Construction and use of an adenoviral vector to express transgenic insulin-like growth factor I in the arcuate nucleus and substantia nigra of young and old rats

HEREÑÚ CB; CRISTINA C; RIMOLDI OJ; BECU-VILLALOBOS D; GOYA RG

Lisbon

Congreso; 12ht Intl. Congress of Endocrinology; 2004

European Society of Endocrinology

Background Insulin-like growth factor-I (IGF-I), which is present in both the developing and adult CNS, possesses important neurotrophic actions and its synthesis as well as its type 1 brain receptor expression decline during aging. Replacement therapy with IGF-I in aged rats ameliorates certain memory capacities.   Objectives a) to construct and test a recombinant adenoviral vector (RAd-IGF1) harboring the gene for IGF-Ib; b) to inject it in the substantia nigra (SN) and arcuate nucleus (ARC) of young and senile rats, and evaluate long-term IGF-I expression in those areas.a) to construct and test a recombinant adenoviral vector (RAd-IGF1) harboring the gene for IGF-Ib; b) to inject it in the substantia nigra (SN) and arcuate nucleus (ARC) of young and senile rats, and evaluate long-term IGF-I expression in those areas. Methods RAd-IGF1, a replication-defective vector was constructed by the two-plasmid method using the FLP recombinase for efficient vector rescue. The IGF-I transgene was placed under the control of a potent mouse cytomegalovirus promoter and its expression in transduced cells or brain tissue was assessed by RIA. Results To reach the ARC and SN, the vector was stereotaxically injected at 1012 plaque forming units (pfu)/ml in a volume of  10 :l saline per side. Two days after surgery the rats were sacrificed and the target areas were dissected by punching out cylindrical specimens that were homogenized and measured. In ARC, control (saline injected) and experimental (vector injected) tissue IGF-I levels were (pg/sample + SE) 3.77 +0.96 and 6.70 +0.79, P=0.045,whereas the corresponding values for SN were 2.60 + 0.79 and 6.64 + 0.79, P=0.011. Conclusion The present results demonstrate that RAd-IGF-I administration can significantly increase IGF-I tissue levels in two important dopaminergic brain areas, thus constituting a suitable tool for experimental gene therapy in the aging CNS.