Elements of angiotensin system are involved in leeches and mollusks immune response modulation.

We present immunocytochemical, biochemical and cellular evidences for the presence of a renin-angiotensin system (RAS) in coelomocytes of invertebrates (leech, Theromyzon tessulatum and mollusk Mytilus edulis). Leech coelomocytes are immunoreactive to polyclonal antisera raised against the T. tessulatum angiotensin-converting enzyme (ACE) and leech brain angiotensin II (AII) and a commercial anti-AT1 receptor. Biochemically, renin, ACE- and AT1-like receptor were identified in the leech immune cells. We further demonstrate that leech AII (10(-6) M) alone does not initiate nitric oxide (NO) release in invertebrate immunocytes but does only after pre-exposing the cells to IL-1 (15.9+/-2.6 nM; P<0.005 vs. 1.1 nM when AII is added alone). Similar results were obtained with human leukocytes (14.5+/-2.7 nM; P<0.005 IL-1+AII vs. 0.9 nM when AII is added alone). Then, an immunocytochemical study performed at the structural and ultrastructural levels confirmed the presence in same immune cells all the molecules of the renin-angiotensin system (RAS) in leeches as epitopes to IL-1-like protein and IL-1-like receptor. This is the first report in invertebrates and of a co-action between cytokines like substances and neuropeptides in an immune process and the involvement of the RAS in modulation of the immune response.

Evidence for an endocannabinoid system in the central nervous system of the leech Hirudo medicinalis.

In invertebrates, like Hydra and sea urchins, evidence for a functional cannabinoid system was described. The partial characterization of a putative CB1 cannabinoid receptor in the leech Hirudo medicinalis led us to investigate the presence of a complete endogenous cannabinoid system in this organism. By using gas chromatography-mass spectrometry, we demonstrate the presence of the endocannabinoids anandamide (N-arachidonoylethanolamine, 21.5+/-0.7 pmol/g) and 2-arachidonoyl-glycerol (147.4+/-42.7 pmol/g), and of the biosynthetic precursor of anandamide, N-arachidonylphosphatidyl-ethanolamine (16.5+/-3.3 pmol/g), in the leech central nervous system (CNS). Anandamide-related molecules such as N-palmitoylethanolamine (32.4+/-1.6 pmol/g) and N-linolenoylethanolamine (5.8 pmol/g) were also detected. We also found an anandamide amidase activity in the leech CNS cytosolic fraction with a maximal activity at pH 7 and little sensitivity to typical fatty acid amide hydrolase (FAAH) inhibitors. Using an antiserum directed against the amidase signature sequence, we focused on the identification and the localization of the leech amidase. Firstly, leech nervous system protein extract was subjected to Western blot analysis, which showed three immunoreactive bands at ca. approximately 42, approximately 46 and approximately 66 kDa. The former and latter bands were very faint and were also detected in whole homogenates from the coelenterate Hydra vulgaris, where the presence of CB1-like receptors, endocannabinoids and a FAAH-like activity was reported previously. Secondly, amidase immunocytochemical detection revealed numerous immunoreactive neurons in the CNS of three species of leeches. In addition, we observed that leech amidase-like immunoreactivity matches to a certain extent with CB1-like immunoreactivity. Finally, we also found that stimulation by anandamide of this receptor leads, as in mammals, to inhibition of cAMP formation, although this effect appeared to be occurring through the previously described anandamide-induced and CB1-mediated activation of nitric oxide release. Taken together, these results suggest the existence of a complete and functional cannabinoid system in leeches.

Cellular localization of a renin-like enzyme in leeches.

OBJECTIVES: The purpose of this study was to localize in leeches the renin-like enzyme previously characterized as well as the leech angiotensin-converting like enzyme (ACE). METHODS: Immunocytochemical as well as whole mount experiments were performed with an antibody raised against a fragment of the leech renin-like enzyme (VLWAAEKTQLDTGSS) and with anti-leech ACE. RESULTS: Anti-leech renin stains the vascular pole of the glomerulus and the afferent arteriole of the rat kidney. Immunostaining of leech sections revealed labeling in neurons and glial cells of the central nervous system (CNS), immunocytes and the nephridial canal, canaliculi and the periphery of the ciliated funnel, as well as the epithelium lining nephridia. Co-localization between antibodies raised against this fragment and a fragment of leech angiotensin-converting enzyme was demonstrated in neurons and glial cells of the leech CNS, as in vertebrates MAIN FINDING: Leech renin is localized in leeches like in vertebrate in the excretory system and in the nervous system. CONCLUSIONS: Our findings suggest the presence of a renin-angiotensin system involved in osmoregulation in leeches.

