A comparison of the growth responses following intramuscular GHRH plasmid administration versus daily growth hormone injections in young pigs.
The efficacy of daily porcine growth hormone (GH) injections versus plasmid-driven porcine GH-releasing hormone (pGHRH) production to promote growth was assessed. Ten-day-old piglets were injected intramuscularly with 0.1, 1, or 3 mg pGHRH, or a control plasmid followed by electroporation. Plasmid constructs were driven by a synthetic muscle-specific promoter. A fifth group received daily injections of GH [0.15 mg/(kg.day)]. Control and pGHRH-treated pigs were pair-fed to GH-treated pigs. Body composition was assessed by dual-energy X-ray absorptiometry (DXA). Weight gains of GH- and pGHRH-treated pigs were greater than of controls (P < 0.001) due to greater lean mass accretion; fat accretion was similar across all treatments. Weight gain of pGHRH- and GH-treated pigs was similar for 6 weeks, but over the final 10 days, only pigs administered the highest plasmid dose maintained higher growth rates. Serum insulin-like growth factor-I (IGF-I) levels were two- to threefold higher in GH- and pGHRH-treated pigs than in controls after 4 weeks (P = 0.05), but subsequently decreased to control levels in the pGHRH-treated group. Organ weights were greater in GH- than pGHRH-treated and control piglets (P < 0.02). These results demonstrate that pGHRH transfer is effective for promoting growth and avoids the need for the frequent injections necessitated with peptide hormone use.
Khan
Amir S
AS
VGX Pharmaceuticals, The Woodlands, Texas, USA.
Draghia-Akli
Ruxandra
R
Shypailo
Roman J
RJ
Ellis
Kenneth I
KI
Mersmann
Harry
H
Fiorotto
Marta L
ML
D015502:Absorptiometry, Photon; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D007273:Injections, Intramuscular / Q000379:methods*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D010957:Plasmids / Q000008:administration & dosage* / Q000235:genetics; D013552:Swine
D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone