Neurokinin B Administration Induces Dose Dependent Proliferation of Seminal Vesicles in Adult Rats.

BACKGROUND: Neurokinin B; an endogenous decapeptide, mediates its reproductive physiological actions through gonadotropin releasing hormone. Despite the potential role of Neurokinin B on seminal vesicles, its effects on seminal vesicles in adult male mammals remain elusive. We aimed to investigate the potentials of variable doses of Neurokinin B, its agonist and antagonist on histomorphology and expression of NK3R on seminal vesicles, and secretory activity of seminal vesicles in adult male rats. METHODS: Adult male Sprague Dawley rats (n=10 in each group) were administered intraperitoneally with Neurokinin B in three variable doses: 1 µg, 1 ηg and 10 ρg while, Senktide (Neurokinin B agonist) and SB222200 (Neurokinin B antagonist) in 1 µg doses consecutively for 12 days. After 12 days of peptide treatment, half of the animals (n=05) in each group were sacrificed while remaining half (n=05) were kept for another 12 days without any treatment to investigate treatment reversal. Seminal vesicles were dissected and excised tissue was processed for light microscopy, immunohistochemistry and estimation of seminal fructose levels. RESULTS: Treatment with Neurokinin B and Senktide significantly increased while SB222200 slightly decrease the seminal vesicles weight, epithelial height and seminal fructose levels as compared to control. Light microscopy revealed increased epithelial height and epithelial folding as compared to control in all Neurokinin B and Senktide treated groups while decreased in SB222200. Effects of various doses of Neurokinin B, Senktide and SB222200 on seminal vesicles weight, epithelial height, seminal fructose levels and histomorphology were reversed when rats were maintained without treatments. Immuno-expression of Neurokinin B shows no change in treatment and reversal groups. CONCLUSION: Continuous administration of Neurokinin B and Senktide effect positively while SB222200 have detrimental effects on cellular morphology, epithelial height and seminal fructose levels in seminal vesicles. Effects of peptide treatments depicted a reversal towards control group when rats were kept without any treatment.

Tachykinins Play a Major Role in Micro and Macrovascular Complications in Type 2 Diabetes Patients.

Diabetes Mellitus is a metabolic disorder, which is characterized by an increase in blood glucose levels. The defects in the secretion or action of insulin are the major cause of diabetes. Increase in the blood glucose level exerts a negative effect on the normal functions of the body organs and this leads to the dysfunctions of cells and tissue and causes vascular complications in diabetic patients. Several studies indicate that neuropeptides are released from the neurosensory cells which are mainly known as tachykinins which provoke major vascular complications in diabetic patients. Tachykinins are known as pro-inflammatory peptides which increase vascular complications and vascular permeability. The duration and severity of diabetes disease increase the risk of vascular complication in patients. The aim of this review is to elaborate the role of tachykinins in microvascular and macrovascular complications in diabetic patients. The study concluded that tachykinins increase micro and macrovascular complications in diabetic patients.

What is the carcinoid syndrome? A critical appraisal of its proposed mediators.

The carcinoid syndrome (CS) is a debilitating disease that affects approximately 20% of patients with neuroendocrine neoplasms (NEN). Due to the increasing incidence and improved overall survival of patients with NEN over recent decades, patients are increasingly suffering from chronic and refractory CS symptoms. At present, symptom control is hampered by an incomplete understanding of the pathophysiology of this syndrome. This systematic review is the first to critically appraise the available evidence for the various hormonal mediators considered to play a causative role in the CS. Overall, evidence for the putative mediators of the CS was scarce and often of poor quality. Based on the available literature, data are only sufficient to agree on the role of serotonin as a mediator of CS-associated diarrhea and fibrosis. A direct role for tachykinins and an indirect role of catecholamines in the pathogenesis of the CS is suggested by several studies. Currently, there is insufficient evidence to link histamine, bradykinin, kallikrein, prostaglandins, or motilin to the CS. To summarize, available literature only sufficiently appoints serotonin and suggests a role for tachykinins and catecholamines as mediators of the CS, with insufficient evidence for other putative mediators. Descriptions of the CS should be revised to focus on these proven hormonal associations to be more accurate and further research is needed into other potential mediators.

