Sensitivity of transformed (phasic to tonic) motor neurons to the neuromodulator 5-HT

Citation
B. Griffis et al., Sensitivity of transformed (phasic to tonic) motor neurons to the neuromodulator 5-HT, COMP BIOC A, 127(4), 2000, pp. 495-504
Citations number
69
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences",Physiology
Journal title
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY
ISSN journal
1095-6433 → ACNP
Volume
127
Issue
4
Year of publication
2000
Pages
495 - 504
Database
ISI
SICI code
1095-6433(200012)127:4<495:SOT(TT>2.0.ZU;2-S
Abstract
Long-term adaptation resulting in a 'tonic-like' state can be induced in ph asic motor neurons of the crayfish, Procambarus clarkii, by daily law-frequ ency stimulation [Lnenicka, G.A., Atwood, H.L., 1985b. Long-term facilitati on and long-term adaptation at synapses of a crayfish phasic motoneuron. J. Neurobiol. 16, 97-110]. To test the hypothesis that motor neurons undergoi ng adaptation show increased responses to the neuromodulator serotonin (5-H T), phasic motor neurons innervating the deep abdominal extensor muscles of crayfish were stimulated at 2.5 Hz, 2 h/day, for 7 days. One day after ces sation of conditioning, contralateral control and conditioned motor neurons of the same segment were stimulated at I Hz and the induced excitatory pos t-synaptic potentials (EPSPs) were recorded from DEL1 muscle fibers innerva ted by each motor neuron type. Recordings were made in saline without and w ith 100 nM 5-HT. EPSP amplitudes were increased by 5-HT exposure in all cas es. Conditioned muscles exposed to 5-HT showed a 2-fold higher percentage o f increase in EPSP amplitude than did control muscles. Thus, the conditione d motor neurons behaved like intrinsically tonic motoneurons in their respo nse to 5-HT. While these results show that long-term adaptation (LTA) exten ds to 5-HT neuromodulation, no phenotype switch could be detected in the po stsynaptic muscle. Protein isoform profiles, including the myosin heavy cha ins, do not change after 1 week of conditioning their innervating motor neu rons. (C) 2000 Elsevier Science Inc. All rights reserved.