confirm the involvement of 5-HT4 in 5-HT-mediated vasorelaxation, blood vessels were exposed to either DMSO (solvent control) or a selective 5-HT4 antagonist (1 × 10-5 M) for 5-min prior to the phenylephrine pre-contraction and 5-HT additions. Antagonism of the 5-HT4 receptor attenuated the vasorelaxation caused by 5-HT. Approximately 94% of the vasorelaxation occurring in response to 5-HT could be accounted for through 5-HT4, providing strong evidence that 5-HT-mediated vasorelaxation occurs through 5-HT4 activation in bovine peripheral vasculature.

BACKGROUND: Real-world data on the effectiveness and safety of lasmiditan, a new medication for acute migraine attacks, is necessary.
METHODS: We performed a prospective, observational, multi-center, real-world study. A total of 48 patients with migraine (44 females, 44.6 ± 12.9 years old) were included in this study.
RESULTS: Twenty-three patients (47.9%) reported they were headache-free two hours after taking lasmiditan and were categorized into the responder group. In total, 44 patients (91.7%) experienced at least one side effect within two hours of taking the medication. Dizziness, somnolence, malaise, nausea, and palpitations were reported by 56.3% (n = 27), 45.8% (n = 22), 37.5% (n = 18), 20.8% (n = 10), and 14.6% (n = 7) of patients respectively. Of 48 patients, 20 (41.7%) indicated that they preferred lasmiditan to their previous acute treatment. There were no predictive factors for efficacy.
CONCLUSIONS: This real-world study demonstrated the efficacy and safety of lasmiditan. More than 90% of patients experienced side effects from lasmiditan. Approximately 40% of patients preferred lasmiditan despite the occurrence of side effects.

Migraine is a common brain condition characterised by disabling attacks of headache with sensory sensitivities. Despite increasing understanding of migraine neurobiology and the impacts of this on therapeutic developments, there remains a need for treatment options for patients underserved by currently available therapies. The first specific drugs developed to treat migraine acutely, the serotonin-5-hydroxytryptamine [5-HT1B/1D] receptor agonists (triptans), seem to require headache onset in order to have an effect, while early treatment during mild pain before headache escalation improves short-term and long-term outcomes. Some patients find treating in the early window once headache has started but not escalated difficult, and migraine can arise from sleep or in the early hours of the morning, making prompt treatment after pain onset challenging. Triptans may be deemed unsuitable for use in patients with vascular disease and in those of older age and may not be effective in a proportion of patients. Headache is also increasingly recognised as being just one of the many facets of the migraine attack, and for some patients it is not the most disabling symptom. In many patients, painless symptoms can start prior to headache onset and can reliably warn of impending headache. There is, therefore, a need to identify therapeutic targets and agents that may be used as early as possible in the course of the attack, to prevent headache onset before it starts, and to reduce both headache and non-headache related attack burden. Early small studies using domperidone, naratriptan and dihydroergotamine have suggested that this approach could be useful; these studies were methodologically less rigorous than modern day treatment studies, of small sample size, and have not since been replicated. The emergence of novel targeted migraine treatments more recently, specifically calcitonin gene-related peptide (CGRP) receptor antagonists (gepants), has reignited interest in this strategy, with encouraging results. This review summarises historical and emerging data in this area, supporting use of the premonitory phase as an opportunity to intervene as early as possible in migraine to prevent attack-related morbidity.

Both clinical and animal studies demonstrated that seizure-induced respiratory arrest (S-IRA) contributes importantly to sudden unexpected death in epilepsy (SUDEP). It has been shown that enhancing serotonin (5-HT) function relieves S-IRA in animal models of SUDEP, including DBA/1 mice. Direct activation of 5-HT3 and 5-HT4 receptors suppresses S-IRA in DBA/1 mice, indicating that these receptors are involved in S-IRA. However, it remains unknown if other subtypes of 5-HT receptors are implicated in S-IRA in DBA/1 mice. In this study, we investigated the action of an agonist of the 5-HT1A (8-OH-DPAT), 5-HT2A (TCB-2), 5-HT2B (BW723C86), 5-HT2C (MK-212), 5-HT6 (WAY-208466) and 5-HT7 (LP-211) receptor on S-IRA in DBA/1 mice. An agonist of the 5-HT receptor or a vehicle was intraperitoneally administered 30 min prior to acoustic simulation, and the effect of each drug/vehicle on the incidence of S-IRA was videotaped for offline analysis. We found that the incidence of S-IRA was significantly reduced by TCB-2 at 10 mg/kg (30%, n = 10; p < 0.01, Fisher\'s exact test) but was not altered by other agonists compared with the corresponding vehicle controls in DBA/1 mice. Our data demonstrate that 5-HT2A receptors are implicated in S-IRA, and 5-HT1A, 5-HT2B, 5-HT2C, 5-HT6 and 5-HT7 receptors are not involved in S-IRA in DBA/1 mice.

