Effect of a serotonergic extrinsic modulatory neuron (MCC) on radula mechanoafferent function in Aplysia

被引:9
作者
Alexeeva, V
Borovikov, D
Miller, MW
Rosen, SC
Cropper, EC
机构
[1] Mt Sinai Med Ctr, Dept Physiol & Biophys, New York, NY 10029 USA
[2] Mt Sinai Med Ctr, Fishberg Res Ctr Neurobiol, New York, NY 10029 USA
[3] Univ Puerto Rico, Dept Anat, San Juan, PR 00901 USA
[4] Univ Puerto Rico, Inst Neurobiol, San Juan, PR 00901 USA
[5] New York State Psychiat Inst, Ctr Neurobiol & Behav, New York, NY 10032 USA
关键词
D O I
10.1152/jn.1998.80.4.1609
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
The serotonergic metacerebral cells (MCCs) and homologous neurons in related mollusks have been extensively investigated within the context of feeding. Although previous work has indicated that the MCCs exert widespread actions, MCC modulation of sensory neurons has not been identified. We characterized interactions between the MCCs and a cell that is part of a recently described group of buccal radula mechanoafferents. The cell, B21, has a peripheral process in the tissue underlying the chitinous radula [the subradula tissue (SRT)]. Previous studies have shown that B21 can fire phasically during ingestive motor programs and provide excitatory drive to the circuitry active during radula closing/retraction. We now show that activity of B21 can be modulated by serotonin (5-HT) and the MCCs. Centrally, although a slow depolarization is typically recorded in B21 as a result of MCC stimulation, this depolarization does not cause B21 to spike. It can, however, increase B21 excitability enabling a pulse that was previously subthreshold to elicit an action potential in B21. B21 is in fact rhythmically depolarized during the radula closing/retraction phase of ingestive motor programs. Thus central effects of the MCCs on radula mechanoafferent activity are only likely to be apparent while B21 is receiving input from the feeding central pattern generator. Peripherally, radula mechanoafferent neurons can be activated 1) when a mechanical stimulus is applied to the biting surface of the SRT and 2) when the SRT contracts. MCC stimulation and 5-HT modulate B21 responses to both types of stimuli. For example, MCC stimulation and low concentrations of 5-HT cause subthreshold mechanical stimuli applied to the SRT to become suprathreshold. 5-HT and MCC stimulation also enhance SRT contractility. Peripheral effects of MCC activity are also likely to be phase dependent. For example, MCC stimulation does not cause B21 to respond to peripheral stimuli with an afterdischarge. Consequently, radula mechanoafferents are likely to be activated when food is present between the radula halves during radula closing/retraction but are not likely to continue to fire as opening/protraction is initiated. In a similar vein, MCC effects on the contractility of the SRT will only be apparent when contractions are elicited by motor neuron activity. SRT motor neurons are rhythmically activated during ingestive motor programs. Thus we have shown that radula mechanoafferent activity can be modulated by the MCCs and that this modulation is likely to occur in a phase-dependent manner.
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页码:1609 / 1622
页数:14
相关论文
共 61 条
[11]   Multiple mechanisms for peripheral activation of the peptide-containing radula mechanoafferent neurons B21 and B22 of Aplysia [J].
Cropper, EC ;
Evans, CG ;
Rosen, SC .
JOURNAL OF NEUROPHYSIOLOGY, 1996, 76 (02) :1344-1351
[12]   DIFFERENTIAL FIRING PATTERNS OF THE PEPTIDE-CONTAINING CHOLINERGIC MOTOR NEURONS B15 AND B16 DURING FEEDING-BEHAVIOR IN APLYSIA [J].
CROPPER, EC ;
KUPFERMANN, I ;
WEISS, KR .
BRAIN RESEARCH, 1990, 522 (01) :176-179
[13]  
DIPRISCO GV, 1990, BRAIN RES, V530, P161
[14]  
Drushel RF, 1997, J EXP BIOL, V200, P735
[15]   MONOSYNAPTIC INTERJOINT REFLEXES AND THEIR CENTRAL MODULATION DURING FICTIVE LOCOMOTION IN CRAYFISH [J].
ELMANIRA, A ;
DICAPRIO, RA ;
CATTAERT, D ;
CLARAC, F .
EUROPEAN JOURNAL OF NEUROSCIENCE, 1991, 3 (12) :1219-1231
[16]   SEROTONIN AND PROCTOLIN MODULATE THE RESPONSE OF A STRETCH-RECEPTOR IN CRAYFISH [J].
ELMANIRA, A ;
ROSSIDURAND, C ;
CLARAC, F .
BRAIN RESEARCH, 1991, 541 (01) :157-162
[17]  
Fox LE, 1997, J NEUROSCI, V17, P6064
[18]   BILATERAL SYMMETRY AND INTERNEURONAL ORGANIZATION IN BUCCAL GANGLIA OF APLYSIA [J].
GARDNER, D .
SCIENCE, 1971, 173 (3996) :550-&
[19]  
GERSCHENFELD HM, 1974, J PHYSIOL-LONDON, V243, P457, DOI 10.1113/jphysiol.1974.sp010762
[20]  
GERSCHENFELD HM, 1978, J PHYSIOL-LONDON, V274, P265