Sarcosine May Induce EGF Production or Inhibit the Decline in EGF Concentrations in Patients with Chronic Schizophrenia (Results of the PULSAR Study)

Abstract

Sarcosine (N-methylglycine), a glutamatergic modulator, reduces the primary negative symp-toms of schizophrenia. These beneficial changes might be mediated by trophic factors such as ep-idermal growth factor (EGF). We assessed associations between initial serum EGF levels or changes in serum EGF levels and symptom severity during the addition of sarcosine to stable an-tipsychotic treatment and thereby evaluate the associations between glutamatergic modulation, clinical changes and peripheral EGF concentrations. 58 subjects with a diagnosis of chronic schizophrenia with dominant negative symptoms, stably treated with antipsychotics completed a prospective 6-month, randomized, double-blind, placebo-controlled study. Subjects received orally 2 grams of sarcosine (n=28) or placebo (n=30) daily. Serum EGF levels and symptom se-verity (using Positive and Negative Syndrome Scale - PANSS and Calgary Depression Scale for Schizophrenia - CDSS) were assessed at baseline, 6 weeks, and 6 months follow-up. Augmenta-tion antipsychotic treatment with sarcosine had no effect on EGF serum levels at any time-points. Only the sarcosine group showed a significant improvement in negative symptoms, general psy-chopathology subscales, and the overall PANSS score. We found reduction of serum EGF levels in the placebo group, but levels in the sarcosine remained stable during the study. Our data indicate that improvement in negative symptoms due to sarcosine augmentation is not mediated by EGF, but effective treatment may induce the production or block the decrease in EGF concentrations, which indicates the neuroprotective effect of treatment and confirms the relationship between neuroprotection and EGF levels.