Monoclonal antibodies to substance P: production, characterization of their fine specificities, and use in immunocytochemistry

Solid-Phase Immobilized Tripod for Fluorescent Renewable Immunoassay. A Concept for Continuous Monitoring of an Immunoassay Including a Regeneration of the Solid Phase

A new concept of immunoassay based on the use of a trifunctional reagent (tripod) and fluorescence resonance energy transfer (FRET) phenomenon is described. This procedure involves differential steps: (1) the tripod bearing (i) a fluorophore, (ii) a molecule structurally close to the target, and (iii) a linker reacts with the solid phase; (2) the solid phase is further activated with an anti-target antibody labeled with a quencher molecule, generating the decrease of the fluorophore emission via FRET; (3) FRET being distance dependent, the presence of the target by competing with the tripod for binding the quencher-labeled antibody leads to a rise of the fluorescence signal; (4) the solid phase is reactivated simply, by adding the quencher-labeled antibody. This method was evaluated in microtiter plates using the susbtance P as model while fluorescein and TAMRA were used as donor and acceptor, respectively. Results clearly illustrated the interest of the method, by allowing (i) a simple regeneration procedure, without requiring any drastic treatment, (ii) a direct fluorescence measurement onto the solid support, leading to a localized and cumulative signal, (iii) an increase of the signal when detecting the target, unlike classical competitive immunoassays, and (iv) a real-time monitoring of the competition and regeneration steps.

Enhancement of antibody responses in DNA vaccination using a vector encoding a universal T-helper cell epitope

DNA vaccination appears as a very promising approach to raise protective antibodies against a variety of proteins from pathogens or tumor cells, but is often hindered by the low immunogenicity of the genetic vectors used for the immunizations. To enhance the humoral response through improvement of the antigenic presentation of newly synthesized proteins upon vaccination, we engineered a plasmid coding for a low immunogenic protein (an scFv, i.e. the single-chain Fragment variable of a well-characterized antibody) fused to a small-size universal T-helper cell epitope derived from tetanus toxin, whose efficiency in classical protein-based immunization protocols has already been demonstrated. We found that immunization of C57Bl/6 mice using this vector greatly enhanced the production not only of specific antibodies recognizing essentially conformational epitopes on the undenatured scFv protein but also of antibodies against linear epitopes on the denatured protein. Since this T-epitope is known to be accommodated by several haplotypes of H-2 molecules in mice, as well as by various class II MHC molecules in humans, the results reported here allow us to conclude that this method could be of general interest for future applications of genetic immunization, including DNA-based vaccinations in humans.

The 5-HT2A receptor is widely distributed in the rat spinal cord and mainly localized at the plasma membrane of postsynaptic neurons

Serotonin (5-HT) plays a major role at the spinal level by modulating most spinal functions through several receptor subtypes including the 5-HT2A receptor. To gain further insight into the cellular role of this receptor, we performed an immunocytochemical study of 5-HT2A receptors in the rat spinal cord, at light and electron microscope levels. The results showed that 5-HT2A receptors were widely distributed in the spinal cord at all segmental levels. Immunolabeling was particularly dense in lamina IX and in the dorsal horn lamina IIi. Immunoreactive cell bodies were numerous in lamina IX, where many but not all motoneurons were labeled, as shown by double labeling with choline acetyltransferase antibodies. Stained cell bodies were also observed in the gray matter. The study at the ultrastructural level focused on the lumbar dorsal horn (laminae I-II) and ventral horn (lamina IX). At both levels, 5-HT2A immunoreactivity was mainly postsynaptic on dendrites and cell bodies. However, a little presynaptic labeling was also observed in axon and axon terminals, some of them containing large granular vesicles attesting to their peptidergic nature. The main result of our study was the "nonsynaptic" plasma membrane localization of 5-HT2A receptors covering a large surface of cell bodies and dendrites, suggesting a paracrine form of action of serotonin. These observations are consistent with a double role (pre- and postsynaptic) for serotonin on these receptors on various cellular targets.

