Antibiotic-induced Microbiome Depletion Selectively Reduces Baseline Hypothalamic Oxytocin Signaling without Affecting MDMA-induced Oxytocin Response in Rats.
Yong Yue, Yi Cai, Rumi Murayama, Xin Ding, Xiayun Wan, Guilin Liu, Hirofumi Hashimoto, Naohiko Anzai, Kenji Hashimoto
Clinical psychopharmacology and neuroscience : the official scientific journal of the Korean College of Neuropsychopharmacology May 31, 2026 Peer reviewed DOI: 10.9758/cpn.25.1381 via PubMed
Summary
Antibiotic-induced depletion of the gut microbiome in male Wistar rats led to a significant reduction in baseline central oxytocin expression in the paraventricular and supraoptic nuclei, but did not affect peripheral oxytocin levels or the oxytocin response to MDMA. Specifically, while microbiome disruption altered baseline signaling, it did not impact the acute increase in oxytocin levels following MDMA administration. This suggests that gut microbiota play a role in maintaining central oxytocin levels under normal conditions, but are not necessary for MDMA's effects.
Study at a glance
| Design | experimental study |
|---|---|
| Population | male Wistar rats |
| Key finding | Antibiotic-induced microbiome depletion reduces baseline central oxytocin expression but does not affect the oxytocin response to MDMA. |
Abstract
To determine whether antibiotic-induced microbiome depletion influences baseline or 3,4-methylenedioxymethamphetamine (MDMA)-induced oxytocin signaling in rats. Male Wistar rats received broad-spectrum antibiotics (ABX) or water for 7 days, followed by a single oral administration of MDMA (30 mg/kg). Plasma oxytocin levels were measured by ELISA, and oxytocin-immunoreactivity in the paraventricular (PVN) and supraoptic (SON) nuclei were quantified by immunofluorescence. ABX treatment induced marked cecal enlargement without affecting body weight, confirming microbiome disruption while maintaining systemic stability. Peripheral oxytocin concentrations were unchanged; however, baseline central oxytocin expression in both the PVN and SON was significantly reduced after ABX treatment. MDMA increased central oxytocin expression, and this response was not significantly altered by microbiome depletion. Similarly, MDMA-induced peripheral oxytocin levels did not differ between control and ABX-treated rats. Antibiotic-induced microbiome depletion selectively attenuates baseline central oxytocin signaling while leaving peripheral oxytocin regulation intact. In contrast, MDMA-induced oxytocin responses in both the brain and circulation are preserved despite microbiome disruption. These findings suggest that gut microbiota contribute to central oxytocin homeostasis under basal conditions but are not essential for acute MDMA-induced oxytocin activation.