Morphine-like substance in leech ganglia. Evidence and immune modulation.

Binding experiments followed by measurement of nitric oxide release revealed an opiate alkaloid high affinity receptor with no affinity to opioids, representing a new mu-subtype receptor in the brain of the leech Theromyzon tessulatum. In addition, evidence of morphine-like substances was found in immunocytochemical studies and HPLC coupled to electrochemical detection (500 mV and 0.02 Hz). Based on previous evidence of the involvement of morphine as an immune response inhibitor, we demonstrate that in leech ganglia injection of lipopolysaccharide (LPS; a potent immunostimulatory agent derived from bacteria) provoked an increase in the level of ganglionic morphine-like substances after a prolonged latency period of 24 h (from 2.4 +/- 1.1 pmol per ganglion to 78 +/- 12.3 pmol per ganglion; P < 0.005; LPS injected 1 microg x mL-1); this effect is both concentration- and time-dependent. Finally, we have demonstrated that morphine, after binding to its own receptor, inhibits leech immunocyte activation through adenylate cyclase inhibition and nitric oxide release. This report confirms that morphine is an evolutionarily stable potent immunomodulator.

Proenkephalin A-derived peptides in invertebrate innate immune processes.

Lipopolysaccharides (LPS) injection into the coelomic fluid of the leech Theromyzon tessulatum stimulates release of proenkephalin A (PEA)-derived peptides as determined by immunoprecipitation and Western blot analyses. This release occurs in the first 15 min after LPS exposure and yields a 5.3-kDa peptide fragment corresponding to the C-terminal part of the precursor. This fragment is then cleaved to free an antibacterial peptide related to mammals arginine phenylalanine extended enkelytin: the peptide B. These PEA processing peptides were characterized using a combination of techniques including reversed-phase HPLC, microsequencing and mass spectrometry. The isolated invertebrate peptide B presents a high sequence homology with the bovine's and the same activity against Gram+bacteria. Titrations revealed the simultaneous appearance of Methionine-enkephalin (ME) and peptide B in invertebrates after stimulation by LPS (in a dose-dependent manner), surgical trauma or electrical stimulations to neural tissues of the mussel. Furthermore, peptide B processing in vitro yields Methionine-enkephalin arginine phenylalanine (MERF), which exhibits via the delta receptors, immunocyte excitatory properties, i.e., movement and conformational changes, but no antibacterial activity. We surmise that this unified response to the various stimuli is a survival strategy for organism by providing immediate antibacterial activity and immunocyte stimulation, thereby reducing any immune latency period needed for an adequate immune response.

Putative leech dopamine1-like receptor molecular characterization: sequence homologies between dopamine and serotonin leech CNS receptors explain pharmacological cross-reactivities.

The biochemical characterization of a serotonin (5HT) receptor and the cloning of a dopamine (DA) receptor in the central nervous system (CNS) of the leech, Theromyzon tessulatum, is presented. Additionally, DA and 5HT binding sites were examined in the CNS by Scatchard analysis which showed a single, relatively high-affinity binding site with a Kd 1.1 nM and a Bmax 126+18 fmol/mg protein for [3H]DA and a Kd 2.1 nM and a Bmax 225 fmol/mg protein for [3H]5HT. The first 88 amino acids of the 5HT receptor, isolated by a 5HT-affinity column followed by anion exchange chromatography and C3 reverse-phase HPLC exhibited a 43% sequence homology with Lymnaea stagnalis 5HT-receptor. The isolated DA receptor revealed a single protein of 45 kDa with an anti-D1-R in Western blot. The first 80 N-terminal amino acid residues and a trypsin digested fragment of 31 residues were obtained, and based on these sequencing data, a molecular biology strategy using reverse transcriptase-polymerase chain reaction, was developed. An amplified 1-kb segment was obtained. The complete deduced sequence of 416 amino acid residues exhibited about 30.6% sequence homology with the vertebrate D1 receptor family. Moreover, we further demonstrate that the leech 5HT and DA receptors also exhibit 30% sequence identity with each other, explaining their pharmacological cross-reactivity. Finally, anti-D1-R immunocytochemistry revealed positive structures in the peripheral and central nervous system, e.g., neurons, sensory fibers and immune cells. This is the first biochemical and molecular characterization of a DA receptor in leeches.

