Neurophysin-I dynamics upon different pituitary provocation tests in healthy participants

Area of Science:

• Endocrinology
• Neuroscience
• Biomarker Discovery

Background:

• Oxytocin (OXT) plays a crucial role in social behavior, but its measurement is challenging.
• Neurophysin-I (NP-I), the carrier protein of OXT, is a stable surrogate biomarker due to equimolar co-release.
• Increasing evidence suggests clinically relevant OXT deficiency, necessitating reliable biomarkers.

Purpose of the Study:

• To evaluate oxytocin (OXT) and neurophysin-I (NP-I) levels in response to four different pituitary provocation tests.
• To assess the potential of NP-I as a stable and reliable surrogate biomarker for OXT activity.

Main Methods:

• Secondary analysis of four interventional diagnostic trials involving 66 participants.
• Participants underwent hypertonic saline, arginine infusion, oral macimorelin, or glucagon injection tests.
• Plasma NP-I and OXT levels were measured at baseline and at specific time points post-stimulation.

Main Results:

• NP-I levels showed minimal increases in response to hypertonic saline and glucagon injection.
• OXT levels exhibited similar trends, with minimal changes observed during hypertonic saline and glucagon tests.
• No significant increases in NP-I or OXT levels were observed following arginine infusion or oral macimorelin tests.

Conclusions:

• Neurophysin-I (NP-I) demonstrated minimal responses to pituitary provocation tests, closely paralleling oxytocin (OXT) dynamics.
• These findings support NP-I's potential as a reliable and technically robust surrogate biomarker for OXT activity.
• Further evaluation of NP-I is warranted in both clinical and experimental settings for OXT deficiency assessment.