Altered responsiveness to 5-HT at the crayfish neuromuscular junction due to chronic p-CPA and m-CPP treatment

Robin L. Cooper; Rachel J. Chase; Jami Tabor

doi:10.1016/S0006-8993(01)02885-2

Altered responsiveness to 5-HT at the crayfish neuromuscular junction due to chronic p-CPA and m-CPP treatment

Robin L. Cooper, Rachel J. Chase, Jami Tabor

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Serotonin (5-HT) levels in the hemolymph of crustaceans has been implied to alter aggressiveness which influences social interactions. The activation of IP3 as a second messenger cascade within crayfish motor neurons in response to application of 5-HT, suggests that the 5-HT receptor subtypes on the motor neurons are analogous to the vertebrate 5-HT2A receptors. Based on evidence in other systems, it would be expected that chronically sustained 5-HT levels in aggressive individuals would result in a compensatory negative feed-back regulation and/or that target tissues would diminish their sensitivity to high levels of circulating, free 5-HT. We addressed the issue of up- and down-regulation in the sensitivity of the responsiveness to exogenously applied 5-HT at the NMJs of crayfish in which the animals have altered endogenous 5-HT levels. Injections of the 5-HT1 and 5-HT2 vertebrate receptor agonist, 1-(3-Chlorophenyl) piperazine dihydrochloride (m-CPP), for 1 week resulted in a decreased responsiveness to application of 5-HT. The compound p-chlorophenylalanine (p-CPA) blocks the enzymatic synthesis of 5-HT and following 7 days of p-CPA injections, a super-sensitivity to exogenous application of 5-HT for both tonic and phasic neuromuscular junctions (NMJs) was observed. However, acute applications of p-CPA and m-CPP, followed by extensive saline washing, did not reveal any altered receptivity to 5-HT application.

Original language	English
Pages (from-to)	143-151
Number of pages	9
Journal	Brain Research
Volume	916
Issue number	1-2
DOIs	https://doi.org/10.1016/S0006-8993(01)02885-2
State	Published - Oct 19 2001

Bibliographical note

Funding Information:
Appreciation is expressed to Mr Austin Cooper and Dr Wendi Neckameyer (St. Louis University School of Medicine) for editorial comments and to Dr Julie G. Hensler (University of Texas Health Science Center at San Antonio, TX) for helpful experimental suggestions. Funding was provided by NSF grants IBN-9808631 (RLC), NSF-ILI-DUE 9850907 (RLC) and an undergraduate training fellowship from Howard Hughes Medical Institute (RJC) as well as a G. Ribble Fellowship for undergraduate studies in the School of Biological Sciences at the University of Kentucky (RJC and JT).

Keywords

Crayfish
Neuromodulation
Presynaptic
Serotonin
Synapse

ASJC Scopus subject areas

General Neuroscience
Molecular Biology
Clinical Neurology
Developmental Biology

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10.1016/S0006-8993(01)02885-2

Cite this

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title = "Altered responsiveness to 5-HT at the crayfish neuromuscular junction due to chronic p-CPA and m-CPP treatment",

abstract = "Serotonin (5-HT) levels in the hemolymph of crustaceans has been implied to alter aggressiveness which influences social interactions. The activation of IP3 as a second messenger cascade within crayfish motor neurons in response to application of 5-HT, suggests that the 5-HT receptor subtypes on the motor neurons are analogous to the vertebrate 5-HT2A receptors. Based on evidence in other systems, it would be expected that chronically sustained 5-HT levels in aggressive individuals would result in a compensatory negative feed-back regulation and/or that target tissues would diminish their sensitivity to high levels of circulating, free 5-HT. We addressed the issue of up- and down-regulation in the sensitivity of the responsiveness to exogenously applied 5-HT at the NMJs of crayfish in which the animals have altered endogenous 5-HT levels. Injections of the 5-HT1 and 5-HT2 vertebrate receptor agonist, 1-(3-Chlorophenyl) piperazine dihydrochloride (m-CPP), for 1 week resulted in a decreased responsiveness to application of 5-HT. The compound p-chlorophenylalanine (p-CPA) blocks the enzymatic synthesis of 5-HT and following 7 days of p-CPA injections, a super-sensitivity to exogenous application of 5-HT for both tonic and phasic neuromuscular junctions (NMJs) was observed. However, acute applications of p-CPA and m-CPP, followed by extensive saline washing, did not reveal any altered receptivity to 5-HT application.",

