Circulating sensory peptide levels within 24 h of human bone fracture.

We designed this study to examine the circulatory levels of wound modulatory peptides [substance P (SP), calcitonin gene related peptide (CGRP] in patients with muscle injuries with bone fractures and within 24 h of the injury. The peripheral plasma levels of these sensory nerve peptides were measured on hospital admission (OA) and 24 h post-injury (PI), using ELISA technique. Mean (s.d) ng/liter of CGRP was higher in patients OA (270 +/- 199), and PI (205 +/- 176); than the controls (3 +/- 81) P < 0.05. Substance P also increased in the patients OA: 101 +/- 50; PI: 46 +/- 3 than controls [8 +/- 9] P < 0.001. Elastase (predictor of posttraumatic complication) was examined and there was no significant differences between patients and control samples (P = NS). This study shows that sensory nerve peptides are increased in bone fracture related injuries up to 24 h after injury. An intact nociceptor system of primary afferent sensory nerves is important for the initiation of the inflammatory process and successful tissue repair as dysfunction of this system could be a contributing factor for a delayed wound healing.     

CGRP和NPY 在大鼠股骨闭合骨折愈合不同阶段的变化及意义

目的:探讨交感神经分泌的神经肽Y(NPY)和感觉神经分泌的钙基因相关肽(CGRP)在体内骨折愈合的不同阶段的变化及意义。方法:选择6-8月龄的雄性大鼠,建立大鼠的股骨闭合骨折模型,术后2、4、8、12周取材。进行扫描电镜,免疫组织荧光染色和血清Elisa检测。结果:1骨折愈合不同时期感觉神经肽类物质CGRP和交感神经肽类物质NPY都有表达,且其含量有先增加后减少的趋势,并在骨折后8周含量达到最高。2骨折愈合不同阶段的大鼠血清感觉神经肽类物质CGRP和交感神经肽类物质NPY均呈上升趋势,差异有统计学意义(P0.05),且NPY的含量比CGRP的含量高。骨折后2-4周,CGRP含量增加较快;骨折后4-8周NPY含量增加较快。结论:骨折愈合的不同阶段,感觉神经肽类物质CGRP和交感神经肽类物质NPY含量先升后降,对不同阶段的骨形成及骨吸收产生影响。     

Design of hydropathically complementary peptides for Big Endothelin affinity purification.

Molecular recognition between Big Endothelin (Big ET) and a computer generated peptide hydropathically complementary to Big ET[16-29] sequence has been studied by analytical high performance liquid affinity chromatography (HPLAC), circular dichroism (CD) and nuclear magnetic resonance (NMR) experiments. Specific binding was observed between solid support immobilized complementary peptide and Big ET[1-38], [1-32], and [16-32], but not with Big ET fragments [1-21], [16-21], [22-32], and [22-38], obtained by chymotrypsin proteolytic degradation. Selectivity in the recognition process was clearly demonstrated by the ability of complementary peptide affinity column to purify the Big ET molecule from complex peptide mixtures, even when present in very low concentrations. Similar selectivity was evidenced with the Big ET fragment [16-32], [NH2-HLDIIWVNTPEHIVPYG-COOH] containing the entire hydropathically complementary sequence. Binding was followed by marked spectroscopic changes, as monitored by circular dichroism and one- and two-dimensional nuclear magnetic resonance experiments. The NMR spectra of the complementary peptides 1:1 mixture showed variations in the chemical shifts of proton resonances in several residues, both in the main chain (amide protons) and in the side chains (aliphatic and aromatic protons). These data support the hypothesis of a multilocalized type of interaction between complementary peptides, where many residues along the peptide chains participate in co-operative stabilizing contacts in the forming complex.     

Turn structures in CGRP C-terminal analogues promote stable arrangements of key residue side chains.