CB1 cannabinoid receptors in amphibian spinal cord: relationships with some nociception markers

The role of cannabinoids in spinal analgesia has so far been investigated in mammals and the interactions between cannabinoid receptors and markers involved in nociception have been described in the rat spinal cord. An endocannabinoid system is well developed also in the amphibian brain. However, the anatomical substrates of pain modulation have been scarcely investigated in anamniotes, neither is there reference to such a role for cannabinoids in lower vertebrates. In the present paper we employed multiple cytochemical approaches to study the distribution of CB1 cannabinoid receptors and their morphofunctional relationships with some nociception markers (i.e. Substance P, nitric oxide synthase, GABA and mu opioid receptors) in the spinal cord of the anuran amphibian Xenopus laevis. We found a co-distribution of CB1 receptors with the aforementioned signaling molecules, as well as a more limited cellular co-localization, in the dorsal and central fields of the spinal cord. These regions correspond to the mammalian laminae I-IV and X, respectively, areas strongly involved in spinal analgesia. Comparison of these results with those previously obtained in the mammalian spinal cord, reveals a number of similarities between the two systems and suggests that cannabinoids might participate in the control of pain sensitivity also in the amphibian spinal cord.

Anti-allergen antibodies can be neutralized by antibodies obtained against a peptide complementary to the allergen: towards a new peptide therapy for allergy

The concept of specific immune treatment against allergic diseases requires the development of antibodies capable of specifically neutralizing anti-allergen antibodies. The aim of the present study was to investigate whether a novel approach, consisting in raising anti-idiotypic blocking antibodies through peptide immunization, could be envisaged in the field of allergy. Using allergy to cow's milk as a model, we prepared polyclonal antibodies against a peptide that is complementary (i.e. hydropathically opposed) to a major epitope of bovine beta-lactoglobulin (BLG), one of the main allergens of bovine milk. Anti-complementary peptide antibodies were found to neutralize in vitro both well-characterized anti-BLG monoclonal antibodies from mice sensitized to BLG and anti-BLG IgE from two patients suffering from milk allergy. These results suggest a new strategy for the functional inhibition of specific disease-associated IgE that may be applicable to the specific treatment of various allergic disorders.

Pharmacological in vitro evaluation of new substance P-cyclodextrin derivatives designed to drug targeting towards NK1-receptor bearing cells

Some biological properties of new bifunctional conjugates designed for drug targeting were evaluated through in vitro experiments. Eight peptidylcyclodextrin compounds were used, which correspond to modified beta- or gamma-cyclodextrin (CD) grafted on neuropeptide substance P (SP) or a shorter derivative (SP(4-11)). Using anti-SP and anti-CD antibodies as molecular probes, we showed that the main structural features of the two moieties of these adducts were preserved. Binding experiments, using CHO cells expressing the human SP-specific NK1 receptor, demonstrated the functionality of all peptidylcyclodextrin derivatives, which exhibited IC50 values in a 10(-9)-10(-7) M range. All compounds were able to induce a pharmacological response, triggering phosphatidylinositol turnover with EC50 values in the same range as the natural ligand. Moreover, autoradiography analysis of rat spinal corn sections proved that [125I]SP binding was dose-dependently displaced by one selected compound (a gamma-CD-SP), showing a similar affinity of this adduct for the rat neurokinin 1 receptor. Our observations demonstrate that these peptidylcyclodextrins efficiently target NK1 receptor-expressing cells.

Distribution and ultrastructure of tachykinin-like immunoreactivity in the frog (Rana esculenta) spinal cord, notably, the dorsal horn

Tachykinins are involved in pain transmission at the spinal level. In frog, at least four tachykinins [TK] have been isolated from the brain, but their organization in the dorsal horn of the spinal cord is still poorly known. We have reexamined TK distribution by immunocytochemistry using an antibody recognizing the sequence common to all tachykinins in the spinal cord and dorsal root ganglia of the green frog Rana esculenta. A dense tachykinin-like immunoreactivity (TK-LI) was observed in the dorsolateral fasciculus or Lissauer's tract running ventromedial to the entry of the dorsal root and in numerous small and medium-sized dorsal root ganglion cells showing a primary afferent origin for part of TK-LI of the dorsal horn. The observation of numerous cell bodies in the dorsal horn, in addition, suggested a local or propriospinal origin. One group of cells was localized at the entrance of the Lissauer's tract TK-LI fibers into the dorsal horn, and another group was localized in the upper dorsal horn, a region with a low density of TK-LI fibers. It was suggested that the latter group may correspond to neurokinin B. Electron microscopic examination of the Lissauer's tract showed numerous immunoreactive axons, some located at the center of glomerular-like arrangements, suggesting that the information brought by these fibers may be transmitted and most probably modulated before their entry in the dorsal horn. In conclusion, the functional organization of tachykinins in the frog spinal cord seems to be similar to that of mammals, albeit with a different morphological organization.