keywords = "Crayfish, Neuromodulation, Presynaptic, Serotonin, Synapse",

author = "Cooper, {Robin L.} and Chase, {Rachel J.} and Jami Tabor",

note = "Funding Information: Appreciation is expressed to Mr Austin Cooper and Dr Wendi Neckameyer (St. Louis University School of Medicine) for editorial comments and to Dr Julie G. Hensler (University of Texas Health Science Center at San Antonio, TX) for helpful experimental suggestions. Funding was provided by NSF grants IBN-9808631 (RLC), NSF-ILI-DUE 9850907 (RLC) and an undergraduate training fellowship from Howard Hughes Medical Institute (RJC) as well as a G. Ribble Fellowship for undergraduate studies in the School of Biological Sciences at the University of Kentucky (RJC and JT).",

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AU - Cooper, Robin L.

AU - Chase, Rachel J.

AU - Tabor, Jami

N1 - Funding Information: Appreciation is expressed to Mr Austin Cooper and Dr Wendi Neckameyer (St. Louis University School of Medicine) for editorial comments and to Dr Julie G. Hensler (University of Texas Health Science Center at San Antonio, TX) for helpful experimental suggestions. Funding was provided by NSF grants IBN-9808631 (RLC), NSF-ILI-DUE 9850907 (RLC) and an undergraduate training fellowship from Howard Hughes Medical Institute (RJC) as well as a G. Ribble Fellowship for undergraduate studies in the School of Biological Sciences at the University of Kentucky (RJC and JT).

PY - 2001/10/19

Y1 - 2001/10/19

N2 - Serotonin (5-HT) levels in the hemolymph of crustaceans has been implied to alter aggressiveness which influences social interactions. The activation of IP3 as a second messenger cascade within crayfish motor neurons in response to application of 5-HT, suggests that the 5-HT receptor subtypes on the motor neurons are analogous to the vertebrate 5-HT2A receptors. Based on evidence in other systems, it would be expected that chronically sustained 5-HT levels in aggressive individuals would result in a compensatory negative feed-back regulation and/or that target tissues would diminish their sensitivity to high levels of circulating, free 5-HT. We addressed the issue of up- and down-regulation in the sensitivity of the responsiveness to exogenously applied 5-HT at the NMJs of crayfish in which the animals have altered endogenous 5-HT levels. Injections of the 5-HT1 and 5-HT2 vertebrate receptor agonist, 1-(3-Chlorophenyl) piperazine dihydrochloride (m-CPP), for 1 week resulted in a decreased responsiveness to application of 5-HT. The compound p-chlorophenylalanine (p-CPA) blocks the enzymatic synthesis of 5-HT and following 7 days of p-CPA injections, a super-sensitivity to exogenous application of 5-HT for both tonic and phasic neuromuscular junctions (NMJs) was observed. However, acute applications of p-CPA and m-CPP, followed by extensive saline washing, did not reveal any altered receptivity to 5-HT application.

AB - Serotonin (5-HT) levels in the hemolymph of crustaceans has been implied to alter aggressiveness which influences social interactions. The activation of IP3 as a second messenger cascade within crayfish motor neurons in response to application of 5-HT, suggests that the 5-HT receptor subtypes on the motor neurons are analogous to the vertebrate 5-HT2A receptors. Based on evidence in other systems, it would be expected that chronically sustained 5-HT levels in aggressive individuals would result in a compensatory negative feed-back regulation and/or that target tissues would diminish their sensitivity to high levels of circulating, free 5-HT. We addressed the issue of up- and down-regulation in the sensitivity of the responsiveness to exogenously applied 5-HT at the NMJs of crayfish in which the animals have altered endogenous 5-HT levels. Injections of the 5-HT1 and 5-HT2 vertebrate receptor agonist, 1-(3-Chlorophenyl) piperazine dihydrochloride (m-CPP), for 1 week resulted in a decreased responsiveness to application of 5-HT. The compound p-chlorophenylalanine (p-CPA) blocks the enzymatic synthesis of 5-HT and following 7 days of p-CPA injections, a super-sensitivity to exogenous application of 5-HT for both tonic and phasic neuromuscular junctions (NMJs) was observed. However, acute applications of p-CPA and m-CPP, followed by extensive saline washing, did not reveal any altered receptivity to 5-HT application.

KW - Crayfish

KW - Neuromodulation

KW - Presynaptic

KW - Serotonin

KW - Synapse

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SN - 0006-8993

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JO - Brain Research

JF - Brain Research

IS - 1-2

ER -

Altered responsiveness to 5-HT at the crayfish neuromuscular junction due to chronic p-CPA and m-CPP treatment

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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