Leech egg-laying-like hormone: structure, neuronal distribution and phylogeny.

Cells immunoreactive to antisera specifically directed against Lymnaea stagnalis caudo dorsal cells egg-laying hormone (CDCH) or against alpha- and beta-peptides (CDCP), encoded on the egg-laying hormone precursor, were detected in central nervous system (CNS) of the rhynchobdellid leech Theromyzon tessulatum. A co-localization of the CDC-like hormone and CDC-like peptides was found in T. tessulatum as in L. stagnalis CNS. approximately 45 immunoreactive cells to the anti-CDCH were detected in leech brain but this number varies according to the stage of the animal life cycle, i.e. it reaches a maximum just before egg-laying while after it decreases to 2-3 cells. CDCH and alpha-CDCP epitopes recognized by anti-CDCH and anti-alpha-CDCP were contained in neurosecretory granules. Following an extensive purification, including HPGPC and reverse-phase HPLC, the CDC-like hormone contained in the T. tessulatum CNA was isolated. The sequence (GSGVSNGGTEMIQLSHIRERQRYWAQDNLRRRFLEK-amide) was established by a combination of automated Edman degradation, arginyl-endopeptidase digestion, electrospray mass spectrometry measurement and carboxypeptidase A treatment. The results demonstrate that the peptide recognized by the anti-CDCH in the leech CNS possesses 27.8, 37.2 and 47.2% sequence identity with Aplysia parvula, Lymnaea stagnalis and Aplysia californica ELH, respectively. This molecule was named the leech egg-laying-like hormone (L-ELH). The secondary structure prediction of the L-ELH and all mollusks ELH, revealed the existence of a conserved segment (segment 29-34) in a strong helicoidal bend that might be important for receptor recognition and/or activation. This finding constitutes the first biochemical characterization of an egg-laying hormone in other invertebrates than mollusks.

Biochemical identification and ganglionic localization of leech angiotensin-converting enzymes.

We demonstrate the presence of a membrane and soluble form of leech Theromyzon tessulatum angiotensin-converting enzyme (ACE). Four steps in the purification of this enzyme include gel-permeation, captopril-sepharose affinity and anion-exchange chromatography followed by a reverse-phase HPLC. The peptidyl dipeptidases (of approximately 120 and approximately 100 kDa) are glycosylated enzymes hydrolysing the Phe8-His9 bond of angiotensin I, exhibiting the same specific activity and Km whereas the soluble ACE exhibits a higher catalytic efficiency. This hydrolysis is inhibited by the ACE-specific antagonist captopril. Western blot analysis of a polyclonal antiserum raised against the first 11 amino-acid residues of the membrane ACE and the N-terminal sequence of the soluble molecule also demonstrates the presence of two ACE enzymes. Anti-ACE immunocytochemistry also supports the presence of two forms of ACE. This material is found in neurons and glia. We demonstrate for the first time the cellular localization and biochemical characterization of ACEs in the central nervous system of an invertebrate. Thus, the leech brain may represent a simple model for the study of these enzymes.

Leech immunocytes contain proopiomelanocortin: nitric oxide mediates hemolymph proopiomelanocortin processing.

This report establishes the presence of mammalian-like proopiomelanocotropic hormone (POMC), and six of its peptides, including adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH), in the immune tissues of the leech Theromyzon tessulatum. The 25.4-kDa protein was purified by high pressure gel permeation chromatography, anti-ACTH-affinity column, and reverse-phase HPLC. Its characterization was performed by Edman degradation, enzymatic treatments, and electrospray mass spectrometry. Leech POMC exhibits considerable amino acid sequence similarity to mammalian POMC. Of the six peptides, three showed high sequence similarity to their vertebrate counterparts met-enkephalin, alpha-MSH, and ACTH: 100, 84.6, and 70%, respectively; whereas gamma-MSH, beta-endorphin, and gamma-lipotropin hormone exhibited only 45, 20, and 10% sequence identity, respectively. No dibasic amino acid residues were found at the C terminus of the gamma- and beta-MSH peptides. In contrast, the leech alpha-MSH was flanked at its C-terminal by the Gly-Arg-Lys amidation signal. ACTH and corticotropin-like intermediary pituitary peptide were also C-terminally flanked by dibasic amino acid residues. The coding region of leech POMC was obtained by reverse transcription-PCR using degenerated oligonucleotide primers. Circulating levels of ACTH and MSH were 10 and 1 fmol/microl hemolymph, respectively. Morphine, in a dose-dependent manner, increased the levels of both peptides threefold; this effect was blocked by naloxone treatment. Similar results were found with the anandamide. Leech ACTH was processed to MSH by the enzymes neutral endopeptidase (24.11) and angiotensin-converting enzyme. Leech alpha-MSH had the same activity as authentic alpha-MSH in two bioasssay systems. Taken together, the study demonstrates that POMC is present in invertebrates and its immunoregulatory actions have been conserved during evolution.

