Unveiling the sensory and interneuronal pathways of the neuroendocrine connectome inDrosophila

Abstract

Neuroendocrine systems in animals maintain organismal homeostasis and regulate stress response. Although a great deal of work has been done on the neuropeptides and hormones that are released and act on target organs in the periphery, the synaptic inputs onto these neuroendocrine outputs in the brain are less well understood. Here, we use the transmission electron microscopy reconstruction of a whole central nervous system in the Drosophila larva to elucidate the sensory pathways and the interneurons that provide synaptic input to the neurosecretory cells projecting to the endocrine organs. Predicted by network modeling, we also identify a new carbon dioxide responsive network that acts on a specific set of neurosecretory cells and which include those expressing Corazonin (Crz) and Diuretic hormone 44 (DH44) neuropeptides. Our analysis reveals a neuronal network architecture for combinatorial action based on sensory and interneuronal pathways that converge onto distinct combinations of neuroendocrine outputs.

A population of neurons that produce hugin and express the diuretic hormone 44 receptor gene projects to the corpora allata in Drosophila melanogaster

“…To understand the role of Hug in D. melanogaster physiology and behavior, neuronal circuits and synaptic connections of Hug neurons have been intensively studied (Bader et al., 2007; Melcher & Pankratz, 2005; Schlegel et al., 2016). Regarding the anatomical relationship between Hug neurons and the CA, the former have been reported to project to the complex including the CA and CC in the adult stage (Melcher & Pankratz, 2005), and to the CC in the larval stage (Hückesfeld et al, 2020). However, these studies have not precisely examined whether a part of Hug neurons project to the CA.…”

A population of neurons that produce hugin and express thediuretic hormone 44 receptorgene projects to the corpora allata inDrosophila melanogaster

“…To understand the role of Hug in D. melanogaster physiology and behavior, neuronal circuits and synaptic connections of Hug neurons have been intensively studied (Bader et al, 2007; Melcher and Pankratz, 2005; Schlegel et al, 2016). Regarding the anatomical relationship between Hug neurons and the CA, the former have been reported to project to the complex including the CA and CC in the adult stage (Melcher and Pankratz, 2005), and to the CC in the larval stage (Hückesfeld et al, 2020). However, these studies have not precisely examined whether a part of Hug neurons project to the CA.…”

Regulation of ecdysone production in Drosophila by neuropeptides and peptide hormones

“…These inputs are relayed to the PG by neuropeptides produced by neurons that innervate the PG and by circulating peptide hormones that activate corresponding receptors on PG cells ( figure 3 ). A study published by Siegmund & Korge [ 45 ] in 2001 described 11 sets of neurosecretory neurons that innervate the ring gland, and a recent study has provided additional information regarding the neuropeptides these express [ 46 ]. Of the 11 sets of neurons that target the broader ring gland, five were shown in the Siegmund & Korge study to directly innervate the PG [ 45 ].…”