Biomedical subjects

M Conrath

Publications and source records attributed to M Conrath.

At least 19 recordsLinked to original sources

PubMed2006

Stability of liquid metal drops affected by a high-frequency magnetic field.

The dynamic behavior of liquid metal drops submitted to a high-frequency magnetic field is investigated experimentally. The motivation for this study comes from the coating industry. In this industry, liquid metals showing a free surface held in a dome-type shape are evaporated by applying electromagnetic pressure. The Galinstan drops are placed on a curved glass plate. A ringlike inductor fed by an alternating electrical current generates the magnetic field. The surface contour of the drop is observed using a high-speed camera system. The data are analyzed by utilizing image processing methods. In the experiment, we vary the inductor current I and the drop volume V while the frequency is fixed at 20 kHz . Upon increasing the inductor current within the range 0 I(C), these symmetric states become unstable to capillary waves. The critical current (critical electromagnetic Bond number) as well as the critical mode number, the critical frequency, and the amplitudes of the waves depend strongly on the volume (Bond number).

Journal Article↗

PubMed2005

Identification of lumbar spinal neurons controlling simultaneously the prostate and the bulbospongiosus muscles in the rat.

Lumbar spinothalamic neurons in the lamina X of the L3-L4 spinal cord segment have been proposed to constitute the spinal ejaculation generator in male rats. Lumbar spinothalamic cells are immunoreactive for galanin and neurokinin-1 receptors. We previously showed that after injection of pseudorabies virus either in the bulbospongiosus muscle or in the prostate, retrogradely labeled cells in the L3-L4 segment also displayed galanin or neurokinin-1 receptor immunoreactivities, demonstrating a direct link between lumbar spinothalamic cells and two anatomical structures involved in the two phases of ejaculation i.e. the emission and the expulsion phases. In order to provide with a more precise anatomical support for the role of lumbar spinothalamic cells in controlling ejaculation, we injected simultaneously in male adult rats two strains of recombinant pseudorabies virus, expressing either beta-galactosidase (PRV-BaBlu) or green fluorescent protein (PRV-152) in the prostate and in the bulbospongiosus muscle, respectively. After 5 days, we performed multiple immunofluorescence experiments to detect PRV-BaBlu, PRV-152 and galanin or neurokinin-1 receptors in transverse sections of the L1-S1 segment. Double- and triple-labeled cells were counted using confocal laser scanning microscope. Double-labeled neurons with the two strains of pseudorabies virus were mainly found at the L3-L4 segment lateral to the central canal in lamina X and represented about 60% of the total number of pseudorabies virus-labeled neurons. All the double pseudorabies virus-labeled neurons also expressed lumbar spinothalamic and most of them neurokinin-1 receptor, identifying them as lumbar spinothalamic neurons. The convergence of retrograde labeling from prostate and bulbospongiosus muscle on the same lumbar spinothalamic cells strongly reinforce their role in the spinal control and coordination of the emission and expulsion of sperm.

Animals↗

PubMed2005

Galanin and neurokinin-1 receptor immunoreactive [corrected] spinal neurons controlling the prostate and the bulbospongiosus muscle identified by transsynaptic labeling in the rat.

Ejaculation requires the coordination of sympathetic, parasympathetic and somatic neural outputs. Timely occurrence of the emission and expulsion of sperm results from an interplay between spinal nuclei innervating the seminal tract and the sexual accessory glands including the prostate on the one hand, and on the other hand perineal striated muscles, particularly the bulbospongiosus muscle. A group of cells essential for ejaculation, located around the central canal and referred to as lumbar spinothalamic neurons have been recently identified. Lumbar spinothalamic neurons are immunoreactive for galanin and neurokinin-1 receptor. In order to investigate the anatomical relationships between lumbar spinothalamic neurons and both the prostate and the bulbospongiosus muscle, pseudorabies virus retrograde tracing technique was used combined with immunohistochemistry. Three to five days after pseudorabies virus injection in the bulbospongiosus muscle or the prostate in male rats, spinal cord sections were processed for double immunofluorescence against pseudorabies virus and galanin or neurokinin-1 receptor. Immunocytochemical experiments against pseudorabies virus and choline acetyltransferase were also performed to discriminate between motoneurons and preganglionic neurons, or interneurons. Spinal sections were examined with confocal laser scanning microscope. Three days after pseudorabies virus injection within the prostate and the bulbospongiosus muscle, sympathetic preganglionic neurons and motoneurons of the dorsomedial nucleus were retrogradely labeled, respectively. Five days after pseudorabies virus injection, transsynaptically labeled choline acetyltransferase-negative neurons were found mainly located in the medial gray surrounding the central canal from L1 to S1. At the L3-L4 level, most of transsynaptically labeled neurons were immunoreactive for galanin and to a lesser extent for neurokinin-1 receptor, strongly suggesting that they could be the lumbar spinothalamic cells. We have thus evidenced connections between these cells and motoneurons of the dorsomedial nucleus and both sympathetic and parasympathetic preganglionic neurons innervating the bulbospongiosus muscle and the prostate, respectively. These anatomical data reinforce the crucial role for lumbar spinothalamic cells in coordinating the spinal control of ejaculation.

