Both growth hormone-releasing peptide 6 (GHRP-6) and growth hormone-releasing hormone (GHRH) have potent GH-releasing activity in animals. We have previously demonstrated that the administration of a plasmid encoding the GHRH gene to pregnant mice and pig augmented long-term growth in first generation progeny,and that the administration of GHRP-6 results in growth augmentation in mice and rabbits. However,it has not yet been reported if GHRP-6 induces intergenerational growth effects in pigs. Ploy lactic-co-glycolic acid (PLGA) microsphere adsorption of treatment proteins enhances gene expression,genetic immunization and the ability to protect plasmid DNA and peptides from degradation. The cur-rent study was conducted to determine the growth performance of piglets born to gilts treated with GHRP-6 incorporated into thermosensitive PLGA-PEG-PLGA triblock copolymers. Gilts were injected intra-muscularly once at day 85 of gestation with 30 mg of GHRP6-loaded thermosensitive PLGA-PEG-PLGA triblock copolymers. Piglets were weighed periodically between birth and 28 days. Mean body weights of piglets born to GHRP-6-treated gilts were 6. 58% to 18. 89% (P < 0. 05 ) greater than those of piglets born to control gilts. This study confirms that enhanced maternal GHRP-6 mediated by thermosensitive PLGA-PEG-PLGA can augment growth of piglets.