Structural characterization of osmoregulator peptides from the brain of the leech Theromyzon tessulatum: IPEPYVWD and IPEPYVWD-amide.

Neurons immunoreactive to an antiserum (a-OT) directed specifically against the C-terminal part (prolyl-leucyl-glycinamide) of vertebrate oxytocin (OT) were detected in the brain of the leech Theromyzon tessulatum. With high pressure gel permeation chromatography followed by reversed-phase HPLC on brain extracts, evidence was given of the presence of three peptides (P1, P2, P3) immunoreactive to a-OT. Results of injection experiments in T. tessulatum and of titrations of each peptide at the different physiological stages of the animals which showed a peak in peptide P1 amount at stage 3B, indicated that P1 is the active OT-like peptide. Using three steps of reversed-phase HPLC, Edman degradation and electrospray mass spectrometry, two sequences for P1 (IPEPYVWD and IPEPYVWD-amide) were found. These peptides differ from peptides to the oxytocin/vasopressin family and are unique in the animal kingdom. Confirmation of their action on the hydric balance and their distribution in the CNS were presented.

Biochemical evidence of the sodium influx stimulating related peptide in the brain of the leech Theromyzon tessulatum.

This paper reports the immunocytochemical and biochemical evidence of a sodium influx stimulating related peptide (SIS-like peptide) in the brain of the leech Theromyzon tessulatum. Cells immunoreactive to both polyclonal antisera raised against the N-terminal (fragment 10-19) or the C-terminal (fragment 67-76) sequences of the purified freshwater snail Lymnaea stagnalis sodium influx stimulating peptide (SISP) was detected in the brain of this leech. These immunocytochemical data were strengthened by biochemical results at the level of the protein and by in vitro translated RNA. By combined techniques i.e. high performance gel permeation chromatography, electrophoresis followed by immunoblot analysis with the two antisera and immunoprecipitation, we established the existence in leeches of a protein of ca 11 kDa and its precursor, a protein of ca 13 kDa related to the SISP. Moreover, results of injections of anti-SISP (10-19) preabsorbed or not with its homologous antigen to Theromyzon tessulatum confirmed the SIS-like substance involvement in osmoregulation by an anti-diuretic function.

Purification, sequence analysis, and cellular localization of a prodynorphin-derived peptide related to the alpha-neo-endorphin in the rhynchobdellid leech Theromyzon tessulatum.

Cells immunoreactive to an antiserum specifically directed against vertebrate alpha-Neo-endorphin (alpha-NE) were detected in the internal wall of anterior and posterior suckers of the rhynchobdellid leech Theromyzon tessulatum. These cells have morphological and ultrastructural characteristics close to the "releasing gland cells" of adhesive organs. The epitope recognized by anti-alpha-NE was contained in granules having a diameter of 0.2-0.3 microm. Previous works involving the brain of this leech demonstrate the existence of approximately 14 neurons immunoreactive to the anti-alpha-NE. Following an extensive purification including high pressure gel permeation and reversed-phase high performance liquid chromatography, epitopes contained in both suckers and central nervous system were isolated. Purity of the isolated peptides was controlled by capillary electrophoresis. Their sequences were determined by a combination of automated Edman degradation, electrospray mass spectrometry measurement, and coelution experiments in reversed-phase high performance liquid chromatography with synthetic alpha-NE. The results demonstrate that epitopes recognized by the anti-alpha-NE in the suckers and the central nervous system are identical to vertebrate alpha-NE (YGGFLRKYPK). This finding constitutes the first biochemical characterization of a prodynorphin-derived peptide in invertebrates. Moreover the isolation of this peptide in the annelida establishes the very ancient phylogenetic origin of alpha-NE as well as its conservation in evolution.

Structural characterization of a novel neuropeptide from the central nervous system of the leech Erpobdella octoculata. The leech osmoregulator factor.

