The Role of Oxytocin in Reward Processing Across the Menstrual Cycle and With Oral Contraceptive Use

IRTG_P06

Oxytocin is a hypothalamic neuropeptide that is best known for its peripheral physiological effects in the female organism i.e., uterine contractions during birth. The neuropeptide furthermore affects reward processing and metabolic functions such as eating behavior and body weight. Oxytocin receptors are present in brain regions associated with the processing of rewards, e.g., ventral tegmental area (VTA), nucleus accumbens (NAcc) and nucleus stria terminalis. Previous studies indicate that oxytocin interacts with sex hormones such as estradiol in a sex-specific manner. Despite known sex differences in oxytocin function, most studies i.e., on the metabolic effects of oxytocin in humans have so far focused on young, healthy men. Intranasal oxytocin administration has emerged as a method to experimentally investigate central nervous effects of oxytocin in the absence of relevant side effects. In the proposed study the investigators aim to systematically investigate the acute effect of intranasal oxytocin on reward processing in relation to circulating and synthetic sex hormones in healthy, naturally cycling women and in women taking hormonal oral contraceptive pills. The investigators will administer 24 international units (IU) of intranasal oxytocin vs. placebo and investigate neural correlates in a 3T MRI scanner including functional imaging during a reward processing task, changes in brain anatomy and connectivity. Additionally, metabolic functions, eating behavior and changes in mood and wellbeing will be assessed and blood will be drawn to assess parameters of hormonal and metabolic status.

2024-02-16

2026-12-31

2026-12-31

Recruiting

100

Inclusion Criteria: * Body-mass index (BMI): 18-28 kg/m2 * Sex: female (since birth) * Normal or corrected vision * Natural menstrual cycle (NC) or intake of hormonal oral contraceptives (OC) * NC: No hormonal contraception for at least 6 months; regular menstrual cycle (between 25 and 31 days) prior to participation * OC: No hormonal contraception for at least 4 months, regular intake of OC pill Exclusion Criteria: * No German language fluency (due to German language test content) * Smoking * Medication taken within the last 6 weeks (except for OCs in the respective group) * Current neurological or psychiatric disease (anamnestic survey) * Current medical problems such as hormonal, metabolic, or chronic diseases (e.g., severe hypertension, diabetes, dysfunctions of the thyroid, or congestive heart failure) * Pregnancy, delivery and lactation (current and within the last year; anamnestic survey, current pregnancy test) * Premenstrual dysphoric disorder (PMDD), endometriosis or polycystic ovary syndrome (PCOS) * Shift work * NC: Any kind of hormonal treatment or contraception * OC: Any kind of hormonal treatment or contraception (except OCs) * Contraindication for MRI: * Non-removable metal objects on or in the body * Tattoos (if MRI-incompatible according to expert guidelines) * Pathological hearing or increased sensitivity to loud noise * Claustrophobia * Operation less than three months ago * Neurological disease or injury * Moderate or severe head injury * Intake of antidepressants or neuroleptics * Restricted vision

{'studyType': 'INTERVENTIONAL', 'phases': ['NA'], 'designInfo': {'allocation': 'RANDOMIZED', 'interventionModel': 'CROSSOVER', 'interventionModelDescription': 'The investigators will assess the effects of oxytocin administration on reward processing and metabolism using a double-blind randomized cross-over design. In a within subject design, participants will get receive both oxytocin and placebo (both conditions) at different time points (approximately 4 weeks apart). After drug/placebo administration we will assess cerebral blood flow and functional connectivity at rest (via functional magnetic resonance imaging (fMRI)) during an effort-based decision-making task.', 'primaryPurpose': 'BASIC_SCIENCE', 'maskingInfo': {'masking': 'TRIPLE', 'maskingDescription': 'Neither participants nor investigators will know at which time point the participant will receive intranasal oxytocin and placebo. The nasal sprays will be prepared by independent members of the university hospital Tübingen.', 'whoMasked': ['PARTICIPANT', 'INVESTIGATOR', 'OUTCOMES_ASSESSOR']}}, 'enrollmentInfo': {'count': 100, 'type': 'ESTIMATED'}}

2024-02-28