Peptides (v.25, #11)

Identification of a peptide binding motif for secreted frizzled-related protein-1 by Yoshiro Chuman; Aykut Üren; Jennifer Cahill; Carole Regan; Vladimir Wolf; Brian K. Kay; Jeffrey S. Rubin (1831-1838).
Secreted Frizzled-related proteins (sFRPs) bind Wnts and modulate their activity. To identify putative sFRP-1 binding motifs, we screened an M13 phage displayed combinatorial peptide library. A predominant motif, L/V-VDGRW-L/V, was present in ∼70% of the phage that bound sFRP-1. Use of peptide/alkaline phosphatase chimeras and alanine scanning confirmed that the conserved motif was important for sFRP-1 recognition. The dissociation constant for a peptide/sFRP-1 complex was 3.9 μM. Additional analysis revealed that DGR was the core of the binding motif. Although Wnt proteins lack this sequence, other proteins possessing the DGR motif may function as novel binding partners for sFRP-1.
Keywords: sFRP-1; Phage display; Peptide motif; Wnt; DGR;

Antibacterial hemoglobin peptides in human menstrual blood by Paweł Mak; Kinga Wójcik; Łukasz Wicherek; Piotr Suder; Adam Dubin (1839-1847).
This work documents that normal menstrual vaginal blood of healthy females is exceptionally rich in hemocidins—hemoglobin (Hb) fragments having bactericidal properties. The peptide fractions were isolated from the plasma of vaginal discharge of three healthy nulliparous women and subjected to identification by automatic sequencing as well as by mass spectrometry. All 44 identified peptides originate from Hb (mainly from the N-terminal part of alpha-globin) and all demonstrated differential killing activity toward Escherichia coli. The screening of antimicrobial activity was performed using two synthetic peptides identical to those found in menstrual blood. These peptides were active mainly toward Gram-negative bacteria and to a less degree toward Gram-positive bacteria. Our results confirm recent observations that Hb-derived fragments manifest pronounced antibacterial activity and suggest that these peptides help in maintaining human vaginal homeostasis during physiologic menstrual bleeding.
Keywords: Hemoglobin; Hemocidins; Antibacterial/antimicrobial peptides; Female urogenital tract; Innate immunity; Reproductive immunology;

Mammalian thioredoxin reductase alters cytolytic activity of an antibacterial peptide by Linda Björkhem-Bergman; Kerstin Jönsson-Videsäter; Christer Paul; Mikael Björnstedt; Mats Andersson (1849-1855).
Granulysin is a disulfide rich 9 kDa human tumoricidal protein produced by cytolytic cells. Here we show that thioredoxin reductase (TrxR) reduced a 23-residue peptide from granulysin (GranF2), and this markedly enhanced the killing of small cell lung cancer cells (SCLC) by GranF2. Cells treated with reduced GranF2 showed rapid ATP deletion within 90 min and strong annexin V staining after 4 h incubation. SCLC with elevated TrxR levels was more sensitive to oxidized GranF2 than normal cells. The levels of TrxR are enhanced in many cancer cells, including SCLC, and it is possible that cytolytic activity of cytolytic cells on SCLC may in part be mediated by granulysin and modulated by TrxR.
Keywords: Granulysin; Protegrin; Defensin; Thioredoxin reductase; Thioredoxin; Glutaredoxin;