The 37-amino acid calcitonin gene-related peptide (CGRP) is a potent endogenous vasodilator thought to be implicated in the genesis of migraine attack. CGRP antagonists may thus have therapeutic value for the treatment of migraine. The CGRP C-terminally derived peptide [D(31),P(34),F(35)]CGRP(27-37)-NH(2) was recently identified as a high-affinity hCGRP(1) receptor selective antagonist. Reasonable CGRP(1) affinity has also been demonstrated for several related analogues, including [D(31),A(34),F(35)]CGRP(27-37)-NH(2). In the study presented here, conformational and structural features in CGRP(27-37)-NH(2) analogues that are important for hCGRP(1) receptor binding were explored. Structure-activity studies carried out on [D(31),P(34),F(35)]CGRP(27-37)-NH(2) resulted in [D(31),P(34),F(35)]CGRP(30-37)-NH(2), the shortest reported CGRP C-terminal peptide analogue exhibiting reasonable hCGRP(1) receptor affinity (K(i) = 29.6 nM). Further removal of T(30) from the peptide's N-terminus greatly reduced receptor affinity from the nanomolar to micromolar range. Additional residues deemed critical for hCGRP(1) receptor binding were identified from an alanine scan of [A(34),F(35)]CGRP(28-37)-NH(2) and included V(32) and F(37). Replacement of the C-terminal amide in this same peptide with a carboxyl, furthermore, resulted in a greater than 50-fold reduction in hCGRP(1) affinity, thus suggesting a direct role for the amide moiety in receptor binding. The conformational properties of two classes of CGRP(27-37)-NH(2) peptides, [D(31),X(34),F(35)]CGRP(27-37)-NH(2) (X is A or P), were examined by NMR spectroscopy and molecular modeling. A beta-turn centered on P(29) was a notable feature consistently observed among active peptides in both series. This turn led to exposure of the critical T(30) residue to the surrounding environment. Peptides in the A(34) series were additionally characterized by a stable C-terminal helical turn that resulted in the three important residues (T(30), V(32), and F(37)) adopting consistent interspatial positions with respect to one another. Peptides in the P(34) series were comparatively more flexible at the C-terminus, although a large proportion of the [D(31),P(34),F(35)]CGRP(27-37)-NH(2) calculated conformers contained a gamma-turn centered on P(34). These results collectively suggest that turn structures at both the C-terminus and N-terminus of CGRP(27-37)-NH(2) analogues may help to appropriately orient critical residues (T(30), V(32), and F(37)) for hCGRP(1) receptor binding.     

Effects of neuropeptides on growth of cultivated rat molar pulp fibroblasts

The effect of the neuropeptides substance P (SP), neurokinin A (NKA), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) on DNA synthesis of dental pulp cells was investigated in cells grown from molar tooth bud explants from 4–6 days old rat pups. A concentration response-assay of the proliferative response of pulpal cells was performed with SP, NPY, NKA, CGRP and VIP (0.01 to 1 nM) in the presence of EGF (10 ng/ml), hydrocortisone (0.4 μg/ml) and 3% FCS, using [³H]thymidine incorporation. The results showed that SP, NKA and CGRP, but not NPY and VIP, increased the cell number in a concentration-dependent manner, with maxima at 10⁻¹⁰ – 10⁻⁹ M (SP, NKA) and 10⁻⁷ M (CGRP). No potentiating effect was noted when cells are simultaneously stimulated with SP and CGRP. The finding that SP, NKA and CGRP have growth regulatory properties on pulpal cells in vitro suggests that sensory neuropeptides may be involved during pulpal development or in wound healing after pulpal injury.     

Insulin hypoglycemia increases the levels of neuropeptide Y and calcitonin gene-related peptide, but not of chromogranins A and B, in rat chromaffin granules

The levels and subcellular distribution of chromogranin A and B, of calcitonin gene-related peptide (CGRP) and of neuropeptide Y (NPY) were investigated in rat adrenals before and after insulin treatment. Six days after insulin-induced hypoglycemia the levels of chromogranin A and B were similar to controls, however those of NPY and CGRP were increased by a factor of 2.5 and 35, respectively. This treatment also elevated mRNA levels of NPY and CGRP, establishing an increased biosynthesis of these two neuropeptides. As shown by subcellular fractionation, all peptides were present in chromaffin granules after insulin treatment. Furthermore, immunostaining at the ultrastructural level demonstrated the co-localization of chromogranin A, NPY and CGRP within the same chromaffin granules. These results establish that insulin-induced hypoglycemia changes the levels of the secretory peptides in chromaffin granules leading to an altered composition of the secretory cocktail. Apparently, the biosynthesis of the secretory peptides and their storage organelles can be regulated in distinct patterns.     

