beta-endorphin and Phenylketonurias

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.

Topics: Adolescent; Adult; beta-Endorphin; Humans; Phenylalanine; Phenylketonurias

An hypothesis of increased endorphinergic activity has been proposed to account for the characteristic symptoms of Rett syndrome. Cerebrospinal fluid samples from eight girls with Rett syndrome were analysed for beta-endorphin (beta-EP) immunoactivity and compared with samples from a control group of 15 children with acute leukaemia in remission. Severity of symptoms was not found to be related to beta-EP level. A group of early-treated adolescents with phenylketonuria had beta-EP levels similar to the Rett syndrome patients, but no symptoms resembling theirs. Therefore it is unlikely that increased levels of beta-EP are of primary pathogenetic significance. The conflicting findings of many earlier reports may be a result of differences between control groups.

Topics: Adolescent; beta-Endorphin; Child; Female; Humans; Leukemia; Male; Neurologic Examination; Phenylketonurias; Reference Values; Rett Syndrome