Correlation between cerebrospinal fluid phenylalanine and beta-endorphin in patients with phenylketonuria.
Previous animal and human studies have suggested an analgesic effect of phenylalanine involving endogenous opioid peptides. Phenylalanine was measured by a HPLC method with electrochemical detection and beta-endorphin by a specific radioimmunoassay in 14 lumbar cerebrospinal fluid samples from 13 patients with phenylketonuria. Cerebrospinal fluid beta-endorphin was also determined in 6 age-matched control subjects. We found a trend towards a higher beta-endorphin level in phenylketonuria (median 26.0 pM, range 13.0-37.8) than in the control subjects (20.6 pM, 12.7-28.0), P = 0.13. Cerebrospinal fluid concentrations of phenylalanine and beta-endorphin were significantly correlated (r = 0.68, P = 0.008). The results support the hypothesis that phenylalanine modifies the central endogenous opioid system.
Department of Clinical Chemistry, Gentofte Hospital, Hellerup, Denmark.
F W
FW
Bach
J B
JB
Nielsen
J
J
Buchholt
H
H
Lou
F
F
Güttler
D000293:Adolescent; D000328:Adult; D006801:Humans; D010649:Phenylalanine / Q000097:blood / Q000134:cerebrospinal fluid*; D010661:Phenylketonurias / Q000134:cerebrospinal fluid*; D001615:beta-Endorphin / Q000134:cerebrospinal fluid*
D010649:Phenylalanine; D001615:beta-Endorphin