Corticotropin-Releasing Hormone: A Novel Stimulator of Somatolactin in Teleost Pituitary Cells

Highlights What are the main findings? CRH could significantly induce pituitary somatolactin secretion and synthesis. CRH-induced SL expression was mainly mediated by the AC/cAMP/PKA pathway. Single-cell transcriptome showed that SL alpha and SL beta were expressed in different cells of the pituitary NIL region. SL alpha and SL beta could regulate hepatocyte lipid metabolism. What is the implication of the main finding? This study supplemented the function of CRH in the grass carp pituitary. This study suggested that there might be another pathway for the CRH response to stress.Highlights What are the main findings? CRH could significantly induce pituitary somatolactin secretion and synthesis. CRH-induced SL expression was mainly mediated by the AC/cAMP/PKA pathway. Single-cell transcriptome showed that SL alpha and SL beta were expressed in different cells of the pituitary NIL region. SL alpha and SL beta could regulate hepatocyte lipid metabolism. What is the implication of the main finding? This study supplemented the function of CRH in the grass carp pituitary. This study suggested that there might be another pathway for the CRH response to stress.Abstract Corticotropin-releasing hormone (CRH) is known for its crucial role in the stress response system, which could induce pituitary adrenocorticotropic hormone (ACTH) secretion to promote glucocorticoid release in the adrenal gland. However, little is known about other pituitary actions of CRH in teleosts. Somatolactin is a fish-specific hormone released from the neurointermediate lobe (NIL) of the posterior pituitary. A previous study has reported that ACTH was also located in the pituitary NIL region. Interestingly, our present study found that CRH could significantly induce two somatolactin isoforms' (SL alpha and SL beta) secretion and synthesis in primary cultured grass carp pituitary cells. Pharmacological analysis further demonstrated that CRH-induced pituitary somatolactin expression was mediated by the AC/cAMP/PKA, PLC/IP3/PKC, and Ca2+/CaM/CaMK-II pathways. Finally, transcriptomic analysis showed that both SL alpha and SL beta should play an important role in the regulation of lipid metabolism in primary cultured hepatocytes. These results indicate that CRH is a novel stimulator of somatolactins in teleost pituitary cells, and somatolactins may participate in the stress response by regulating energy metabolism.