Developmental changes in 5-hydroxytryptamine-induced rhythmic activity in the spinal cord of rat fetuses in vitro.
The roles played by glycine- and glutamate-mediated synaptic transmission in the generation of 5-hydroxytryptamine (5-HT)-induced rhythmic activity were examined in isolated spinal cord preparations from fetal rats. Bath application of 5-HT (0.1-30 microM) evoked rhythmic activity in lumbar ventral roots at and after E14.5. Bath application of strychnine (5 microM), a glycine-receptor antagonist, reduced the frequency of the rhythmic activity to 37% of control at E14.5. Although, kynurenate (4 mM), a glutamate-receptor antagonist, had little effect at this stage, it completely abolished the 5-HT-induced rhythmic activity at and after E18.5, when strychnine had little effect on the frequency. These results indicate that, at and shortly after its onset, the rhythmic activity is driven mainly by glycinergic rather than glutamatergic excitatory synaptic inputs, but that the latter become dominant later on.
Nakayama
K
K
Department of Physiology, Institute of Basic Medical Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8575, Japan.
Nishimaru
H
H
Kudo
N
N
D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005333:Fetus / Q000196:embryology* / Q000378:metabolism; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D018684:Glycine Agents / Q000494:pharmacology; D007736:Kynurenic Acid / Q000494:pharmacology; D008124:Locomotion / Q000187:drug effects* / Q000502:physiology; D009415:Nerve Net / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D010507:Periodicity; D051381:Rats; D017208:Rats, Wistar / Q000196:embryology* / Q000378:metabolism; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism; D018009:Receptors, Glycine / Q000037:antagonists & inhibitors / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D013331:Strychnine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018684:Glycine Agents; D017470:Receptors, Glutamate; D018009:Receptors, Glycine; D012701:Serotonin; D018698:Glutamic Acid; D007736:Kynurenic Acid; D013331:Strychnine; D005998:Glycine