Intrinsic Neurosecretory Cells Research Articles

Ultrastructural localization of unique neurosecretory granules in the corpora cardiaca of the stable fly, Stomoxys calcitrans, and the tsetse fly, Glossina morsitans.

Ultrastructural analysis of the corpora cardiaca of the stable fly, Stomoxys calcitrans, and the tsetse fly, Glossina morsitans, revealed the presence of elementary neurosecretory granules (ENG) unique to the intrinsic neurosecretory cells (INC) of these species. In addition to electron-dense spheres, the INC of the corpus species. In addition to electron-dense spheres, the INC of the corpus cardiacum of the stable fly contain electrondense angular granules, either square or rectangular in shape, while the INC of the tsetse fly contain electron-dense spindle-shaped ENG. The distinctive granules of these INC can be traced within nerves to their sites of storage and release, eliminating the need for labeling with artificial probes. Although the INC of the corpus cardiacum of most species have been found to be fuchsinophilic, neither the INC of the stable fly nor the tsetse fly are aldehyde-fuchsinophilic. These peptigenic cells offer neuroendocrinologists a unique opportunity to study the physiology and biochemistry of neurosecretory cells.

Ultrastructural localization of unique neurosecretory granules in the corpora cardiaca of the stable fly, Stomoxys calcitrans, and the Tsetse Fly, Glossina morsitans

Ultrastructural analysis of the corpora cardiaca of the stable fly, Stomoxys calcitrans, and the tsetse fly, Glossina morsitans, revealed the presence of elementary neurosecretory granules (ENG) unique to the intrinsic neurosecretory cells (INC) of these species. In addition to electron-dense spheres, the INC of the corpus cardiacum of the stable fly contain electron-dense angular granules, either square or rectangular in shape, while the INC of the tsetse fly contain electron-dense spindle-shaped ENG. The distinctive granules of these INC can be traced within nerves to their sites of storage and release, eliminating the need for labeling with artificial probes. Although the INC of the corpus cardiacum of most species have been found to be fuchsinophilic, neither the INC of the stable fly nor the tsetse fly are aldehyde-fuchsinophilic. These peptigenic cells offer neuroendocrinologists a unique opportunity to study the physiology and biochemistry of neurosecretory cells. J. Morphol. 240:155–168, 1999. Published 1999 Wiley-Liss, Inc.

Transfer of memory B cells to a patient with leukocyte adhesion deficiency from her HLA-identical sibling donor

In mosquitoes, the corpus allatum (CA) and the neurosecretory system each produce a hormone essential for egg development. Ablation experiments showed that when the female takes a blood meal 2–3 days after emergence, CA hormone had been secreted, whereas the neurosecretory hormone (EDNH) had been produced but was stored in the axons that form the corpus cardiacum. The cardiacum had accumulated enough EDNH for maturation of several batches of eggs.Nerve-sectioning and parabiosis experiments indicated that blood-feeding initiates some hemolymph-borne stimulus to the cardiacum that resulted in the release of enough EDNH, within 8–16 hr, for egg maturation. EDNH did not persist in the circulation after eggs were mature. Thus, the corpus cardiacum appears to regulate egg maturation by storing and “metering” the release of EDNH for each batch of eggs.Electron micrographs of Aedes sollicitans showed that the corpus cardiacum is both a ganglion and a neurohemal organ; it has no intrinsic neurosecretory cells. Bioassay of corpora cardiaca demonstrated that paraldehyde-fuchisin staining was not correlated with the presence of EDNH.

Crustacean Hyperglycemic Hormone‐like Peptides in Crab and Locust Peripheral Intrinsic Neurosecretory Cells

Crustacean hyperglycemic hormone-like peptides in crab and locust peripheral intrinsic neurosecretory cells

Biotin-containing proteins of the insect nervous system, a potential source of interference with immunocytochemical localization procedures