Polyprotein cleavage mechanism of SARS CoV Mpro and chemical modification of the octapeptide by Qi-Shi Du; Shu-Qing Wang; Yu Zhu; Dong-Qing Wei; Hong Guo; Suzanne Sirois; Kuo-Chen Chou (1857-1864).
The cleavage mechanism of severe acute respiratory syndrome (SARS) coronavirus main proteinase (Mpro or 3CLpro) for the octapeptide AVLQSGFR is studied using molecular mechanics (MM) and quantum mechanics (QM). The catalytic dyad His-41 and Cys-145 in the active pocket between domain I and II seem to polarize the π-electron density of the peptide bond between Gln and Ser in the octapeptide, leading to an increase of positive charge on C(CO) of Gln and negative charge on N(NH) of Ser. The possibility of enhancing the chemical bond between Gln and Ser based on the “distorted key” theory [Anal. Biochem. 233 (1996) 1] is examined. The scissile peptide bond between Gln and Ser is found to be solidified through “hybrid peptide bond” by changing the carbonyl group CO of Gln to CH2 or CF2. This leads to a break of the π-bond system for the peptide bond, making the octapeptide (AVLQSGFR) a “distorted key” and a potential starting system for the design of anti SARS drugs.
Keywords: SARS; Coronavirus main proteinase; Inhibitor; Distorted key theory; Drug design; Octapeptide; KZ7088;

Computational peptide dissection of Melan-a/MART-1 oncoprotein antigenicity by Raj Tiwari; Jan Geliebter; Alberta Lucchese; Abraham Mittelman; Darja Kanduc (1865-1871).
We have mapped the linear antigenic determinant of a commercial MAb raised in the mouse against the melanoma-associated-antigen Melan-A/MART-1. The B cell epitope on the Melan-A/MART-1 oncoprotein is located in the 15-mer amino acid sequence 101–115 PPAYEKLSAEQSPPP, within residues 102–106. The definition of the antigenic sequence on Melan-A/MART-1 oncoprotein was reached following analyses of MHC II binding potential and similarity level to the mouse proteome, that put into evidence the 15-mer amino acid sequence 101–115 PPAYEKLSAEQSPPP as the top scoring peptide in binding H2-Ad molecules and the epitopic sequence residues 102–106 (i.e., the peptide sequence PAYEK) as having low-similarity level to the mouse proteome. Dot-blot epitope mapping immunoassay identified proline residue 102 as critical, based on its effect on antibody recognition. The present study adds to previous companion reports in validating the hypothesis that low-similarity to the host’s proteome and binding potential to MHC II molecules are essential concurring factors in the modulation of the pool of epitopic sequences.
Keywords: Melan-A/MART-1; Epitope prediction; MHC binding potential; Similarity level; Nonself discrimination; Computational biology;

Efficacy of human β-casein fragment (54–59) and its synthetic analogue compound 89/215 against Leishmania donovani in hamsters by Preeti Sharma; Nasib Singh; Ravendra Garg; Wahajul Haq; Anuradha Dube (1873-1881).
The characteristic feature of visceral leishmaniasis (VL) is the profound impairment of immune system of the infected host, which contributes significantly to the partial success of antileishmanial chemotherapy. Since in VL, cure is the combinatorial effect of drug and immune status of the host, the rationale approach towards antileishmanial chemotherapy would be to potentiate the immune functioning of the host to extract desired results. Towards this direction several rationally designed analogues of human β-casein fragment (54–59) were evaluated for their ability to stimulate the non-specific resistance in hamsters against Leishmania donovani infection. By virtue of being derived from the food protein casein derivatives may be devoid of unwanted side effects associated with the substances of microbial origin, e.g. muramyl dipeptide (MDP). Out of this one peptide Val-Glu-Gly-Ile-Pro-Tyr (compound 89/215) had been reported to have such activity. In this communication, the prophylactic and therapeutic efficacy of the peptide along with its natural sequence has been evaluated in detail against experimental VL in hamsters. Their use as an adjunct to chemotherapy was also explored. Human β-casein fragment, compound 89/215 and MDP were tested in vivo at various dose levels wherein compound 89/215 showed superiority over MDP at 3 mg/kg × 2 given intraperitoneally (i.p.). Compound 89/215 sensitized peritoneal macrophages acquired considerable resistance and only 24% of the cells were found infected in comparison to control peritoneal macrophages where 76.4% of the cells were found infected. Similarly, the efficacy of sodium antimony gluconate (SAG) in hamsters pretreated with compound 89/215 enhanced significantly (P < 0.001). This peptide also exhibited considerably good therapeutic efficacy when evaluated either alone or in combination with SAG in established infection of L. donovani.
Keywords: Human β-casein; Combination therapy; Sodium antimony gluconate; Macrophage migration index; Non-specific resistance;