Animals↗

PubMed2003

Expression and G-protein coupling of mu-opioid receptors in the spinal cord and dorsal root ganglia of polyarthritic rats.

Although chronic inflammatory pain is known to be associated with hypersensitivity to mu opioid receptor agonists, no evidence for changes in the expression and/or characteristics of central mu opioid receptors has yet been reported in relevant models of this type of pain. In the present study, both immunohistochemical and autoradiographic approaches were used to address this question in polyarthritic rats, on the 4th week after intradermal injection of complete Freund's adjuvant, when inflammatory pain was at its maximum. Immunohistochemical labeling with specific anti-mu opioid receptor antibodies and autoradiographic labeling with [3H]DAMGO showed an upregulation of mu opioid receptors in the dorsal root ganglia but no changes in the density of these receptors in the dorsal horn at the level of L4-L6 segments in polyarthritic compared to age-paired control rats. On the other hand, autoradiographic quantification of the concentration-dependent increase in [35S]GTP-gamma-S binding by the mu-opioid receptor agonist DAMGO did not show any significant differences within the lumbar dorsal horn between polyarthritic and control rats. These data indicate that chronic inflammatory pain caused by polyarthritis was associated with an increased expression of mu-opioid receptors in dorsal root ganglion sensory neurones that did not result in an increased spinal density of these receptors, in spite of their well established axonal transport in the central portion of primary afferent fibres to the dorsal horn. In contrast, axonal transport of mu-opioid receptors in the peripheral portion of these fibres probably accounts for the increased receptor density in inflamed tissues already reported in the literature.

Analgesics, Opioid↗

PubMed2002

Pre- and postsynaptic localizations of the CB1 cannabinoid receptor in the dorsal horn of the rat spinal cord.

Several lines of evidence show that endogenous and exogenous cannabinoids modulate pain transmission at the spinal level through specific cannabinoid-1 (CB1) receptors. Since anatomical data concerning spinal CB1 receptors are rather contradictory, we studied the cellular and subcellular localizations of the CB1 receptors by immunocytochemistry. Results show a dual pre- and postsynaptic localization of CB1 receptors. Presynaptic receptors are evidenced by the labeling of (1) heterogeneous dorsal root ganglion neurons and (2) axons of Lissauer's tract. Postsynaptic receptors are shown by the labeling of numerous interneurons in the outer part of lamina II. Double immunolabelings show that lamina II outer CB1 neurons, probably islet cells, may also contain GABA or nitric oxide synthase. Numerous CB1-containing neurons in lamina X are also immunostained with anti-nitric oxide synthase (NOS) antibody. Under the electron microscope, CB1 immunoreactivity is exclusively localized postsynaptically in both somatic and dendritic compartments. The absence of labeling on primary afferent axon terminals is discussed and compared to the absence of labeling on terminals or vesicle-containing dendrites of islet cells, where a presynaptic localization was expected according to data of the literature.

Afferent Pathways↗

PubMed2002

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.

Animals↗

PubMed2001

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.

Animals↗

PubMed2001

CB1-cannabinoid and mu-opioid receptor co-localization on postsynaptic target in the rat dorsal horn.

