Morphological correlates of serotonin-neuropeptide Y interactions in the rat suprachiasmatic nucleus: Combined radioautographic and immunocytochemical data

Summary The morphological substrate of putative serotonin (5-HT)/neuropeptide Y (NPY) interactions in thé suprachiasmatic nucleus (SCN) was investigated by combined radioautography and immunocytochemistry after intraventricular administration of (³H)5-HT in the rat. In the ventral portion of the SCN, the distribution of (³H)5-HT uptake sites overlapped closely the NPY-immunoreactive terminals. Previous investigations have shown that the dense 5-HT and NPY innervations of the SCN originate in different structures, i.e., the midbrain raphe nuclei and the ventral lateral geniculate nucleus, respectively. Accordingly, in the present study, destruction of 5-HT afferents by 5,7-dihydroxytryptamine was not found to induce any modification in NPY staining and, in ultrastructural immuno-radioautographic preparations, two distinct pools of axonal varicosities could be identified. Both 5-HT and NPY terminals established morphologically defined synaptic junctions, sometimes on the same neuronal target. Some cases of direct axo-axonic appositions between the two types of terminals were also encountered. These data constitute additional criteria for characterizing the cytological basis of the multiple transmitter interactions presumably involved in the function of the SCN as a central regulator of circadian biological rhythms.     

Localization and characterization of neuropeptide Y-like peptides in the brain and islet organ of the anglerfish (Lophius americanus)

Summary Results from a previous report demonstrate that more than one molecular form of neuropeptide Y-like peptide may be present in the islet organ of the anglerfish (Lophius americanus). Most of the neuropeptide Y-like immunoreactive material was anglerfish peptide YG, which is expressed in a subset of islet cells, whereas an additional neuropeptide Y-like peptide(s) was localized in islet nerves. To learn more about the neuropeptide Y-like peptides in islet nerves, we have employed immunohistochemical and biochemical methods to compare peptides found in anglerfish islets and brain. Using antisera that selectively react with either mammalian forms of neuropeptide Y or with anglerfish peptide YG, subsets of neurons were found in the brain that labelled with only one or the other of the antisera. In separate sections, other neurons that were labelled with either antiserum exhibited similar morphologies. Peptides from brains and islets were subjected to gel filtration and reverse-phase high performance liquid chromatography. Radioimmunoassays employing either the neuropeptide Y or peptide YG antisera were used to examine chromatographic eluates. Immunoreactive peptides having retention times of human neuropeptide Y and porcine neuropeptide Y were identified in extracts of both brain and islets. This indicates that peptides structurally similar to both of these peptides from the neuropeptide Y-pancreatic polypeptide family are expressed in neurons of anglerfish brain and nerve fibers of anglerfish islets. The predominant form of neuropeptide Y-like peptide in islets was anglerfish peptide YG. Neuropeptide Y-immunoreactive peptides from islet extracts that had chromatographic retention times identical to human neuropeptide Y and porcine neuropeptide Y were present in much smaller quantities. These results are consistent with the hypothesis that peptides having significant sequence homology with human neuropeptide Y and porcine neuropeptide Y are present in the nerve fibers that permeate the islet.     

Isolation and structure of corazonin, a cardioactive peptide from the American cockroach

Corazonin, a new cardioaccelerating peptide, has been isolated from the corpora cardiaca of the American cockroach, Periplaneta americana, and its structure determined to be Glp-Thr-Phe-Gln-Tyr-Ser-Arg-Gly-Trp-Thr-Asn-amide. The peptide stimulated heart beat at concentrations as low as 0.2 nM, which makes it the most potent insect cardioactive neuropeptide.     

Localization of neuropeptide Y-immunoreactive cells and fibres in the brain of the Japanese quail