Peptide immunocytochemistry in afferent neurons from lower gut in rats

Several peptides were detected in primary sensory neurons located in nodose and dorsal root ganglia and projecting from rat cecum and rectosigmoid, through a combination of retrograde staining by the fluorescent tracer DY-2HCl and of the immunofluorescent procedure of Coons. The three larger cell populations thus identified stored immunoreactive components respectively similar to calcitonin gene-related peptide (CGRP), substance P (SP), and a peptide related to peptide histidine methionine (PHM). The later immunoreactivity consisted of a single molecular form with an apparent molecular weight smaller than PHM itself. Fewer cells contained components immunologically similar to somatostatin 14 (ST14), to the 1-14 N-terminal sequence of somatostatin 28 (1-14 S28), and to neuropeptide Y (NPY). Neonatal treatment with capsaicin resulted in a drastic reduction of immunoreactivity for SP, PHM, ST14, 1-14 S28, and in a partial reduction of CGRP-like positive perikarya. These results demonstrate that several peptides are potentially involved in the sensory innervation of the lower gut in rat.     

Innervation of lower airways and neuropeptide effects on bronchial and vascular tone in the pig

Summary The occurrence and distribution of peptide-containing nerve fibres [substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), neuropeptide Y (NPY)] and noradrenergic nerve fibres [tyrosine hydroxylase (TH)- and dopamine beta hydroxylase (DBH)-positive] in the airways of the pig were studied by means of immunohistochemistry. SP- and CGRP-immunoreactive (-IR) nerve fibres were present close to and within the lining respiratory epithelium, around blood vessels, within the tracheobronchial smooth muscle layer and around local tracheobronchial ganglion cells. The content of CGRP- and neurokinin A (NKA)-like immunoreactivity (-LI) measured by radioimmunoassay (RIA) was twice as high in the trachea compared to that in the peripheral bronchi. SP was a more potent constrictor agent than NKA on pig bronchi in vitro. CGRP had a relaxant effect on precontracted pig bronchi. On blood vessels CGRP exerted a relaxant effect that was more pronounced on pulmonary arteries than on bronchial arteries. VIP/PHI-IR fibres were seen in association with exocrine glands and in the tracheobronchial smooth muscle layer. VIP-positive nerve fibres were abundant around blood vessels in the trachea but sparse or absent around blood vessels in the peripheral bronchi. This histological finding was supported by RIA; it was shown that the content of peptides displaying VIP-like immunoreactivity (-LI) was 18 times higher in the trachea compared to peripheral bronchi. VIP was equally potent as CGRP in relaxing precontracted pig bronchi in vitro. Both bronchial and pulmonary arteries were relaxed by VIP. NPY was colocalized with VIP in tracheal periglandular nerve fibres and in nerve fibres within the tracheobronchial smooth muscle layer. NPY was also present in noradrenergic (DBH-positive) vascular nerve fibres. The content of NPY was much higher (15-fold) in the trachea compared to small bronchi. NPY caused a contraction of both pulmonary and bronchial arteries. The bronchial smooth muscle contraction to field stimulation in vitro was purely cholinergic. A non-cholinergic relaxatory effect following field stimulation was observed after bronchial precontraction. Capsaicin had no effect on pig bronchi in vitro.     

Affinity enhancement of complementary peptide recognition.

A peptide hydropathically complementary to Big Endothelin [Big ET] residues 16-29 has been synthesized in a multimeric form starting from an octadentate polylysine core, essentially in a way similar to the procedure used for the production of multiple antigenic peptides [MAP's]. Interaction between the multimeric complementary peptide [8 delta ET] and the Big ET fragment 16-32 containing the target complementary region, also synthesized in a multimeric form [8ET], was evaluated by analytical high performance affinity chromatography and solid phase binding assays. While the binding interaction between the monomerics peptide pair was in the micromolar range, the recognition between the corresponding multimeric form was characterized by enhanced binding affinity of at least two orders of magnitude. In solution, complex formation between multimeric complementary peptide and target Big ET sequence in the monomeric and multimeric form was accompanied by precipitation at concentrations higher than 0.5 mg/mL and 0.1 mg/mL, respectively. Polyclonal antibodies raised against the multimeric target sequence recognized multimeric and monomeric ET target sequences with binding affinities similar to binding affinities exhibited by the multimeric complementary peptide. Multimerization of hydropathically complementary peptides could provide an improved opportunity to measure and thus probe quantitative binding properties of complementary peptides.     

