Submitted to: Animal Science Progress Report
Publication Type: Other
Publication Acceptance Date: 10/12/1999
Publication Date: N/A
Technical Abstract: The objective was to characterize the expression of growth hormone receptor (GHR) 1A and GHR 1B mRNA in liver of castrated male pigs (Exp. 1; 1, 14, 28, and 42 d of age, n=6/age group) and intact male pigs treated with recombinant porcine somatotropin (rpST) or control (Exp. 2; 21, 42, and 77 d of age; n=4 pigs/treatment/age). The porcine GHR 1A and GHR 1B cDNA were ecloned and were homologous to GHR cDNA isolated from other species. Ribonuclease protection assays were used to measure GHR 1A and GHR 1B mRNA. Liver expressed GHR 1A and GHR 1B mRNA, whereas muscle, uterus, and ovary expressed GHR 1B mRNA. The GHR 1A mRNA in the liver of castrated male pigs (Exp. 1) was expressed at very low levels and 2 of 6 pigs expressed a high level of GHR 1A on d 42. The GHR 1B mRNA, however, was detected at all ages and the amount of GHR 1B increased (P<.05) on d 42. The liver of intact male pigs (Exp. 2) expressed GHR 1B mRNA by 21 d whereas a high level of GHR 1A mRNA was not detected until d 42 (P<.10). Administration of rpST had no effect on expression of GHR 1A or GHR 1B mRNA. In conclusion, GHR mRNA in porcine liver was composed of at least two variants (GHR 1A and GHR 1B). The GHR 1B mRNA was the major GHR mRNA in pig liver before 77 d of age. The GHR 1A mRNA increased after 42 d of age.