Glycine blocks the pressor response to L-glutamate microinjected into the nucleus tractus solitarii of conscious rats.
Microinjection of L-glutamate into the nucleus tractus solitarii (NTS) of conscious freely moving Wistar rats (240-260 g) produces pressor (+48 +/- 4 mmHg) and bradycardic (-153 +/- 20 bpm) responses. In the present study L-glutamate (2.5 nmol/100 nl) was microinjected before and after microinjection of increasing doses of glycine (10, 25 and 50 nmol/100 nl, N = 6) or saline (vehicle/100 nl, N = 6) into the NTS. Microinjections of increasing doses of glycine into the NTS produced a dose-dependent reduction in the pressor but not in the bradycardic responses to L-glutamate. [10 nmol (+29 +/- 5 mmHg and -110 +/- 18 bpm), 25 nmol (+12 +/- 7 mmHg and -88 +/- 21 bpm) and 50 nmol (+4 +/- 2 mmHg and -100 +/- 31 bpm)] The dose-dependent blockade of the pressor response to L-glutamate by glycine suggests an inhibitory neuromodulatory role for this amino acid in the sympatho-excitatory activity produced by L-glutamate microinjection into the NTS.
Mauad
H
H
Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
Colombari
E
E
Bonagamba
L G
LG
Machado
B H
BH
D000818:Animals; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects*; D003243:Consciousness; D018698:Glutamic Acid / Q000187:drug effects*; D005998:Glycine / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000187:drug effects*
D018698:Glutamic Acid; D005998:Glycine