Receptor autoradiography as mean to explore the possible functional relevance of neuropeptides: focus on new agonists and antagonists to study natriuretic peptides, neuropeptide Y and calcitonin gene-related peptides

Over the past 20 years, receptor autoradiography has proven most useful to provide clues as to the role of various families of peptides expressed in the brain. Early on, we used this method to investigate the possible roles of various brain peptides. Natriuretic peptide (NP), neuropeptide Y (NPY) and calcitonin (CT) peptide families are widely distributed in the peripheral and central nervous system and induced multiple biological effects by activating plasma membrane receptor proteins. The NP family includes atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP). The NPY family is composed of at least three peptides NPY, peptide YY (PYY) and the pancreatic polypeptides (PPs). The CT family includes CT, calcitonin gene-related peptide (CGRP), amylin (AMY), adrenomedullin (AM) and two newly isolated peptides, intermedin and calcitonin receptor-stimulating peptide (CRSP). Using quantitative receptor autoradiography as well as selective agonists and antagonists for each peptide family, in vivo and in vitro assays revealed complex pharmacological responses and radioligand binding profile. The existence of heterogeneous populations of NP, NPY and CT/CGRP receptors has been confirmed by cloning. Three NP receptors have been cloned. One is a single-transmembrane clearance receptor (NPR-C) while the other two known as CG-A (or NPR-A) and CG-B (or NPR-B) are coupled to guanylate cyclase. Five NPY receptors have been cloned designated as Y(1), Y(2), Y(4), Y(5) and y(6). All NPY receptors belong to the seven-transmembrane G-protein coupled receptors family (GPCRs; subfamily type I). CGRP, AMY and AM receptors are complexes which include a GPCR (the CT receptor or CTR and calcitonin receptor-like receptor or CRLR) and a single-transmembrane domain protein known as receptor-activity-modifying-proteins (RAMPs) as well as an intracellular protein named receptor-component-protein (RCP). We review here tools that are currently available in order to target each NP, NPY and CT/CGRP receptor subtype and establish their respective pathophysiological relevance.     

Immunocytochemical demonstration of vertebrate neuropeptides in the earthworm Lumbricus terrestris (Annelida,Oligochaeta)

Summary The localisation and distribution of 10 vertebrate-derived neuropeptides in the earthworm, Lumbricus terrestris, have been determined by an indirect immunofluorescence technique. The peptides are pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), neuropeptide Y (NPY), glucagon (C-terminal), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), gastrinreleasing peptide (GRP), calcitonin gene-related peptide (CGRP), neurotensin (NT), and met-enkephalin. For 6 of the peptides — PYY, NPY, PHI, glucagon, GRP and CGRP — this is the first demonstration of their presence in any annelid, and NT has not previously been described in an oligochaete. Cell bodies and nerve fibres immunoreactive to the 10 peptides occur throughout the CNS. In the PNS, epidermal sensory cells displayed immunoreactivities to PP and PYY, and PP-, PYY-, NPY-, PHI- and GRP-like immunoreactivities occurred in nerve fibres supplying the main body muscles. Nerve fibres immunoreactive to PP and PYY are also associated with the innervation of the gut (pharynx, oesophageal glands, and mid and posterior regions of the intestine). No endocrine cells immunoreactive for any of the antisera tested could be identified in the gut epithelium, suggesting that dual location of peptides in the brain and gut epithelium is a phenomenon that occurred at a later stage in evolution. No immunoreactive elements were detected in any of the organs and ducts of the reproductive and excretory systems.     

An immunocytochemical study of cutaneous innervation and the distribution of neuropeptides and protein gene product 9.5 in man and commonly employed laboratory animals.

