... examined the role of a locust FGLa/AST (Scg-AST-6) in the gut. Proctolin and Scg-AST-6 have opposing effects on gut contraction, where proctolin dose-dependently increases gut muscle tension, while Scg-AST-6 inhibits both muscle tension and spontaneous and neurogenic contractions in a dose-dependent manner...

...J. L. Wilkens; T. Shinozaki; T. Yazawa; H. E. D. J. ter Keurs SUMMARY At the threshold concentration (1-10 pmol l -1 ), the neuropeptide hormones proctolin (PR) and the FLRFamide-like peptide (FLP) F 2 cause an increase in amplitude of electrically evoked contractions (each contraction is a brief...

...% reduction of the voltage at 10 –7 mol l –1 . A. aegypti neuropeptide F and proctolin reduced V te at submicromolar concentrations. At 10 –6 mol l –1 ,neuropeptide F reduced V te by 30% and proctolin reduced V te by 50%. In contrast, A. aegypti allatotropin, A. aegypti head peptides I and III and A. aegypti...

... . A half-maximal response for the LemTRPs and LomTK I was obtained at 5×10 −9 mol l −1 . In both species, the neuropeptide proctolin stimulated foregut contractions. Using an antiserum to LomTK I, we demonstrated that in both species there are LomTK-like-immunoreactive (LomTK-LI) cell bodies and fibers...

... and dorsal abdominal) exhibits a unique spectrum of responses to a battery of neurotransmitters (acetylcholine, glutamic acid, γ -aminobutyric acid) and neurohormones (dopamine, octopamine, 5-hydroxytryptamine, crustacean cardioactive peptide, FLRFamide-related peptides F1 and F2, and proctolin...

... proctolin, crustacean cardioactive peptide (CCAP) and the FMRFamide-related peptides F1 and F2, all of which are found in the pericardial organs located immediately upstream of the heart. Cardioexcitatory activity has been demonstrated by these four peptides in both isolated and semi-isolated arthropod...

... mosquitoes ( Aedes aegypti ). Proctolin, leucomyosuppressin (LMS), serotonin and octopamine, which are known to modulate insect muscle contractions, and a mosquito neuropeptide, Aedes Head Peptide I (Aea-HP-I), which inhibits host-seeking behavior, were tested in the bioassays. LMS depressed contractile...

...Jim H. Belanger; Ian Orchard ABSTRACT The pentapeptide proctolin has multiple effects on the locust oviposition digging system. At the neuromuscular junction of the ventral opener muscle, it has a concentration-dependent range of modulatory effects. At low concentrations (10 −10 mol l −1...

... one tonic (RM 1 ) and one phasic (RM 2 ). Previous studies have shown that the sensitivity of the sensory neurones to passive stretch could be enhanced by serotonin and proctolin. Here we show that the receptor muscles and their exoskeletal muscle homologues are also responsive to serotonin, proctolin...

... −1 ) and proctolin (10 −8 mol l −1 ) induce contractions of the muscle, while GABA (10 −4 mol l −1 ) reduces potassium-induced depolarizations. HPLC, bioassay and immunological methods show that proctolin is associated with all of the ventral ovipositor muscles, and combined back-filling...

...C. A. Bishop; M. E. Krouse; J. J. Wine ABSTRACT Using the single-channel patch-clamp technique we have recently shown that the peptide cotransmitter proctolin can potentiate the activity of a large (38 pS in 137 mmol l −1 Ba 2+ ; 26 pS in 137 mmol l −1 Ca 2+ ), depolarization-inducible Ca 2...

...Valerie M. Pasztor; David L. Macmillan ABSTRACT A comparative survey is presented of the responsiveness of crustacean mechanoreceptors to the neurohormones proctolin, octopamine and serotonin. Seven identifiable primary afferents were examined in the crayfish Cherax destructor and the lobster...

...J. R. Groome; W. H. Watson, III ABSTRACT The biochemical mechanisms by which octopamine, catecholamines and the peptide proctolin exert their actions on Limulus cardiac muscle were investigated. Amines produced long-lasting increases in the amplitude of contractions evoked by electrical stimulation...

... that alter motoneuronal output. We have localized serotonin to identified neurones in the lobster ventral nerve cord and have shown further that the pentapeptide proctolin coexists with the amine in these cells. Such neurones provide a convenient system in which to study the functional interactions between...

...Taketeru Kuramoto; Arinobu Ebara ABSTRACT Systolic pressure in the abdominal artery of the lobster Panulirus japonicus (Von Siebold) was decreased by contraction of the cardioarterial valve located at the posterior exit of the heart. Crustacean neurohormones, octopamine and proctolin, induced...

...Peter D. Evans ABSTRACT The modes of action of the modulatory compounds octopamine, 5-hydroxytryptamine (5-HT) and proctolin on the frequency of the myogenic rhythm of the extensor-tibiae muscle of the hindleg of the locust, Schisto-cerca americana gregaria , have been investigated. 5-HT...

...W. H. Watson, III; G. J. Augustine; J. A. Benson; R. E. Sullivan ABSTRACT Synthetic proctolin increases the force but not the rate of heart contractions of Limulus in a time- and dose-dependent manner. The threshold of this effect is 3 X 10 −10 M and the ED S0 is approximately 10 −10 M...