When the biotinylated Manduca sexta adipokinetic hormone gene was used as a probe for in situ hybridization, the intrinsic neurosecretory cells were stained with a biotin detection system that contained streptavidin or avidin. Further experiments showed that the DNA probe was not necessary for staining these cells by streptavidin-alkaline phosphatase, and that they were not stained by alkaline phosphatase alone. Similarly, the intrinsic neurosecretory cells were stained directly by streptavidin conjugated to a fluorescent dye. Other parts of the central nervous system could also be stained with streptavidin-alkaline phosphatase but not as readily as the intrinsic neurosecretory cells of the corpora cardiaca. Further analysis demonstrated three biotin-containing proteins in the intrinsic neurosecretory cells of the corpora cardiaca and in the brain. The most abundant of these proteins, when analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, was found to have a molecular weight of 130,000, which is the size of the subunits of pyruvate carboxylase, a biotin-containing enzyme. The same protein was recognized by an antiserum against an insect pyruvate carboxylase, indicating that this protein is probably pyruvate carboxylase. The results reported here indicate that the intrinsic neurosecretory cells of the corpora cardiaca may contain pyruvate carboxylase in a concentration higher that other cells of the central nervous system. We also note that caution is necessary to avoid false positive results if an avidin containing detection system is used for in situ hybridization or immunocytochemistry.

Postembryonic proliferation of neuroendocrine cells expressing adipokinetic hormone peptides in the corpora cardiaca of the locust.

Neuroendocrine glands that synthesize and secrete peptide hormones regulate the levels of these peptide messengers during development. In this article we describe a mechanism for regulating neuropeptide levels in the corpora cardiaca of the locust Schistocerca gregaria, a neuroendocrine gland structurally analogous to the vertebrate adenohypophysis. A set of five colocalized peptide hormones of the adipokinetic hormone family is synthesized in intrinsic neurosecretory cells in the corpora cardiaca. During postembryonic development there are progressive changes in the absolute and relative levels of these five peptide hormones. We show that the ability of the gland to increase peptide synthesis is due to a 100-fold increase in the number of cells which make up the gland. The gland grows by the addition of new cells derived from symmetrical division of undifferentiated precursor cells within the corpora cardiaca. We show, using double-label immunocytochemistry, that cells born in the glandular lobe mature into cells that express adipokinetic hormone peptides. The pattern of cell birth and peptide expression can account for the dramatic increase in postembryonic peptide levels.

Storage site of glycogen phosphorylase activating hormone in larvae of Manduca sexta

Corpora cardiaca of Manduca sexta were examined by light and by electron microscopy. In the posterior part of the corpora cardiaca there are 6 or 7 large intrinsic neurosecretory cells whose contents stain strongly with paraldehydfuchsin. These cells are full of neurosecretory granules, with a diameter of about 200 nm (range 80–400 nm), and appear to represent the intrinsic glandular part of the corpora cardiaca of M. sexta. The remainder of the corpora cardiaca consists mainly of axons containing secretory granules of about 100 nm, but larger granules were seen also. Larval corpora cardiaca are the only source of glycogen phosphorylase activating hormone and at least 90% of the total activity was associated with the posterior region of the corpora cardiaca containing the intrinsic neurosecretory cells. The Golgi bodies in these cells appeared to be active. The data suggest that the glycogen phosphorylase activating hormone may be synthesized, stored and released from the intrinsic neurosecretory cells. In corpora cardiaca of larvae starved for 1 h some ultrastructural changes are seen, which might be indications of secretion of the glycogen phosphorylase activating hormone.

Octopamine and cyclic AMP mediate release of adipokinetic hormone I and II from isolated locust neuroendocrine tissue

Octopamine serves as a neurotransmitter in the glandular lobe of the locust corpus cardiacum where it regulates adipokinetic hormone (AKH) secretion from intrinsic neurosecretory cells. Two AKHs (AKH I and II) from the corpus cardiacum of Locusta have been sequenced and synthesized. We have now demonstrated that octopamine mediates release of both AKH I and II from Locusta corpora cardiaca in vitro. Octopamine, IBMX, and forskolin have previously been shown to elevate levels of cAMP in the glandular lobe. In this paper we demonstrate that IBMX and forskolin mediate secretion of AKH I and AKH II thus mimicking the effects of octopamine in this tissue. The cAMP analogs dibutyryl cAMP and 8-bromo cAMP also elicit release of AKH and a subthreshold concentration of IBMX potentiates the effects of octopamine. These observations demonstrate that cAMP participates in regulating AKH release and support the hypothesis that octopamine mediates hormone release at least in part via changes in intracellular levels of cAMP. The release of AKH I and AKH II is apparently regulated by similar mechanisms. The hyperlipemic activity of AKH II released into the perfusates following stimulation by octopamine and agents which elevate cAMP levels is significantly lower than that of AKH I. This differential response is probably due both to the reduced lipid-mobilizing effect of AKH II relative to AKH I, as well as to the release of greater amounts of AKH I.

