Quantification of Locusta diuretic hormone in the central nervous system and corpora cardiaca: influence of age and feeding status, and mechanism of release.
Locusta-DH is known to have a hormonal function in the control of post-feeding diuresis in the migratory locust. This study has quantified Locusta-DH in tissues from V(th) instar nymphs and adults, and investigated the K+-induced release of the peptide from corpora cardiaca. Locusta-DH is present in thoracic and abdominal ganglia, but the amounts are small (25-200 fmol) compared with brain (approximately 1 pmol) and corpora cardiaca ( > 5 pmol) from 14-day old locusts. About 50% of the immunoreactive material in corpora cardiaca coelutes with Locusta-DH on reversed-phase HPLC. An earlier eluting fraction is also biologically active, suggesting locusts have a second, previously undetected, CRF-related peptide. The amount of peptide stored in corpora cardiaca varies with age and physiological status. Reductions on day 1 of the adult instar and immediately after feeding suggest Locusta-DH controls post-eclosion as well as post-feeding diureses. Locusta-DH is released by a Ca2+-dependent mechanism from corpora cardiaca held in salines containing > or =40 mM K+. This is blocked by verapamil, implicating L-type Ca2+ channels. Release is most rapid shortly after transfer to a high K+ saline, and more peptide is released from glands allowed to recover in normal saline between successive K+ depolarisations.
Audsley
N
N
Department of Biology, Birkbeck College, London, UK.
Goldsworthy
G J
GJ
Coast
G M
GM
D000375:Aging / Q000378:metabolism; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002490:Central Nervous System / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004435:Eating; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017952:Ganglia, Invertebrate / Q000737:chemistry; D006110:Grasshoppers / Q000737:chemistry*; D007301:Insect Hormones / Q000032:analysis*; D009490:Neurosecretory Systems / Q000737:chemistry; D011188:Potassium / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D007301:Insect Hormones; C072468:diuretic peptide, Locusta-DP; D019284:Thapsigargin; D014700:Verapamil; D011188:Potassium