AMINO-ACID LEVELS IN THE HYPOTHALAMUS AND RESPONSE TO N-METHYL-D-ASPARTATE AND OR DIZOCILPINE ADMINISTRATION DURING SEXUAL-MATURATION IN FEMALE RATS

Amino acid concentration in the anterior preoptic area and medial basa l hypothalamus was determined by HPLC in female rats: (1) at 16 (prepu bertal) vs. 30 (peripubertal) days of age and (2) after N-methyl-D-asp artate (NMDA) or dizocilpine (MK-801) administration in both groups. 3 0-day-old rats had higher levels of aspartate (Asp; 24%), glutamate (G lu; 49%) and glycine (Gly; 44%) and lower levels of taurine (Tau; 43%) than 16-day-old rats. In 16-day-old rats, NMDA (30 mg/kg, s.c., 10 mi n) increased the Glut concentration (48%). This effect was prevented b y MK-801 pretreatment (1 mg/kg, s.c., 1 h), which did not modify amino acid concentrations per se. In 30-day-old rats, NMDA treatment increa sed Glut (24%) and asp (42%) levels. MK-801 pretreatment abolished NMD A-induced changes and reduced Tau (26%) and Gly (30%) levels. MK-801 a dministration alone reduced the concentration of Glut (39%), Asp (54%) , Tau (33%) and Gly (31%). It is concluded that both (1) the concentra tion of Asp, Glu, Gly and Tau and (2) the changes induced by NMDA rece ptor activation or blockade are different at 16 vs. 30 days of age. Th e existence of a tonic (positive) control on amino acid levels linked to the NMDA receptor which would be immature or absent at 16 days of a ge is suggested.