Actions of kinin peptides in the stomatogastric ganglion of the crabCancer borealis

Abstract

Penaeus vannamei, but they have yet to be studied in the STG of any species. We identified kinin-like immunolabeling (KLI) in the pericardial organs (POs) in C. borealis, but there was no KLI within the STG. The POs are a major source of hormonal influence on the STG. Pevkinin peptides activated the pyloric circuit and they caused a modest increase in the speed of ongoing pyloric rhythms. This modest influence on cycle speed resulted in part from pevkinin excitation of the lateral pyloric neuron, whose strengthened inhibitory synapse onto the pyloric pacemaker neurons limited the pevkinin-mediated increase in cycle speed. The pevkinin excitation of the pyloric rhythm was not strong enough to interfere with the previously documented, gastric mill rhythm-mediated weakening of the pyloric rhythm. Pevkinin also had little influence on the gastric mill rhythm. These results indicate that the kinin peptides have distinct and selective modulatory actions on the pyloric rhythm.

State Dependence of Spike Timing and Neuronal Function in a Motor Pattern Generating Network

“…Potentially, these findings may also apply, although not yet proven, in vertebrate preparations based on previous work (Berkowitz and Stein, 1994;Pena et al, 2004). Conversely, in the crab, hyperpolarization of neuron LP is effective in changing program speed during application of one neuromodulator but not the other (Saideman et al, 2006;Thirumalai et al, 2006). Thus, it remains to be determined whether changes in the timing of the neurons that control phase transitions in these vertebrate and invertebrate preparations may be altered in a similar manner as that observed for B64.…”

“…Specifically, this happened when the network state changed attributable to alterations in contextual stimuli, e.g., the presence of peptides (Saideman et al, 2006;Thirumalai et al, 2006). These peptides changed the network speed without altering the type of motor program generated by the CPG.…”

“…Distinct programs can be generated by altering the activity of a subset of CPG elements whose sustained firing is either differentially recruited into or switched between specific phases in different motor programs (Flamm and Harris-Warrick, 1986;Nusbaum and Marder, 1989;Berkowitz and Stein, 1994;Combes et al, 1999;Weiss, 2002, 2005;Pena et al, 2004). However, to function differently, principal CPG neurons need not show a major change of phasing of sustained firing (Saideman et al, 2006;Thirumalai et al, 2006). Of particular interests are phase-transition neurons, i.e., neurons that terminate one phase of the program and initiate the next phase.…”

Crustacean neuropeptides

“…Data on the distribution of insect kinins in crustaceans are limited to members of the Decapoda [48, 50, [171][172][173], where they have been found both in regions of central neuropil and in neuroendocrine sites, suggesting autocrine/ paracrine and hormonal functioning [48,173].…”

“…Physiologically, application of insect kinins to the STG excited the pyloric rhythm, particularly in preparations with slow ongoing motor patterns [173]. In addition, they consistently enhanced activity in the dorsal gastric (DG) neuron, a member of the gastric mill neural circuit, although the peptide did not elicit or alter the full motor program per se [173,174].…”