Quantitative measurement of bitagged recombinant proteins using an immunometric assay: application to an anti-substance P recombinant antibody

We have developed two different immunometric assays to directly quantify both the total and the active fractions of a recombinant antibody (single chain fragment variable, or ScFv) as obtained in a crude extract from an Escherichia coli expression system. For total determination, the assay is based on the simultaneous recognition of two different peptide Tag sequences (Ha-Tag and Myc-Tag) at each of the N- and C-terminal extremities of the recombinant protein. A monoclonal antibody (mAb 12CA5, directed against Ha-Tag), coated on microtiter plates, is used for capture, and the mAb 9E10 (directed against Myc-Tag), labeled with acetylcholinesterase (AChE, EC 3.1.1.7), acts as tracer. In parallel, for the determination of the active fraction, the capture is performed using microtiter plates coated with the antigen, while solid-phase-immobilized ScFv is measured using the same 9E10 tracer mAb. A synthetic peptide in which the two Tag sequences were joined was used as a standard, thus avoiding the laborious purification of a recombinant protein as reference. The method was applied to the direct measurement, in periplasmic extracts, of the total and active fractions of an ScFv produced at different induction temperatures.

Muscarinic M2-receptors in rat thoracic dorsal root ganglia

The occurrence and distribution of the muscarinic M2-receptor subtype (M2R) was investigated in rat thoracic dorsal root ganglia (DRG). Messenger RNA for M2R was demonstrated by RT-PCR in total RNA from DRG. Immunoreactivity to M2R-protein was localized to 26% of sensory neurons, the majority of them (85%) belonging to the size class of 25-40 microm in diameter. Double-labeling (immuno)histochemistry revealed that all M2R-immunoreactive neurons bind the lectin, I-B4, whereas they are generally devoid of substance P-immunoreactivity. These data show the presence of M2R on a subpopulation of presumably nociceptive primary afferent neurons, thereby extending previous pharmacological and electrophysiological studies that indicated a role of M2R and/or M4R in inhibition of calcium channel currents in rat sensory neurons (Wanke, E., Bianchi, L., Mantegazza, M., Guatteo, E., Macinelli, E. and Ferroni, A., Muscarinic regulation of Ca2+ currents in rat sensory neurons: channel and receptor types, dose-response relationships and cross-talk pathways. Eur. J. Neurosci., 6 (1994) 381-391).

A monoclonal antibody to the ligand-binding domain of the neurokinin 1 receptor (NK1-R) for the neuropeptide substance P

Monoclonal antibodies to the binding site of the NK1 receptor for the neuropeptide substance P were produced in mice using the complementary or antisense peptide methodology. Among several anti-peptide monoclonal antibodies, we selected the mAb12 antibody which specifically crossreacted, through its paratope, with a binding site present on membranes from rat parotid gland cells, with an affinity close to 2 x 10(-7) M and with membranes from CHO cells expressing human brain NK1 receptors. Immunocytochemical investigations using mAb12 revealed immunostaining whose distribution in the dorsal horns of rat spinal cord fits well with the known location of NK1 receptors. In both biochemical and immunocytochemical experiments, the competition occurring between the antibody and substance P, or a substance P-protein conjugate, indicates that mAb12 recognizes a membrane epitope located at or near the substance P binding domain on the NK1 receptor. Immunization of mice with mAb12 led to the production of specific anti-substance P antibodies, again suggesting that mAb12 shares common structural features with the neuropeptide. This monoclonal antibody can now be used in further biochemical or cytochemical characterizations of NK1 receptors. Owing to its fine specificity, mAb12 could also serve as a molecular model for designing peptides, possibly displaying pharmacological properties in the various processes in which substance P is involved, e.g. immunomodulation, inflammation or chronic pain.

Use of conformationally constrained peptides for a topographical analysis of the combing site of a monoclonal anti-substance P antibody

The topography of the binding site of a monoclonal anti-substance P antibody directed toward the C-terminal pentapeptide of substance P, Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2, was analyzed further using a wide range of constrained analogues of substance P. Results obtained in the present study show the following: (a) The binding subsites of Phe7 and Phe8 are large and deep, accommodating various side chains, including nonaromatic amino acids. (b) In contrast, the binding pockets for Gly-Leu-Met-NH2 appear more restrictive. Consequently, five residues in the peptide are necessary for the high binding affinity to the antibody, the C-terminal tripeptide determining the binding specificity. These data, which appear to contradict those previously published, illustrate the limits of conclusions drawn from studies generally carried out using exclusively Ala-substituted peptides. In addition, the present results indicate that the topography of the binding site of this monoclonal antibody differs from that of the specific substance P neurokinin-1 receptor, in agreement with the differences observed in the fine specificities of these two substance P binding macromolecules.