Cannabinoids and opioids interact in the control of nociception at the spinal level. Likely, several mechanisms are involved, with one of them being co-localization of cannabinoid and opioid receptors. In order to validate this hypothesis, a double labeling study of CB1 cannabinoid receptors and mu-opioid receptors in the dorsal horn of the rat spinal cord was performed. A strong co-localization of CB1 and mu-opioid receptors was observed in lamina II interneurons at the ultrastructural level. The physiological consequences of the co-localization are discussed.

Animals↗

PubMed2001

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.

Animals↗

PubMed1999

Immunocytochemical evidence of vesicular localization of the orphan transporter RXT1 in the rat spinal cord.

Rxt1, a member of the Na+/Cl- orphan transporter family, exhibits numerous features suggesting a role as plasma membrane transporter. Despite numerous attempts, its substrate has not yet been identified, although immunocytochemical studies have shown that Rxt1 distribution generally matches that of glutamate or GABA. In order to further characterize Rxt1, its detailed immunocytochemical distribution in the rat spinal cord and dorsal root ganglia was studied at both light microscope and ultrastructural levels. The widespread distribution of Rxt1 in spinal cord and ganglia cannot be correlated with any known classical or peptidergic transmitter. Rxt1 is expressed in a subpopulation of glutamatergic primary afferent fibers, in large and medium-sized ganglion cells, while small glutamate cells exhibit generally no Rxt1-like immunoreactivity. In the spinal cord, Rxt1-immunoreactive cell body distribution is quite ubiquitous since Rxt1 is expressed in all laminae in various neuronal types like interneurons, some projection neurons and motoneurons. Some of these neurons are cholinergic. At the electron microscope level, the peroxidase labeling was never localized to the plasma membrane, but rather associated with different organelles including the outer membrane of small synaptic vesicles and large granular vesicles. This localization resembles that of vesicular transporters detected with the same method and suggests that Rxt1, in contrast to other Na+/Cl- transporters, is expressed on vesicles. This was confirmed using a pre-embedding silver-intensified colloidal gold method. Indeed, most gold particles appeared to be localized into the axoplasm on synaptic vesicle accumulations; only few gold particles were observed close to the plasma membrane. These results suggest that Rxt1, despite its molecular characteristics predicting a plasma membrane localization, might be a vesicular transporter.

Animals↗

PubMed1999

Unexpected localization of the Na+/Cl--dependent-like orphan transporter, Rxt1, on synaptic vesicles in the rat central nervous system.

Numerous features of its primary structure demonstrate that the orphan transporter Rxt1 belongs to the Na+/Cl--dependent neurotransmitter plasma membrane transporter superfamily, which includes the dopamine, norepinephrine, serotonin and gamma-aminobutyric acid (GABA) transporters. Initial immunocytochemical investigations with affinity-purified antibodies have established that Rxt1 is localized, almost exclusively, in axon terminals of glutamatergic neurons and subsets of GABAergic neurons in the CNS. Further studies were carried out to determine its subcellular distribution. In a first series of experiments, PC-12 cells were transfected with plasmids encoding either the dopamine transporter or Rxt1. Immunofluorescence experiments showed that the dopamine transporter was expressed in these cells, and, as expected, addressed to their plasma membrane. Surprisingly, this was never the case with Rxt1, which was targeted to the same subcellular compartment as synaptophysin, a vesicular protein. In a second set of experiments, subcellular fractionation of rat striatum showed that Rxt1, but not the dopamine transporter, was relatively abundant in the purified synaptic vesicle fraction. Finally, electron microscopic immunocytochemistry with anti-Rxt1 antibodies showed peroxidase as well as pre- and post-embedding immunogold labelling confined to the intracellular compartment in various brain regions. Moreover, quantitative analysis of post-embedding experiments demonstrated that the immunogold particles corresponding to Rxt1 immunoreactivity were mostly localized to small synaptic vesicles. These data indicate that, in contrast with the other members of the Na+/Cl--dependent neurotransmitter transporter superfamily, which are targeted to the plasma membrane, Rxt1 is distributed as a vesicular protein in the CNS.

Animals↗

PubMed1998

The rat dermorphin-like immunoreactivity is supported by an aminopeptidase resistant peptide.

