Intranasal administration of neuropeptide Y significantly antagonized stress-induced colonic dysmotility via central GABA receptors in male rats.

Stress plays a major role in the pathogenesis of many diseases. Central neuropeptide Y (NPY) counteracts the biological actions of corticotropin-releasing factor (CRF) and attenuates stress responses. Intracerebroventricular (ICV) administration of NPY significantly antagonized the inhibitory effects of chronic complicated stress (CCS) on gastrointestinal (GI) dysmotility in rats. However, ICV administration is an invasive technique. The effect of intranasal administration of NPY on the hypothalamus-pituitary-adrenal (HPA) axis and GI motility in CCS conditions have not been studied, and the inhibitory mechanism of NPY on CRF through the γ-aminobutyric acid (GABA) receptor needs to be further investigated. A CCS rat model was set up, and NPY was intranasally administered every day before the stress loading. Furthermore, ICV administration of a GABA receptor antagonist was performed daily. Hypothalamic CRF and NPY expressions were evaluated, serum corticosterone and NPY levels were analyzed, and colonic motor functions were assessed. CCS rats showed significantly increased CRF expression and corticosterone levels, which resulted in enhanced colonic motor functions. Intranasal NPY significantly increased hypothalamic mRNA expression and reduced mRNA expression and plasma corticosterone levels, helping to restore colonic motor functions. However, ICV administration of the GABA receptor antagonist significantly abolished these effects induced by NPY. In conclusion, intranasal administration of NPY upregulates the hypothalamic NPY system. NPY may, through the GABA receptor, significantly antagonize overexpressed central CRF and attenuate HPA axis activity in CCS conditions, influencing and helping to restore colonic motor function.