Bovine placental lactogen is a potent stimulator of growth and displays strong binding to hepatic receptor sites of coho salmon

• Published in: General and comparative endocrinology Vol. 95; no. 1; p. 31
• Main Authors: Devlin, R H, Byatt, J C, McLean, E, Yesaki, T Y, Krivi, G G, Jaworski, E G, Clarke, W C, Donaldson, E M
• Format: Journal Article
• Language: English
• Published: United States 01-07-1994
• Subjects: Animals; Cattle; Dose-Response Relationship, Drug; Growth Hormone - pharmacology; Liver - metabolism; Microsomes, Liver - metabolism; Oncorhynchus kisutch - growth & development; Oncorhynchus kisutch - physiology; Placental Lactogen - pharmacology; Prolactin - pharmacology; Receptors, Peptide - metabolism
• ISSN: 0016-6480
• DOI: 10.1006/gcen.1994.1099

Juvenile coho salmon were treated with bovine placental lactogen (bPL) and bovine growth hormone (bGH) to examine the growth promoting activities of these proteins in a lower vertebrate. Fish were intraperitoneally injected either with 0.5 or 5.0 micrograms/g bPL or with 5.0 micrograms/g bGH once a week for 5 weeks. After only a single injection and 1 week of growth, the high dose of bPL stimulated a significant increase in weight and length relative to untreated fish or fish treated with a control protein, bovine serum albumin. At the end of the experiment, all hormone-treated groups were significantly larger than controls. Fish treated with 5 micrograms/g bPL gained more than three times as much weight as controls. The 5.0 micrograms/g bGH group grew at the same rate as fish treated with one-tenth this dose of bPL, indicating that bPL is a potent stimulator of growth in this species. Radioreceptor assays performed on coho salmon liver membrane preparations indicate that bPL binds with approximately 430-fold higher affinity than bGH, and some 8000-fold higher affinity than bovine prolactin. The action of bPL relative to the structure and function of salmonid pituitary hormones is discussed.