Cerebrospinal fluid (CSF) neuropeptide Y- and somatostatin-like immunoreactivities in man

We have measured cerebrospinal fluid (CSF) neuropeptide Y-like immunoreactivity (NPY-LI) and somatostatin-like immunoreactivity (SLI) in control subjects and in patients with various neurologic disorders. We observed a significant reduction in CSF SLI in control subjects over 60 years of age, compared with the younger controls. CSF SLI was significantly decreased in multiple sclerosis (MS), or Guillain-Barre syndrome, compared with that of age-matched control subjects. A reduced concentration of NPY-LI was found in CSF of patients with MS. We have also examined the molecular heterogeneity of peptide-LI in CSF. Gel chromatography, not high performance liquid chromatography (HPLC), suggested two NPY immunoreactive materials in CSF. Gel chromatography and HPLC revealed three SLI components in CSF: somatostatin 14, somatostatin 28 and a higher molecular weight precursor. Our results suggest that 1) there may be more than one form of NPY in human CSF, and 2) somatostatin neurons might be more susceptible to alteration than NPY neurons in various pathological conditions and aging.