These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Relationships between the thyroid and somatotropic axes in steers. I: Effects of propylthiouracil-induced hypothyroidism on growth hormone, thyroid stimulating hormone and insulin-like growth factor I.
    Author: Elsasser TH, Rumsey TS, Norton SA.
    Journal: Domest Anim Endocrinol; 1992 Oct; 9(4):261-71. PubMed ID: 1473346.
    Abstract:
    The effects of propylthiouracil (PTU)-induced thyroid hormone imbalance on GH, TSH and IGF-I status in cattle were examined. In the first study, four crossbred steers (avg wt 350 kg) were fed a diet dressed with PTU (0, 1, 2 or 4 mg/kg/d BW) in a Latin square design with four 35-d periods. On day 29 in each period, steers were challenged with an intrajugular bolus of thyrotropin releasing hormone (TRH, 1.0 microgram/kg). Blood samples were obtained to assess the change in plasma GH and TSH as affected by PTU. Plasma IGF-I was measured from blood samples obtained before and after (every 6 hr for 24 hr) intramuscular injection of bovine GH (0.1 mg/kg, day 31). Doses of 1 and 2 mg/kg PTU increased plasma T4 (P < .01). At 4 mg/kg, PTU depressed T4 concentrations to 30% of control (P < .01). Plasma T3 linearly decreased with increasing doses of PTU (P < .01). Plasma TSH increased when PTU was fed at 4 mg/kg (P < .05) while the TSH response to TRH declined with increasing PTU (P < .02). Neither basal nor TRH-stimulated plasma concentration of GH was affected by PTU; the IGF-I response to GH tended to increase at the 1 and 2 mg/kg PTU (P < .01). In a second study 24 crossbred steers were fed PTU (1.5 mg/kg) for 119 d in a 2 x 2 factorial design with implantation of the steroid growth effector, Synovex-S (200 mg progesterone + 20 mg estradiol), as the other main effect. Basal plasma GH and IGF-I were not affected by PTU treatment. Synovex increased plasma concentration (P < .01) of IGF-I without an effect on plasma GH. The data suggest that mild changes in thyroid status associated with PTU affects regulation of T3, T4 and TSH more than GH or IGF-I in steers.
    [Abstract] [Full Text] [Related] [New Search]