Intranasal Administration of Oxytocin Attenuates Stress Responses Following Chronic Complicated Stress in Rats.

BACKGROUND/AIMS: Gastrointestinal (GI) symptoms may develop when we fail to adapt to various stressors of our daily life. Central oxytocin (OXT) can counteract the biological actions of corticotropin-releasing factor (CRF), and in turn attenuates stress responses. Administration (intracerebroventricular) of OXT significantly antagonized the inhibitory effects of chronic complicated stress (CCS) on GI dysmotility in rats. However, intracerebroventricular administration is an invasive pathway. Intranasal administration can rapidly deliver peptides to the brain avoiding stress response. The effects of intranasal OXT on hypothalamus-pituitary-adrenal axis and GI motility in CCS conditions have not been investigated. METHODS: A CCS rat model was set up, OXT 5, 10, or 20 μg were intranasal administered, 30 minutes prior to stress loading. Central CRF and OXT expression levels were analyzed, serum corticosterone and OXT concentrations were measured, and gastric and colonic motor functions were evaluated by gastric emptying, fecal pellet output, and motility recording system. RESULTS: Rats in CCS condition showed significantly increased CRF expression and corticosterone concentration, which resulted in delayed gastric emptying and increased fecal pellet output, attenuated gastric motility and enhanced colonic motility were also recorded. OXT 10 μg or 20 μg significantly reduced CRF mRNA expression and the corticosterone concentration, OXT 20 μg also helped to restore GI motor dysfunction induced by CCS. CONCLUSION: Intranasal administration of OXT has an anxiolytic effect and attenuates the hypothalamus-pituitary-adrenal axis in response to CCS, and gave effects which helped to restore GI dysmotility, and might be a new approach for the treatment of stress-induced GI motility disorders.