The cutaneous nerves of rat, cat, guinea pig, pig, and man were studied by immunocytochemistry to compare the staining potency of general neural markers and to investigate the density of nerves containing peptides. Antiserum to protein gene product 9.5 (PGP 9.5) stained more nerves than antisera to neurofilaments, neuron-specific enolase (NSE), and synaptophysin or histochemistry for acetylcholinesterase (AChE). Peptidergic axons showed species variation in density of distribution and were most abundant in pig and fewest in man. However, the specific peptides in nerves innervating the various structures were consistent between species. Nerve fibers immunoreactive for calcitonin gene-related peptide (CGRP) and/or vasoactive intestinal polypeptide (VIP) predominated in all the species; those immunoreactive to tachykinins (substance P and neurokinin A [NKA]) and neuropeptide tyrosine (NPY) were less abundant. Neonatal capsaicin, at the doses employed in this study, destroyed approximately 70% of CGRP- and tachykinin-immunoreactive sensory axons; whereas 6-hydroxydopamine (6-OHDA) at the doses employed resulted in a complete loss of NPY and tyrosine hydroxylase (TH) immunoreactivity without affecting VIP, CGRP, and tachykinins. Thus, this study confirms that antiserum to PGP 9.5 is the most suitable and practical marker for the demonstration of cutaneous nerves. Species differences exist in the density of peptidergic innervation, but apparently not for specific peptides. Not all sensory axons immunoreactive for CGRP and substance P/NKA are capsaicin-sensitive. However, all sympathetic TH- and NPY-immunoreactive axons are totally responsive to 6-OHDA; but no change was seen in VIP-immunoreactive axons, suggesting some demarcation of cutaneous adrenergic and cholinergic sympathetic fibers.     

Helical structure and self-association in a 13 residue neuropeptide Y Y2 receptor agonist: relationship to biological activity

The solution structure and self-association behaviour of a 13 residue peptide analogue of the C-terminal region of human neuropeptide Y (NPY) have been investigated. NMR analysis of Ac[Leu(28,31)]NPY(24-36), a potent Y2 receptor agonist, shows that it is unstructured in aqueous solution at 5-20 degrees C, but forms a well-defined helix (encompassing residues 25-35) in 40% trifluoroethanol/water at 20 degrees C. Sedimentation experiments show that, in contrast to many peptides in aqueous trifluoroethanol, Ac[Leu(28,31)]NPY(24-36) associates to form a trimer or, more likely, a tetramer in 40% trifluoroethanol, even though it is monomeric in water. This is consistent with the observation of inter-molecular nuclear Overhauser enhancements in trifluoroethanol. Possible models of the associated form that are consistent with the NMR data are described. The relevance of the helical structure observed in trifluoroethanol to the structure of this peptide bound to the NPY Y2 receptor is discussed.     

肺内调节肽对兔支气管上皮细胞与嗜酸性粒细胞粘附功能的影响及机制探讨

为了探讨肺内调节肽在各类过敏性炎症发生,发展中的作用,我们观察了血管活性肠肽（vasoactive intestinal peptide,VIP)、表皮生长因子（epidermal growth factor,EGF)、内皮素-1（endothelin-1,ET-1)、降钙素基因相关肽（calcitonin gene-related peptide,CGRP)在未受应激与臭氧应激两种条件下对支气管上皮细胞（bronchial epithelial cell,BEC)与嗜酸性粒细胞（eosinophil,EOS)粘附的影响,结果发现,VIP、EGF可使O3应激的BEC与EOS的粘附率下降,下调气道上皮炎症反应：ET-1、CGRP可使未受应激的BEC与EOS的粘附率增加,诱发炎症损伤反应;CGRP还能加重臭氧的应激反应;ET-1、CGRP的效应可被W7、H7阻断,抗细胞间粘附分子-1（intercel-lular adhesion molecule,ICAM-1)抗体能阻断BEC与EOS的粘附,提示介导BEC与EOS粘附的粘附分子可能是ICAM-1。     

Neuropeptide Y inhibits estrous behavior and stimulates feeding via separate receptors in Syrian hamsters