What Is the Correlation between Preeclampsia and Cancer? The Important Role of Tachykinins and Transition Metal Ions.

Metal ions are irreplaceable in many biological processes. They are components of numerous metalloproteins and serve as cofactors or structural elements for enzymes. Interestingly, iron, copper and zinc play important roles in accelerating or preventing neoplastic cell transformation. Noteworthily, a lot of proliferative and invasive mechanisms are exploited by both malignant tumors and pregnancy. Cancer cells, as well as developing placenta cells, create a microenvironment supportive of immunologic privilege and angiogenesis. Therefore, pregnancy and cancer progression share many similarities. Moreover, during preeclampsia and cancer, significant changes in relevant trace element concentrations, tachykinin levels, expressions of neurokinin receptors, oxidative stress and angiogenic imbalance are observed. This sheds a new light on the role of metal ions and tachykinins in cancer progression and pregnancy, especially in preeclamptic women.

Identification of TAC1 Associated with Alzheimer's Disease Using a Robust Rank Aggregation Approach.

BACKGROUND: Alzheimer's disease (AD) brings heavy burden to society and family. There is an urgent need to find effective methods for disease diagnosis and treatment. The robust rank aggregation (RRA) approach that could aggregate the resulting gene lists has been widely utilized in genomic data analysis. OBJECTIVE: To identify hub genes using RRA approach in AD. METHODS: Seven microarray datasets in frontal cortex from GEO database were used to identify differential expressed genes (DEGs) in AD patients using RRA approach. STRING was performed to explore the protein-to-protein interaction (PPI). Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses were utilized for enrichment analysis. Human Gene Connectome and Gene Set Enrichment Analysis were used for functional annotation. Finally, the expression levels of hub genes were validated in the cortex of 5xFAD mice by quantitative real-time polymerase chain reaction. RESULTS: After RRA analysis, 473 DEGs (216 upregulated and 257 downregulated) were identified in AD samples. PPI showed that DEGs had a total of 416 nodes and 2750 edges. These genes were divided into 17 clusters, each of which contains at least three genes. After functional annotation and enrichment analysis, TAC1 is identified as the hub gene and may be related to synaptic function and inflammation. In addition, Tac1 was found downregulated in cortices of 5xFAD mice. CONCLUSION: In the current study, TAC1 is identified as a key gene in the frontal cortex of AD, providing insight into the possible pathogenesis and potential therapeutic targets for this disease.

Female Infertility Is Associated with an Altered Expression Profile of Different Members of the Tachykinin Family in Human Granulosa Cells.

Neurokinin B (NKB) and its cognate receptor, NK3R, play a key role in the regulation of reproduction. NKB belongs to the family of tachykinins, which also includes substance P and neurokinin A, both encoded by the by the gene TAC1, and hemokinin-1, encoded by the TAC4 gene. In addition to NK3R, tachykinin effects are mediated by NK1R and NK2R, encoded by the genes TACR1 and TACR2, respectively. The role of these other tachykinins and receptors in the regulation of women infertility is mainly unknown. We have analyzed the expression profile of TAC1, TAC4, TACR1, and TACR2 in mural granulosa and cumulus cells from women presenting different infertility etiologies, including polycystic ovarian syndrome, advanced maternal age, low ovarian response, and endometriosis. We also studied the expression of MME, the gene encoding neprilysin, the most important enzyme involved in tachykinin degradation. Our data show that TAC1, TAC4, TACR1, TACR2, and MME expression is dysregulated in a different manner depending on the etiology of women infertility. The abnormal expression of these tachykinins and their receptors might be involved in the decreased fertility of these patients, offering a new insight regarding the diagnosis and treatment of women infertility.

Effects of Substance P and Neurokinin A on the Contractile Activity of Inflamed Porcine Uterus.