The cDNA for leucomyosuppressin in Blattella germanica and molecular evolution of insect myosuppressins by Lluı̈sa Vilaplana; José Castresana; Xavier Bellés (1883-1889).
Myosuppressins are a group of 10-residues FMRFamide-related peptides reported in Dictyoptera, Orthoptera, Lepidoptera and Diptera. Myosuppressins inhibit visceral muscle contractions and, in the cockroach Blattella germanica, inhibit food intake. In B. germanica, the cDNA of leucomyosuppressin (LMS) has been cloned and sequenced. The deduced precursor is 96 amino acids long and contains a single copy of LMS. Brain mRNA levels remain constant during the first reproductive cycle of adult females, whereas those in the gut show a slight decline during the time of maximal food intake. Comparison of myosuppressin precursors of different species reveals that all have the same organization. Phylogenetic analysis suggests that the precursor experienced an accelerated evolution in Lepidoptera and Diptera with respect to Dictyoptera, whereas only Lepidoptera has radical changes in the bioactive peptide.
Keywords: Myosuppressin; Leucomyosuppressin; Blattella germanica; German cockroach; Gene expression; Antimyotropic activity;

Evidence for brain-derived neurotrophic factor-like neuropeptide in brain of the silk moth Bombyx mori during postembryonic periods by Chan Woo Park; Jin Hee Kim; Kang Min Kim; Jae Sam Hwang; Seok Woo Kang; Ho Suck Kang; Byung Pil Cho; Chai Hyeock Yu; Hak Ryul Kim; Bong Hee Lee (1891-1897).
Brain-derived neurotrophic factor-like neuropeptide is produced in the brain of the silk moth, Bombyx mori. Immunocytochemical studies of brain and retrocerebral complex of larvae, prepupae, pupae and adults showed that four pairs of median neurosecretory cells and six pairs of lateral neurosecretory cells which had different immunoreactivities to BDNF peptide. Day-1 adult brains showed no evidence of neurons stained by anti-BDNF antibodies. Those reactivities, which were much stronger in median cells than in lateral cells, were the weakest in an earliest larval stage and a latest pupal stage but the strongest in late larval stage. Median neurosecretory cells projected their axons into the contralateral corpora allata by decussation in the median region, nerve corpora cardiaca (NCC) I, and nerve corpora allata (NCA) I, whereas lateral neurosecretory cells extended their axons to the ipsilateral corpora allata via NCC II and NCA I.
Keywords: Brain-derived neurotropic factor-like neuropeptide; MNC; LNC; Brains; Corpus allatum; Insect;

The neuro-endocrine X-organ sinus-gland complex of crustaceans produces and releases the neuropeptides of the crustacean hyperglycemic hormone (cHH)/molt-inhibiting hormone (MIH)/gonad-inhibiting hormone (GIH) family that regulate important physiological processes, such as growth, reproduction and molting. We cloned two full-length cDNAs encoding the preprocHH-A and preprocHH-B of the Norway lobster Nephrops norvegicus of 132 and 131 amino acid residues. The two cHHs differ in the preprohormone but not in the mature peptide sequence. The mature cHH was expressed in bacteria as GST fusion protein that, in bioassay, shows a hyperglycemic activity similar to that of native cHH present in an eyestalk extract.
Keywords: Decapod; cHH precursor-related peptide; Bioassay; cDNA cloning;