Psychedelic substances such as lysergic acid diethylamide (LSD) and psilocybin show potential for the treatment of various neuropsychiatric disorders1-3. These compounds are thought to mediate their hallucinogenic and therapeutic effects through the serotonin (5-hydroxytryptamine (5-HT)) receptor 5-HT2A (ref. 4). However, 5-HT1A also plays a part in the behavioural effects of tryptamine hallucinogens5, particularly 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), a psychedelic found in the toxin of Colorado River toads6. Although 5-HT1A is a validated therapeutic target7,8, little is known about how psychedelics engage 5-HT1A and which effects are mediated by this receptor. Here we map the molecular underpinnings of 5-MeO-DMT pharmacology through five cryogenic electron microscopy (cryo-EM) structures of 5-HT1A, systematic medicinal chemistry, receptor mutagenesis and mouse behaviour. Structure-activity relationship analyses of 5-methoxytryptamines at both 5-HT1A and 5-HT2A enable the characterization of molecular determinants of 5-HT1A signalling potency, efficacy and selectivity. Moreover, we contrast the structural interactions and in vitro pharmacology of 5-MeO-DMT and analogues to the pan-serotonergic agonist LSD and clinically used 5-HT1A agonists. We show that a 5-HT1A-selective 5-MeO-DMT analogue is devoid of hallucinogenic-like effects while retaining anxiolytic-like and antidepressant-like activity in socially defeated animals. Our studies uncover molecular aspects of 5-HT1A-targeted psychedelics and therapeutics, which may facilitate the future development of new medications for neuropsychiatric disorders.

UNASSIGNED: Migraine headache is a common and potentially debilitating disorder often treated by physician associates/assistants (PAs) and other providers. With the recent advances in new drugs and device technology for the treatment of migraine, the American Headache Society has released a consensus statement on both preventive and acute strategies for clinical practice. The US FDA has recently approved various types of medications and devices for the treatment and prevention of migraine attacks including several calcitonin gene-related peptide (CGRP) receptor inhibitors, a selective serotonin receptor agonist (SSRA), noninvasive vagus nerve stimulation (nVNS), external trigeminal nerve stimulation (e-TNS), and external concurrent occipital and trigeminal neurostimulation (eCOT-NS), among other pharmacologic and nonpharmacologic options. This article provides a review of migraine prevention and acute treatment protocol, highlighting new approaches to both.

OBJECTIVE: Sudden unexpected death in epilepsy (SUDEP) is an underestimated complication of epilepsy. Previous studies have demonstrated that enhancement of serotonergic neurotransmission suppresses seizure-induced sudden death in evoked seizure models. However, it is unclear whether elevated serotonin (5-HT) function will prevent spontaneous seizure-induced mortality (SSIM), which is characteristic of human SUDEP. We examined the effects of 5-HT-enhancing agents that act by three different pharmacological mechanisms on SSIM in Dravet mice, which exhibit a high incidence of SUDEP, modeling human Dravet syndrome.
METHODS: Dravet mice of both sexes were evaluated for spontaneous seizure characterization and changes in SSIM incidence induced by agents that enhance 5-HT-mediated neurotransmission. Fluoxetine (a selective 5-HT reuptake inhibitor), fenfluramine (a 5-HT releaser and agonist), SR 57227 (a specific 5-HT3 receptor agonist), or saline (vehicle) was intraperitoneally administered over an 8-day period in Dravet mice, and the effect of these treatments on SSIM was examined.
RESULTS: Spontaneous seizures in Dravet mice generally progressed from wild running to tonic seizures with or without SSIM. Fluoxetine at 30 mg/kg, but not at 20 or 5 mg/kg, significantly reduced SSIM compared with the vehicle control. Fenfluramine at 1-10 mg/kg, but not .2 mg/kg, fully protected Dravet mice from SSIM, with all mice surviving. Compared with the vehicle control, SR 57227 at 20 mg/kg, but not at 10 or 5 mg/kg, significantly lowered SSIM. The effect of these drugs on SSIM was independent of sex.
CONCLUSIONS: Our data demonstrate that elevating serotonergic function by fluoxetine, fenfluramine, or SR 57227 significantly reduces or eliminates SSIM in Dravet mice in a sex-independent manner. These findings suggest that deficits in serotonergic neurotransmission likely play an important role in the pathogenesis of SSIM, and fluoxetine and fenfluramine, which are US Food and Drug Administration-approved medications, may potentially prevent SUDEP in at-risk patients.

