[Iguana]

IGF-1 Studies:

If you are considering IGF-1 these are definitely worth a read!

Aim. To investigate whether intracavernosal injection of IGF-1 protein can restore erectile function in the aging rat.

Results. After IGF-1 treatment, the ICP responses was significantly increased as the young control group in both the IGF-1 1 µg/kg and the IGF-1 10 µg/kg group compared with the vehicle-only group at 4 and 8 weeks (P < 0.05). Masson's trichrom staining showed the percentage of cavernosal smooth muscle was increased in IGF-1 treatment group. IGF-1 increased e-NOS expression. NOS activities and cGMP concentrations were also significantly increased in IGF-1 treatment rats.

Conclusions. IGF-1 improved erectile function in aged rats via restoration the integrity of smooth muscle of corpus cavernosum and modulation of NO-cGMP pathways. Pu, X-Y, Wang X-H, Gao W-C, Yang Z-H, and Li S-L. Insulin-like growth factor-1 restores erectile function in aged rats: Modulation the integrity of smooth muscle and nitric oxide-cyclic guanosine monophosphate signaling activity. J Sex Med **;**:**–**.

http://www.blackwell-synergy.com/do...09.2008.00817.x

I may have posted an exerpt from this study earlier. I ran across it again and wanted to re-post because this is such a definitive study. This was not done on rats, this was done on cultures of human corpus cavernosa smooth muscle cells. This pretty much says it all. IGF-1 does in fact increase smooth muscle cells.

Effects of Insulin-Like Growth Factor-1 on Proliferation of Human Corpus Cavernosal Smooth Muscle Cells.

Kim MK, Park K, Lee HS, Ahn K, Lee HC.

Department of Urology, Chonnam National University Medical School, Gwangju, Korea. kpark@chonnam.ac.kr
Department of Microbiology, Chonnam National University Medical School, Gwangju, Korea.
Department of Anatomy, Chonnam National University Medical School, Gwangju, Korea.

PURPOSE: Insulin-like growth factor-1 (IGF-1) promotes the proliferation and migration of penile cavernous smooth muscle cells in the rat. The goals of this study were to evaluate the expression of IGF-1 and IGF-1 receptor (IGF-1R) in human corpus cavernosal smooth muscle cells (HCCSMCs) and to investigate the effect of IGF-1 on the proliferation of these cells in vitro. MATERIALS AND METHODS: The HCCSMCs were cultured from five impotent patients. The smooth muscle cells were identified by immunofluorescent stain. Total RNA was extracted, and IGF-1 gene expression was determined by RT-PCR. The IGF-1R immunoreactivity was examined by fluorescent Immunocytochemistry. Cell growth was assessed with a novel proliferation assay based on bioreduction of the fluorescent dye, Alamar blue. RESULTS: Endogenous IGF-1 mRNA expression was detected by RT-PCR analysis. The HCCSMCs were positive for IGF-IR. The proliferation of HCCSMCs increased with the dose in response IGF-1 in the culture medium in concentrations up to 100 ng/ml. CONCLUSIONS: Both IGF-1 and IGF-1R are expressed endogenously in human corpus cavernosal smooth muscle cells. IGF-1 promotes the proliferation of these cells in vitro.