Oxytocin in Postmenopausal Women

The primary endpoint is the Area under the curve (AUC) of circulating plasma NP-I assessed over four standardized study visits within one month, corresponding to mid-menstruation, mid-follicular phase, ovulation, and mid-luteal phase in premenopausal women, and four weekly visits in postmenopausal women. The primary comparison will be the NP-I AUC between premenopausal and postmenopausal participants

Phase-specific plasma OXT/NP-I concentrations at each study visit

Estradiol for confirmation of cycle phase and assessment of hormonal correlates

Perceived anxiety symptoms assessed by validated questionnaires (State-Trait Anxiety Inventory). The State-Trait Anxiety Inventory score measures general trait anxiety using a 20-item subscale rated on a 1-to-4 scale. Total scores range from 20 to 80, with higher numbers showing greater general anxiety.

Perceived depressive symptoms assessed by validated questionnaires (Becks Depression Inventory-II). The Beck Depression Inventory-II total score ranges from 0 to 63. Standard severity thresholds are minimal depression (0-13), mild depression (14-19), moderate depression (20-28), and severe depression (29-63).

Sleep quality over one month assessed by a validated questionnaire (Pittsburgh Sleep Quality Index) after a sleep counselling session (session at baseline visit). The Pittsburgh Sleep Quality Index ranges from 0 to 21, with higher scores indicating greater sleep difficulties.

Climacteric symptoms, assessed by a validated questionnaire (Menopause rating scale (MRS)). MRS is an 11-item self-assessment tool designed to measure symptom severity and quality of life in aging women. The total MRS score ranges from 0 to 44 points, with higher scores indicating more severe symptoms and a poorer outcome.

Emotion recognition performance (accuracy and reaction time), assessed by a computerized facial emotion recognition task (Facial Emotion Recognition Test)

Empathy, assessed by validated questionnaire-based measures (Empathy Quotient). The Empathy Quotient (EQ) test is a 60-item questionnaire intended to measure levels of empathy in adults. The total EQ score ranges from 0 to 80 points, with higher scores indicating greater empathy and a better outcome.

Socio-affective processing, assessed by validated questionnaire-based measures (Toronto Alexithymia Scale-20). The scale was designed to assess the three factors: (a) difficulty identifying feelings (DIF), (b) difficulty describing feelings (DDF), and (c) external-oriented thinking (EOT). The TAS-20 score measures alexithymia on a scale from 20 to 100 with higher scores indicating greater levels of alexithymia and a poorer outcome.

Subjective stress ratings, assessed using a Numerical Rating Scale (NRS). Subjective stress reflects an individual's self-reported psychological and emotional distress. Fear will be assessed on an NRS ranging from 0 (no fear) to 10 (extreme fear/panic), with higher scores indicating greater perceived fear.

Stress reactivity is assessed using a standardized social stress test, including autonomic measures (heart rate and blood pressure)

Assessed using a standardized social stress test, including endocrine stress markers (e.g. salivary or plasma cortisol)

Body mass index

Blood pressure

Fasting glucose (± insulin/Homeostatic Model Assessment for Insulin Resistance)

Lipid profile (total cholesterol)

Fat mass

Bone turnover markers (e.g., N-terminal propeptide of type I collagen)

Calcium-phosphate metabolism (e.g. 25-hydroxyvitamin D (Vitamin-D))

Subjective craving, quantified by ratings (Numerical Rating scale 0-10) on two days during the menstrual and ovulation phase

Eating behavior (type of food, amount of food, frequency of food intake, meal structure) assessed by the eating protocol on one day during the menstrual and ovulation phases

Progesterone for confirmation of cycle phase and assessment of hormonal correlates

Luteinizing Hormone for confirmation of cycle phase and assessment of hormonal correlates

Follicle Stimulating hormone for confirmation of cycle phase and assessment of hormonal correlates.

Waist circumference

Heart rate

Lipid profile (low-density lipoprotein)

Lipid profile (high-density lipoprotein)

Lipid profile (triglycerides)

Lean mass (bioimpedance)

Bone turnover markers (e.g., C-terminal telopeptide ± osteocalcin)

Calcium-phosphate metabolism (e.g. Parathyroid Hormone)

Temporal Oxytocin over Neurophysin-1 secretion profile including group and time interaction and intra-individual variability across four visits.