Disturbances in uterine contractile activity contribute to the development of inflammation, and recent evidence indicates that tachykinins, including substance P (SP) and neurokinin A (NKA), are involved in controlling uterine function. Here, we determined the effect of Escherichia coli (E. coli)-induced inflammation on expression of protein receptor subtypes for substance P (NK1R) and neurokinin A (NK2R) in the pig myometrium as well as their role in contractility of inflamed uterus. The severe acute endometritis developed in the E. coli group and the expression of NK1R and NK2R proteins increased in the myometrium. Compared to the pre-administration period, SP (10-6 M) reduced the amplitude and frequency in the myometrium of the E. coli group and the amplitude was higher and the frequency was lower versus other groups. NKA reduced the amplitude and increased the frequency in endometrium/myometrium of the E. coli group. In this group, the amplitude was lower and the frequency was higher than in the CON and SAL groups. Our research showed that NK2R (10-6 M) antagonist application abolished the NKA inhibitory effect on uterine amplitude. The application of the NK1R (10-5 M) antagonist together with SP revealed that the inhibitory effect of SP on uterine contractility is achieved independently of the NKR1. Additionally, taking into account the fact that NKA shows an inhibitory effect with the use of NK2R on uterine amplitude suggests the possibility of therapeutic use of the antagonist as a drug increasing uterine contractility in inflammation.

TAC3/TACR3 System Function in the Catadromous Migration Teleost, Anguilla japonica.

Neurokinin B (NKB), a member of the tachykinin (TAC) family, plays important roles in mammalian neuropeptide secretion in related to reproduction. However, its potential role in spawning migration teleost is less clear. In the present study, Japanese eel (Anguilla japonica) was employed to study the performance of NKB in regulating reproduction. Results showed that two tac3 and one tacr3 genes were identified in Japanese eel. Sequence analysis showed that two tac3 transcripts, tac3a and tac3b, encode four NKBs: NKBa-13, NKBa-10, NKBb-13, and NKBb-10. However, compared with other species, a mutation caused early termination of TACR3 protein was confirmed, leading to the loss of the 35 amino acid (aa) C-terminal of the receptor. Expression analysis in different tissues showed that both tac3a and tac3b mRNAs were highly expressed in the brain. In situ hybridization localized both tac3a and tac3b mRNAs to several brain regions, mainly in the telencephalon and hypothalamus. Because of the mutation in TACR3 of Japanese eel, we further analyzed whether it could activate the downstream signaling pathway. Luciferase assay results showed the negative regulation of cAMP Response Element (CRE) and Sterol Response Element (SRE) signal pathways by Japanese eel NKBs. Intraperitoneal injection of four different NKB mature peptides at 100 ng/g had negative effect on either gnrh or gth gene expression. However, the high concentration of NKBa-10 and NKBb-13 (1,000 ng/g) upregulated mgnrh and fshb or lhb expression level significantly, which may be mediated by other receptors. In general, the NKBs/NK3Rs system has important functions in regulating eel puberty onset.

Tachykinin/neurokinin 3 receptor antagonists: In silico ADME/T analysis of novel compounds for menopause hot flashes therapy

SUMMARY Introduction: Neurokinin-B receptor (NK3R) activation is tightly involved in the onset of vasomotor symptoms during menopause, yet there are still no NK3R antagonistic drugs approved for hot flashes therapy. Determining the pharmacokinetic properties of current drug candidates is crucial for scaffold identification and prediction of feasible outcomes in future clinical trials. Aim: To develop a pharmacokinetic profile of new NK3R blockers with hot flashes reducing activity and by comparing them with trial-suspended NK3R antagonists (Osanetant & Talnetant), it is expected to identify enhanced properties in novel compounds. Methodology: For in silico evaluation, Smiles were retrieved from PubChem and DrugBank, and further analysis was carried out through ADMETlab and SwissADME to calculate compounds drug-likeness and pharmacokinetics. Results: Pavinetant & Fezoline-tant and SB-222.200 & SB-218.795 exhibited higher compliance with drug-likeness rules and more suitable physicochemical properties when compared to Osanetant & Talnetant. ADME/T evaluation showed considerable disparities between groups, yet no significant difference was reported. Pharmacokinetic properties varied irregularly among studied compounds. Conclusion: Novel NK3R antagonists exhibit enhanced properties when compared to formerly suspended ones. Fezolinetant is predicted to have more favorable outcomes based on in silico evaluation.

