Kainic acid depresses the ex vivo release of dynorphin B and glutamate from rat hippocampal mossy fiber synaptosomes.
This experiment examined the effects of intracerebroventricularly (i.c.v.) administered kainic acid (KA) on the subsequent ex vivo release of L-glutamate (Glu) and dynorphin B-like immunoreactivity (Dyn B-LI) from isolated rat hippocampal mossy fiber (MF) synaptosomes at 4.5 h, 20 h or 48 h after administration of 0.5 microgram/microliter KA. The Dyn B-LI content in the synaptosomal fraction initially decreased at 4.5 h and then rebounded and remained elevated above control levels at 20 h and 48 h. The K(+)-evoked release of Dyn B-LI from the synaptosomes was markedly depressed at 4.5 h after KA and remained significantly below control levels at 20 h and 48 h. In contrast, KA caused no change in the K(+)-evoked release of Glu at 4.5 h as compared to control levels, but did result in a significant decrease in Glu release at 20 h and 48 h. These data indicate a persistent effect of i.c.v. KA on neurotransmission at MF-CA3 synapses in rat hippocampus, resulting in a suppression of the release of Glu as well as the opioid peptide, Dyn B.
Department of Anatomy and Cell Biology, East Carolina University School of Medicine, Greenville, NC 27858-4354.
J N
JN
Simpson
R L
RL
Gannon
J F
JF
McGinty
D M
DM
Terrian
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004399:Dynorphins / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D005089:Exocytosis / Q000187:drug effects; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007276:Injections, Intraventricular; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D011498:Protein Precursors / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D004723:Endorphins; D005971:Glutamates; D011498:Protein Precursors; D012333:RNA, Messenger; C036448:pre-prodynorphin; D018698:Glutamic Acid; D004399:Dynorphins; C036200:rimorphin; D007608:Kainic Acid; D002118:Calcium