Plasma levels of neuropeptides in Alzheimer's disease

Abstract

Background. In the central nervous system, several neuropeptides are believed to be involved in the pathophysiology of Alzheimer's disease (AD). Indeed, previous studies have documented that glucagon-like peptide 1 (GLP-1) possesses neurotropic properties and can reduce amyloid-β peptide levels in the brain in vivo. Moreover, the concentrations of neuropeptide Y (NPY) seem to be altered in the cerebrospinal fluid of patients with AD and in subjects with major depression. Finally, among the modifications induced by aging, a dysregulation of the ghrelin–growth hormone (GH) system has been reported.

Methods. We investigated the plasma concentrations of these neuropeptides in 14 subjects with AD. Data obtained from these patients were compared with data from an age- and weight-matched healthy group.

Results. No significant differences were found between the two groups in relation to plasma levels of GLP-1, NPY, ghrelin and GH. Peripheral NPY concentrations were positively correlated with ghrelin levels in both groups, and with plasma GLP-1 concentration only in controls.

Conclusion. On the basis of our results, peripheral levels of these neuropeptides seem not to serve as biochemical markers of AD.

Keywords:

• Alzheimer's disease
• growth hormone
• ghrelin
• glucagon-like peptide 1
• neuropeptide Y