Are behavioral responses to sucrose stimulation modulated by PKG?
To establish if the responses of the digging rhythm to sucrose stimulation are modulated via a NO/cGMP-PKG signaling pathway, the PKG inhibitor KT-5823 was bath applied to the terminal abdominal ganglion and the valves repeatedly stimulated with 1 M sucrose. A 10 min bath application with 10 μM KT-5823 resulted in a statistically significant increase in the duration of cessation of the digging rhythm, from a control value of 15.1 ± 6.2 s to a test value of 66.1 ± 10.5 s (mean ± SEM, n = 5 animals; P < 0.05, Mann–Whitney U-test) (Figure 5Ei). A recording of the ventral opener muscle showed an increase in the cessation of the digging rhythm for test stimulations of the ovipositor valves with 1 M sucrose compared with control (Figure 5Eii). In summary, NO was found to be involved in the modulation of responses to both chemicals used in the analysis. Increases and decreases of NO levels within the terminal abdominal ganglion both significantly influenced the cessation of the digging rhythm
