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The effects of serotonin and ecdysone on primary sensory neurons in crayfish
Author(s) -
Cooper Robin L.,
Ward Elizabeth,
Braxton Recennah,
Li Hao,
Warren Wendy M.
Publication year - 2003
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.10272
Subject(s) - crayfish , hemolymph , sensory system , sensory neuron , moulting , serotonin , biology , medicine , neuroscience , endocrinology , neuron , stretch receptor , stimulation , hormone , receptor , ecology , larva , biochemistry
The overall behaviors and motivational states observed during social interactions and throughout the molting cycle of crayfish have been linked to the effects of humoral neuromodulators. Both serotonin (5‐HT) and a molt‐related hormone, 20‐hydroxyecdysone (20‐HE), are known to be present in the hemolymph of crustaceans. To determine if they alter the activity of a primary sensory neuron that monitors proprioceptive information, we examined their effects on the activity of the slow‐adapting muscle receptor organ (MRO) of the crayfish abdomen, a model sensory system that has been extensively studied. 5‐HT within the range of 100 nM to 1 μM, increases the firing frequency of the neuron during sustained stimulation. In experiments in which 20‐HE was added alone, an increase in the firing frequency also occurred, although to a lesser degree than that for 5‐HT at the same concentrations. When the MRO is first exposed to 20‐HE, followed sequentially by 5‐HT, the activity increases to about the same degree as in the reverse order of exposure. This outcome indicates that mixtures of these endogenous neuromodulators, at various levels, are more important in alternating behavior than the absolute level of any one of them introduced alone. Microsc. Res. Tech. 60:336–345, 2003. © 2003 Wiley‐Liss, Inc.