TABLE 1

Pretreatment with glycine and glutamine or glycyl-d-glutamine does not inhibit acquisition of a place preference to morphine Rats were conditioned with morphine or saline on alternate days for 6 days. On days 1, 3, and 5 of place preference conditioning, they were treated with saline, glycine (Gly) and glutamine (Gln) (100 nmol each amino acid), or glycyl-d-glutamine (Gly-d-Gln; 100 nmol) i.c.v. followed 2 min later by saline or morphine sulfate (2.5 mg/kg) i.p. and were confined in a conditioning chamber for 30 min. On days 2, 4, and 6, they were treated with saline i.p. and confined to the alternate conditioning chamber for 30 min. The numbers in parentheses indicate the number of animals in each group. The data represent the difference in the amount of time rats spent in the two conditioning chambers during place preference testing and were analyzed by Student's t test.