Summary In the present study, we have demonstrated, by means of the biotin-avidin method, the widespread distribution of neuropeptide Y (NPY)-immunoreactive structures throughout the whole brain of the Japanese quail (Coturnix coturnix japonica). The prosencephalic region contained the highest concentration of both NPY-containing fibres and perikarya. Immunoreactive fibres were observed throughout, particularly within the paraolfactory lobe, the lateral septum, the nucleus taeniae, the preoptic area, the periventricular hypothalamic regions, the tuberal complex, and the ventrolateral thalamus. NPY-immunoreactive cells were represented by: a) small scattered perikarya in the telencephalic portion (i.e. archistriatal, neostriatal and hyperstriatal regions, hippocampus, piriform cortex); b) medium-sized cell bodies located around the nucleus rotundus, ventrolateral, and lateral anterior thalamic nuclei; c) small clustered cells within the periventricular and medial preoptic nuclei. The brainstem showed a less diffuse innervation, although a dense network of immunopositive fibres was observed within the optic tectum, the periaqueductal region, and the Edinger-Westphal, linearis caudalis and raphes nuclei. Two populations of large NPY-containing perikarya were detected: one located in the isthmic region, the other at the boundaries of the pons with the medulla. The wide distribution of NPY-immunoreactive structures within regions that have been demonstrated to play a role in the control of vegetative, endocrine and sensory activities suggests that, in birds, this neuropeptide is involved in the regulation of several aspects of cerebral functions.Abbreviations AA archistriatum anterius - AC nucleus accumbens - AM nucleus anterior medialis - APP avian pancreatic polypeptide - CNS centrai nervous system - CO chiasma opticum - CP commissura posterior - CPi cortex piriformis - DIC differential interferential contrast - DLAl nucleus dorsolateralis anterior thalami, pars lateralis - DLAm nucleus dorsolateralis anterior thalami, pars medialis - E ectostriatum - EW nucleus of Edinger-Westphal - FLM fasciculus longitudinalis medialis - GCt substantia grisea centralis - GLv nucleus geniculatus lateralis, pars ventralis - HA hyperstriatum accessorium - Hp hippocampus - HPLC high performance liquid chromatography - HV hyperstriatum ventrale - IF nucleus infundibularis - IO nucleus isthmo-opticus - IP nucleus interpeduncularis - IR immunoreactive - LA nucleus lateralis anterior thalami - LC nucleus linearis caudalis - LFS lamina frontalis superior - LH lamina hyperstriatica - LHRH luteinizing hormone-releasing hormone - LoC locus coeruleus - LPO lobus paraolfactorius - ME eminentia mediana - N neostriatum - NC neostriatum caudale - NPY neuropeptide Y - NIII nervus oculomotorius - NV nervus trigeminus - NVI nervus facialis - NVIIIc nervus octavus, pars cochlearis - nIV nucleus nervi oculomotorii - nIX nucleus nervi glossopharyngei - nBOR nucleus opticus basalis (ectomamilaris) - nCPa nucleus commissurae pallii - nST nucleus striae terminalis - OM tractus occipitomesencephalicus - OS nucleus olivaris superior - PA palaeostriatum augmentatum - PBS phosphate-buffered saline - POA nucleus praeopticus anterior - POM nucleus praeopticus medialis - POP nucleus praeopticus periventricularis - PP pancreatic polypeptide - PYY polypeptide YY - PVN nucleus paraventricularis magnocellularis - PVO organum paraventriculare - R nucleus raphes - ROT nucleus rotundus - RP nucleus reticularis pontis caudalis - Rpc nucleus reticularis parvocellularis - RPgc nucleus reticularis pontis caudalis, pars gigantocellularis - RPO nucleus reticularis pontis oralis - SCd nucleus subcoeruleus dorsalis - SCv nucleus subcoeruleus ventralis - SCNm nucleus suprachiasmaticus, pars medialis - SCNl nucleus suprachiasmaticus, pars lateralis - SL nucleus septalis lateralis - SM nucleus septalis medialis - Ta nucleus tangentialis - TeO tectum opticum - Tn nucleus taeniae - TPc nucleus tegmenti pedunculo-pontinus, pars compacta - TSM tractus septo-mesencephalicus - TV nueleus tegmenti ventralis - VeL nucleus vestibularis lateralis - VLT nucleus ventrolateralis thalami - VMN nucleus ventromedialis hypothalami A preliminary report of this study was presented at the 15th Conference of European Comparative Endocrinologists, Leuven, Belgium, September 1990     

Distribution of opioidergic,sympathetic and neuropeptide Y-positive nerves in the sphincter of Oddi and biliary tree of the monkey,Macaca fascicularis

Summary The opioidergic, sympathetic and neuropeptide Y-positive innervation of the sphincter of Oddi (common bile duct sphincter and pancreatic duct sphincter), as well as other segments of the extrahepatic biliary tree was studied in the monkey by use of immunohistochemistry. Methionine-enkephalin-positive nerves were seen to innervate the smooth muscle of all portions of the sphincter of Oddi and also local ganglion cells. No methionine-enkephalin-positive nerves could be detected in the common bile duct, pancreatic duct or gallbladder. Tyrosine hydroxylase-positive nerves occurred between smooth muscle bundles and also ran to local ganglion cells as well as along the common bile duct. Neuropeptide Y-positive nerves were observed within smooth muscle of the sphincter of Oddi (all portions), common bile duct, pancreatic duct and gallbladder. No evidence of any differential innervation of the pancreatic duct and common bile duct sphincters could be detected with these markers.     