Prevaccination with diluted Freund adjuvant prevents the development of chronic pain and transient release of cerebrospinal fluid substance P in adjuvant-induced arthritis in rats

Parallel time courses of preclinical and behavioural pain-related parameters and levels of substance P-like immunoreactivity in plasma (plasma-SPLI) and cerebrospinal fluid (CSF-SPLI) were studied in 2 groups of rats injected with an arthritogenic solution (concentrated Freund adjuvant) over a 9-week post-infection (PI) period; 1 group was pretreated with saline (control) and 1 pretreated with diluted Freund adjuvant (immunized). In control rats all symptoms of adjuvant-induced arthritis (AIA) developed while in immunized rats AIA symptoms were significantly reduced or did not appear. A significant increase in plasma-SPLI was obvious as early as the 2nd week PI and remained at this level in both groups of animals until the end of the 9-week PI observation period, but with a significantly higher increase in control versus immunized group at all stages. In contrast, CSF-SPLI transiently peaked only in the control group at 3 weeks PI whereas CSF-SPLI values did not differ from one week to another in both groups of rats. These results suggest that successive injections of diluted Freund adjuvant impairs the development of chronic inflammation and pain in AIA in rats, as well as the transient increase in SP release in CSF at 3 weeks PI, but not the long-lasting increased SP release in plasma. Since there is a clear dissociation between our biochemical and preclinical and behavioral data, this study does not provide evidence for the role of substance P as a possible biologic marker of chronic pain either in plasma or in CSF.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuronal phenotypes in mouse dorsal root ganglion cell cultures: enrichment of substance P and calbindin D-28k expressing neurons in a defined medium

The primary sensory neurons in mouse dorsal root ganglia consist of diversified subpopulations which express distinct phenotypic characteristics such as substance P or calbindin D-28k. To determine whether neuronal phenotypes are altered or not in in vitro cultures carried out in a defined synthetic medium, dissociated dorsal root ganglion cells from newborn mice were grown in the alpha-modified minimum essential medium either supplemented with 10% fetal calf serum or serum-free. About 80% of the neurons survived after 5 days of culture in both media, but only 35% or 65% were rescued after 12 days in serum-free or fetal calf serum supplemented medium, respectively. The neuronal subpopulations expressing substance P or calbindin D-28k displayed similar morphological properties in both media and a higher resistance to culture conditions than the whole neuronal cell population, especially in serum-free medium. It is therefore concluded that a defined synthetic medium offers reproducible conditions to culture dorsal root ganglion cells for at least 5 days, stimulates the expression of substance P and enriches preferentially neuronal phenotypes expressing substance P or calbindin D-28k, for a longer period of culture.

Effects of intranigral injections of colchicine on the expression of some neuropeptides in the rat forebrain: an immunohistochemical and in situ hybridization study

In the present study, we describe the neurochemical effects of intranigral injections of colchicine in the rat forebrain using immunohistochemistry and in situ hybridization. The observations on the injected side are compared to the contralateral one and to the sham-operated rats. We demonstrate that such injections are able to strongly enhance the immunoreactivity for Met-enkephalin (ME), substance P (SP) and neuropeptide Y (NPY) in numerous nerve cell bodies of the limbic system (injected side), whereas the levels of the corresponding mRNAs are differently modified according to the region examined. A clear correlation between the enhancement of the immunostaining for ME and SP and that of the preproenkephalin (PPA) and preprotachychinin gene transcripts was observed in neuronal perikarya of the medial amygdaloid nucleus (SP), of the dorsolateral hypothalamus (ME) and of the ventromedial hypothalamic nucleus (SP). These observations are interpreted as an induction--or increased expression--of neuropeptide genes in neuronal perikarya postsynaptic to nerve fibers originating in the midbrain and brain stem. In this case, colchicine is thought to block the electrophysiological activity of ascending nerve fibers (anterograde and postsynaptic effect). In the case where the enhancement of the immunoreactivity for the studied neuropeptides was associated with no change or a decreased expression of the corresponding genes in the same brain areas, colchicine may have blocked the axoplasmic transport of peptides in nerve fibers projecting to the midbrain and/or brain stem (6). This may result in a retrograde accumulation of peptides in the nerve cell bodies of origin and, eventually, in a negative feedback regulation of the corresponding encoding genes in these perikarya (retrograde and presynaptic effect of colchicine). The drastic behavioral effects of bilateral intranigral injections of colchicine, on ingestive behavior in particular, have been studied in a following paper.

