Novel function of prolactin on the urodele amphibian brain

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K06256
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44040:Morphology and anatomical structure-related
• Research Institution: Toho University
• Principal Investigator: Hasunuma Itaru 東邦大学, 理学部, 准教授 (40434261)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 神経新生 / プロラクチン / 間脳 / 視索前野 / 有尾両生類 / アカハライモリ

Outline of Final Research Achievements

We previously demonstrated that prolactin (PRL) stimulated the proliferation of neural stem cells in the preoptic area of an adult newt. In this study, we demonstrated that the PRL receptor (PRLR) and IGF-I and II were expressed in the complex of the choroid plexus-paraphysis, and PRLR and IGF-I receptor were expressed in the neural stem cells of the newt. One possible mechanism underlying the regulation of the proliferation of cells by PRL is that PRL transported from the blood to the cerebrospinal fluid via the PRLR expressed in the complex of choroid plexus-paraphysis directly stimulates the proliferation of the cells. Another possible mechanism is that PRL stimulates the expression of IGF-I and II in the complex of choroid plexus-paraphysis, and IGF-I and II enhance the proliferation of the cells. In the future, neurosphere assay should be performed to possibly provide evidence to whether PRL directly or indirectly stimulates the proliferation of the neural stem cells of newt.

Free Research Field

比較内分泌学

Academic Significance and Societal Importance of the Research Achievements

齧歯目動物でPRLが神経前駆細胞の増殖を促すとの報告があるが、PRLが直接細胞増殖を促す確たる証明はまだない。本研究では有尾両生類のイモリでもPRLが神経前駆細胞の増殖を促すことを示し、またPRLが直接神経前駆細胞に作用する直接作用の可能性とPRLが第三脳室脈絡叢-副生体複合体に発現するIGF-I, IIの合成を促し、IGF-I, IIが細胞増殖に関わる間接作用の可能性を示すことができた。PRLやIGF-I, IIが実際にイモリ神経前駆細胞の増殖を促すかをin vitroで証明するなども必要ではあるが、PRLの脳に対する新たな作用機序の可能性を示す成果であると言える。