The effects of the excitatory amino acid antagonist kynurenic acid on synaptic transmission to supraoptic neuroendocrine cells.
The magnocellular neuroendocrine system of the mammalian hypothalamus regulates numerous physiological functions by releasing the peptide hormones oxytocin and vasopressin from the neurohypophysis. Although several substances are known to promote hormone release, relatively little research has been aimed at testing the hypothesis that excitatory amino acids (EAAs) mediate synaptic transmission in this neuroendocrine system. In the present experiments, intracellular recordings in slices of rat hypothalamus revealed that kynurenic acid, a specific antagonist of EAA receptors, strongly and reversibly blocked excitatory postsynaptic potentials (EPSPs) in supraoptic neurons. The profound antagonism of EPSPs by kynurenic acid strongly suggests that EAAs may be an important class of fast excitatory neurotransmitter within this central regulatory nucleus.
Gribkoff
V K
VK
Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112.
Dudek
F E
FE
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007736:Kynurenic Acid / Q000494:pharmacology*; D009490:Neurosecretory Systems / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
D007736:Kynurenic Acid