Explore the vast range of titles available.

Sighs are long, deep breaths expressing sadness, relief or exhaustion. Sighs also occur spontaneously every few minutes to reinflate alveoli, and sighing increases under hypoxia, stress, and certain psychiatric conditions. Here we use molecular, genetic, and pharmacologic approaches to identify a peptidergic sigh control circuit in murine brain. Small neural subpopulations in a key breathing control centre, the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG), express bombesin-like neuropeptide genes neuromedin B ( Nmb ) or gastrin-releasing peptide ( Grp ). These project to the preBötzinger Complex (preBötC), the respiratory rhythm generator, which expresses NMB and GRP receptors in overlapping subsets of ~200 neurons. Introducing either neuropeptide into preBötC or onto preBötC slices, induced sighing or in vitro sigh activity, whereas elimination or inhibition of either receptor reduced basal sighing, and inhibition of both abolished it. Ablating receptor-expressing neurons eliminated basal and hypoxia-induced sighing, but left breathing otherwise intact initially. We propose that these overlapping peptidergic pathways comprise the core of a sigh control circuit that integrates physiological and perhaps emotional input to transform normal breaths into sighs. The peptidergic neuronal circuit controlling sigh generation has been identified as ~200  Nmb- or Grp -expressing neurons in the RTN/pFRG breathing control centre of the medulla that project to ~200 receptor-expressing neurons in the respiratory rhythm generator, the preBötzinger Complex. Sigh centre neurons identified Although sighs are an integral part of breathing and respiratory physiology, little is known about the neuronal circuits controlling this behaviour. Here, Mark Krasnow and colleagues identify a small subset of genetically defined neurons in the medulla that project to the preBötzinger complex (preBötC), the respiratory rhythm generator, to drive sighing. Inhibition of this connection could completely eliminate sighs, while regular breathing was left intact. The authors propose a mechanism by which specific preBötC neurons may integrate physiological and possibly emotional inputs to turn regular breaths into sighs when appropriate.

Neurokinin 2 receptor (NK2R), a G protein‐coupled receptor for neurokinin A (NKA), a tachykinin family member, regulates various physiological functions including pain response, relaxation of smooth muscle, dilation of blood vessels, and vascular permeability. However, the precise role and regulation of NK2R expression in cancer cells have not been fully elucidated. In this study, we found that high NK2R gene expression was correlated with the poor survival of colorectal cancer patients, and Interferon (IFN‐α/β) stimulation significantly enhanced NK2R gene expression level of colon cancer cells in a Janus kinas 1/2 (JAK 1/2)‐dependent manner. NKA stimulation augmented viability/proliferation and phosphorylation of Extracellular‐signal‐regulated kinase 1/2 (ERK1/2) levels of IFN‐α/β‐treated colon cancer cells and NK2R blockade by using a selective antagonist reduced the proliferation in vitro. Administration of an NK2R antagonist alone or combined with polyinosinic‐polycytidylic acid, a synthetic analog of double‐stranded RNA, to CT26‐bearing mice significantly suppressed tumorigenesis. NK2R‐overexpressing CT26 cells showed enhanced tumorigenesis and metastatic colonization in both lung and liver after the inoculation into mice. These findings indicate that IFN‐α/β‐mediated NK2R expression is related to the malignancy of colon cancer cells, suggesting that NK2R blockade may be a promising strategy for colon cancers. IFN‐α/β induced neurokinin 2 receptor (NK2R), a G protein‐coupled receptor for neurokinin A in a JAK1/2‐dependent manner. NK2R expression was related to the tumorigeneis and mietastatic colonization of colon cancer cells. Therefore, NK2R blockade will be a promising strategy for colon cancers.

