Immunohistochemical localization of gastrin-cholecystokinin-like material in the central nervous system of the migratory locust

Localization of cholecystokinin-like immunoreactivity in the central nervous system of Triatoma infestans (Insecta: Heteroptera)

The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.

Immunocytochemical mapping of serotonin and neuropeptides in the accessory medulla of the locust, Schistocerca gregaria

Accumulating evidence suggests that pigment-dispersing hormone-immunoreactive neurons with ramifications in the accessory medulla of the insect brain are involved in circadian pacemaking functions. We have used immunocytochemical techniques to investigate the neurochemical organization of the accessory medulla in the locust Schistocerca gregaria. Local neurons with arborizations largely restricted to the accessory medulla are immunoreactive with antisera against serotonin, Manduca sexta allatotropin, and Diploptera punctata allatostatin 7. Projection neurons with arborizations in the accessory medulla and fibers to the lamina and/or several areas in the midbrain including the posterior optic tubercles, the inferior and the superior protocerebrum show Phe-Met-Arg-Phe (FMRF)amide-, gastrin/cholecystokinin-, crustacean cardioactive peptide-, and substance P immunoreactivities. A unique neuron with tangential ramifications in the medulla and lamina and varicose terminals in the accessory medulla contains a peptide related to locustatachykinin I/II. Double-label experiments show colocalization of pigment-dispersing hormone-immunoreactivity with substances related to gastrin/cholecystokinin, FMRFamide, substance P, or crustacean cardioactive peptide in certain projection neurons of the accessory medulla. The results suggest that neuropeptides and biogenic amines play major neuroactive roles in the accessory medulla of the locust. The abundance and extensive colocalization of neuropeptides in the locust accessory medulla is discussed with respect to the possible involvement of this brain area in circadian pacemaking functions.

Colocalization of octopamine and FMRFamide related peptide in identified heart projecting (DUM) neurones in the locust revealed by immunocytochemistry

Immunocytochemical techniques are employed to reveal colocalization of octopamine with FMRFamide related peptide in the locust ventral nervous system. In each unfused pregenital abdominal ganglia (A4-A6) there are 3 octopamine-like immunoreactive neurones. By combining intracellular Lucifer yellow staining with subsequent immunocytochemistry these are individually identified as the efferent dorsal unpaired median (DUM) neurones DUM-1 and DUM-2, which innervate abdominal tergal and respectively sternal skeletal muscles, and DUM heart-1, an FMRFamide-like immunoreactive neurone which projects to the heart and associated alary muscles. Colocalization of octopamine- and FMRFamide-like immunoreactivity in DUM heart-1 is verified by alternate staining of consecutive sections. With respect to locust ventral ganglia, this investigation shows that colocalization of octopamine with an FMRFamide related peptide is restricted to a single DUM cell occurring in each abdominal ganglion 2-7, which most likely corresponds to segmental homologues of DUM heart-1.

Localisation of sulfakinin neuronal pathways in the blowfly Calliphora vomitoria

The distribution of neurones immunoreactive to antisera raised against the undecapeptide C-terminal fragment of drosulfakinin II (DrmSKII), Asp-Gln-Phe-Asp-Asp-Tyr(SO3H)-Gly-His-Met-Arg-Phe-NH2, has been studied in the blowfly Calliphora vomitoria. Antisera were preabsorbed with combinations of the parent antigen, the tetrapeptide Phe-Met-Arg-Phe-NH2 and cholecystokinin, the vertebrate sulfated octapeptide (CCK-8), Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2, in order to ensure specificity for the sulfakinin peptides of C. vomitoria (the nonapeptide callisulfakinin I is identical to drosulfakinin I and callisulfakinin II differs from DrmSK II only by the presence of -Glu3-Glu4- in place of -Asp3-Asp4-). Only four pairs of sulfakinin-immunoreactive neurons have been visualised in the entire nervous system. These occur in the brain: two pairs of cells situated medially in the caudo-dorsal region close to the roots of the ocellar nerve and two other pairs at the same level but positioned more laterally. Despite the small number of sulfakinin-immunoreactive cells, there are extensive projections to many areas of neuropile in the brain and the thoracic ganglion. The pathway of the medial sulfakinin cells extends into each of the three thoracic ganglia and a metameric arrangement of sulfakinin neuronal projections is also seen in the abdominal ganglia. Neither the dorsal neural sheath of the thoracic ganglion, nor the abdominal nerves contain sulfakinin-immunoreactive material. These observations suggest that the sulfakinins of the blowfly function as neurotransmitters or neuromodulators. They do not appear to have a direct role in gut physiology, as has been shown by in vitro bioassays for the sulfakinins of orthopterans and blattodeans. In addition to the neurones that display specific sulfakinin immunoreactivity, other cells within the brain and thoracic ganglion are immunoreactive to cholecystokinin/gastrin antisera. There are, therefore, at least two types of dipteran neuropeptides with amino acid sequences that are similar to the vertebrate molecules cholecystokinin and gastrin.