A role of anti-verotoxin antibody immunoreactive peptide, Virp5, from rat spinal cord by Naohisa Ishikawa; Guo-Gang Feng; Yoshitake Ito; Yoshihiro Hotta; Yasushi Wakida; Hidetsugu Murakami; Michio Yajima; Atsuko Ishikawa; Takashi Yokochi (1909-1916).
An anti-verotoxin 2 (VT2) antibody immunoreactive 5-kDa polypeptide (Virp5), has been obtained through screening of the rat spinal cord cDNA library with the aid of anti-VT2 antibody. Virp5 was mainly expressed in the central nervous system, liver and kidney, and localized at glia-like cells and nerve fibers in the central nervous system, vascular endothelial cells and hepatic cells in the liver, as well as epithelial cells of distal tubules in the kidney. Intravenous administration of purified Virp5 elicited a dose-dependent increase in blood pressure. These results suggest that Virp5 commonly exists in the body, being partly playing a role in regulating the blood pressure.
Keywords: Virp5; Verotoxin 2; Vascular endothelial cell; Spinal cord;

The thrombin peptide, TP508, enhances cytokine release and activates signaling events by Antonella Naldini; Fabio Carraro; Cosima T. Baldari; Silvia Rossi Paccani; Claudia Bernini; Michael J. Keherly; Darrell H. Carney (1917-1926).
The thrombin peptide, TP508, accelerates tissue repair and initiates a cascade of cellular events. We have previously shown that α-thrombin induces cytokine expression in human mononuclear cells. We, therefore, investigated the possibility that TP508 might activate cytokine production and intracellular signaling pathways associated with cytokine activation. Our results show that TP508 induces cytokine expression in human mononuclear cells. TP508 treatment enhances extracellular signal-regulated kinase (Erk1/2) activities in U937 cells, as well as Erk1/2 and p38 activation in Jurkat T cells. These data support the hypothesis that TP508 may accelerate tissue repair through the activation of the inflammatory response.
Keywords: Thrombin; Thrombin peptide; TP508; Interleukin-1; Interleukin-2; Erk; p38; Mononuclear leucocytes; Jurkat; U937;

Diurnal levels of Fos immunoreactivity are elevated within hypocretin neurons in lactating mice by Rodrigo A. España; Craig W. Berridge; Stephen C. Gammie (1927-1934).
The hypocretins modulate arousal via actions across multiple terminal fields. Thus, alterations in hypocretin neurotransmission may contribute to altered sleep patterns observed during lactation. This study examined whether lactation is associated with alterations in the number of hypocretin neurons and in diurnal Fos-immunoreactivity within hypocretin neurons in female mice. Alterations in Fos-immunoreactivity were also examined within two hypocretin terminal regions; the medial preoptic area and the locus coeruleus. Fos-immunoreactivity was increased within hypocretin neurons and the medial preoptic area in lactating females. No differences were observed in the number of hypocretin neurons or in Fos-immunoreactivity within the locus coeruleus.
Keywords: Orexin; Medial preoptic area; Locus coeruleus; Arousal;

Systemic and intra-dorsal periaqueductal gray injections of cholecystokinin sulfated octapeptide (CCK-8s) induce a panic-like response in rats submitted to the elevated T-maze by Janaina Menezes Zanoveli; Cristina Ferreira Netto; Francisco Silveira Guimarães; Hélio Zangrossi (1935-1941).
The neuropeptide cholecystokinin (CCK) has been implicated in fear and anxiety. CCK is found in the CNS in several molecular forms such as the tetrapeptide (CCK-4) and, mainly, the sulfated octapeptide (CCK-8s) fragments. Administration of CCK-4 induces panic attacks in humans and increases the expression of different anxiety-related behaviors in laboratory animals. The effects of CCK-8s on fear and anxiety are less straightforward and seem to be influenced, among other factors, by the route of the peptide administration and the animal model employed. In other to further investigate the role of CCK-8s in fear and anxiety, in the present study we analyzed the effect of CCK-8s in male Wistar rats submitted to the elevated T-maze. This animal model of anxiety was developed in order to separate generalized anxiety (inhibitory avoidance) and panic-like (escape) responses in the same rat. The effect of CCK-8s in this test was also investigated after injection of the peptide into the dorsal periaqueductal gray (DPAG). This brainstem area is rich in CCK receptors and has consistently been implicated in the mediation of fear and anxiety responses. The results showed that both the intraperitoneal and intra-DPAG injections of CCK-8s potentiated one-way escape behavior, suggesting a panicogenic action. In contrast, the injection of the CCK2 receptor antagonist CR2945 inhibited the expression of this behavior, a panicolytic-like effect. Therefore, the elevated T-maze, in contrast to other animal models of anxiety, can detect the anxiety-eliciting effects of CCK-8s both after its systemic and central administration. Also, the results provide further evidence about the involvement of a CCK-mediated mechanism within the DPAG in the regulation of panic-related defensive behaviors.
Keywords: Dorsal periaqueductal gray; Cholecystokinin; Panic; Anxiety; Elevated T-maze;