Central injections of neuropeptide Y (NPY) increase food intake in Syrian hamsters; however, the effect of NPY on sexual behavior in hamsters is not known nor are the receptor subtypes involved in feeding and sexual behaviors. We demonstrate that NPY inhibits lordosis duration in a dose-related fashion after lateral ventricular injection in ovariectomized, steroid-primed Syrian hamsters. Under the same conditions, we compared the effect of two receptor-differentiating agonists derived from peptide YY (PYY), PYY-(3-36) and [Leu(31),Pro(34)]PYY, on lordosis duration and food intake. PYY-(3-36) produced a 91% reduction in lordosis duration at 0.24 nmol. [Leu(31),Pro(34)]PYY was less potent, producing a reduction in lordosis duration (66%) only at 2.4 nmol. These results suggest NPY effects on estrous behavior are principally mediated by Y2 receptors. PYY-(3-36) and [Leu(31),Pro(34)]PYY stimulated comparable dose-related increases in total food intake (2 h), suggesting Y5 receptors are involved in feeding. The significance of different NPY receptor subtypes controlling estrous and feeding behavior is highlighted by results on expression of Fos immunoreactivity (Fos-IR) elicited by either PYY-(3-36) or [Leu(31),Pro(34)]PYY at a dose of each that differentiated between the two behaviors. Some differences were seen in the distribution of Fos-IR produced by the two peptides. Overall, however, the patterns of expression were similar. Our behavioral and anatomic results suggest that NPY-containing pathways controlling estrous and feeding behavior innervate similar nuclei, with the divergence in pathways controlling the separate behaviors characterized by linkage to different NPY receptor subtypes.     

Bone and joint neuropathy in rats with type-2 diabetes

We have previously demonstrated that Goto-Kakizaki (GK) rats with spontaneous type-2 diabetes and peripheral neuropathy exhibit regional osteopathic changes. In the present study on 18 GK rats and 21 control Wistar rats, the occurrence of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), and the autonomic neuropeptide Y (NPY) was analysed in bone and joints, dorsal root ganglia and lumbar spinal cord by immunohistochemistry and radioimmunoassay (RIA). Immunohistochemistry disclosed a predominance of immunoreactivities in vessel-related nerve fibers, although some were also seen in free terminals. While SP, CGRP and NPY in periosteum, cortical bone and synovium was confined to neuronal tissue, the bone marrow in addition exhibited an abundance of NPY-positive megakaryocytes. Apart from this cellular source of NPY, the observations suggest that the three neuropeptides analysed in bone and joints are of neuronal origin. Quantification by RIA showed a significant decrease of NPY in cortical bone (-36%), bone marrow (-66%) and ankle (-29%) of GK rats. CGRP was decreased in the spinal cord (-19%) and dorsal root ganglia (-26%) but was unchanged in bone and joints, as with SP. Given the suggested anabolic role of NPY and CGRP on bone, neuropeptidergic deficit in diabetes may prove to be an important factor underlying the development of regional osteopenia.     

肺内调节肽对兔支气管上皮细胞分泌白介素的影响

为探讨肺内调节肽对气管上皮细胞（brochial epithelial cells,BECs）分泌功能的影响,实验观察了兔BECs在未受应激与臭氧应激两种条件下白细胞介素（interleukin,ILs）的分泌。结果发现：血管活性肠肽（vasoac-tive intestinal peptide,VIP）以未受应激BECs存在抑制作用,并使用臭氧应激BECs分泌ILs下降;表皮生长因子（epi-dermal growth factor,EGF）使未受应激BECs IL-1、IL-8分泌增加,使臭氧应激的BECs ILs分泌降低;内皮素-1（endothelin-1,ET-1）、降钙素基因相关肽(calctionin gene-related peptide,CGRP）可使未受应激的BECs分泌ILs增加,CGRP还可使臭氧应激的BECs ILs分泌增加。结果提示：肺内调节肽可调控BECs ILs的分泌,在调控气道炎症损伤信号传递方面具有一定的作用。     

Tissue distribution and innervation pattern of peptide immunoreactivities in the rat pancreas.