Introducción: la activación del receptor de neuroquinina-B (NK3R) está estrechamente relacionada con la aparición de síntomas vasomotores durante la menopausia, no obstante, a la fecha no se reportan fármacos antagonistas de NK3R aprobados para el manejo de sofocos. La evaluación de las propiedades farmacocinéticas de los compuestos inhibidores de NK3R resulta indispensable para la identificación de potenciales farmacóforos y para la estimación de posibles resultados en ensayos clínicos. Objetivo: determinar las características farmacocinéticas de los nuevos compuestos inhibidores de NK3R con propiedades reductoras de los fogajes asociados a la menopausia, y por medio de un análisis comparativo con los antagonistas de NK3R cuyo ensayo clínico fue suspendido (Osanetant & Talnetant), se espera identificar propiedades superiores en los nuevos compuestos desarrollados. Metodología: se obtuvieron los códigos Smiles a partir de PubChem y DrugBank, posteriormente, el análisis se basó en el cálculo de las propiedades farmacocinéticas y drug-like mediante las plataformas ADMETlab y SwissADME. Resultados: Pavi-netant & Fezolinetant y SB-222.200 & SB-218.795 exhiben mejores propiedades fisicoquímicas y cumplen a mayor cabalidad las reglas drug-likeness al compararse con Osanetant & Talnetant. La evaluación ADMET reveló variaciones entre los grupos, pero ninguna fue significativa. Las propiedades farmacocinéticas varían de forma irregular entre los distintos compuestos. Conclusiones: los antagonistas de NK3R recientemente desarrollados exhibieron propiedades superiores frente a los compuestos de ensayos suspendidos. Los resultados del estudio in silico permiten deducir que el Fezolinetant podría tener mejores resultados en futuros ensayos clínicos.

Introdução: a ativação do receptor de neuroquinina-B (NK3R) está intimamente relacionada ao aparecimento de sintomas vasomotores durante a menopausa, entretanto, até o momento não há relatos de drogas antagonistas de NK3R aprovadas para o manejo das ondas de calor. A avaliação das propriedades farmacocinéticas de compostos inibidores de NK3R é essencial para a identificação de potenciais farmaco-foros e para a estimativa de possíveis resultados em ensaios clínicos. Objetivo: determinar as características farmacocinéticas dos novos compostos inibidores de NK3R com propriedades redutoras de ondas de calor associadas à menopausa, e através de uma análise comparativa com os antagonistas de NK3R cujo ensaio clínico foi suspenso (Osanetant & Talnetant), espera-se identificar propriedades superiores nos compostos recém-desenvolvidos. Metodologia: os códigos Smiles foram obtidos do PubChem e DrugBank, posteriormente, a análise foi baseada no cálculo das propriedades farmacocinéticas e farmacocinéticas utilizando as plataformas ADMETlab e SwissADME. Resultados: Pavinetant & Fezolinetant e SB-222.200 & SB-218.795 apresentam melhores propriedades físico-químicas e atendem mais plenamente às regras de ""drug-likeness" quando comparados ao Osanetant & Talnetant. A avaliação ADMET revelou variações entre os grupos, mas nenhuma foi significativa. As propriedades farmacocinéticas variam irregularmente entre os diferentes compostos. Conclusões: os antagonistas de NK3R recém-desenvolvidos exibiram propriedades superiores em relação aos compostos de teste suspensos. Os resultados do estudo in silico permitem-nos deduzir que o Fezolinetant poderá ter melhores resultados em futuros ensaios clínicos.

Tachykinins, new players in the control of reproduction and food intake: A comparative review in mammals and teleosts.