C-terminally truncated human VPAC1 receptors were constructed and stably transfected in Chinese hamster ovary (CHO) cells. Selected clones expressing comparable receptor densities were studied for ligand’s binding properties, basal and stimulated adenylate cyclase activity. The wild-type (1–457) receptor served as reference. The binding properties of all the constructions were preserved. As judged by the intrinsic activity of the partial agonist Q3-VIP, the shortest receptors have a moderate impairment of the coupling efficacy to Gαs protein. Cells expressing the VPAC1 (1–436) and (1–441) truncated receptors had a two- to three-fold higher basal adenylate cyclase activity than those expressing the wild-type or the VPAC1 (1–444), (1–433), (1–429), (1–421) and (1–398) receptor. The stimulatory effect of VIP and other agonist was preserved. This suggested that VPAC1 (1–436) and (1–441) receptors had a constitutive activity. The selective VPAC1 receptor antagonist Ac His1 [d-Phe2, K15, R16, L27] VIP (3–7)/GRF (8–27) reduced by 60% the basal activity with an EC50 value of 3 nM comparable to its IC50 value for binding. This agonist behaved thus like an inverse agonist on the constitutively active VPAC1 receptors generated by C-terminal truncation and expressed in CHO cells.
Keywords: VPAC1 receptor; Inverse agonism; Constitutive activity; Truncated recombinant receptors;

The aminoterminal fragment of substance P (SP), SP1–7, has been suggested to modulate the expression of opiate tolerance and withdrawal behaviors in rodents. However, the mechanism of this effect is not yet clarified. Using a rat model we have previously demonstrated that SP1–7 affects dopamine transmission and the expression of the dopamine D2-receptor gene transcript in the nucleus accumbens during naloxone precipitated morphine withdrawal. In the present study, we have applied autoradiography to investigate the effect of the heptapeptide on the binding of dopamine D1- and D2-receptors in mesocorticolimbic brain areas of male rats during morphine withdrawal. Morphine dependent animals were treated with an injection of SP1–7 into the ventral tegmental area prior to naloxone challenge. The result indicated that the SP fragment elicited a significant decrease in specific binding to D1-like receptors in the caudate putamen, nucleus accumbens shell, nucleus accumbens core, substantia nigra and medial globus pallidus. Radioligand binding to dopamine D2-like receptors was also altered by SP1–7. The heptapeptide induced a decreased density of these sites in the ventral tegmental area but an increased binding in the substantia nigra and the frontal cortex. The observed alterations in the D1- and D2-like receptor density could reflect activations in dopamine pathways associated with the above-mentioned brain regions. The result provides further evidence for the modulatory effect of SP1–7 on dopamine systems during opioid withdrawal, suggesting the possible role for the heptapeptide to regulate morphine withdrawal reactions.
Keywords: Autoradiography; Dopamine D1-like receptors; Dopamine D2-like receptors; Substance P N-terminal metabolite SP1–7;