An identified dorsal unpaired median neurone and bilaterally projecting neurones exhibiting bovine pancreatic polypeptide-like/FMRFamide-like immunoreactivity in abdominal ganglia of the migratory locust

Three antisera were used to study the distribution and anatomy of bovine pancreatic polypeptide (BPP)-like/FMRFamide-like immunoreactive neurones within the unfused abdominal ganglia of the migratory locust, Locusta migratoria. All the antisera used stained two or more clusters of perikarya, localized anteriorly and posteriorly near the midline within each unfused abdominal ganglion. Double labelling experiments with intracellular dye injection, or differential backfilling, combined with subsequent immunostaining were carried out to identify these neurones. Two of the antisera (antisera 1 and 2, both raised against FMRFamide) stained three groups of midline neurones, located anterior dorsal, anterior ventral and posterior dorsal within the ganglion. Neurones of the former of these two clusters projected via the anterior median nerve to a neurohaemal organ. The posterior cluster of midline cells comprised immunopositive perikarya all but one of which also projected via the anterior median nerve to innervate the neurohaemal organ. Double labelling with Lucifer yellow and antisera 1 and 2 showed that the remaining neurone was the previously identified dorsal unpaired median (DUM)heart 1 neurone. The third antiserum (AK141), also raised against FMRFamide, stained neurones within an anterior dorsal cluster, and in a posterior cluster. Double labelling with differential Co2+/Ni(2+)-backfilling and the antiserum 3 (AK141) demonstrated that the large neurones of both clusters belonged to the population of bilaterally projecting neurones (BPNs), including the DUMheart1 neurone. Since the antisera cross-react with BPP and fail to label neurones when preadsorped with BPP or FMRFamide, we conclude that the labelled neurones contain polypeptides of the FMRFamide/BPP-family.

Multiple peptide immunoreactivities in the nervous system of Aeschna cyanea (Insecta, Odonata). An immunohistochemical study using antisera to cholecystokinin octapeptide, somatoliberin, vasoactive intestinal peptide, motilin and proctolin

By use of the indirect immunoperoxidase method, the brain, the suboesophageal ganglion and the corpora cardiaca of the dragonfly Aeschna cyanea have been shown to be immunoreactive to proctolin antiserum and to several mammalian peptide antisera including unsulfated cholecystokinin octapeptide (CCK-8 NS) (Andriès et al. 1989), vasoactive intestinal peptide (VIP), human somatoliberin (hGRF) (Andriès et al. 1984) and motilin antisera. Immunohistochemical studies have been performed on material fixed in a solution of picricacid paraformaldehyde or in Bouin Hollande's sublimate solution. Antisera were applied on alternate sections or, according to the elution-restaining method of Tramu et al. (1978), one after another on the same section. Multiple peptide immunoreactivities appear expressed in the brain and the suboesophageal ganglion. Cells reactive to both hGRF and VIP antisera show also gastrin/CCK-like immunoreactivity and some of them are also detected by motilin antiserum. Besides, some cells immunopositive to CCK-8 NS and motilin antisera do not show hGRF or VIP immunoreactivity. At least, two pairs of protocerebral cells appear immunoreactive to both CCK-8 NS and proctolin antisera. Therefore, the present observations support our previously developed idea (Andriès et al. 1989) that the population of CCK-like cells is heterogenous.