Time course of variations in rabbit cerebrospinal fluid levels of calcitonin gene-related peptide- and substance P-like immunoreactivity in experimental subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Cerebral vasospasm after subarachnoid hemorrhage may result partially from the imbalance between vasodilator and vasoconstrictor factors. The vasodilator peptides substance P and calcitonin gene-related peptide contained in the trigeminovascular system are involved in the vasomotor phenomenon occurring after subarachnoid hemorrhage. The delayed arterial narrowing may reflect the time course of the release of these peptides. Therefore, we followed the time course of the changes in cerebrospinal fluid immunoreactivity of substance P and calcitonin gene-related peptide in a model of experimental subarachnoid hemorrhage.

METHODS

Cerebrospinal fluid samples were taken in the basal state and at 30 minutes, 24 hours, and 3 days after a single injection of 1 mL autologous arterial blood into the cisterna magna of rabbits using a percutaneous suboccipital route. Substance P-like and calcitonin gene-related peptide-like immunoreactivities were determined in centrifuged cerebrospinal fluid and plasma by use of enzyme immunoassay.

RESULTS

Early (30 minutes) after induced subarachnoid hemorrhage, there was a large increase in cerebrospinal fluid substance P-like immunoreactivity (P < .01) and calcitonin gene-related peptide-like immunoreactivity (P < .01). Arterial and hemorrhagic cerebrospinal fluid levels of substance P-like immunoreactivity were different (P < .03), indicating that the increased cerebrospinal fluid level did not result only from the blood contamination. Twenty-four hours after induced subarachnoid hemorrhage, the immunoreactivities of substance P and calcitonin gene-related peptide remained significantly higher than the basal level (P < .01). At day 3, both immunoreactivities had decreased to a level nonsignificantly different from the basal level.

CONCLUSIONS

The early high values of the cerebrospinal fluid immunoreactivities for substance P and calcitonin gene-related peptide, apart from the contamination by arterial blood, probably resulted from the depletion of neurotransmitter peptides from the trigeminovascular fibers.

Calbindin D-28k- and substance P-immunoreactive primary sensory neurons: peripheral projections in chick hindlimbs

The peripheral projections of two distinct subpopulations of primary sensory neurons, expressing either calbindin D-28k or substance P, were studied in chick hindlimbs by immunodetecting calbindin D-28k with a rabbit antiserum and substance P with a mouse monoclonal antibody. Calbindin D-28k-immunoreactive axons provided an innervation restricted to specific mechanoreceptors such as muscle spindles, Herbst and Merkel corpuscles, or collars of feather follicles but were absent from Golgi tendon organs. In contrast, substance P-positive axons spread out diffusely in muscles and skin, formed loose plexuses, and extended free branches to the endomysium, arteries, superficial dermis, or dermal pulp of feather follicles. The present results show that calbindin D-28k- and substance P-immunoreactive primary sensory neurons provide distinct modes of innervation to selective targets in peripheral tissues. The results suggest a possible correlation between CaBP-expressing nerve endings and rapidly adapting mechanoreceptors.

Neurochemistry, connectivity and plasticity of small intensely fluorescent (SIF) cells in the rat superior cervical ganglion

