TY - JOUR
T1 - Release of peptide cotransmitters from a cholinergic motor neuron under physiological conditions
AU - Cropper, Elizabeth C.
AU - Price, David
AU - Tenenbaum, Renata
AU - Kupfermann, Irving
AU - Weiss, Klaudiusz R.
PY - 1990
Y1 - 1990
N2 - In previous studies, we demonstrated that B15, one of the two cholinergic motor neurons of the accessory radula closer muscle of Aplysia, synthesizes two peptides, small cardioactive peptides A and B (SCPA and SCPB), that, when exogenously applied, increase the size and relaxation rate of muscle contractions elicited by motor neuron stimulation. In the present experiments, we obtained evidence that the SCPs are released under physiological conditions. Specifically, we characterized firing patterns of motor neuron B15 during normal behavior, simulated them in vitro, and demonstrated that this type of neuronal activity produces decreases in SCP levels in neuronal processes and terminals. We also obtained evidence that suggests that enough SCP is released under physiological conditions to modulate neuromuscular activity in the accessory radula closer. We demonstrated that physiological activity of neuron B15 produces significant increases in muscle cAMP levels. Furthermore, increases in the size and relaxation rate of muscle contractions can be produced by changes in stimulation parameters that are also likely to maximize effects of released endogenous SCPA and SCPB.
AB - In previous studies, we demonstrated that B15, one of the two cholinergic motor neurons of the accessory radula closer muscle of Aplysia, synthesizes two peptides, small cardioactive peptides A and B (SCPA and SCPB), that, when exogenously applied, increase the size and relaxation rate of muscle contractions elicited by motor neuron stimulation. In the present experiments, we obtained evidence that the SCPs are released under physiological conditions. Specifically, we characterized firing patterns of motor neuron B15 during normal behavior, simulated them in vitro, and demonstrated that this type of neuronal activity produces decreases in SCP levels in neuronal processes and terminals. We also obtained evidence that suggests that enough SCP is released under physiological conditions to modulate neuromuscular activity in the accessory radula closer. We demonstrated that physiological activity of neuron B15 produces significant increases in muscle cAMP levels. Furthermore, increases in the size and relaxation rate of muscle contractions can be produced by changes in stimulation parameters that are also likely to maximize effects of released endogenous SCPA and SCPB.
KW - Aplysia
KW - Arousal
KW - Modulation
KW - Muscle contractility
KW - Small cardioactive peptide
UR - http://www.scopus.com/inward/record.url?scp=0025017315&partnerID=8YFLogxK
M3 - Article
C2 - 2153979
AN - SCOPUS:0025017315
SN - 0027-8424
VL - 87
SP - 933
EP - 937
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 3
ER -