Bilaterally projecting neurones in pregenital abdominal ganglia of the locust: anatomy and peripheral targets

The anatomy and physiology of neurones with axons in left and right homologous nerves was studied in abdominal ganglia of the migratory locust, Locusta migratoria, by using a differential cobalt/nickel staining method. These neurones reside within two clusters at the anterior and posterior ends of all unfused abdominal ganglia. Each cluster contains at least seven neurones with bilaterally projecting axons. All neurones of the anterior cluster possess bilaterally projecting axons which leave the ganglion through nerve 2 (= sternal nerve) or nerve 1 (= tergal nerve). Additional axon collaterals, which are present in some of these neurones leave through either nerve 1 or nerve 2 of the right or left side of the ganglion. With few exceptions, the neurones show further asymmetries in their dendritic arborizations. Neurones of the posterior group also have bilaterally projecting axons that leave the ganglion through nerve 1 or nerve 2. Among these neurones are the two large posterior dorsal unpaired median (DUM) neurones with bilaterally symmetrical axons that were described earlier as DUM1 and DUM2. They innervate the skeletal muscles of an abdominal segment. Two other cells of this cluster have anatomical properties similar to the DUM1 neurone and were termed DUMheart1A and DUMheart1B. The rest resemble the bilaterally projecting neurones of the anterior group. With the exception of the two classic DUM neurones (DUM1 and DUM2), all neurones of the anterior and posterior cluster innervate the heart or a neurohaemal area.

Tryptophanyl-tRNA synthetase-like immunoreactivity in the central nervous system and midgut of the migratory locust. Comparisons with gastrin-cholecystokinin-like and octopamine-like immunoreactivity

A tryptophanyl-tRNA synthetase (TrpRS)-immunoreactivity is localized in various neurosecretory cells of all ganglia of the central nervous system of the Orthoptera Locusta migratoria, except in deutocerebrum, and in endocrine cells of the midgut. It has been observed that TrpRS-like material never co-localizes either with CCK-like or octopamine-like material. TrpRS immunoreactive perikarya and processes that ramify extensively throughout the neuropiles have been detected in the protocerebrum, optic lobes, tritocerebrum, suboesophageal, thoracic and abdominal ganglia. In the lateral protocerebrum, a particular TrpRS pathway different from the lateral gastrin cholecystokinin (CCK-8(s] pathway is revealed, certain of these processes terminating in the glandular part of the corpora cardiaca. In the metathoracic ganglion, have been observed numerous immunoreactive cell bodies and processes in the neuropiles. Some of them constitute a major pathway and which are distinct from octopamine (OA) cells but in close vicinity with the latter. In the midgut immunopositive TrpRS-like cells are dispersed among the regenerative and digestive cells of the epithelium; they are different from gastrin-cholecystokinin positive cells. The various TrpRS-like immunoreactivities identified in Locusta indicate that TrpRS-like material may occur in different tissues of organisms other than Vertebrates. These results suggest also that TrpRS-like enzyme could be involved in functions other than aminoacylation, as in Vertebrates.

Gastrin-cholecystokinin-like and neuroparsin-like immunoreactivities in the brain and retrocerebral neuroendocrine complex of the cockroach Blattella germanica

Using single and double labelling techniques respectively, brain-corpora cardiaca-corpora allata complexes of the cockroach Blattella germanica have been immunohistochemically investigated with antisera raised against either the vertebrate peptide gastrin-cholecystokinin (CCK-8(s] and/or the locust neurohormone neuroparsin (NPA). Single immunolabelling with anti-CCK-8(s) reveals immunoreactive perikarya and processes in median and lateral parts of protocerebrum, optic lobes, deutocerebrum and tritocerebrum. Some fibres originating in median and lateral protocerebrum are intrinsic to the brain, whereas others terminate in the nervous areas of the corpora cardiaca. Single immunolabelling with anti-NPA reveals immunoreactive cell bodies in the median part of the protocerebrum and their processes terminate both in the nervous area of the corpora cardiaca and between the intrinsic secretory cells of this neurohaemal organ. Double immunolabelling with anti-CCK-8(s) and anti-NPA enables a description of the anatomical relations between the processes and the endings of these two neurosecretory systems.