Serotonin transduction cascades mediate variable changes in pyloric network cycle frequency in response to the same modulatory challenge.
A fundamental question in systems biology addresses the issue of how flexibility is built into modulatory networks such that they can produce context-dependent responses. Here we examine flexibility in the serotonin (5-HT) response system that modulates the cycle frequency (cf) of a rhythmic motor output. We found that depending on the preparation, the same 5-min bath application of 5-HT to the pyloric network of the California spiny lobster, Panulirus interruptus, could produce a significant increase, decrease, or no change in steady-state cf relative to baseline. Interestingly, the mean circuit output was not significantly different among preparations prior to 5-HT application. We developed pharmacological tools to examine the preparation-to-preparation variability in the components of the 5-HT response system. We found that the 5-HT response system consisted of at least three separable components: a 5-HT(2betaPan)-like component mediated a rapid decrease followed by a sustained increase in cf; a 5-HT(1alphaPan)-like component produced a small and usually gradual increase in cf; at least one other component associated with an unknown receptor mediated a sustained decrease in cf. The magnitude of the change in cf produced by each component was highly variable, so that when summed they could produce either a net increase, decrease, or no change in cf depending on the preparation. Overall, our research demonstrates that the balance of opposing components of the 5-HT response system determines the direction and magnitude of 5-HT-induced change in steady-state cf relative to baseline.
Spitzer
Nadja
N
Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, GA 30302-4010, USA.
Cymbalyuk
Gennady
G
Zhang
Hongmei
H
Edwards
Donald H
DH
Baro
Deborah J
DJ
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D002069:Butaclamol / Q000494:pharmacology; D002461:Cell Line, Transformed; D018492:Dopamine Antagonists / Q000494:pharmacology; D004347:Drug Interactions; D017952:Ganglia, Invertebrate / Q000166:cytology* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D033521:Palinuridae; D010879:Piperazines / Q000494:pharmacology; D044282:Receptor, Serotonin, 5-HT1A / Q000235:genetics; D044348:Receptors, Serotonin, 5-HT2 / Q000235:genetics; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014162:Transfection / Q000379:methods
D018492:Dopamine Antagonists; D007295:Inositol Phosphates; D010879:Piperazines; D044348:Receptors, Serotonin, 5-HT2; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; C018406:1-(3-trifluoromethylphenyl)piperazine; D012701:Serotonin; D002069:Butaclamol