Abstract Context Polycystic ovary syndrome (PCOS), a highly prevalent endocrine disorder characterized by hyperandrogenism, is the leading cause of anovulatory infertility. Objective This proof-of-concept study evaluated clinical efficacy and safety of the neurokinin 3 (NK3) receptor antagonist fezolinetant in PCOS. Methods This was a phase 2a, randomized, double-blind, placebo-controlled, multicenter study (EudraCT 2014-004409-34). The study was conducted at 5 European clinical centers. Women with PCOS participated in the study. Interventions included fezolinetant 60 or 180 mg/day or placebo for 12 weeks. The primary efficacy end point was change in total testosterone. Gonadotropins, ovarian hormones, safety and tolerability were also assessed. Results Seventy-three women were randomly assigned, and 64 participants completed the study. Adjusted mean (SE) changes in total testosterone from baseline to week 12 for fezolinetant 180 and 60 mg/day were −0.80 (0.13) and −0.39 (0.12) nmol/L vs −0.05 (0.10) nmol/L with placebo (P < .001 and P < .05, respectively). Adjusted mean (SE) changes from baseline in luteinizing hormone (LH) for fezolinetant 180 and 60 mg/d were −10.17 (1.28) and −8.21 (1.18) vs −3.16 (1.04) IU/L with placebo (P < .001 and P = .002); corresponding changes in follicle-stimulating hormone (FSH) were −1.46 (0.32) and −0.92 (0.30) vs −0.57 (0.26) IU/L (P = .03 and P = .38), underpinning a dose-dependent decrease in the LH-to-FSH ratio vs placebo (P < .001). Circulating levels of progesterone and estradiol did not change significantly vs placebo (P > .10). Fezolinetant was well tolerated. Conclusion Fezolinetant had a sustained effect to suppress hyperandrogenism and reduce the LH-to-FSH ratio in women with PCOS.

Substance P (SP) is a highly conserved member of the tachykinin peptide family that is widely expressed throughout the animal kingdom. The numerous members of the tachykinin peptide family are involved in a multitude of neuronal signaling pathways, mediating sensations and emotional responses (Steinhoff et al. in Physiol Rev 94:265–301, 2014). In contrast to receptors for classical transmitters, such as glutamate (Parsons et al. in Handb Exp Pharmacol 249–303, 2005), only a minority of neurons in certain brain areas express neurokinin receptors (NKRs) (Mantyh in J Clin Psychiatry 63:6–10, 2002). SP is also expressed by a variety of non-neuronal cell types such as microglia, as well as immune cells (Mashaghi et al. in Cell Mol Life Sci 73:4249–4264, 2016). SP is an 11-amino acid neuropeptide that preferentially activates the neurokinin-1 receptor (NK1R). It transmits nociceptive signals via primary afferent fibers to spinal and brainstem second-order neurons (Cao et al. in Nature 392:390–394, 1998). Compounds that inhibit SP’s action are being investigated as potential drugs to relieve pain. More recently, SP and NKR have gained attention for their role in complex psychiatric processes. It is a key goal in the field of pain research to understand mechanisms involved in the transition between acute pain and chronic pain. The influence of emotional and cognitive inputs and feedbacks from different brain areas makes pain not only a perception but an experience (Zieglgänsberger et al. in CNS Spectr 10:298–308, 2005; Trenkwaldner et al. Sleep Med 31:78–85, 2017). This review focuses on functional neuronal plasticity in spinal dorsal horn neurons as a major relay for nociceptive information.

The neuropeptide substance P (SP) is important in pain and inflammation. SP activates the neurokinin-1 receptor (NK1R) to signal via Gq and Gs proteins. Neurokinin A also activates NK1R, but leads to selective Gq signaling. How two stimuli yield distinct G protein signaling at the same G protein-coupled receptor remains unclear. We determined cryogenic-electron microscopy structures of active NK1R bound to SP or the Gq-biased peptide SP6–11. Peptide interactions deep within NK1R are critical for receptor activation. Conversely, interactions between SP and NK1R extracellular loops are required for potent Gs signaling but not Gq signaling. Molecular dynamics simulations showed that these superficial contacts restrict SP flexibility. SP6–11, which lacks these interactions, is dynamic while bound to NK1R. Structural dynamics of NK1R agonists therefore depend on interactions with the receptor extracellular loops and regulate G protein signaling selectivity. Similar interactions between other neuropeptides and their cognate receptors may tune intracellular signaling.Determination of the cryo-EM structures of active neurokinin-1 receptor bound to substance P or the Gq biased peptide SP6–11 reveals that interactions with the receptor extracellular loops regulate G protein signaling selectivity.

