Hormone releasing factors and releasing hormones are signaling molecules produced by glands in multicellular organisms. The glands that secrete Luteinizing hormones LHRG and LH, FSH comprise the endocrine signaling system. The term growth hormone releasing hormone GHRH is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signaling) or nearby cells (paracrine signaling). Human recombinant LHRG and GHRH are produced in E. coli or in yeast cells.
Rats are used to make rat monoclonal anti mouse antibodies. There are less rat- than mouse clones however. Rats genes from rodents of the genus Rattus norvegicus are often studied in vivo as a model of human genes in Sprague-Dawley or Wistar rats.