Site-directed antibodies against synthetic related dermorphin peptides were previously produced and characterized. One of them, which specifically recognizes the crucial 'opioid message' (the N-terminal part of the dermorphin molecule (i.e. Tyr-D-Ala-Phe-Gly) was selected in order to detect and locate endogenous dermorphin-like molecules in rat, mouse and guinea pig tissues. Dermorphin-like peptides were found to be present in tissues known to contain peptides such as neurons in the central nervous system, nerve fibers in the gut and B and T immune cells. With all the tissues assayed, the HPLC profile obtained on the immunoreactive material showed the same main peak eluted at a retention time of 32 +/- 1 min. The results of biochemical experiments in which enzymatic treatments were performed on the dermorphin-like immunoreactivity indicate the immunoreactivity is a peptide resistant to aminopeptidase hydrolysis. This finding suggests the presence of a residue conferring resistance to proteolytic processes of this kind, which is likely to be a D-amino acid residue.

Aminopeptidases↗

PubMed1998

Substance P receptor immunodetection in the spinal cord: comparative use of direct anti-receptor antibody and anti-complementary peptide antibody.

The immunolocalization of substance P (SP) receptors was compared in the rat spinal cord using either a direct anti-substance P NK1-receptor antibody (anti-SPR) or an anti-complementary peptide antibody (anti-CP). The first antibody recognizes an intracellular epitope, the C-terminal tail of the NK1-receptor. The second antibody recognizes an extracellular epitope located at or near the ligand-binding domain because anti-CP antibody and SP were previously shown to compete for binding to the receptor. At the light microscope level, it was observed that anti-CP antibody labels both laminae I and II of the dorsal horn, while anti-SPR antibody labels exclusively lamina I, except at the lumbar level. This could suggest that spinal NK1 receptors are heterogeneous. Anti-SPR antibodies may recognize an NK1 receptor subclass confined to lamina I. Conversely, anti-CP antibody may recognize either another receptor subclass or two different subclasses present in laminae I and II. At the electron microscope level, labeling was localized either on the intracellular or the extracellular face of the plasma membrane depending on the location of the epitope recognized by both antibodies on the transmembrane receptor. However, using either antibody, the ultrastructural labeling was found at non-junctional sites, suggesting that SP may act in a non-synaptic manner on all putative receptor subclasses.

Animals↗

PubMed1997

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.

Animals↗

PubMed1995

Ultrastructural study of substance P receptors in the dorsal horn of the rat spinal cord using monoclonal anti-complementary peptide antibody.

A monoclonal antibody directed against a peptide (PS5) specified by RNA complementary to the mRNA coding for substance P (SP), was used to label SP receptors in the rat spinal cord as demonstrated by light and electron microscopy. An immunocytochemical method (avidin-biotin-peroxidase) was used on vibratome sections from rats perfused with paraformaldehyde. Immunoreactivity was observed principally in the two superficial layers of the dorsal horn, in lamina X and the region of motoneurons. The labeling was absent when the antibody was preincubated with the complementary peptide (PS5) used as immunogen. Competition between the anti-complementary peptide antibody and different ligands was tested by preincubation of tissue sections with the ligand in the presence of peptidase inhibitors before addition of the antibody. A specific agonist (SP) or antagonist (spantide, RP 67580) at 10(-6)M led to total absence of labeling. These results indicate that under our experimental conditions, the anti-complementary peptide antibody recognizes a SP binding site in the rat spinal cord. Electron microscopic study of the two superficial laminae of the dorsal horn showed that immunolabeling was mainly localized extracellularly at apposing neuronal plasma membranes. It was mostly associated with axodendritic or axosomatic appositions. Occasionally labeling was observed between two axon terminals. In all cases, these appositions were non-junctional. Generally, neuronal processes involved in these appositions did not contain large granular vesicles. These observations suggest that SP may act in a diffuse, nonsynaptic manner probably on targets distant from SP release sites.

Amino Acid Sequence↗

PubMed1994

Ultrastructural study of delta-opioid receptors in the dorsal horn of the rat spinal cord using monoclonal anti-idiotypic antibodies.