Applying double-labelling immunofluorescence, the peptide content of solitary and clustered small intensely fluorescent (SIF) cells, identified by an antiserum to a selective membrane glycoprotein marker, synaptophysin, was correlated with the presence of catecholamines in the rat superior cervical ganglion. Most of synaptophysin-immunoreactive solitary and clustered SIF cells apparently contained dopamine (indicated by tyrosine hydroxylase-TH) but not noradrenaline (indicated by dopamine-beta-hydroxylase-DBH). Frequently, immunoreactivities for substance P or rarely, neuropeptide Y were colocalized in TH-immunolabeled cells of both types. Immunostaining for vasoactive intestinal polypeptide was found only in solitary SIF cells and was visible in TH-immunoreactive, as well as in TH-nonreactive cells. Very few solitary SIF cells were TH- and DBH-immunoreactive. Solitary and clustered SIF cells, as a rule, were encircled by leu-enkephalin-positive fibres which were also met-enkephalin-arg6-phe7-immunoreactive, indicating proenkephalin as precursor. SIF cells were additionally approached by varicose fibres which contained immunoreactivity for calcitonin gene-related peptide (CGRP) but not for enkephalins. As observed by immuno-electronmicroscopy, fibres that were immunostained for leu-enkephalin or CGRP, deeply invaginated into SIF cell somata. In addition to close membrane appositions, CGRP-immunolabeled fibres exhibited efferent synaptic contacts wih elements of SIF cell clusters. SIF cells were non-reactive to enkephalin-antisera in control ganglia and after transection of the postganglionic nerves (axotomy); but both types exhibited leu-enkephalin in preganglionically transected ganglia (decentralization) in which enkephalin-immunoreactive fibre baskets were absent. Synthesis of enkephalin in SIF cells after decentralization was confirmed by in situ hybridization demonstrating intracytoplasmic proenkephalin messenger-RNA. The findings are indicative for a differential neurochemical equipment of SIF cells in the rat superior cervical ganglion, which mainly is independent to a topographical classification. Moreover, they demonstrate the involvement of two neuropeptides in preganglionic SIF cell innervation. Finally, the observations indicate the capacity of SIF cells for proenkephalin-expression in response to preganglionic denervation.

Fine distribution of substance P-like immunoreactivity in the dorsal nucleus of the vagus nerve in cats

The ultrastructure of substance P (SP)-immunoreactive elements in the cat dorsal motor nucleus of the vagus nerve was examined using pre- and post-embedding immunocytochemical procedures. Substance P-like immunoreactivity was observed in axon terminals and axon fibres which were mostly unmyelinated. Quantitative data showed that at least 16% of axon terminals contained SP. Their mean diameter was larger than that of their non-immunoreactive counterparts. Most (83%) SP-containing terminals were seen to contact dendrites but some were observed adjoining soma or entirely embedded in the cytoplasm of vagal neurons (4.5%). Only 0.5% were observed to contact soma of internuerons. A few immunoreactive axon terminals (4%) were observed in contact with non-immunoreactive axon terminals. Round agranular vesicles and numerous dense core vesicles were visible in most SP-containing axon terminals (84.6%). The immunogold procedure showed the preferential subcellular location of SP to be dense core vesicles. In 32.4% of cases, SP-containing terminals were involved in synaptic contacts that were generally of the asymmetrical Gray type 1 and mainly apposed dendrites. The theoretical total of synaptic contacts was 74.5% and this suggests the existence of weak non-synaptic SP innervation involving approximately 25% of SP-containing axon terminals. No axo-axonic synapses were observed in the dorsal vagal nucleus. These results support the hypothesis that SP found in the dorsal vagal nucleus originates partly from vagal afferents and is involved in direct modulation of visceral functions mediated by vagal preganglionic neurons.

Properties of monoclonal antibodies to thyroliberin (TRH) induced by different immunogens: comparison with pituitary TRH receptor

Thyroliberin E-H-P-NH2 (TRH) is a small neuropeptide pGlu-His-Pro-NH2 widely distributed in neural sites. The aim of this work was to obtain an antibody molecule with the nearest properties to that of TRH-receptor in GH3 cells. Different TRH-protein conjugates were prepared and utilized to induce monoclonal antibodies in mice. Several monoclonal antibodies were obtained using E-H-P-NH2 (TRH) coupled either to the histidyl residue (immunogen I) or to the prolyl residue (immunogen II). Antibodies generated using immunogen I and immunogen II were characterized in a radioimmunoassay system and an enzyme immunoassay system respectively. Their selectivities regarding a series of TRH related peptides were compared to those of rabbit polyclonal antibodies using three differently labelled TRH (tritiated-TRH, mono-iodinated-TRH and TRH-OH-acetyl-cholinesterase) as tracers and to prolactin secreting cells TRH receptors using 3H-TRH. Whatever the immunogen, the stereospecificity of monoclonal antibodies tested were found more different from TRH receptor characteristics than rabbit polyclonal antibodies.

