Glutamatergic regulation of histamine release from rat hypothalamus.
A microdialysis method was used to study the effects of glutamate on the in vivo release of histamine from the anterior hypothalamic area of rats anesthetized with urethane. Infusion of 1 mM glutamate through a microdialysis probe increased histamine release to about 150% of the basal release. Infusion of N-methyl-D-aspartate (NMDA, 0.1 mM) caused a similar increase. Glutamate-evoked histamine release was completely blocked by D-(-)-2-amino-5-phosphonopentanoic acid (AP5, 0.1 mM), a specific antagonist of NMDA receptors. AP5 alone also reduced histamine release to about 60% of the basal level. Infusion of tetrodotoxin (100 nM) reduced histamine release to about 30% of the basal release, but had no effect on glutamate-evoked release. These results clearly indicate that glutamate enhances histamine release through NMDA receptors located on histaminergic nerve terminals, and suggest that there is a tonic glutamatergic regulation of this release.
Okakura
K
K
Department of Pharmacology II, Faculty of Medicine, Osaka University, Japan.
Yamatodani
A
A
Mochizuki
T
T
Horii
A
A
Wada
H
H
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D006636:Histamine Release / Q000187:drug effects*; D007032:Hypothalamus, Anterior / Q000378:metabolism*; D016202:N-Methylaspartate / Q000494:pharmacology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D005971:Glutamates; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D013779:Tetrodotoxin; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate