The effects of 5-HT on sensory, central and motor neurons driving the abdominal superficial flexor muscles in the crayfish

Strawn, J. R.; Neckameyer, Wendi S.; Cooper, Robin L.

doi:10.1016/s0305-0491(00)00287-x

Cited by 37 publications

(27 citation statements)

References 57 publications

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“…Since serotonin increases the number of vesicles that are released with evoked stimulation (Southard et al, 2000;Strawn et al, 2000;Wang and Zucker, 1998), we postulate that MDMA will behave similarly to 5-HT in the crayfish preparation. The signaling molecule Ins(1,4,5)P3 is one such compound that could be key for MDMA's action.…”

Section: Discussionmentioning

confidence: 97%

Actions of MDMA at glutamatergic neuromuscular junctions

Sparks

Dasari

Cooper

2004

Neuroscience Research

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Abstract3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") compels mammalian serotonergic neurons to release serotonin (5-HT). In this study, MDMA altered synaptic transmission presynaptically by enhancing quantal release in two model glutamatergic synapses-the neuromuscular junction (NMJ) of the crayfish opener muscle, which is enhanced by exogenous 5-HT application, and the NMJ of a larval body wall muscle in Drosophila melanogaster, which is insensitive to exogenous 5-HT application. At the crayfish NMJ, MDMA mimicked the actions of 5-HT but only at a substantially higher concentration. At the Drosophila NMJ, MDMA altered synaptic transmission but not through a 5-HT receptor.Using simple invertebrate preparations, we have demonstrated an additional non-serotonergic mechanism of MDMA activity that has not yet been addressed in vertebrate systems and that may play an important role in understanding the mechanism of action for a commonly abused drug.

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Section: Discussionmentioning

confidence: 97%

Actions of MDMA at glutamatergic neuromuscular junctions

Sparks

Dasari

Cooper

2004

Neuroscience Research

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“…It is well established that numerous neuromodulators are present in the crayfish hemolymph; but how the neuromodulators alter behavior of the whole animal are not fully understood and are somewhat controversial (Livingston et al, 1980;Yeh et al, 1996;Cooper et al, 2001;Listerman et al, 2000;Strawn et al, 2000;Doernberg et al, 2001;Tabor and Cooper, 2002). Recently it was shown that the neuromodulator octopamine in some cases antagonize 5-HT's effects of enhancing synaptic transmission (Djokaj et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Previous investigations on the effect of 5-HT altering input resistance of a crayfish muscle had shown a slight increase. The difference could contribute to a larger EPSP for given amount of same synaptic current (Strawn et al, 2000) but differences in the currents were not noticeable. The mean of the percent change in synaptic charge for 5 tonic and 5 phasic preparations demonstrates that the tonic terminals had a greater enhancement in synaptic transmission induced by 5-HT as compared to phasic terminals ( Fig.…”

Section: Effect Of 5-ht On the Synaptic Chargementioning

confidence: 99%

“…At crayfish NMJs, 5-HT enhances synaptic transmission (Dudel, 1965;Florey and Florey, 1954;Fisher and Florey, 1983). Primarily, 5-HT enhances the probability of vesicular fusion during evoked transmission, but it can also increase the number of vesicular release sites (Southard et al, 2000;Strawn et al, 2000). The cellular mechanism may involve phosphorylation of vesicular docking related synaptic proteins, enhancing the number of vesicles to be released upon an evoked response (He et al, 1999;Cooper et al, 2001;Tabor and Cooper, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Intrinsic differences in sensitivity to 5-HT between high- and low-output terminals innervating the same target

Cooper

Dönmezer

Shearer

2003

Neuroscience Research

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The differential action of neuromodulators on synapses of various efficacy provides additional fine tuning of synaptic regulation beyond frequency induced plasticity. We used the well-characterized high-and low-output motor nerve terminals, of the tonic and phasic neuromuscular junctions (NMJs) in the walking leg extensor muscle of the crayfish, to investigate differential actions of serotonin (5-HT) since both terminals innervate the same target. The excitatory postsynaptic potentials of the tonic NMJ are enhanced to a greater extent than for the phasic NMJs during exposure to 5-HT (100 nM). Macropatch current recordings at identified sites along the motor nerve terminals and quantal analysis indicate that mean quantal content is substantially increased by 5-HT. The overall probability of vesicular release increases to a greater extent at tonic terminals than at phasic terminals when exposed to 100 nM 5-HT. Measures in the area (i.e. charge) of spontaneous quantal currents indicate no difference in postsynaptic receptivity to the glutamatergic synaptic transmission upon exposure to 5-HT. The results provide new details concerning differential modulation of low-and high-output synapses present on the same target tissue. #

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“…Fur-ther investigations on sensory neurons could relate the mechanisms of neuromodulators to those known at neuromuscular junctions with varying synaptic efficacy Cooper 1995, 1996;LaFramboise et al, 2000). Recently, we have been addressing the influence of these neuromodulators on motor nerve terminals Cooper, 1999, 2000;Griffis et al, 2000;He et al, 1999;Southard et al, 2000) and central integration of sensory input (Strawn et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

The effects of serotonin and ecdysone on primary sensory neurons in crayfish

Cooper¹,

Ward²,

Braxton³

et al. 2003

Microscopy Res & Technique

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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 M, 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.

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The effects of 5-HT on sensory, central and motor neurons driving the abdominal superficial flexor muscles in the crayfish

Cited by 37 publications

References 57 publications

Actions of MDMA at glutamatergic neuromuscular junctions

Actions of MDMA at glutamatergic neuromuscular junctions

Intrinsic differences in sensitivity to 5-HT between high- and low-output terminals innervating the same target

The effects of serotonin and ecdysone on primary sensory neurons in crayfish

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