Set Of Neuropeptides Research Articles

Prothoracicostatic Activity of the Ecdysis-Regulating Neuropeptide Crustacean Cardioactive Peptide (CCAP) in the Desert Locust.

Accurate control of innate behaviors associated with developmental transitions requires functional integration of hormonal and neural signals. Insect molting is regulated by a set of neuropeptides, which trigger periodic pulses in ecdysteroid hormone titers and coordinate shedding of the old cuticle during ecdysis. In the current study, we demonstrate that crustacean cardioactive peptide (CCAP), a structurally conserved neuropeptide described to induce the ecdysis motor program, also exhibits a previously unknown prothoracicostatic activity to regulate ecdysteroid production in the desert locust, Schistocerca gregaria. We identified the locust genes encoding the CCAP precursor and three G protein-coupled receptors that are activated by CCAP with EC50 values in the (sub)nanomolar range. Spatiotemporal expression profiles of the receptors revealed expression in the prothoracic glands, the endocrine organs where ecdysteroidogenesis occurs. RNAi-mediated knockdown of CCAP precursor or receptors resulted in significantly elevated transcript levels of several Halloween genes, which encode ecdysteroid biosynthesis enzymes, and in elevated ecdysteroid levels one day prior to ecdysis. Moreover, prothoracic gland explants exhibited decreased secretion of ecdysteroids in the presence of CCAP. Our results unequivocally identify CCAP as the first prothoracicostatic peptide discovered in a hemimetabolan species and reveal the existence of an intricate interplay between CCAP signaling and ecdysteroidogenesis.

Agatoxin-like peptides in the neuroendocrine system of the honey bee and other insects

We investigated the peptide inventory of the corpora cardiaca (CC) of the honey bee, Apis mellifera, by direct tissue profiling using MALDI-TOF MS combined with proteomic approaches focusing on cysteine-containing peptides. An agatoxin-like peptide (ALP) was identified as a component of the glandular part of the CC and was associated with the presence of the adipokinetic hormone in mass spectra. Although abundant in the CC, ALP does not belong to the toxins observed in the venom gland of A. mellifera. Homologs of ALP are highly conserved in major groups of arthropods and in line with this we detected ALP in the CC of non-venomous insects such as cockroaches and silverfish. In the American cockroach, Periplaneta americana, ALP was also identified in the CNS and stomatogastric nervous system. This is the first report that establishes the presence of ALPs in the neuroendocrine tissues of insects and further studies are necessary to reveal common functions of these peptides, e.g. as antimicrobial agents, ion channel modulators or classical neuropeptides. Biological significanceAmong the messenger molecules of the nervous system, neuropeptides represent the structurally most diverse class and basically participate in the regulation of all physiological processes. The set of neuropeptides, their functions and spatial distribution are particularly well-studied in insects. Until now, however, several potential neuropeptide receptors remained orphan, which indicates the existence of so far unknown ligands. In our study, we used proteomic methods such as cysteine modification, enzymatic digestion and peptide derivatization, combined with direct tissue profiling by MALDI-TOF mass spectrometry, for the discovery of novel putative messenger molecules in the neuroendocrine system. The described presence of agatoxin-like peptides in the nervous system of the honey bee and other insects was overseen so far and is thus a remarkable addition to the very well studied neuropeptidome of insects. It is not yet clear, if these toxin-like peptides act as antimicrobial agents, ion channel modulators or classical neuropeptides.

Neurochemistry and Plasticity of the Median Eminence and Neural Pituitary Lobe in Relation to Background Adaptation of Xenopus laevis

Using immunocytochemistry and morphometry we have supported our hypothesis that magnocellular neurons in the preoptic area of the brain of Xenopus laevis release identical sets of neuropeptides containing not only the previously identified vasotocin, mesotocin, corticotropin-releasing factor, thyrotropin-releasing hormone, brain-derived neurotrophic factor, urocortin 1, and pituitary adenylate cyclase-activating peptide but also mesotocin and met-enkephalin from both neurohemal areas in the pituitary neural lobe and in the median eminence. We also show that the external zone of the median eminence is plastic, depending in size on the state of background illumination.

Molecular evolution of neuropeptides in the genus Drosophila

The first genomic and chemical characterization of fruit fly neuropeptides outside Drosophila melanogaster provides insights into the evolution of the neuropeptidome in this genus.

The VD1/RPD2 neuronal system in the central nervous system of the pond snail Lymnaea stagnalis studied by in situ hybridization and immunocytochemistry.

VD1 and RPD2 are two giant neuropeptidergic neurons in the central nervous system (CNS) of the pond snail Lymnaea stagnalis. We wished to determine whether other central neurons in the CNS of L. stagnalis express the VD1/RPD2 gene. To this end, in situ hybridization with the cDNA probe of the VD1/RPD2 gene and immunocytochemistry with antisera specific to VD1 and RPD2 (the alpha 1-antiserum, Mab4H5 and ALMA 6) and to R15 (the alpha 1 and 16-mer antisera) were performed on alternate tissue sections. A VD1/RPD2 neuronal system comprising three classes of neurons (A1-A3) was found. All neurons of the system express the gene. Division into classes is based on immunocytochemical characteristics. Class A1 neurons (VD1 and RPD2) immunoreact with the alpha 1-antiserum, Mab4H5 and ALMA 6. Class A2 neurons (1-5 small and 1-5 medium sized neurons in the visceral and right parietal ganglion, and two clusters of small neurons and 5 medium-sized neurons in the cerebral ganglia) immunoreact with the alpha 1-antiserum and Mab4H5, but not with ALMA 6. Class A3 neurons (3-4 medium-sized neurons and a cluster of 4-5 small neurons located in the pedal ganglion) immunoreact with the alpha 1-antiserum only. All neurons of the system are immunonegative to the R15 antisera. The observations suggest that the neurons of the VD1/RPD2 system produce different sets of neuropeptides. A group of approximately 15 neurons (class B), scattered in the ganglia, immunostained with one or more of the antisera, but did not react with the cDNA probe in in situ hybridization.

Expression of the egg-laying hormone genes in peripheral neurons and exocrine cells in the reproductive tract of the mollusc Lymnaea stagnalis

The neuroendocrine caudodorsal cells play an important role in the control of reproduction in Lyrmaea stagnalis. These neurons produce at least nine neuropeptides which are encoded by caudodorsal cell hormone-I and -II genes. The role of some of these peptides in the control of reproduction has been established. The present study demonstrates that the transcription and translation of the caudodorsal cell hormone genes also proceeds abundantly in the reproductive tract of this hermaphroditic animal. In the female part of the reproductive tract neurons were found to express gene I. These neurons are most likely involved in the control of transport of the eggs and egg-masses and in the regulation of secretory activity from the female accessory sex glands. In the male part of the reproductive tract exocrine secretory cells express gene I or gene II. The gene products are secreted into the male duct and transferred to the female copulant during copulation. Furthermore, putative sensory neurons in the skin were found to express gene I. The results indicate that in L. stagnalis the complex process of reproduction is regulated—at least in part—by a set of neuropeptides which are encoded by a small multigene family, viz. the caudodorsal cell gene family.