Peptide histidine methionine and vasoactive intestinal peptide levels in human cerebrospinal fluid: age-related changes and absence of a correlation with serum prolactin

Low cerebrospinal fluid concentrations of peptide histidine valine and somatostatin-28 in Alzheimer's disease: altered processing of prepro-vasoactive intestinal peptide and prepro-somatostatin

Recent studies have indicated that deposition of beta amyloid peptide in the brains of patients with senile dementia of the Alzheimer type (SDAT) is a consequence of abnormal processing of the beta amyloid protein precursor. In addition, reduced concentrations of various peptides have been measured in post-mortem brain tissue and cerebrospinal fluid (CSF) of patients with SDAT. We determined concentrations of the peptides derived from prepro-vasoactive intestinal peptide (VIP)--peptide histidine methionine-27 (PHM-27), peptide histidine valine (PHV) and VIP--and peptides derived from prepro-somatostatin (prepro-SS), SS-14 and SS-28, in CSF of patients with SDAT by radioimmunoassay combined with high performance liquid chromatography. We found significantly reduced levels of total PHM-immunoreactivity (IR) and PHV, and unaltered levels of PHM-27 and VIP in SDAT, compared with those in controls. Total SS-IR and SS-28 concentrations were significantly reduced in SDAT, while SS-14 levels did not differ from those of controls. These results suggest that an altered processing of the prepro-peptides of VIP and SS may occur in SDAT and that these alterations might have a significant role in the pathogenesis of SDAT.

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.