Neurokinin-1 receptor antagonism by SR140333: enhanced in vivo ACh in the hippocampus and promnestic post-trial effects by Emriye Kart; Gerhard Jocham; Christian P. Müller; Cerstin Schlömer; Marcus L. Brandão; Joseph P. Huston; M. Angélica de Souza Silva (1959-1969).
Substance P (SP) has memory-promoting, reinforcing and anxiolytic-like effects when applied systemically or centrally. Such effects may be mediated by the neurokinin-1 (NK-1) receptor, since SP preferentially binds to this receptor. We measured the effects of a selective non-peptide NK-1 receptor antagonist, SR140333 (1, 3 and 9 mg/kg i.p.) on ACh levels in frontal cortex, amygdala and hippocampus by microdialysis and HPLC. Levels of ACh in the hippocampus increased dose-dependently immediately after treatment. The same doses of SR140333 given post-trial had minor facilitative effects on inhibitory avoidance learning and open-field habituation, but did not have reinforcing effects in a conditioned place preference (CPP) task. The selective action of NK-1 receptor antagonism on hippocampal ACh may be related to its positive influence on learning.
Keywords: NK-1 receptor antagonist; Acetylcholine; Amygdala; Frontal cortex; Hippocampus; In vivo microdialysis; Open-field; Habituation; Inhibitory avoidance; Memory; Conditioned place preference; Reinforcement; Rats;

Eledoisin and Kassinin, but not Enterokassinin, stimulate ion transport in frog skin by Claudio Lippe; Vito Bellantuono; Concetta Ardizzone; Giuseppe Cassano (1971-1975).
In frog skin, tachykinins stimulate the ion transport, estimated by measuring the short-circuit current (SCC) value, by interacting with NK1-like receptors. In this paper we show that Kassinin (NK2 preferring in mammals) increases the SCC, while Enterokassinin has no effect. Therefore, either 2 Pro residues or 1 Pro and 1 basic amino acid must be present in the part exceeding the C-terminal pentapeptide. Eledoisin (NK3 preferring in mammals) stimulation of SCC is reduced by CP99994 and SR48968 (NK1 and NK2 antagonists) and not affected by SB222200 (NK3 antagonist). None of the three antagonists affects Kassinin stimulation of SCC.
Keywords: Eledoisin; Ion transport; Kassinin; Skin; Tachykinins;

Urotensin-II activates l-arginine/nitric oxide pathway in isolated rat aortic adventitia by Li Lin; Wen-Hui Ding; Wei Jiang; Yong-Gang Zhang; Yong-Fen Qi; Wen-Jun Yuan; Chao-Shu Tang (1977-1984).
Urotensin-II (U-II), a cyclic peptide widely expressed in blood vessels, has diverse vascular actions that range from potent vasoconstriction to vasodilation. Although, U-II-induced vasodilation has been shown to be partially dependent on nitric oxide (NO), the involvement of vascular adventitia-derived NO, remains unknown. The present study aimed to elucidate the activation of U-II on l-arginine/NO pathway in isolated rat aortic adventitia. In adventitia of thoracic and abdominal aortas, the l-arginine/NO pathway was similarly characterized: the uptake of l-[3H]arginine was Na+-independent, with the peak occurring over around 40 min incubation; the total NO synthase (NOS) activity was mostly calcium-independent (>90%), and significantly inhibited by a specific iNOS inhibitor AMT; the production of NO metabolites nitrate and nitrite (NO x ) was stimulated by l-arginine but not by d-arginine. In aortic adventitia exposed to rat U-II (10−9 and 10−8  M) for 6 h, the V max of l-[3H]arginine uptake over 40 min incubation was significantly increased, while the K m of l-[3H]arginine uptake showed no significant change. Besides, the iNOS mRNA level was up-regulated, the total NOS activity, largely calcium-independent, was significantly induced, and the NO x production was significantly stimulated by U-II. According to the same protocol as U-II, the positive control lipopolysaccharide (LPS, 10 μg/ml), which had been established to activate adventitial l-arginine/NO pathway, increased l-[3H]arginine uptake, iNOS activity and NO x production to a greater extent than U-II. In addition, the total NOS activities induced by 3 and 6 h incubation of U-II and LPS were significantly inhibited by a specific inhibitor of protein synthesis, actinomycin D. In conclusion, the results showed that rat U-II activated l-arginine/NOS/NO pathway in rat aortic adventitia, suggesting a potential contributive role of adventitia-derived NO in the vasodilator response of U-II.
Keywords: Urotensin; Nitric oxide; Adventitia; Rat.;