In vertebrates, the tachykinin system includes tachykinin genes, which encode one or two peptides each, and tachykinin receptors. The complexity of this system is reinforced by the massive conservation of gene duplicates after the whole-genome duplication events that occurred in vertebrates and furthermore in teleosts. Added to this, the expression of the tachykinin system is more widespread than first thought, being found beyond the brain and gut. The discovery of the co-expression of neurokinin B, encoded by the tachykinin 3 gene, and kisspeptin/dynorphin in neurons involved in the generation of GnRH pulse, in mammals, put a spotlight on the tachykinin system in vertebrate reproductive physiology. As food intake and reproduction are linked processes, and considering that hypothalamic hormones classically involved in the control of reproduction are reported to regulate also appetite and energy homeostasis, it is of interest to look at the potential involvement of tachykinins in these two major physiological functions. The purpose of this review is thus to provide first a general overview of the tachykinin system in mammals and teleosts, before giving a state of the art on the different levels of action of tachykinins in the control of reproduction and food intake. This work has been conducted with a comparative point of view, highlighting the major similarities and differences of tachykinin systems and actions between mammals and teleosts.

Molecular Segmentation of the Spinal Trigeminal Nucleus in the Adult Mouse Brain.

The trigeminal column is a hindbrain structure formed by second order sensory neurons that receive afferences from trigeminal primary (ganglionic) nerve fibers. Classical studies subdivide it into the principal sensory trigeminal nucleus located next to the pontine nerve root, and the spinal trigeminal nucleus which in turn consists of oral, interpolar and caudal subnuclei. On the other hand, according to the prosomeric model, this column would be subdivided into segmental units derived from respective rhombomeres. Experimental studies have mapped the principal sensory trigeminal nucleus to pontine rhombomeres (r) r2-r3 in the mouse. The spinal trigeminal nucleus emerges as a plurisegmental formation covering several rhombomeres (r4 to r11 in mice) across pontine, retropontine and medullary hindbrain regions. In the present work we reexamined the issue of rhombomeric vs. classical subdivisions of this column. To this end, we analyzed its subdivisions in an AZIN2-lacZ transgenic mouse, known as a reference model for hindbrain topography, together with transgenic reporter lines for trigeminal fibers. We screened as well for genes differentially expressed along the axial dimension of this structure in the adult and juvenile mouse brain. This analysis yielded genes from multiple functional families that display transverse domains fitting the mentioned rhombomeric map. The spinal trigeminal nucleus thus represents a plurisegmental structure with a series of distinct neuromeric units having unique combinatorial molecular profiles.

Tachykinin NK2 antagonist for treatments of various disease states.

Tachykinin NK2 receptors are distributed in periphery, in the smooth muscle of the respiratory, gastrointestinal, genitourinary tract, and within the brain. Substance P (SP), neurokinin A (NKA), and neurokinin B (NKB) are endogenous ligands for NK2 receptors and are active in the peripheral and central nervous systems. NK2 antagonists have the potential to reduce airway motor responses and prevent hyperactivity by inhibiting NKA-induced bronchoconstriction in asthmatic patients. Due to its abundance, peripherally and centrally, tachykinin NK2 receptor antagonists have high potential in treating various disease states ranging from asthma to irritable bowel syndrome, to detrusor hyperactivity, to anxiety. This review is an evaluation of NK2 receptor antagonists as possible therapeutics for a myriad of pharmacological treatments.

Characterization of the Action of Tachykinin Signaling on Pulsatile LH Secretion in Male Mice.

The alternation of the stimulatory action of the tachykinin neurokinin B (NKB) and the inhibitory action of dynorphin within arcuate (ARH) Kiss1 neurons has been proposed as the mechanism behind the generation of gonadotropin-releasing hormone (GnRH) pulses through the pulsatile release of kisspeptin. However, we have recently documented that GnRH pulses still exist in gonadectomized mice in the absence of tachykinin signaling. Here, we document an increase in basal frequency and amplitude of luteinizing hormone (LH) pulses in intact male mice deficient in substance P, neurokinin A (NKA) signaling (Tac1KO), and NKB signaling (Tac2KO and Tacr3KO). Moreover, we offer evidence that a single bolus of the NKB receptor agonist senktide to gonad-intact wild-type males increases the basal release of LH without changing its frequency. Altogether, these data support the dispensable role of the individual tachykinin systems in the generation of LH pulses. Moreover, the increased activity of the GnRH pulse generator in intact KO male mice suggests the existence of compensation by additional mechanisms in the generation of kisspeptin/GnRH pulses.

