Molecular size distribution of somatostatin-like immunoreactivity in the cerebrospinal fluid of patients with degenerative brain disease.

The molecular size distribution of somatostatin-like immunoreactivity (SLI) in the cerebrospinal fluid (CSF) of patients with brain disease was investigated by separation with a Sephadex G-25 superfine column and subsequent radioimmunoassay of the eluate. Marked heterogeneity of SLI in the CSF of control subjects as well as in demented patients, was observed. Controls and schizophrenics exhibited an SLI distribution pattern consisting mainly of two pronounced peaks: the first eluting with the void volume of the column; the second being compatible with a peptide of N-terminally extended somatostatin-14. SLI from the CSF of patients with senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID) and normal pressure hydrocephalus (NPH) showed the same two peaks found in controls and schizophrenics; and in addition, a third peak co-eluting with somatostatin-14. However, this peak was more pronounced in patients with SDAT and MID than in patients with NPH. Re-chromatography of G-25 sf void volume immunoreactivity afforded two fractions of an apparent molecular weight of about 10,000 daltons and 15,500 daltons, respectively.