Microdialysis methods for in vivo neuropeptide measurement in the stalk-median eminence in the Rhesus monkey.

Direct measurement of neuropeptides in the hypothalamus is essential for neuroendocrine studies. However, the small quantities of peptides released at their neuroterminals and relatively large molecular sizes make these measurements difficult. We have evaluated microdialysis probes with two membrane materials (polycarbonate and polyarylethersulfone, both: molecular cut off 20,000 Da) in vitro, and adapted the method for in vivo hypothalamic sample collection in non-human primates.