A possible role of tachykinin-related peptide on an immune system activity of mealworm beetle, Tenebrio molitor L.

Tachykinin-related peptides (TRPs) are important neuropeptides. Here we show that they affect the insect immune system, especially the cellular response. We also identify and predict the sequence and structure of the tachykinin-related peptide receptor (TRPR) and confirm the presence of expression of gene encoding TRPR on Tenebrio molitor haemocytes. After application of the Tenmo-TRP-7 in T. molitor the number of circulating haemocytes increased and the number of haemocytes participating in phagocytosis of latex beads decreased in a dose- and time-dependent fashion. Also, Tenmo-TRP-7 affects the adhesion ability of haemocytes. Six hours after injection of Tenmo-TRP-7, a decrease of haemocyte surface area was observed under both tested Tenmo-TRP-7 concentrations (10-7 and 10-5 M). The opposite effect was reported 24 h after injection, which indicates that the influence of Tenmo-TRP-7 on modulation of haemocyte behaviour differs at different stages of stress response. Tenmo-TRP-7 application also resulted in increased phenoloxidase activity 6 and 24 h after injection. The assessment of DNA integrity of haemocytes showed that the injection of Tenmo-TRP-7 at 10-7 M led to a decrease in DNA damage compared to control individuals. This effect was only visible 6 h after Tenmo-TRP-7 application. After 24 h, Tenmo-TRP-7 injection increased DNA damage. We also confirmed the expression of immune-related genes in nervous tissue of T. molitor. Transcripts for genes encoding receptors participating in pathogen recognition processes and antimicrobial peptides were detected in T. molitor brain, retrocerebral complex and ventral nerve cord. These results may indicate a role of the insect nervous system in pathogen recognition and modulation of immune response similar to vertebrates. Taken together, our results support the notion that tachykinin-related peptides probably play an important role in the regulation of the insect immune system. Moreover, some resemblances with action of tachykinin-related peptides and substance P showed that insects can be potential model organisms for analysis of hormonal regulation of conserved innate immune mechanisms.

Overexpression of Substance P in pig airways increases MUC5AC through an NF-kß pathway.

Substance P (SP) is a tachykinin that regulates airway mucous secretion in both health and disease. Our study aimed to determine whether overexpression of SP without pre-existing inflammation was sufficient to induce changes in mucin secretion and transport in small airways. Utilizing porcine precision-cut lung slices, we measured the impact of AAV-mediated overexpression of SP on airway physiology ex vivo. Immunofluorescence signal intensity for MUC5AC was significantly increased in SP-overexpressed precision-cut lung slices compared to GFP controls. No difference in MUC5B signal intensity between treatments was detected. SP-overexpressed precision-cut lung slices also exhibited decreased IL10 mRNA, an important inhibitor of mucous cell metaplasia. Overt deficits in mucociliary transport were not noted, though a trend for decreased mean transport speed was detected in methacholine-challenged airways overexpressing SP compared to GFP controls. Pharmacologic inhibition of the NF-kß pathway abrogated the effects of overexpression of SP on both MUC5AC and IL10. Collectively, these data suggest that overexpression of SP in the absence of existing inflammation increases MUC5AC via activation of the NF-kß pathway. Thus, these data further highlight SP as a key driver of abnormal mucous secretion and underscore NF-kß signaling as a pathway of potential therapeutic intervention.

Congenital ablation of Tacr2 reveals overlapping and redundant roles of NK2R signaling in the control of reproductive axis.

