Neuromuscular transmission in the visceral muscle of locust oviduct

Peripheral distribution of presynaptic sites of abdominal motor and modulatory neurons inManduca sexta larvae

“…It has been demonstrated that locust DUM neurons are capable of releasing octopamine in a manner that is Ca 2ϩ sensitive, is dependent on the firing frequency of the DUM neuron, and is accelerated in the presence of high-potassium saline (Morton and Evans, 1984;Orchard and Lange, 1987). Electron microscopy of UM neuron varicosities on body wall or visceral muscles (Hoyle et al, 1980;Kiss et al, 1984;Rheuben, 1995) and of type II terminal varicosities on D. melanogaster abdominal muscles (Atwood et al, 1993;Jia et all., 1993) have shown both dense-cored and less numerous, clear vesicles. In addition to octopamine, type II terminals in D. melanogaster contain glutamate (Johansen et al, 1989), but the postsynaptic specializations surrounding these varicosities are not immunopositive for either type of anti-glutamate receptor antiserum (DCluRIIA, DGluRIIB; Petersen et al, 1997).…”

“…At the ultrastractural level, dendritic neuronal processes in the central nervous system and peripheral neuromuscular terminals of the UM neurons appear to contain large dense-core vesicles, together with less numerous, small clear vesicles. However, dense-core vesicles, which are thought to contain octopamine, were never found in typical presynaptic specializations, suggesting that octopamine may be released nonsynaptically (Oertal et al, 1975;Hoyle et al, 1980;Kiss et al, 1984;Watson, 1984;Atwood et al, 1993;Rheuben, 1995;Pflü ger and Watson, 1995).…”

Mating, seminal fluid components, and sperm cause changes in vesicle release in the Drosophila female reproductive tract

“…Any of these effectors could potentially modulate the contractile activity of reproductive tract musculature. A paradigm for what could be modulated is offered by locusts (Locusta migratoria), whose oviducts are innervated by neurons whose neuroactive substances (including the neuropeptides SchistoFLRFamide and proctolin, the neuromodulator octopamine, and probably the neurotransmitter glutamate) mediate muscle contraction (22)(23)(24)(25)(26)(27). Two recent reports indicate that octopamine also regulates ovulation in D. melanogaster (28,29).…”

Neuromuscular transmission in an insect visceral muscle

“…Despite the fascinating problem of visceral muscle control, much of our understanding of their neuromuscular mechanisms is derived from a rather limited number of preparations and species Yamamoto and Fukami, 1980;Kiss, Varanka, and Benedeczky, 1984). Similarly, only a few studies have examined the pharmacology of neuromuscular transmission in these muscles (Brown, 1967;Cook and Holman, 1975;Miller and James, 1976).…”

“…In addition, it has been postulated that a myotropic peptide can also act upon the locust oviducts to increase the force and frequency of spontaneous contractions, resulting in the transport of eggs during oviposition (Girardie and Lafon-Cazal, 1972;Okelo, 1971). Little is known of the physiology of neuromuscular transmission in oviduct muscle, although recent papers have begun to broach this problem (Lange and Orchard, 1984a, b;Lange, Orchard, and Loughton, 1984;Kiss, Varanka, and Benedeczky, 1984). Only one such study has examined the pharmacology of neuromuscular transmission in these muscles (Lange and Orchard, 198413) although the pharmacological control of spontaneous contractions has also been examined (Cook, 1981;Cook and Meola, 1978;Cook, Holman, and Meola, 1984).…”