Porcine somatotropic regulation of thymic weight, thymosin beta 4, and insulin-like growth factors in lean and obese swine.
Experiment 1 involved genetically lean and obese gilts and barrows injected for 42 d with 0, 2, or 4 mg/d of porcine somatotropin (pST; n = 96). Blood was collected at 0, 6, and 24 h after the initial pST injection and thereafter every 2 wk. Experiment 2 involved lean and obese gilts and barrows (n = 48) that were administered implants that released 0, 2, or 4 mg/d of pST for 42 d. Blood was collected at d 0, 7, 14, 28, and 42 of the study. Thymic weights and a final blood sample were collected at the end of the 42-d trial. Thymic weights increased (P < .01) with dose of pST in injected and implanted animals. Thymosin beta 4 increased (P < .05) in a pST dose-dependent manner in injected and implanted animals, but concentrations were increased more in implanted animals. Concentrations of thymosin beta 4 decreased or reached a plateau in gilts but continued to increase in barrows to the end of the trial. Thymosin alpha 1 concentrations were increased (P < .01) in barrows compared with gilts, but the concentrations were not related to dose of pST. Concentrations of pST in injected animals increased (P < .01) within 6 h after injection and had returned to basal concentrations by 24 h after injection. Concentrations of pST in implanted animals were dose-dependent (P < .05) and remained increased throughout the trial. Concentrations of IGF-I and -II were pST-dependent (P < .01) and increased throughout the trial period. Outside of the pST dose relationships, temporal changes in thymosin beta 4 were not highly related to changes in pST, IGF-I, or IGF-II. The pST dose-related increases in thymic weights and thymosin beta 4 concentrations are consistent with pST stimulation of the immune function in conjunction with overall increases of growth and efficiency of live weight gain in swine.
Wise
T
T
Roman L. Hruska U.S. Meat Animal Research Center, USDA, Clay Center, NE 68933-0166.
Klindt
J
J
Buonomo
F C
FC
Yen
J T
JT
D000818:Animals; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007273:Injections, Intramuscular / Q000662:veterinary; D008297:Male; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000662:veterinary; D009929:Organ Size / Q000187:drug effects; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013002:Somatomedins / Q000378:metabolism*; D013552:Swine / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D013553:Swine Diseases / Q000235:genetics / Q000378:metabolism; D013947:Thymosin / Q000097:blood*; D013950:Thymus Gland / Q000187:drug effects*; D000099201:Thymosin beta(4)
D003692:Delayed-Action Preparations; D004343:Drug Implants; D013006:Growth Hormone; D011994:Recombinant Proteins; D013002:Somatomedins; D013947:Thymosin; D000099201:Thymosin beta(4)