Effect of serotonin and calcium on the supercontractile muscles of the adult blowfly crop

Role of Phote-HrTH (Phormia terraenovae hypertrehalosemic hormone) in modulating the supercontractile muscles of the crop of adult Phormia regina Meigen

“…Even if the same protocols (time, sequence, washing, supply, etc.) were used, as in the case of 5-HT (Liscia et al, 2012), we cannot exclude that the receptor kinetics elicited by Phote-HrTH are different from those of 5-HT in our previous paper (Liscia et al, 2012). Further investigation is needed to better clarify the relative contribution of calcium release and/or calcium influx plus the receptor kinetics involved in the two neuro-hormonal transduction mechanisms (i.e., 5-HT and Phote-HrTH).…”

“…Colony flies were provided separately with water and granulated sugar. Handling of the larvae and pupae were as previously described (Liscia et al, 2012).…”

“…This makes the difference with the 5-HT-induced calcium mechanism. In the presence of 5-HT, but in the absence of extracellular calcium, crop contractions cannot be sustained for a long period of time because extracellular calcium ions are critical for crop contractions to occur (Liscia et al, 2012). Also, the different protocols used could justify the differences in the Phote-HrTH effects that were encountered between the two experimental protocols, the crop contraction rate for both P4 and P5 being more sensitive to the peptide in the bioassays than in the electrophysiological experiments.…”

“…P. regina has generally been the researchers' choice for studies on feeding regulation in Diptera (Dethier, 1976). Liscia et al (2012) later demonstrated, using both bioassay and electrophysiological techniques, that the crop muscle activity of P. regina was calcium dependent and that serotonin, presumably from the thoracico-abdominal ganglion neural plexus, increased contractions of pump 4 (P4) of the crop. This P4 is located just prior to the crop lobes (see Fig.…”

“…Diagram modified fromLiscia et al (2012) showing the various pumps (P) and sphincters or valves (V), and recording electrode placement for P4 and P5 using P. regina.…”