Purification of a material immunoreactive to an antiserum against the C-terminal part of the oxytocin (Pro-Leu-Gly-amide) and present in the central nervous system of the Pharyngobdellid leech Erpobdella octoculata was performed by reversed-phase high performance liquid chromatography combined with both enzyme-linked immunosorbent and dot immunobinding assays for oxytocin. The amino acid sequence of the purified peptide (Ile-Pro-Glu-Pro-Tyr-Val-Trp-Asp) was established by Edman degradation and confirmed by electrospray mass spectrometry measurement. When injected in leeches, purified or synthetic peptides exert an anti-diuretic effect, the most effective ranged between 10 pmol and 1 nmol. They provoked an uptake of water 1-2 h post-injection. Furthermore, electrophysiological experiments conducted in the leech Hirudo medicinalis revealed an inhibition of the potency of Na+ conductances of leech skin by this peptide. Immunocytochemical studies with an antiserum against synthetic oxytocin-like molecule provided the cytological basis for existence of a neuropeptide, since large amounts of immunoreactive neurons were detected in the central nervous systems of E. octoculata. The purified molecule is both different to peptides of the oxytocin/vasopressin family and is a novel neuropeptide in the animal kingdom. It was named the leech osmoregulator factor (LORF). An identification of the proteins immunoreactive to an antiserum against oxytocin performed at the level of both central nervous systems extracts and in vitro central nervous system-translated RNA products indicated that in the two cases, a single protein was detected. These proteins with a molecular masses of, respectively, approximately 34 kDa (homodimer of 17 kDa) for the central nervous systems extracts and approximately 19 kDa for in vitro central nervous system-translated RNA products were not recognized by the antiserum against MSEL- and VLDV-neurophysin (proteins associated to oxytocin and vasopressin), confirming that LORF did not belong to the oxytocin/vasopressin family.

Isolation and structural characterization of enkephalins in the brain of the rhynchobdellid leech Theromyzon tessulatum.

This paper reports the purification of four peptides related to enkephalins from the brain of the leech Theromyzon tessulatum. After reverse-phase HPLC purification, the sequence of the enkephalins (YGGFM, YGGFL, FM, FL) was established by a combination of automated Edman degradation, electrospray mass spectrometry measurement, and co-elution experiments in reverse-phase HPLC with synthetic peptides. ELISA titrations performed on each purified peptide indicated that the major amount was borne by the leucine-enkephalin. The ratio of leucine-enkephalin and methionine-enkephalin of 2:1 is in line with previous immunocytochemical data obtained on T. tessulatum brains. The presence of enkephalins in T. tessulatum, an animal belonging to the oldest group of coelomate metazoans (the Annelida) establishes the very ancient phylogenetic origin of opioids and their conservation in the course of evolution.

Structural characterization of a diuretic peptide from the central nervous system of the leech Erpobdella octoculata. Angiotensin II Amide.

Purification of a material immunoreactive to an antiserum against angiotensin II and present in the central nervous system of the pharyngobdellid leech Erpobdella octoculata was performed by reversed-phase high pressure liquid chromatography combined with both enzyme-linked immunosorbent assay and dot immunobinding assays for angiotensin II. Establishment of the amino acid sequence by Edman degradation, electrospray, and fast atom bombardement mass spectrometry measurements and enzymatic treatment by carboxypeptidase A indicated that this "central" angiotensin II-like material, the first one fully characterized in the animal kingdom, is an angiotensin II amide. This finding constitutes also the first biochemical characterization of a peptide of the angiotensin family in an invertebrate. Synthetic angiotensin II amide exerts, when injected in leeches, a diuretic effect and is, 1 and 2 h postinjection, 100-fold more potent than vertebrate angiotensin II. An identification of the proteins immunoreactive to an antiserum against angiotensin II performed at the level of both central nervous system extracts and in vitro central nervous system-translated RNA products indicated that in the two cases, two proteins were detected. Their molecular masses, which were, respectively, approximately 14 and approximately 18 kDa for the central nervous system extracts and approximately 15 and approximately 19 kDa for in vitro central nervous system-translated RNA products, differ from that of angiotensinogen (approximately 60 kDa), the precursor of vertebrate angiotensin II.

Oxytocin-like peptide: a novel epitope colocalized with the FMRFamide-like peptide in the supernumerary neurons of the sex segmental ganglia of leeches--morphological and biochemical characterization; putative anti-diuretic function.