Mechanisms in the brain controlling secretion of gonadotropin hormones in pigs, particularly luteinizing hormone (LH), are poorly understood. Kisspeptin is a potent LH stimulant that is essential for fertility in many species, including pigs. Neurokinin B (NKB) acting through neurokinin 3 receptor (NK3R) is involved in kisspeptin-stimulated LH release, but organization of NKB and NK3R within the porcine hypothalamus is unknown. Hypothalamic tissue from ovariectomized (OVX) gilts was used to determine the distribution of immunoreactive kisspeptin, NKB, and NK3R cells in the arcuate nucleus (ARC). Almost all kisspeptin neurons coexpressed NKB in the porcine ARC. Immunostaining for NK3R was distributed throughout the preoptic area (POA) and in several hypothalamic areas including the periventricular and retrochiasmatic areas but was not detected within the ARC. There was no colocalization of NK3R with gonadotropin-releasing hormone (GnRH), but NK3R-positive fibers in the POA were in close apposition to GnRH neurons. Treating OVX gilts with the progestin altrenogest decreased LH pulse frequency and reduced mean circulating concentrations of LH compared with OVX control gilts (P < 0.01), but the number of kisspeptin and NKB cells in the ARC did not differ between treatments. The neuroanatomical arrangement of kisspeptin, NKB, and NK3R within the porcine hypothalamus confirms they are positioned to stimulate GnRH and LH secretion in gilts, though differences with other species exist. Altrenogest suppression of LH secretion in the OVX gilt does not appear to involve decreased peptide expression of kisspeptin or NKB. Summary sentence Components of the KNDy system in the pig are characterized for the first time and pig-specific features such as a lack of immunopositive NK3R expression in the ARC and resistance to inhibition of kisspeptin protein expression by a progestin are identified.

Neurokinin 3 receptor antagonists are potential non-hormonal therapies for the treatment of vasomotor symptoms in menopausal women as options are scarce for those who cannot or do not want to take hormone therapy. Fezolinetant is one of the first non-hormonal neurokinin 3 receptor antagonists in development for the treatment of vasomotor symptoms due to menopause. This study investigated the safety and efficacy of fezolinetant for the treatment of moderate-to-severe vasomotor symptoms associated with menopause. SKYLIGHT 1 is a randomised, double-blind, placebo-controlled, 12-week, phase 3 trial with a 40-week active treatment extension. This trial was done at 97 facilities across the USA, Canada, Czech Republic, Hungary, Poland, Spain, and the UK. Women aged 40–65 years with an average of seven or more moderate-to-severe hot flashes per day were randomly assigned (1:1:1) to once-daily exact-matched placebo, fezolinetant 30 mg, or fezolinetant 45 mg. Randomisation was done using a web-based interactive response system and investigators, project team members, clinical staff, and participants were masked to treatment assignment. Coprimary endpoints were mean change in frequency and severity of vasomotor symptoms from baseline to weeks 4 and 12. The efficacy and safety analyses comprised all randomly assigned participants who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov (NCT04003155) and is completed. Between July 11, 2019, and Aug 11, 2021, 2205 women were recruited of whom 175 were assigned to placebo, 176 to fezolinetant 30 mg, and 176 to fezolinetant 45 mg (175 in the placebo group, 174 in the fezolinetant 30 mg group, and 173 in the fezolinetant 45 mg received at least one dose [safety analysis set]). One participant randomly assigned to fezolinetant 45 mg received fezolinetant 30 mg in error, so the efficacy analysis set (full analysis set) consisted of 173 in the fezolinetant 30 mg group and 174 in the fezolinetant 45 mg group. 23 participants in the placebo group, 31 in the fezolinetant 30 mg group, and 13 in the fezolinetant 45 mg group discontinued treatment before week 12, mostly due to adverse events or participant withdrawal. Compared with placebo, fezolinetant 30 mg and fezolinetant 45 mg significantly reduced the frequency of vasomotor symptoms at week 4 (difference in change in least squares mean –1·87 [SE 0·42; p<0·001], –2·07 [SE 0·42; p<0·001]) and week 12 (–2·39 [SE 0·44; p<0·001], –2·55 [SE 0·43; p<0·001]). Compared with placebo, fezolinetant 30 mg and 45 mg significantly reduced the severity of vasomotor symptoms at week 4 (–0·15 [0·06; p=0·012], –0·19 [0·06; p=0·002]) and week 12 (–0·24 [0·08; p=0·002], –0·20 [0·08; p=0·007]). Improvements in frequency and severity of vasomotor symptoms were observed after 1 week and maintained over 52 weeks. During the first 12 weeks, treatment-emergent adverse events occurred in 65 (37%) of 174 women in the fezolinetant 30 mg group, 75 (43%) of 173 in the fezolinetant 45 mg group, and 78 (45%) of 175 in the placebo group. The incidence of liver enzyme elevations was low (placebo n=1; fezolinetant 30 mg n=2; fezolinetant 45 mg n=0) and these events were generally asymptomatic, transient, and resolved while on treatment or after treatment discontinuation. Data support the clinical use of fezolinetant as a non-hormonal treatment for vasomotor symptoms associated with menopause. The study was placebo-controlled for 12 weeks followed by a 40-week blinded extension to assess the maintenance of effect. Furthermore, the population studied was diverse and representative of the potential target population for fezolinetant therapy. Further characterisation of the benefit of fezolinetant on quality of life, including on symptoms of mood and sexual wellbeing, merits investigation. Astellas Pharma.

