In Vivo Electroporation Enhances Foreign SS And GRF Gene Expression Efficiency In Muscle Of Mice

Somatostation (SS) and Growth Hormone-releasing Factor (GRF) are synthesized and secreted by hypothalamus, which could control synthesis and secretor of growth hormone of hypophysis and regulate GH concentrations in animal and human bodies.Both gene transfection of GRF expression plasmid and neutralization of endo-SS could promote the growth of animals. Intramuscular injection is extensively used in vivo, but it is limited by the low exogenous gene expression level.In this research, GRF and SS/HBsAg eukarya expression plasmids were transferred into muscle of mice, followed by electroporation in vivo.AAV-lacZ plasmaids(50μL(1μg/μL))were transferred into muscle of mice by electroporation in vivo in four different voltages 0v, 50v, 100v, 150v. Through X-gal staining and the examination ofβ-Galactosidase activities, 100v was the best compatible voltage.The accumulative weight gain of mice of the group pIRES-HBsAg/SS plasmids transferred into muscle of mice by electroporation in vivo were 7.33% highe(rp>0.05)than controls. The accumulative weight gain of mice of the group pIRES-HBsAg/SS plasmids injected were 6.57% higher (p>0.05)than controls.Mice injected with the highest pIRES-GRF plasmid dose (50μg) showed reduced rates of weight gain. We explored the possibility of reducing the plasmid quantity needed to achieve improved growth and changes in the hormonal profile of mice. Groups of six mice were injected with pcDNA3-GRF(1-32) (5μg, 10μg ) and electroporated using caliper electrodes. The group,which was injected with 5μg of plasmid had the greatest weight gain, with statistically non-significant differences tocontrols by 30 days after injection (13.13±0.57 g vs. 11.78±0.53g). Thus, the minimal plasmid dose (5μg) with injection at optimum age using the caliper electrodes resulted in the best growth performances.In this report, we have shown that as little as 5μg plasmid delivered under the proper electroporation conditions could have an important biological impact on animal growth. Larger plasmid quantities are not necessary and may be detrimental through development of neutralizing antibodies and strong negative feedback onto the GRF-GH-IGF-I axis.Plasmid-mediated GRF gene transfer has emerged as an excellent candidate for agricultural applications to optimize production and animal welfare. We have engineered a GRF-expressing plasmid that is efficiently expressed in skeletal muscle following intramuscular injection enhanced by electroporation. It is hopefull to be developed as practical technique.