A large number of oxytocin (OT)-like neurons were detected in the sex segmental ganglia (SG5, SG6) of three species of leeches belonging to different orders: Theromyzon tessulatum, Hirudo medicinalis and Erpobdella octoculata. In this latter species, an epitope close to the vertebrate OT by its C-terminal part (MSH release inhibiting factor: MIF), localized in granules of a size diameter of ca 120 nm and colocalized with FMRFamide(FMRFa)-like material was demonstrated. With reverse phase-high performance liquid chromatography, evidence was given that the two epitopes (OT and FMRFa) colocalized in the same neurons were biochemically different. A titration of OT per SG indicated that the OT-like amount was considerably higher in sex SG than in non-sex SG (ca. 5 pmol vs. ca. 0.5 pmol). Moreover, at the level of sex SG, this amount was ca. 3-fold higher in immature leeches than in mature specimens. Injections of extracts of SG of E. octoculata and of fragments of OT (Tocinoic acid or MIF) to T. tessulatum, indicated that MIF (the epitope found in the sex SG) and sex SG have the same anti-diuretic effect on the leeches injected. These results pointed to an anti-diuretic role of the leech OT-like substance.

Evidence for angiotensin-like molecules in the central nervous system of the leech Theromyzon tessulatum (O.F.M.). A possible diuretic effect.

1. Cells in the central nervous system of the leech Theromyzon tessulatum were revealed with an antiserum against angiotensin II. Among these cells, a group of 4-5 pairs of neurons, called beta giant cells, and located in the posterior compartments of the supraesophageal ganglion was particularly investigated. 2. The amount of angiotensin II-like substance(s) in the brain increased notably in the days immediately following the third meal. 3. Injections of angiotensin II, fragments 1-4 or 5-8 or angiotensin II and of angiotensin III into stage 3 leeches showed that fragment 5-8 of angiotensin II was the most effective: it provokes a loss of mass of the leeches, which could express a diuretic effect.

[Characterization of immunoreactive neurons in the central nervous system of the leech Theromyzon tessulatum using monoclonal antibodies]. / Caractérisation de neurones immunoréactifs dans le système nerveux central de la sangsue Theromyzon tessulatum à l'aide d'anticorps monoclonaux.

Two mouse hybridomas producing monoclonal antibodies Tt9 and Tt 159 directed against antigens of supraesophageal ganglia of the leech T. tessulatum were selected to study the neuroendocrine control of osmoregulation in this species. One, Tt 159 reacted with an antigenic determinant of cells recognized by an anti-angiotensin antibody, the other, Tt 9, with neurons immunoreactive to the anti-vasopressin.

Immunohistochemical localization of opioid peptides in the brain of the leech Theromyzon tessulatum.

By use of antisera directed against met-enkephalin, leu-enkephalin, dynorphin or α-neoendorphin, immunoreactive structures were visualized in the central nervous system and proboscis of the leech Theromyzon tessulatum. Their distribution in the various compartments of the supra- and subesophageal ganglia was mapped. No correspondence could be established between the neurons containing met- or leu-enkephalin-like substances and the different types of neurosecretory cells classically described in Hirudinea. Successive localization of leu- and met-enkephalin on the same section revealed that these two peptides occur in different neurons. Only one cell located in compartment 6 of the supraesophageal ganglion was both dynorphin- and leu-enkephalin-positive. The other dynorphinimmunoreactive cells were not stained with the anti-leuenkephalin serum. The α-neoendorphin-immunopositive cells were leu-enkephalin immunonegative and vice versa.

[Evidence of apparent vasopressin and oxytocin peptides in the brain of the leech Rhynchobdelle Theromyzon tessulatum (O.F.M.)]. / Mise en évidence de peptides apparentés à la vasopressine et à l'ocytocine dans le cerveau de l'hirudinée Rhynchobdelle Theromyzon tessulatum (O.F.M.).

Vasopressin- and oxytocin-immunoreactive cells have been demonstrated in the brain of the leech Theromyzon tessulatum. A mapping of their localization in the different compartments of the brain has been undertaken. The cells immunohistochemically identified have been compared to previously described cell types defined by classical staining methods for neurosecretory material. Preliminary results obtained with high performance liquid chromatography confirm the presence in brain homogenates of substances with chromatographic properties similar to that of vertebrate nonapeptides. The possible role of these vasopressin- and oxytocin-like substances in osmoregulation is discussed.