Biochemical evidence for the GABA regulation of vasopressin levels in microdissected brain structures after servo-controlled hypotension.
Discrete brain structures were analysed for gamma-aminobutyric acid (GABA) and vasopressin content in normo- and hypotensive rats treated with the glutamic acid decarboxylase inhibitor, 3-mercaptopropionic acid (MPA) and the GABAA agonist muscimol. In the normotensive group treated with MPA only, the concentration of vasopressin increased in the supraoptic nucleus, indicating an inhibitory role for GABA. In the hypotensive group a rise in the vasopressin level in the nucleus of the solitary tract was detected and the GABA level decreased in the supraoptic nucleus. Muscimol decreased the concentration of vasopressin in the nucleus of the solitary tract. The changes in the concentration of vasopressin may be a result of increased or decreased activation of the GABAergic system. The results show that the GABA- and vasopressinergic systems somehow interact although the more precise way of action remains to be clarified.
Magnusson
A
A
Department of Medical Pharmacology, Biomedical Centre, Uppsala, Sweden.
Höglund
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U
Sjöquist
M
M
D015097:3-Mercaptopropionic Acid / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007022:Hypotension / Q000378:metabolism*; D008297:Male; D009118:Muscimol / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D013438:Sulfhydryl Compounds / Q000494:pharmacology*; D014667:Vasopressins / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D004791:Enzyme Inhibitors; D013438:Sulfhydryl Compounds; D014667:Vasopressins; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D015097:3-Mercaptopropionic Acid