Quantitative analytical mass spectrometry of endogenous neuropeptides in human pituitaries

This manuscript reviews state-of-the-art mass spectrometric (MS) methodology for the qualitative (amino acid sequence determination) and quantitative analysis of opioid neuropeptides in human pituitary tissue. Those analytical data are required for the elucidation of the basic molecular mechanisms involved in tumor formation and to test the hypothesis that metabolic defects in neuropeptidergic system processing is a contributing factor to human anterior pituitary tumor formation. Several different neuropeptide products that derive metabolically from the proenkephalin A and proopiomelanocortin (POMC) precursors have been analyzed separately and together in human pituitaries, including post-mortem controls and post-surgical tumors. The quantification, with optimal molecular specificity, of a peptide in a tissue is an important measurement because the amount of an endogenous peptide reflects the ratio of its synthesis to its degradation and thus, any defects in those processes may be reflected in the amount of a peptide.

Expression of substance P and preprotachykinin mRNA by primary sensory neurons in culture: regulation by factors present in peripheral and central target tissues

Primary sensory neurons display various neuronal phenotypes which may be influenced by factors present in central or peripheral targets. In the case of DRG cells expressing substance P (SP), the influence of peripheral or central targets was tested on the neuronal expression of this neuropeptide. DRG cells were cultured from chick embryo at E6 or E10 (before or after establishment of functional connections with targets). Preprotachykinin mRNA was visualized in DRG cell cultures by either Northern blot or in situ hybridization using an antisense labeled riboprobe, while the neuropeptide SP was detected by immunostaining with a monoclonal antibody. In DRG cell cultures from E10, only 60% of neurons expressed SP. In contrast, DRG cell cultures performed at E6 showed a significant hybridization signal and SP-like immunoreactivity in virtually all the neurons (98%). The addition of extracts from muscle, skin, brain or spinal cord to DRG cells cultured at E6 reduced by 20% the percentage of neurons which express preprotachykinin mRNA and SP-like immunoreactivity. Our results indicate that factors issued from targets inhibit SP-expression by a subset of primary sensory neurons and act on the transcriptional control of preprotachykinin gene.

Substance P-like-immunoreactive sensory neurons in dorsal root ganglia of the chick embryo: ontogenesis and influence of peripheral targets

The expression of substance P (SP) was studied in sensory neurons of developing chick lumbosacral dorsal root ganglia (DRG) by using a mixture of periodic acid, lysine and paraformaldehyde as fixative and a monoclonal antibody for SP-like immunostaining. The first SP-like-immunoreactive DRG cells appeared first at E5, then rapidly increased in number to reach a peak (88% of ganglion cells) at E8, and finally declined (59% at E12, 51% after hatching). The fall of the SP-like-positive DRG cells resulted from two concomitant events affecting a subset of small B-neurons: a loss of neuronal SP-like immunoreactivity and cell death. After one hindlimb resection at an early (E6) or late (E12) stage of development (that is before or after establishment of peripheral connections), the DRG were examined 6 days later. In both cases, a drastic neuronal death occurred in the ispilateral DRG. However, the resection at E6 did not change the percentage of SP-like-positive neurons, while the resection at E12 severely reduced the proportion of SP-like-immunoreactive DRG cells (25%). In conclusion, connections established between DRG and peripheral target tissues not only promote the survival of sensory neurons, but also control the maintenance of SP-like-expression. Factors issued from innervated targets such as NGF would support the survival of SP-expressing DRG cells and enhance their SP content while other factors present in skeletal muscle or skin would hinder SP expression and therefore lower SP levels in a subset of primary sensory neurons.

Anti-substance P anti-idiotypic antibodies modulate the secretory process in the rat parotid gland in vitro

Anti-idiotypic antibodies (anti-Id) obtained in rabbits in response to immunization with polyclonal anti-substance P antibodies (anti-SP) were shown to bind specifically and with high affinity to membranes from rat parotid gland cells. Whereas substance P (SP) was unable to displace anti-Id from membrane binding sites, anti-Id partly inhibited the binding of radiolabelled substance P. Like substance P, anti-Id were able to trigger protein secretion by parotid cells i.e. to behave as physiological agonists of the neuropeptide. Under our experimental conditions, the biological effects of both ligands appear to be additive. Unlike substance P, however, anti-Id did not potentiate the secretory response induced by a beta-adrenoceptor agonist. Taken together, the present results might indicate that anti-Id interact with epitope(s) at or/and near the peptide-combining site on the substance P receptor. These data demonstrate further the possibility of raising pharmacologically active anti-receptor antibodies through the immunological anti-idiotypic approach.

