The aim of the present study is to assess whether cumulative endogenous neurophysin I secretion over one month differs between premenopausal and postmenopausal women. Using repeated measurements of neurophysin-I (NP-I, equimolar surrogate marker of oxytocin) across defined physiological time points, this study investigates oxytocin system regulation under cyclic and non-cyclic hormonal conditions.
The primary hypothesis is that cumulative NP-I release, expressed as the area under the curve (AUC) is lower in the postmenopausal group compared to the premenopausal group.