BACKGROUND: The objective of this analysis was to gain new insights into the patient characteristics and other factors associated with lasmiditan usage and clinical outcomes under conditions resembling the real-world setting.
METHODS: This was a post hoc analysis of data from the 12-month, open-label extension (OLE) of the phase 3, double-blind, randomized, controlled CENTURION trial, which examined the efficacy and safety of lasmiditan as acute treatment across four migraine attacks. Patients completing the main study who treated ≥ 3 attacks could continue in the OLE. The initial lasmiditan dose was 100 mg, with dose adjustments to 50 mg or 200 mg allowed at the investigator\'s discretion. Patient and clinical characteristics were summarized by dosing pattern and completion status. Safety was assessed based on adverse event (AE) frequency by number of doses.
RESULTS: In total, 445 patients treated ≥ 1 migraine attacks with lasmiditan during the OLE, 321 of whom (72.1%) completed the study. Forty-seven percent of patients remained on the 100-mg initial dose during the OLE whereas 20.2% used both 100 mg and 50 mg, 30.6% used both 100 mg and 200 mg, and 6 (1.3%) used multiple dose levels. All dosing patterns were associated with clinical and patient-reported improvement; however, the 100-mg group had the highest proportion of patients reporting improvement in the Patient Global Impression of Change - Migraine Headache Condition (56.5% vs 33.4%-52.2%). In comparison, all three groups that made dose adjustments had higher rates of completion compared to the 100-mg group (72.1%-83.3% vs 68.9%). The frequency of AEs decreased with continued use of lasmiditan. Concomitant triptans and lasmiditan use did not increase AE frequency.
CONCLUSIONS: Based on high persistence and patient satisfaction rates, the 100-mg dose appears optimal for most patients. For those who adjusted dose levels, dose adjustments appeared beneficial to improve efficacy or tolerability, retaining patients on treatment. Collectively, the data suggest that patients who experienced efficacy continued to use lasmiditan regardless of the occurrence or frequency of AEs, and continued use appeared associated with fewer AEs.
BACKGROUND: European Union Drug Regulating Authorities Clinical Trials Database (EudraCT): 2018-001661-17; ClinicalTrials.gov: NCT03670810; registration date: September 12, 2018.

Serotonin, while conventionally recognized as a neurotransmitter in the CNS, has recently gained attention for its role in the kidney. Specifically, serotonin is not only synthesized in the kidney, but it also regulates glomerular function, vascular resistance, and mitochondrial homeostasis. Because of serotonin\'s importance to mitochondrial health, this review is focused on the role of serotonin and its receptors in mitochondrial function in the context of acute kidney injury, chronic kidney disease, and diabetic kidney disease, all of which are characterized by mitochondrial dysfunction and none of which has approved pharmacological treatments. Evidence indicates that activation of certain serotonin receptors can stimulate mitochondrial biogenesis (MB) and restore mitochondrial homeostasis, resulting in improved renal function. Serotonin receptor agonists that induce MB are therefore of interest as potential therapeutic strategies for renal injury and disease. SIGNIFICANCE STATEMENT: Mitochondrial dysfunction is associated with many human renal diseases such as acute kidney injury, chronic kidney disease, and diabetic kidney disease, which are associated with increased morbidity and mortality. Unfortunately, none of these pathologies has an FDA-approved pharmacological intervention, underscoring the urgency of identifying new therapeutics for such disorders. Studies show that induction of mitochondrial biogenesis via serotonin (5-hydroxytryptamine, 5-HT) receptors reduces kidney injury markers, restores mitochondrial and renal function after kidney injury, and decreases mortality, suggesting that targeting 5-HT receptors may be a promising therapeutic avenue for mitochondrial dysfunction in kidney diseases. While numerous reviews describe the importance of mitochondria and mitochondrial quality control mechanisms in kidney disease, the relevance of 5-HT receptor-mediated mitochondrial metabolic modulation in the kidney has yet to be thoroughly explored.

OBJECTIVE: Lasmiditan holds important potential in treating migraine, but its ideal dose remains elusive. This meta-analysis is conducted based on aggregate data and aims to compare the efficacy of lasmiditan 200 mg versus 100 mg for acute treatment of migraine attack.
METHODS: PubMed, Embase, Web of Science, EBSCO, and Cochrane Library databases were systematically searched, and we included the randomized controlled trials comparing the efficacy of lasmiditan 200 mg versus 100 mg for migraine patients. This meta-analysis was conducted using the random-effect model or fixed-effect model based on the heterogeneity. The primary outcome was pain free at 2 hours. Secondary outcomes included pain relief at 2 hours, pain free at 24 hours, most bothersome symptom free at 2 hours, and adverse events.
RESULTS: Seven randomized controlled trials and 6515 patients were included in this meta-analysis. Compared with lasmiditan 100 mg for migraine patients, lasmiditan 200 mg was able to significantly improve pain free at 2 hours (odd ratio [OR], 1.28; 95% confidence interval [CI], 1.14-1.44; P < 0.0001) and pain free at 24 hours (OR, 1.35; 95% CI, 1.14-1.60; P = 0.0005), but showed no effect on pain relief at 2 hours (OR, 1.00; 95% CI, 0.90-1.12; P = 0.98) or most bothersome symptom free at 2 hours (OR, 0.93; 95% CI, 0.83-1.03; P = 0.17). Lasmiditan 200 mg was associated with the increase in adverse events compared with lasmiditan 100 mg (OR, 1.28; 95% CI, 1.15-1.43; P < 0.0001).
CONCLUSIONS: Lasmiditan 200 mg is more effective to improve pain free at 2 hours and 24 hours than lasmiditan 100 mg for the acute treatment of migraine patients.