Tachykinin (TAC) signaling is an important element in the central control of reproduction. TAC family is mainly composed of substance P (SP), neurokinin A (NKA), and NKB, which bind preferentially to NK1, NK2, and NK3 receptors, respectively. While most studies have focused on the reproductive functions of NKB/NK3R, and to a lesser extent SP/NK1R, the relevance of NK2R, encoded by Tacr2, remains poorly characterized. Here, we address the physiological roles of NK2R in regulating the reproductive axis by characterizing a novel mouse line with congenital ablation of Tacr2. Activation of NK2R evoked acute luteinizing hormone (LH) responses in control mice, similar to those of agonists of NK1R and NK3R. Despite the absence of NK2R, Tacr2-/- mice displayed only partially reduced LH responses to an NK2R agonist, which, nonetheless, were abrogated after blockade of NK3R in Tacr2-/- males. While Tacr2-/- mice displayed normal pubertal timing, LH pulsatility was partially altered in Tacr2-/- females in adulthood, with suppression of basal LH levels, but no changes in the number of LH pulses. In addition, trends for increase in breeding intervals were detected in Tacr2-/- mice. However, null animals of both sexes were fertile, with no changes in estrous cyclicity or sex preference in social behavioral tests. In conclusion, stimulation of NK2R elicited LH responses in mice, while congenital ablation of Tacr2 partially suppressed basal and stimulated LH secretion, with moderate reproductive impact. Our data support a modest, albeit detectable, role of NK2R in the control of the gonadotropic axis, with partially overlapping and redundant functions with other tachykinin receptors.NEW & NOTEWORTHY We have explored here the impact of congenital ablation of the gene (Tacr2) encoding the tachykinin receptor, NK2R, in terms of neuroendocrine control of the reproductive axis, using a novel Tacr2 KO mouse line. Our data support a modest, albeit detectable, role of NK2R in the control of the gonadotropic axis, with partially overlapping and redundant functions with other tachykinin receptors.

Tachykinin antagonists ameliorate surgically induced impairment of gastrointestinal motility in rats.

The protective effects of tachykinin receptor antagonists: SR140333 (NK1 receptor), SR48968 (NK2 receptor), and SB222200 (NK3 receptor) were tested in rats against a surgically induced postoperative inhibition of gut motility, a common complication of abdominal surgery. The small intestinal transit of Evans blue was measured 24-h post-surgery in untreated rats and animals subjected to skin incision, laparotomy, or laparotomy followed by gut evisceration and manipulation. Surgical procedures were conducted under diethyl ether anesthesia. In comparison to untreated and ether-anesthetized rats, animals undergoing skin incision, laparotomy, or laparotomy with gut evisceration and manipulation showed a significant decrease in the intestinal transit of Evans blue. The pretreatment with NK1 (3-100 µg/kg), NK2 (3-30 µg/kg), and NK3 (10-300 µg/kg) blockers before surgery ameliorated the inhibitory effects of gut manipulation in a dose-dependent manner. Moreover, the submaximal and maximal doses of NK3 antagonists showed a trend toward reversing not only the inhibition caused by gut manipulation but also laparotomy. An additive effect of combining submaximal doses of NK1-3 blockers was observed in animals pretreated with NK1  + NK2 compared to single-agent NK1 and NK2 . Additionally, doublets: NK1  + NK3 or NK2  + NK3 and a triplet: NK1  + NK2  + NK3 proved to be more effective than NK2 antagonist alone. In contrast, NK1-3 blockers have not markedly affected the intestinal propulsion in untreated rats or animals subjected to skin incision or laparotomy. NK1-3 blockers ameliorated the suppressed small-bowel gut motility 24 post-surgery. Combined pretreatment with NK1-3 antagonists provided selective, additive benefits compared to single agents.

Mass spectrometric studies on the peptide integrity of substance P and related human tachykinins in human biofluids.

The neurokinin-1 receptor plays a profound role in inflammatory processes and is involved in immune cell differentiation, cytokine release, and mast cell activation. Due to their similar peptide structures, the neurokinin-1 receptor does not discriminate between the endogenous ligands substance P (SP) and human hemokinin-1 (hHK-1), which both demonstrate biological receptor affinity. In addition, due to cross-reactivity, the current bioanalytical method of choice-immunoassays-also displays limitations in differentiating between these peptides. Thus, a recently developed mass spectrometric assay was utilized for the selective quantification of SP and hHK-1 in various biofluids and tissue. By applying the sample processing protocols developed, SP was quantified in porcine brain tissue (4.49 ± 0.53 nM), human saliva (113.3 ± 67.0 pM), and human seminal fluid (0.52 ± 0.15 nM) by mass spectrometric analysis. As previously reported, neither SP nor hHK-1 could be detected in human plasma by mass spectrometry. Comparison with analysis using a commercial immunoassay of the same plasma sample revealed SP like-immunoreactivity concentrations of 37.1-178.0 pM. The previously reported carboxylic acid of SP, whose identity was confirmed by high-resolution mass spectrometric analysis, did not show cross-reactivity in the applied immunoassay and did not contribute to SP-like immunoreactivity results. Subsequent compound discovery of the immunocaptured substance indicated the presence of a precursor of SP as possible cross-reactor in human plasma samples. The found cross-reactivity might be the cause for the high variance of SP plasma levels in former determinations.

