title: Electrical activity of neurosecretory axons from the brain of Rhodnius prolixus: relation of changes in the pattern of activity to endocrine events during the moulting cycle.
abstract: Ongoing electrical activity was recorded from the axons of neurosecretory cells from the brain of 5th instar Rhodnius prolixus throughout the moulting cycle. Dramatic changes in both the frequency and pattern of electrical activity occur at specific times during the cycle, enabling the timing of release of neurohormones from the brain to be inferred. The level of transport of stainable secretion appears to be closely coupled to the electrical activity at all times. Activity is low in unfed Rhodnius, but within minutes of the insect taking a blood meal, there is a rapid appearance of bursting activity from a number of units, in conjunction with apparently continuous firing components. The bursting activity declines at about 2 h remaining low for the following 5 days, at which time there is a resurgence in the bursting pattern for a few hours. Both peaks of bursting activity immediately precede increases in haemolymph titer of ecdysones, suggesting that release of prothoracotropic hormone occurs on these two occasions. The continuously firing components initiated at feeding maintain a high level for 5 days indicating release of other brain neurosecretions. Intense electrical activity in the form of bursting activity and high apparently continuous pattern resumes shortly before ecdysis and continues until 12 h after. The relationship of neurohormone release at this time to bursicon and ecdysis behavior is discussed.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D004435:Eating; D004440:Ecdysone / Q000502:physiology; D005071:Evoked Potentials / Q000187:drug effects; D007301:Insect Hormones / Q000502:physiology*; D008675:Metamorphosis, Biological / Q000187:drug effects; D009489:Neurosecretion / Q000187:drug effects; D012239:Rhodnius; D012964:Sodium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D007301:Insect Hormones; D004440:Ecdysone; D003035:Cobalt; D013779:Tetrodotoxin; D012964:Sodium; D002118:Calcium