Vasopressin‐immunoreactive neurons and neurohemal systems in cockroaches and mantids

Abstract

Vasopressin-like neuropeptides of insects are of special interest because of their possible function as hormones and neuromodulators. Therefore, this study was undertaken by using whole-mount immunofluorescent staining by two antisera that recognize different types of vasopressin-like immunoreactive groups of neurons in the cockroaches Periplaneta americana, Leucophaea maderae, Nauphoeta cinerea, Diploptera punctata, and Blaberus discoidalis and in the mantids Litaneuria minor and Tenodera aridifolia sinensis. Using an antiserum to Arg/vasopressin, only two cells, the paired ventral paramedian (PVP) neurons, were immunostained in the central nervous system (CNS) of the cockroaches. These cells are located in the subesophageal ganglion, project throughout the CNS, and appear to be neurosecretory. Their varicose collaterals extend into the dorsal (motor) neuropil of the segmental ganglia, and this neuropil may be the principal site of the release of their neurosecretion. The PVP neurons were also stained by an antiserum to Lys/vasopressin; in addition, this antiserum stained several other groups of neurons, most of which appeared to be neurosecretory. Two pairs of Lys/vasopressin-immunoreactive cells are similar to the PVP neurons in that they are located in the subesophageal ganglion, extend through the ventral nerve cord, have collaterals in the dorsal neuropil of the segmental ganglia, and appear to be neurosecretory within the CNS. In addition, midventral and anteroventral clusters of Lys/vasopressin-immunoreactive neurosecretory neurons in the subesophageal ganglion project neurohemal release sites on the corpora allata. Other types of Lys/vasopressin-immunoreactive neurons include median and lateral neurosecretory cells of the protocerebrum and neurosecretory cells in the tritocerebrum, all of which project to the corpora cardiaca. In the abdominal ganglia there are posterolateral clusters of Lys/vasopressin neurosecretory neurons, and these cells extend to neurohemal release sites on the transverse and lateral cardiac nerves. In mantids the anti-Arg/vasopressin and anti-Lys/vasopressin antisera stained most of the same groups of neurons that these antisera recognized in cockroaches. The results of this study suggest that there are two or more vasopressin-like peptides in cockroaches and mantids and that these peptides may be released either as hormones in the blood or as neurosecretions within the CNS. Their function(s) in these insects remains to be determined.

Vasopressin-like peptide and its receptor function in an indirect diuretic signaling pathway in the red flour beetle

“…Another exception is the recently sequenced holometabolous species Nasonia, whose genome reveals putative avpl and avpl-r genes. The presence of vasopressin-immunoreactive neurons was reported for locusts, cockroaches, mantids, and the Colorado potato beetle (Davis and Hildebrand, 1992;Veenstra, 1984), whereas such activity is absent in B. mori (Remy et al, 1979). The lack of sequences encoding both the ligand and the receptor in multiple species and the general consensus regarding the presence/lack of immunoreactive cells strongly support the conclusion that the gene is truly missing in most holometabolous insects examined with the exception of Coleoptera and of Nasonia.…”

“…This observation was later extended to other locust species, cockroaches and mantids (Davis and Hildebrand, 1992;Tyrer et al, 1993). The discovery of AVP immunoreactivity in locust led to the isolation and identification of the AVPL peptide and to studies of its diuretic function in locust MT Schooley et al, 1987).…”

Oxytocin‐like signaling in ants influences metabolic gene expression and locomotor activity

“…Previously immunostaining of CNS tissue of grasshoppers (52), cockroaches, and a mantis species (53) revealed that neuronal projections from the 2 inotocin-positive neurosecretory cell bodies in SEG differ in some insects, allowing us to classify them into 2 groups: 1 ) “Schistocerca-type” grasshoppers and cockroaches that show no significant VP-like immune-reactive (VPLI) neuron branching in peripheral nerves or optic lobes and 2 ) “Locusta-type” grasshoppers that contain extensive branching by the VPLI neurons in the peripheral nerves and optic lobes. Here, we identified the same 2 inotocin-positive cells in the SEG in all castes of ants and detected neuronal projections.…”

Allatostatin‐like‐immunoreactive neurons of the tobacco hornworm, Manduca sexta , and isolation and identification of a new neuropeptide related to cockroach allatostatins

“…The appearance of these branches is very similar to that of the neuroendocrine processes found in neurohemal organs, suggesting that peptidergic interneurons that have neurosecretory-like processes provide a general paracrine (nonsynaptic) release within the nervous system. Examples of this type of peptidergic interneuron include in the Argvasopressin-immunoreactive, descending interneurons of the SeG of cockroaches and grasshoppers (Davis and Hildebrand, 1992;Tyrer et al, 1993) and the PBAN-ir descending interneurons and CCAP-ir interneuron 704 of M. sexta (Davis et al, , 1996. Moreover, nonsynaptic exocytosis of dense-core vesicles has been shown in the neuropil of cockroaches (Buma and Roubos, 1986).…”