Stress induces nucleobindin-1 mRNA and nesfatin-1-like peptide stimulates cortisol secretion in goldfish

Stress is a state of disrupted homeostasis triggered by physical or psychological stimuli that elicit adaptive responses at the molecular and cellular levels. In fish, the hypothalamus-pituitary-interrenal (HPI) axis mediates stress responses. Nesfatin-1 and a nesfatin-1-like peptide (NLP), derived from nucleobindin-1 (NUCB1), have been implicated in stress hormone regulation in mammals. This study investigated the cell-specific expression of NUCB1/NLP in HPI tissues and its effects on stress response in goldfish <i>(Carassius auratus)</i>. NUCB1 mRNA is abundant in the hypothalamus, pituitary, and several other peripheral tissues of goldfish. NUCB1/NLP-like immunoreactivity was found in the brain and pituitary, co-localized with corticotropin-releasing factor receptor 1 (CRF-R1) in the hypothalamus, and with adrenocorticotrophic hormone (ACTH) in the pituitary. In vivo netting and restraint stress increased <i>nucb1</i> and <i>crf-r1</i> mRNAs in the brain and <i>acth</i> mRNA in the pituitary, as determined by RT-qPCR. Intraperitoneal injection of NLP increased cortisol in circulation, <i>crf-r1</i> mRNA in the brain and <i>acth</i> mRNA in the pituitary. These findings suggest that NUCB1/NLP is a new player in mediating the endocrine stress response of goldfish through the HPI axis.