Use of anti-idiotypic antibodies as probes for in vitro and in vivo identification of substance P receptor

In order to develop immunological tools for studying the receptor of the neuropeptide substance P (SP), anti-idiotypic antibodies (anti-Id abs) were produced by immunization with anti-SP antibodies whose specificity was close to that of the SP receptor. Immunological studies revealed structural similarity between some anti-Id abs and SP itself. As a consequence, these anti-Id abs were able to bind to mammalian SP receptors. These antibodies were used in immunocytochemistry to label SP receptors both in the rat spinal cord and in rat and guinea pig peripheral tissues (parotid gland and trachea, respectively). Like SP, anti-Id abs were able to trigger protein secretion by isolated rat parotid gland cells. Finally, it was shown that anti-Id abs in vivo modulated reactivity to chemical stimuli. These antibodies therefore appear to be promising tools for further biochemical, cytochemical, and pharmacological characterization of SP receptors.

Detailed immunoautoradiographic mapping of enkephalinase (EC 3.4.24.11) in rat central nervous system: comparison with enkephalins and substance P

The metallopeptidase enkephalinase known to participate in the inactivation of endogenous enkephalins and, possibly, other neuropeptides such as tachykinins, was visualized by autoradiography using a [125I]iodinated monoclonal antibody. A detailed mapping of the enzyme in rat brain and spinal cord was established on 10-micron serial sections prepared in a frontal plane as well as a few sections in a sagittal plane. On adjacent sections, and for the purpose of comparison, substance P-like and enkephalin-like immunoreactivities were also visualized by autoradiography using a 125I-monoclonal antibody and a polyclonal antibody detected by a secondary 125I-anti-rabbit antibody respectively. Histological structures were identified on adjacent Nissl-stained sections. Using the highly sensitive 125I-probe, enkephalinase immunoreactivity was found to be distributed in a markedly heterogeneous manner in all areas of the central nervous system. Immunoreactivity was undetectable in white matter areas, for example the corpus callosum or fornix, and had a laminar pattern in, for example, the cerebral cortex or hippocampal formation. Hence, although immunodetection was not performed at the cellular level, a major neuronal localization of the peptidase is suggested. The latter is consistent with the detection of a strong immunoreactivity in a pathway linking the striatum to the globus pallidum, the entopeduncular nucleus and the substantia nigra, as well as with a series of biochemical and lesion data. The strong immunoreactivity also present in choroid plexuses and ependymal cells as well as in the intermediate lobe and in scattered cells of the anterior lobe of the pituitary suggests that populations of glial and endocrine cells also express the peptidase. The highest density of enkephalinase immunoreactivity was observed in basal ganglia and limbic areas (caudate putamen, globus pallidus, nucleus accumbens, olfactory tubercles) as well as in areas involved in pain control mechanisms (superficial layers of the spinal nucleus of the trigeminal nerve or of the dorsal horn of the spinal cord) which also display the highest immunoreactivities for both enkephalins and substance P (except in globus pallidus for the latter). These localizations account for the opioid-like analgesic and motor effects of enkephalinase inhibitors inasmuch as a selective or predominant participation of the peptidase in enkephalin inactivation is assumed. A number of other areas appear richly endowed in both enkephalinase and enkephalins whereas substance P is hardly detectable. This is particularly the case for the olfactory bulb, bed nucleus of the accessory olfactory tract, the cerebellum (where enkephalinase mainly occurs in the molecular layer) and the hippocampal formation (namely in the molecular layer of the dentate gyrus).(ABSTRACT TRUNCATED AT 400 WORDS)

Increased reactivity to chemical but not to heat noxious stimuli in mice producing anti-idiotypic antibodies for substance P

Mice immunized against anti-substance P (anti-SP) monoclonal antibodies produced anti-SP anti-idiotypic antibodies (SPAb2). In a previous report. SPAb2 antibodies were found to have in vitro biological activity i.e. to behave either as agonists or as antagonists for substance P (SP) depending on the biological test. In this study, the involvement of SPAb2 in in vivo biological activity has been tested. Because of the possible implication of SP in the generation and transmission of nociceptive information, we have tested the responsiveness of SPAb2 responding mice in behavioral nociceptive tests. SPAb2 mice showed very small behavioral variations in the hot plate test as compared with a control group of mice immunized against an unrelated monoclonal antibody. In the formalin test, however, SPAb2 mice displayed a significant increase in paw licking time, which was significantly correlated with SPAb2 serum concentration. These results are discussed in terms of the use of SPAb2 as pharmacological tools for studying the biological properties of SP receptors and more generally of auto anti-idiotypic antibodies in modulating behavioral responses.