Identification of neuroendocrine cells producing a diuretic hormone in the tobacco hornworm moth,Manduca sexta

Summary Separate antisera were raised to the N- and C-terminal half of the diuretic hormone from Manduca sexta. Antisera against the two halves of this peptide recognized the same cells in M. sexta, and preabsorption of the antisera with the peptides used as antigens abolished the immunoreactivity, confirming their specificity. The antisera reacted with two median neurosecretory cells on each side of the protocerebral groove in larvae, and with a group of about 80 small median neurosecretory cells in the adult, as well as their axons to, and their axon terminals in, the corpora cardiaca. During the early pupal stages, small cells, which are possibly derived from a common neuroblast, differentiate into immunoreactive neurosecretory cells, which explains the large increase in cell numbers in the adult. In the sleepy sulphur butterfly, Eurema nicippe, homologous median neurosecretory cells in the adult were immunoreactive with both antisera.     

Behavioral and biochemical assessment of time-related changes in globus pallidus and striatal dopamine induced by intranigrally administered neurotensin

Microinjection of neurotensin (NT; 2 and 5 μg) into the substantia nigra zona compacta caused an increase in dopamine (DA) and DA metabolites in the rodent globus pallidus and striatum which persisted for at least 20 hours after peptide administration. Similar NT treatments given unilaterally into the nigra caused circling away from the injected side in amphetamine-pretreated rats, but were without effect when microinjected into saline-pretreated animals. Circling also occurred when the animals were given amphetamine 20 hours after intranigral NT administration. Contralateral rotation was observed with unilateral intranigral injections of gamma-hydroxybutyric acid (GHB; 400 μg) or with lower intranigral GHB doses (250 μg) in amphetamine-pretreated animals. The effects of GHB and NT differed in the manner in which the animals rotated as well as in the profile of DA and DA metabolite changes induced by these drugs. These studies indicated that: (1) dopaminergic functions of the globus pallidus are influenced, like the striatum, by manipulations of the substantia nigra; (2) NT and GHB likely act via different mechanisms to effect nigral dopamine-containing cells; and (3) NT was capable of inducing changes in dopamine neurons which had long term consequences.     

Organization of the nervous system of physonectid siphonophores

Summary An antiserum to the sequence Arg-Phe-amide (RFamide) was used to stain the nervous systems of various physonectid siphonophores. In the stem of Nanomia bijuga, this antiserum stained an ectodermal nerve net, which was interrupted, at regular intervals, by transverse collars of neurons. Injection of Lucifer yellow into the giant axon of the stem showed that this axon was dye-coupled to an ectodermal nerve net that resembled the RFamide-positive network. Ectodermal nets of neurons were also found in the pneumatophore, gastrozooids, tentacles and tentilla. At the junctions of the pneumatophore, the gastrozooids, the dactylozooids and the gonozooids with the stem, and at the junctions of tentacles and tentilla, collars or rings of neurons occurred. The stem was connected to the phyllozooids and nectophores by muscular lamellae, which were bordered by chains of neurons. At the margin of the nectophores, an immunoreactive nerve ring was found. Connected to this ring and located in theseitliche Zapfen (sidely-located patche), were two agglomerations of nerve cells. On the upper side of the bell margin, positioned at 90° relative to the seitliche Zapfen, a delta-shaped neuronal structure was found. This structure was connected to the nerve ring and was associated with a muscle, which ran a short distance along the exumbrellar surface.The nervous systems of Agalma elegans, Forskalia edwardsi, Forskalia leuckarti and Halistemma rubrum resembled that of Nanomia bijuga in all major respects.     

Monoclonal Antibodies Allow Precipitation of Esterasic but Not Peptidasic Activities Associated with Butyrylcholinesterase

Commercially available and affinity-purified butyrylcholinesterases isolated from human serum were examined for their esterasic activity and their ability to hydrolyze various neuropeptides, including neurotensin, substance P, and leucine-enkephalin. The three pools that displayed the lowest esterasic activities were shown to hydrolyze neurotensin with the same HPLC degradative pattern. By contrast, noticeable qualitative and quantitative discrepancies were observed when hydrolyses of substance P and leucine-enkephalin by these three butyrylcholinesterase pools were studied. The pool that exhibited the highest esterasic activity appeared to be homogeneously constituted by 90- and 180-kDa protein bands by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and was totally unable to hydrolyze these three neuropeptides. This suggested that the three other butyrylcholinesterase preparations could be contaminated by exogenous peptidases. This was confirmed by means of three distinct monoclonal antibodies directed toward human serum butyrylcholinesterase. The three IgG-purified fractions precipitated the esterasic activity, whereas they failed to precipitate the neuropeptide-hydrolyzing activities whatever the substrate examined. Altogether, these results demonstrate that peptidases associated with butyrylcholinesterase are contaminating enzymes that cannot be considered as intrinsic activities of this enzyme.