The distribution of calcitonin gene-related peptide (CGRP), substance P/tachykinin (SP/TK), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and gastrin-releasing peptide (GRP) immunreactivities (IR) in the rat pancreas was investigated using radioimmunoassay and immunohistochemistry. CGRP, NPY and VIP tissue contents are much higher than GRP and SP/TK concentrations. Peptide-containing nerves are distributed to both the exocrine and endocrine pancreas. However, differences exist in terms of density and targets of innervation for each peptidergic system. In the acini and through the stroma, fibers IR for CGRP, NPY and VIP are greater than GRP- and SP/TK-containing processes. The vasculature is supplied by a prominent NPY, CGRP and, to a lesser extent, SP/TK innervation. VIP-IR is found occasionally, and GRP-IR is never detected, in fibers associated with blood vessels. Around ducts, CGRP- and NPY-positive neurites are greater than SP/TK- greater than or equal to VIP-IR fibers, whereas GRP-containing nerves are not visualized. In the islets, the density of peptidergic nerves is: VIP-, GRP- greater than or equal to CGRP-IR greater than NPY or SP/TK. In intrapancreatic ganglia. VIP- and, to a lesser extent, NPY-IRs are found in numerous neuronal cell bodies and in nerve fibers; GRP-IR is present in numerous nerve processes and in few cell bodies; CGRP- and SP/TK-IRs are detected only in fibers wrapping around unlabeled ganglion cells. The majority of CGRP-IR fibers contain SP/TK-IR. The existence of differential patterns of peptidergic nerves suggests that peptides exert their effects on pancreatic functions via different pathways.     

Ca2+ phospholipid-dependent and independent phosphorylation of synthetic peptide substrates by protein kinase C

Several synthetic peptides reproducing fragments of protamines have been used as model substrates for Ca2+/phospholipid-dependent protein kinase C, tested both in the absence of any effector (basal conditions) and upon activation by either Ca2+ and phosphatidylserine (or diacylglycerol) or limited proteolysis. Only the peptide Arg4-Tyr-Gly-Ser-Arg6-Tyr [Ga(52-65)] shares the unique property of protamines of being readily phosphorylated even under basal conditions. Optimal activity in the absence of effectors is observed with Tris/HCl buffer pH 7.5; Pipes and Hepes are less effective at pH 7.5, and at pH 6.5 basal phosphorylation is reduced. Under the best conditions for basal phosphorylation of Ga(52-65), its derivative with ornithine replaced for arginine and those corresponding to its C-terminal fragments Gly-Ser-Arg6-Tyr [Ga(57-65)] and Gly-Ser-Arg3 [Ga(57-61)], as well as the peptides Pro-Arg5-Ser2-Arg-Pro-Val-Arg [Th(1-12)], Arg4-Tyr-Arg2-Ser-Thr-Val-Ala [Th(13-23)] and Arg2-Leu-Ser2-Leu-Arg-Ala are not significantly affected though all of them, like histones, are more or less readily phosphorylated upon activation of protein kinase C by Ca2+/phosphatidylserine. The peptide Ser2-Arg-Pro-Val-Arg [Th(7-12)] however, corresponding to the C-terminal part of Th(1-12), is not phosphorylated even in the presence of activators. Limited proteolysis can roughly mimic the Ca2+/phosphatidylserine effect inducing however different extents of activation depending on the nature of the peptide substrates. Our results support the following two conclusions. Basal phosphorylation by protein kinase C in the absence of any effector requires peptide substrates whose target residue(s) are included between two extended arginyl blocks and is also dependent on pH and nature of the buffer. Peptides having extended clusters of either arginyl or ornithyl residues on the C-terminal side of serine are also readily phosphorylated, but they need activation of protein kinase by either Ca2+/phosphatidylserine or limited proteolysis. The same is true of peptides having basic residues only on the N-terminal side, or even on both sides but in limited number.     

The first selective agonist for the neuropeptide YY5 receptor increases food intake in rats

The first Y(5) receptor-selective analog of neuropeptide Y (NPY), [Ala(31),Aib(32)]NPY, has been developed and biologically characterized. Using competition binding assays on cell lines that express different Y receptors, we determined the affinity of this analog to be 6 nm at the human Y(5) receptor, >500 nm at the Y(1) and Y(2) receptors, and >1000 nm at the Y(4) receptor. Activity studies performed in vitro using a cAMP enzyme immunoassay, and in vivo using food intake studies in rats, showed that the peptide acted as an agonist. Further peptides obtained by the combination of the Ala(31)-Aib(32) motif with chimeric peptides containing segments of NPY and pancreatic polypeptide displayed the same selectivity and even higher affinity (up to 0.2 nm) for the Y(5) receptor. In vivo administration of the new Y(5) receptor-selective agonists significantly stimulated feeding in rats. The NMR solution structures of NPY and [Ala(31),Aib(32)]NPY showed a different conformation in the C-terminal region, where the alpha-helix of NPY was substituted by a more flexible, 3(10)-helical turn structure.