Neurokinin B (NKB) is a hypothalamic neuropeptide binding preferentially to the neurokinin 3 receptor. Expression of the gene encoding NKB is elevated in postmenopausal women. Furthermore, rodent studies suggest that NKB signalling may mediate menopausal hot flushes. However, the effects of NKB administration on hot flushes have not been investigated in humans. To address this, we performed a randomised, double-blinded, placebo-controlled, 2-way cross-over study. Ten healthy women were admitted to a temperature and humidity-controlled research unit. Participants received 30 minute intravenous infusions of NKB and vehicle in random order. Symptoms, heart rate, blood pressure, sweating and skin temperature were compared between NKB and vehicle in a double-blinded manner. Eight of ten participants experienced flushing during NKB infusion with none experiencing flushing during vehicle infusion (P = 0.0007). Significant elevations in heart rate (P = 0.0106 vs. pre-symptoms) and skin temperature measured using skin probe (P = 0.0258 vs. pre-symptoms) and thermal imaging (P = 0.0491 vs. pre-symptoms) characteristic of menopausal flushing were observed during hot flush episodes. Our findings provide evidence that NKB administration can cause hot flushes in women. Further studies are required to determine if pharmacological blockade of NKB signalling could inhibit hot flushes during the menopause and during treatment for sex-steroid dependent cancers.

A hypothalamic pulse generator located in the arcuate nucleus controls episodic release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) and is essential for reproduction. Recent evidence suggests this generator is composed of arcuate “KNDy” cells, the abbreviation based on coexpression of kisspeptin, neurokinin B, and dynorphin. However, direct visual evidence of KNDy neuron activity at a single-cell level during a pulse is lacking. Here, we use in vivo calcium imaging in freely moving female mice to show that individual KNDy neurons are synchronously activated in an episodic manner, and these synchronized episodes always precede LH pulses. Furthermore, synchronization among KNDy cells occurs in a temporal order, with some subsets of KNDy cells serving as “leaders” and others as “followers” during each synchronized episode. These results reveal an unsuspected temporal organization of activation and synchronization within the GnRH pulse generator, suggesting that different subsets of KNDy neurons are activated at pulse onset than afterward during maintenance and eventual termination of each pulse. Further studies to distinguish KNDy “leader” from “follower” cells is likely to have important clinical significance, since regulation of pulsatile GnRH secretion is essential for normal reproduction and disrupted in pathological conditions such as polycystic ovary syndrome and hypothalamic amenorrhea.