Mechanisms underlying enhanced contractile response to endothelin-1 in diabetic rat basilar artery by Takayuki Matsumoto; Shintaro Yoshiyama; Tsuneo Kobayashi; Katsuo Kamata (1985-1994).
We investigated the influence of streptozotocin-induced diabetes on the responsiveness of the rat basilar artery to endothelin-1 (ET-1) and nitric oxide (NO), which is known to counteract ET-1. In basilar arteries isolated from diabetic rats: (a) the ET-1-induced contraction was enhanced, (b) the contraction induced by NG-nitro-l-arginine [a nitric oxide synthase (NOS) inhibitor] was weaker, and (c) the levels of the mRNAs for ETA/ETB receptors and prepro-ET-1, but not for NOS, were significantly elevated (all versus age-matched controls). These data indicate that ET-1-induced vasoconstriction may be increased in the diabetic rat basilar artery, and that this hyper-reactivity to ET-1 may be due to an overproduction of ET-1, an up-regulation of ETA/ETB receptors, and a defect in the bioavailability of NO.
Keywords: Basilar artery; Contraction; Diabetes; Endothelin; Nitric oxide; Streptozotocin;

Intracerebroventricular injection of neuropeptide EI increases serum LH in male and female rats by Andrés M. Attademo; Mariela Sánchez-Borzone; Mercedes Lasaga; Maria Ester Celis (1995-1999).
Melanin concentrating hormone (MCH) precursor-derived neuropeptide EI (NEI) has not yet been extensively studied. The aim of this study was to determine the effect of neuropeptide EI on serum levels of LH in normal male rats and chronically ovariectomized (CHR-OVX) female rats treated with estrogen benzoate (EB) and with a low dose of progesterone. The peptide, administered intracerebroventricularly in male and chronically ovariectomized female rats, increased LH serum levels compared to the controls injected with artificial cerebrospinal fluid. It is important to note that there is some relation between neuropeptide EI–melanin concentrating hormone and α-melanocyte stimulating hormone (α-MSH) indicating that all three peptides are associated in a complex inter-relationship. Therefore, the question that arises is if neuropeptide EI could also be related with the receptors for melanin concentrating hormone or α-melanocyte stimulating hormone.
Keywords: LH release; Neuropeptide EI (NEI); Intracerebroventricular (icv) injection; Male and female rats; Ovariectomized rats;

Introductory notes by Jan A. Fischer; Walter Born (2001-2002).

Adrenomedullin receptors: pharmacological features and possible pathophysiological roles by Kenji Kuwasako; Yuan-Ning Cao; Yasuko Nagoshi; Kazuo Kitamura; Tanenao Eto (2003-2012).
Three receptor activity modifying proteins (RAMPs) chaperone calcitonin-like receptor (CLR) to the cell surface. RAMP2 enables CLR to form an adrenomedullin (AM)-specific receptor that is sensitive to AM-(22–52) (AM1 receptor). RAMP3 enables CLR to form an AM receptor sensitive to both calcitonin gene-related peptide (CGRP)-(8–37) and AM-(22–52) (AM2 receptor), though rat and mouse AM2 receptors show a clear preference for CGRPα-(8–37) over AM-(22–52). RAMP1 enables CRL to form the CGRP-(8–37)-sensitive CGRP1 receptor, which can also be activated by higher concentrations of AM. Here we review the available information on the pharmacological features and possible pathophysiological roles of the aforementioned AM receptors.
Keywords: Adrenomedullin; Antagonist; Calcitonin-like receptor; Heterodimer; Receptor activity modifying protein; Transfection;

