Glycine inhibition of glutamate evoked-release of norepinephrine in the hypothalamus is strychnine-insensitive.
The effects of glycine (GLY), D-serine (D-SER), kynurenic acid (KYN), and 7-Cl kynurenic acid (7-Cl KYN), on the evoked release of endogenous norepinephrine (NE) by L-glutamate (L-GLU) in rat hypothalamic slices was investigated. KYN (500 and 100 microM) and 7-Cl KYN (10 microM) blocked evoked release of NE by L-GLU (1 mM). The inhibitory effects of 100 microM KYN on evoked release of NE by L-GLU were reversed by 10 microM and 100 microM D-SER and, but not 10 or 100 microM GLY. When KYN was not present in the superfusate, superfusion with either 10 or 100 microM GLY alone simultaneously with 1 mM L-GLU blocked the evoked release of NE produced by L-GLU. The addition of strychnine (3 or 100 microM) to the superfusate did not block the inhibitory effects of 10 microM GLY on L-GLU-evoked NE release. These findings suggest that a novel strychnine-resistant GLY receptor is present in the rat hypothalamus.
Department of Pharmacology, Mount Sinai School of Medicine, City University of New York, New York.
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Johnson
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Blandina
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Goldfarb
D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005998:Glycine / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013331:Strychnine / Q000494:pharmacology*
D018691:Excitatory Amino Acid Antagonists; D013331:Strychnine; D005998:Glycine; D009638:Norepinephrine