The blood-feeding bug Rhodnius prolixus ingests a large blood meal, and this is followed by a rapid diuresis to eliminate excess water and salt. Previous studies have demonstrated that serotonin and an unidentified peptide act as diuretic factors. In other insects, members of the corticotropin-releasing factor (CRF)-related peptide family have been shown to play a role in post-feeding diuresis. Using fluorescence immunohistochemistry and immunogold labelling with antibodies to the Locusta CRF-like diuretic hormone (Locusta-DH) and serotonin, we have mapped the distribution of neurones displaying these phenotypes in R. prolixus. Strong Locusta-DH-like immunoreactivity was found in numerous neurones of the central nervous system (CNS) and, in particular, in medial neurosecretory cells of the brain and in posterior lateral neurosecretory cells of the mesothoracic ganglionic mass (MTGM). Positively stained neurohaemal areas were found associated with the corpus cardiacum (CC) and on abdominal nerves 1 and 2. In addition, Locusta-DH-like immunoreactive nerve processes were found over the posterior midgut and hindgut. Double-labelling studies for Locusta-DH-like and serotonin-like immunoreactivity demonstrated some co-localisation in the CNS; however, no co-localisation was found in the medial neurosecretory cells of the brain, the posterior lateral neurosecretory cells of the MTGM or neurohaemal areas. To confirm the presence of a diuretic factor in the CC and abdominal nerves, extracts were tested in Malpighian tubule secretion assays and cyclic AMP assays. Extracts of the CC and abdominal nerves caused an increase in the rate of secretion and an increase in the level of cyclic AMP in the Malpighian tubules of fifth-instar R. prolixus. The presence of the peptide in neurohaemal terminals of the CC and abdominal nerves that are distinct from serotonin-containing terminals indicates that the peptide is capable of being released into the haemolymph and that this release can be independent of the release of serotonin.
Recognising our community as we approach JEB's centenary
In this Editorial, Craig Franklin, Michaela Handel and Kathryn Knight reflect on recent developments at JEB and acknowledge the support of the community during what has been a particularly challenging year. Looking forward, they discuss the journal’s centenary celebrations in 2023.
Our Transformative Journals have exceeded their OA growth targets
In the field: an interview with Roger Hanlon
Roger Hanlon talks about his fieldwork experiences diving all over the planet to understand cephalopod camouflage and communication.
How climbing parrots achieve pitch stability while ascending
Climbing parrots push and pull with their feet on ladder rungs and push with their tails to prevent themselves from toppling backward as they ascend.
Towards understanding the neural origins of hibernation
Madeleine Junkins, Sviatoslav Bagriantsev and Elena Gracheva review the role of the nervous system in hibernation, arguing that it actively promotes and supports the hibernation process rather than simply enduring it.
Social media
