Is glycine an inhibitory synaptic transmitter in the substantia nigra?
Nigral tissue accumulated 14C-glycine by an energy-, temperature- and sodium-dependent mechanism; the transport process was inhibited by small neutral amino acids and had an apparent Km of 143 microM and Vmax of 787 nmol/g/min. Re-release of accumulated 14C-glycine was initially extremely rapid (40% in first 5 min) and subsequently accelerated by +40 mM K+ in a Ca2+-dependent manner. Intranigral kainate (0.25 microgram) lowered the levels of striatal DA (63%) and nigral GABA (25%) ipsilaterally, but not nigral glycine. Injections of glycine or strychnine (10--100 micrograms) into one SN induced slow ipsiversive or contraversive turning respectively. The evidence for glycine as a neurotransmitter in SN is discussed.
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D005998:Glycine / Q000494:pharmacology / Q000502:physiology*; D006801:Humans; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D018377:Neurotransmitter Agents / Q000502:physiology*; D051381:Rats; D013239:Stereotyped Behavior / Q000187:drug effects; D013378:Substantia Nigra / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
D000596:Amino Acids; D018377:Neurotransmitter Agents; D007608:Kainic Acid; D005998:Glycine