The present study has been carried out to determine if
glycine, an allosteric modulator of
NMDA receptor, is involved in the vascular effect induced by the activation of the CNS
NMDA receptors.Icv
NMDA (from 0.01 to 1µg/rat in the 3rd ventricle) caused a significant increase in arterial blood pressure in conscious freely moving rats. Moreover, the
hypertension was associated with behavioural modifications (jumping, rearing, teething and running).
Glycine pretreatment (1 and 10µg/raticv), significantly increased the
NMDA hypertension.
Glycine alone did not cause any arterial blood pressure modification while it induced a slight sedation.
HA-966 (an antagonist of the
glycine site on
NMDA receptor) administration (1-10µg/raticv 5 min before
glycine) significantly antagonized the
glycine effects on
NMDA hypertension.Alone
HA-966 neither modified arterial blood pressure nor antagonized
NMDA hypertension. In conclusion, our investigations confirm
NMDA receptor involvement in cardiovascular function and they demonstrate thatin vivo
glycine positively modulates
NMDA receptors.