Neurogenic tachykinin mechanisms in experimental nephritis of rats.

We demonstrated earlier that renal afferent pathways combine very likely "classical" neural signal transduction to the central nervous system and a substance P (SP)-dependent mechanism to control sympathetic activity. SP content of afferent sensory neurons is known to mediate neurogenic inflammation upon release. We tested the hypothesis that alterations in SP-dependent mechanisms of renal innervation contribute to experimental nephritis. Nephritis was induced by OX-7 antibodies in rats, 6 days later instrumented for recording of blood pressure (BP), heart rate (HR), drug administration, and intrarenal administration (IRA) of the TRPV1 agonist capsaicin to stimulate afferent renal nerve pathways containing SP and electrodes for renal sympathetic nerve activity (RSNA). The presence of the SP receptor NK-1 on renal immune cells was assessed by FACS. IRA capsaicin decreased RSNA from 62.4 ± 5.1 to 21.6 ± 1.5 mV s (*p < 0.05) in controls, a response impaired in nephritis. Suppressed RSNA transiently but completely recovered after systemic administration of a neurokinin 1 (NK1-R) blocker. NK-1 receptors occurred mainly on CD11+ dendritic cells (DCs). An enhanced frequency of CD11c+NK1R+ cell, NK-1 receptor+ macrophages, and DCs was assessed in nephritis. Administration of the NK-1R antagonist aprepitant during nephritis reduced CD11c+NK1R+ cells, macrophage infiltration, renal expression of chemokines, and markers of sclerosis. Hence, SP promoted renal inflammation by weakening sympathoinhibitory mechanisms, while at the same time, substance SP released intrarenally from afferent nerve fibers aggravated immunological processes i.e. by the recruitment of DCs.

Rfamide-related peptide-3 suppresses the substance P-induced promotion of the reproductive performance in female rats modulating hypothalamic Kisspeptin expression.

RFamide-related peptide-3 (RFRP-3) has been postulated as the suppressor of the reproductive axis at hypothalamic, pituitary and gonadal levels. Considering the hypothalamic level, RFRP-3 can suppress the activity of gonadotropin-releasing hormone (GnRH) neurons and their upstream neuronal stimulator, namely; the kisspeptin neurons. The effects of the RFRP-3 on the other regulators of GnRH neurons, however, are not completely investigated. Furthermore, substance P (SP) has been known as one of the coordinators of GnRH/ luteinizing hormone (LH) and the kisspeptin/G protein-coupled receptor 54 (GPR54) systems. The present study was aimed at investigating the impacts of RFRP-3 on the effects of SP on the reproductive performance in ovariectomized female rats. After intracerebroventricular (ICV) cannulation, the rats were subjected to the ICV injection of either SP or RFRP-3 and simultaneous injection of them and their selective antagonists. Blood and hypothalamic samplings and also sexual behavioral test were carried out on two main groups of rats. The analyses of the results of LH radioimmunoassay, gene expression assay for hypothalamic Gnrh1, Kisspeptin and Gpr54 accompanied by sexual behavioral examination revealed that the SP administration promotes reproductive behavior and GnRH/LH system and upregulates Kisspeptin expression. The RFRP-3 administration suppressed reproductive behavior, GnRH / LH system and Kisspeptin expression; however, the simultaneous injection of SP and RFRP-3 was devoid of significant alterations in the assessed parameters. The results showed that RFRP-3 can modulates the impacts of SP on the reproductive performance in ovariectomized female rats in part through adjusting Kisspeptin expression.