Hormonal rhythm and behavioural trends in insects

Circadian rhythmicity in the timing of secretion and release of many of the neurohormones appears to be a common phenomenon in insects. Involvement of hormonal components in the locomotor activity rhythm in cockroaches, crickets etc. has not yet been proved unequivocally eventhough some of the findings along these lines support this. Many of the physiological events in insects occur only once in each individual’s life-time-gated events. Release of eclosion hormone in insects is determined both by a circadian clock and by the developmental competence of the insect. Periodic release ofPTTH which influence the moulting process in larvae has been established to be gated. Induction of prodromal signs of pupation as a result of gated release of PTTH in some insects have been confirmed. Intrinsic neurosecretory cells of cc release a hormone (calling hormone) in a rhythmic fashion which affect the pheromone release and subsequent initiation of calling behaviour in some of the lepidopteran virgin females. Production of proctodone by the epithelial cells of hindgut also follows a rhythm bringing about diapause in some of the insects.

The cardiacal neurosecretory system and associated organs of an adult mosquito, Aedes aegypti

Unlike most other insects, mosquitoes do not possess discrete corpora cardiaca composed of neuropile, intrinsic neurosecretory cells and glial cells. Cells homologous with the intrinsic neurosecretory cells of other insects are located at the junction of the neck and thorax of mosquitoes, close to the corpora allata. These cells are named cardiacal neurosecretory cells. Axons run forwards from the cardiacal neurosecretory cells into the allatal nerves. Neurosecretory release sites occur over almost the whole of the nervi corporum cardiacorum, allatal nerves and oesophageal nerves, and these nerves constitute a very extensive neurohaemal organ for many of the cerebral neurosecretory cells. The neurosecretory release sites of the cardiacal neurosecretory cells appear to be in the allatal nerves and possibly also on the perikarya of these cells.

Synaptic transmission elevates adenosine 3′, 5′-monophosphate (cyclic AMP) in locust neurosecretory cells

The release of adipokinetic hormones from the neurosecretory cells within the glandular lobe of the corpus cardiacum (CC) of locusts is under the synaptic control of axons within the nervi corporis cardiaca II (NCC II). This synapse has been shown to be aminergic with the transmitter tentatively identified as octopamine. We show here that stimulation of the presynaptic nerves in NCC II produces an increase in adenosine 3',5'-monophosphate (cyclic AMP) in the glandular lobe. Application of octopamine mimics the effect of nerve stimulation. These and other experiments lead us to believe the increase in cyclic AMP is coupled to the process of synaptic transmission, and that the increase occurs within the intrinsic neurosecretory cells of the glandular lobe.

Ultrastructure of the corpus cardiacum and corpus allatum of the house cricket Acheta domesticus.

The ultrastructure of the corpus cardiacum (CC) and corpus allatum (CA) of the house cricket, Acheta domesticus, is described. Axon profiles within the CC contain neurosecretory granules 160-350 nm in diameter which are indistinguishable from those found in type I neurosecretory cells of the pars intercerebralis and in the nervus corporis cardiaci I. The CC itself contains two cell types: intrinsic neurosecretory cells and glial cells. Intrinsic NSC cytoplasm contains Golgi bodies and electron dense neurosecretory granules 160-350 nm in diameter. Synaptoid configurations with 20-50 nm diameter electron lucent vesicles were observed within axon profiles of the CC. The structure of the CA is relatively uniform with one cell type predominating. Typical CA cells possess large nucleoli, active Golgi complexes, numerous mitochondria, and occassional microtubules. Groups of dark staining cells scattered throughout the CA of some animals were interpreted as evidence of cellular death.

