Insulin-like growth factor-1 gene therapy improves the levels of mRNA and protein of endothelial nitric oxide synthase in aging related erectile dysfunction in rats

Abstract

To explore the effects of gene transfer of insulin like growth factor-1 (IGF-1) on the penis of senile rats and the altered levels of mRNA and protein of endothelial nitric oxide synthase (eNOS). Ten young (4 months) and 20 senile (24 months) Sprague-Dawley male rats were selected. The senile rats were divided into 2 groups: phosphate buffer solution (PBS)-only (n = 10) and 100 µg IGF-1 plasmid treatment group (n = 10). After a 4-week injection of IGF-1, the responses of intracavernous pressure (ICP) with electrical stimulation to the cavernous nerve and systemic mean arterial pressure (MAP) were evaluated. In the control and transfected senile rats, the levels of eNOS mRNA and protein were examined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot respectively. The ICP/MAP and total ICP were significantly higher in the young control group versus the PBS-only group at Week 4 (P < 0.05). The ICP/MAP and total ICP were significantly higher in the young control group and the 100 µg IGF-1 treatment group versus the PBS-only group at Week 4 (P < 0.05). The levels of mRNA and protein of eNOS were higher in the 100 µg IGF-1 treatment group versus the PBS-only group at Week 4 (0.62 ± 0.16 vs 0.25 ± 0.08, 0.71 ± 0.19 vs 0.27 ± 0.09, both P < 0.05, respectively). The gene therapy of IGF-1 can ameliorate erectile functions and improve the levels of mRNA and protein of eNOS in senile rats.