Adrenomedullin in the treatment of pulmonary hypertension by Noritoshi Nagaya; Kenji Kangawa (2013-2018).
Adrenomedullin (AM) is a potent, long-lasting pulmonary vasodilator peptide. Plasma AM level is elevated in patients with primary pulmonary hypertension (PPH), and circulating AM is partially metabolized in the lungs. These findings suggest that AM plays an important role in the regulation of pulmonary vascular tone and vascular remodeling. We have demonstrated the effects of three types of AM delivery systems: intravenous administration, inhalation, and cell-based gene transfer. Despite endogenous production of AM, intravenously administered AM at a pharmacologic level decreased pulmonary vascular resistance in patients with PPH. Inhalation of AM improved hemodynamics with pulmonary selectivity and exercise capacity in patients with PPH. Cell-based AM gene transfer ameliorated pulmonary hypertension rats. These results suggest that additional administration of AM may be effective in patients with pulmonary hypertension. AM may be a promising endogenous peptide for the treatment of pulmonary hypertension.
Keywords: Adrenomedullin; Pulmonary hypertension; Inhalation; Gene therapy;

The pharmacology of CGRP-responsive receptors in cultured and transfected cells by D.L. Hay; A.C. Conner; S.G. Howitt; M.A. Takhshid; J. Simms; K. Mahmoud; D.R. Poyner (2019-2026).
Historically, CGRP receptors have been classified as CGRP1 or CGRP2 subtypes, chiefly depending on their affinity for the antagonist CGRP8–37. It has been shown that the complex between calcitonin receptor-like receptor (CRLR or CL) and receptor activity modifying protein (RAMP) 1 provides a molecular correlate for the CGRP1 receptor; however, this does not explain the range of affinities seen for CGRP8–37 in isolated tissues. It is suggested that these may largely be explained by a combination of methodological factors and CGRP-responsive receptors generated by CL and RAMP2 or RAMP3 and complexes of RAMPs with the calcitonin receptor.
Keywords: CGRP; Calcitonin receptor-like receptor; RAMP1; RAMP2; RAMP3; CL; CGRP8–37; Calcitonin receptor; BIBN4096BS;

The hormone calcitonin (CT) of thyroid C-cell origin, the neuropeptides α- and β-calcitonin gene-related peptide (CGRP), the widely expressed hormone and tissue factor adrenomedullin (AM), and amylin (AMY) that is co-produced with insulin in pancreatic β-cells, are structurally related peptides. They have in common six or seven amino acid ring structures, linked by disulfide bridges between cysteine residues, and amidated carboxyl termini that are both required for biological activity. The actions of the peptides in vivo have traditionally been studied after intravenous and intracerebroventricular administration. As a result, CT lowers serum calcium and reduces pain perception. α- and βCGRP and AM are highly potent vasodilatory peptides. AMY inhibits food intake through its action in the area postrema of the brain. Physiological actions of the peptides summarized in the present review have been defined through gene knockout and overexpression strategies.
Keywords: Adrenomedullin; Amylin; Calcitonin gene-related peptide; Knockout; Transgene;

In this review, we describe the structure and biological properties of calcitonin receptor-stimulating peptide-1 (CRSP-1), CRSP-2 and CRSP-3, the novel members of the CGRP family. CRSP-1, which has been identified in the pig, cow, dog, and horse, is a specific ligand for the calcitonin (CT) receptor, and porcine CRSP-1 elicits a 100-fold greater effect on a recombinant porcine CT receptor than porcine CT, although this peptide has high structural similarity with CGRP. CRSP-1 is expressed and synthesized mainly in the central nervous system (CNS), pituitary and thyroid gland. In an in vivo experiment, bolus administration of CRSP-1 into rats reduced the plasma calcium concentration, but did not alter blood pressure, indicating its action as a CT receptor agonist in the peripheral circulation. In the CNS, CRSP-1 is also deduced to be an endogenous agonist for the CT receptor. CRSP-2 has been identified in the pig and dog, and CRSP-3 has been identified only in the pig. They are expressed and synthesized mainly in the CNS and thyroid gland. However, their endogenous molecular forms, receptors, and biological activity remain unidentified.
Keywords: Calcitonin receptor-stimulating peptide; Calcitonin; Calcitonin gene-related peptide; cAMP; Central nervous system;