The Corpus Cardiacum Neurosecretory Cells of Schistocerca gregaria. Electron Microscopy of Resting and Secreting Cells

AbstractThe corpora cardiaca of Schistocerca consist of a neurohaemal part containing mainly extrinsic neurosecretory axons coming from the brain, and of a glandular part consisting mainly of intrinsic neurosecretory cells. Some extrinsic axons penetrate into the glandular region, and innervate intrinsic corpus cardiacum neurosecretory cells. The fine structure of the latter has been examined and related to other neurosecretory cell types. Secretion occurs by exocytosis. Omega‐profiles are more frequently observed in corpora cardiaca stimulated electrically or by acetylcholine than in the controls.

Regenerated corpora cardiaca and hyperglycemic factor in Locusta migratoria

In Locusta migratoria, de novo “corpora cardiaca” are produced singly from the regeneration of each nervus corporis cardiaci internus after previous section of the nerves. The de novo glands are free from intrinsic neurosecretory cells, glandular lobe tissue, and lateral cerebral neurosecretory cell material. Extracts of the de novo glands induce hyperglycemia in Periplaneta americana similar to that produced by extracts of the neurosocretory storage lobes of normal corpora cardiaca. It is concluded that the hyperglycemic factor in the neurosecretory storage lobes of the corpora cardiaca in Locusta migratoria originates in the medial neurosecretory cells of the brain, not in the intrinsic neurosecretory cells of the glands, nor in contaminating glandular lobe tissue.

Regulation of egg maturation in the mosquito by the neurosecretory system: the role of the corpus cardiacum

In mosquitoes, the corpus allatum (CA) and the neurosecretory system each produce a hormone essential for egg development. Ablation experiments showed that when the female takes a blood meal 2–3 days after emergence, CA hormone had been secreted, whereas the neurosecretory hormone (EDNH) had been produced but was stored in the axons that form the corpus cardiacum. The cardiacum had accumulated enough EDNH for maturation of several batches of eggs. Nerve-sectioning and parabiosis experiments indicated that blood-feeding initiates some hemolymph-borne stimulus to the cardiacum that resulted in the release of enough EDNH, within 8–16 hr, for egg maturation. EDNH did not persist in the circulation after eggs were mature. Thus, the corpus cardiacum appears to regulate egg maturation by storing and “metering” the release of EDNH for each batch of eggs. Electron micrographs of Aedes sollicitans showed that the corpus cardiacum is both a ganglion and a neurohemal organ; it has no intrinsic neurosecretory cells. Bioassay of corpora cardiaca demonstrated that paraldehyde-fuchisin staining was not correlated with the presence of EDNH.

An electron microscopic study of the corpus cardiacum of adult Drosophila melanogaster and its afferent nerves.

AbstractThe left and right afferent nerves to the corpus cardiacum contain approximately 50 and 90 axons, respectively, when they enter the gland. Both bifurcate within the gland, so that four nerves leave the corpus cardiacum. These, however, contain a total of 90 axons. Of the 50 axons unaccounted for 30 are believed to terminate in the corpus cardiacum and 20 in the corpus allatum. The corpus cardiacum contains 12 intrinsic neurosecretory cells which are disposed laterally with respect to the extrinsic axons. Many of these contain neurosecretory spheres and presumably originate in the brain. The intrinsic corpus cardiacum cells also contain neurosecretory granules, and they produce short cytoplasmic processes which interdigitate with the extrinsic axons.

Ultrastructural studies on the corpora cardiaca‐allata complex of the adult alfalfa weevil, Hypera postica

AbstractThe organization of the corpora cardiaca and corpora allata of the female alfalfa weevil, Hypera postica, generally parallels that reported for other insects with extrinsic neurosecretory axons, intrinsic neurosecretory cells, and interstitial or glial cells appearing in both glands.Connecting the brain with the cardiacum are the extrinsic neurosecretory axons containing granules between 600 and 2200 Å. Granules with a diameter of up to 4000 Å are found in the intrinsic secretory cells of the corpus cardiacum.From the lobed corpus cardiacum, axons extend along a short nerve trunk into the ovoid corpus allatum. A characteristic of this gland is the presence of a layer of axons, ensheathing most of the corpus allatum and situated beneath an external basement membrane. These axons are believed to have their origin in the protocerebral neurosecretory cells. Although the c. allatum is known to be engaged in the release of hormonally active material, the cytoplasmic organization does not strongly reflect such activity.The glands of the diapausing weevil appear similar to those of the active weevil with a reduction in cytoplasm and a consequent folding of the plasma membrane.