Reproductive Regulation of PrRPs in Teleost: The Link Between Feeding and Reproduction.

Chuanhui Xia,Yunyi Xie,Tianyi Cai,Yu Ouyang,Ruixin Du,Zhan Yin,Lingling Zhou,Xiangfeng Qin,Wei Li,Guangfu Hu,Xuetao Shi

doi:10.3389/fendo.2021.762826

Abstract

Prolactin-releasing peptide (PrRP), a sort of vital hypothalamic neuropeptide, has been found to exert an enormous function on the food intake of mammals. However, little is known about the functional role of PrRP in teleost. In the present study, two PrRP isoforms and four PrRP receptors were isolated from grass carp. Ligand-receptor selectivity displayed that PrRP1 preferentially binds with PrRP-R1a and PrRP-R1b, while PrRP-R2a and PrRP-R2b were special receptors for PrRP2. Tissue distribution indicated that both PrRPs and PrRP-Rs were highly expressed in the hypothalamus-pituitary-gonad axis and intestine, suggesting a latent function on food intake and reproduction. Using grass carp as a model, we found that food intake could significantly induce hypothalamus PrRP mRNA expression, which suggested that PrRP should be also an anorexigenic peptide in teleost. Interestingly, intraperitoneal (IP) injection of PrRPs could significantly induce serum luteinizing hormone (LH) secretion and pituitary LHβ and GtHα mRNA expression in grass carp. Moreover, using primary culture grass carp pituitary cells as a model, we further found that PrRPs could directly induce pituitary LH secretion and synthesis mediated by AC/PKA, PLC/IP3/PKC, and Ca2+/CaM/CaMK-II pathways. Finally, estrogen treatment of prepubertal fish elicited increases in PrRPs and PrPR receptors expression in primary cultured grass carp hypothalamus cells, which further confirmed that the PrRP/PrRPR system may participate in the neuroendocrine control of fish reproduction. These results, taken together, suggest that PrRPs might act as a coupling factor in feeding metabolism and reproductive activities in teleost.

Highlights

Prolactin-releasing peptide (PrRP), as a vital anorexigenic peptide, played an important role in food intake and energy metabolism [1,2,3]
Using grass carp as a model, we found that food intake could significantly induce hypothalamus PrRP mRNA expression, which suggested that PrRP should be an anorexigenic peptide in teleost
Using primary culture grass carp pituitary cells as a model, we further found that PrRPs could directly induce pituitary luteinizing hormone (LH) secretion and synthesis mediated by adenylate cyclase (AC)/protein kinase A (PKA), phospholipase C (PLC)/inositol trisphosphate PKC (IP3)/PKC, and Ca2+/CaM/calmodulin kinase (CaMK)-II pathways

Summary

Introduction

Prolactin-releasing peptide (PrRP), as a vital anorexigenic peptide, played an important role in food intake and energy metabolism [1,2,3]. Central administration of PrRP could reduce food intake and body weight [2]. PrRP-receptor-knockout (GPR10-/-) mice tended to become obese and showed conspicuous increases in body weight [4], in which attached fat mass increased and energy expenditures decreased [5]. In goldfish, IP or intra-cerebroventricular (ICV) administration of PrRP could dosedependently inhibit food intake, feeding could significantly induce hypothalamus PrRP mRNA expression [10]. Little is known about the regulatory mechanism of feeding-induced hypothalamus PrRP expression

Methods

Results

Conclusion