The ultrastructural localization of delta-opioid receptors was studied using monoclonal anti-idiotypic antibody prepared with an anti-D-Ala2-D-Leu5-enkephalin. Immunocytochemical techniques were used on vibratome sections from rats perfused with paraformaldehyde. A high density of immunoreactivity was observed in the dorsal horn of the spinal cord, particularly the two superficial layers, the dorsolateral funiculus and the area surrounding the central canal. The labelling was absent when the antibody was preincubated with the immunogen. Competition between the anti-idiotypic antibody and different ligands, delta or mu, was controlled by preincubation of tissue sections with the ligand in the presence of peptidase inhibitors for 3-4 h before addition of the anti-idiotypic antibody. Enkephalin, dermenkephalin and naltrindole induced disappearance of the labelling at 10(-9) M while dermorphin or dermorphin Lys7 were ineffective at the same concentration. Lamina II of the dorsal horn was studied by electron microscopy. The immunolabelling was mainly localized on cell membranes at appositions between the two neurons. About one third were localized between an axon terminal and a dendrite, the same proportion of labellings were between two axon terminals. Labelling was occasionally observed at appositions between a glomerular terminal and a dendrite or a terminal or at axoglial appositions. Axosomatic localizations were rare. The presynaptic localization of the labelling is in favor of a presynaptic mechanism of action for delta-opioids in the spinal cord, providing that these receptors are functional. delta-Opioid peptides probably act non-synaptically since receptors were never localized on synaptic differentiations.

Animals↗

PubMed1994

Antipeptide polyclonal antibodies that recognize a substance P-binding site in mammalian tissues: a biochemical and immunocytochemical study.

We used complementary peptide methodology to obtain antibodies against the receptor for the neuropeptide substance P, specifically directed at the ligand-binding domain. Rabbits were immunized with two distinct peptides derived from the sequence of the RNA complementary to the mRNA for substance P. Binding experiments revealed that antipeptide polyclonal antibodies were able to recognize, through their paratope, a specific binding site on the rat parotid cell membranes. Substance P and antibodies competed for this binding site, because preincubation of membranes in the presence of substance P significantly reduced antibody binding, and conversely, preincubation of membranes in the presence of antibodies partly inhibited the binding of radioiodinated substance P. Immunocytochemical experiments performed on the rat cervical spinal cord show that the distribution of labeling by antibodies is similar to that observed by conventional autoradiography using 125I-substance P. Here again, control experiments demonstrated that antibodies and substance P were competing for the same binding site on the spinal cord. These biochemical and immunocytochemical data indicate that antipeptide antibodies recognize a substance P membrane binding site in nervous and nonnervous mammalian tissues. This site is likely to correspond to the NK1 specific receptor for substance P.

Amino Acid Sequence↗

PubMed1994

Expression of preproenkephalin A gene and presence of Met-enkephalin in dorsal root ganglia of the adult rat.

The expression of the preproenkephalin A gene was investigated in adult rat dorsal root ganglia (DRG). A radioimmunoassayable Met-enkephalin (ME)-like material was detected in 0.1 M HCl extracts of rat DRG, representing approximately 60 pg of ME equivalents/mg of protein. Chromatographic analyses indicated that the major component of the ME-like material coeluted with authentic ME. In northern blot experiments on total RNA extracted from DRG, a cDNA probe corresponding to the entire coding region of rat preproenkephalin A mRNA yielded a single band of the expected size for this mRNA, i.e., 1.5 kb. Polymerase chain reaction (PCR) experiments were carried out with DRG, striatum, and liver cDNAs using two primers flanking the 1,371-1,771 base region of the preproenkephalin A gene. Thirty PCR cycles performed on both striatum and DRG cDNAs generated a single band of 400 bp, as expected, whereas only trace amounts of this product were detectable using liver cDNAs. Nucleotide sequencing of the PCR product obtained with DRG cDNAs revealed a 100% homology with the 1,371-1,771 sequence of the preproenkephalin A gene. In situ hybridization with a cRNA probe showed that about 3.5% of DRG cells expressed the preproenkephalin A transcript. However, most of these cells probably did not process proenkephalin to enkephalins, as thorough immunohistochemical investigations with anti-ME antibodies allowed the detection of only one in approximately 6,000 cells (in 30 sections of DRG) that exhibited ME-like immunoreactivity. Cells expressing preproenkephalin A mRNA were intermediate-sized neurons, suggesting that primary afferent ME-containing fibers belong to the A category and may participate in a local (spinal) inhibitory control of nociception.

Amino Acid Sequence↗