Table 1.
Main Outcomes of Elevated Endogenous GDNF in Aged Gdnfwt/hyper Mice
| Phenotypes Reported in Previous Studies | Method | Reference | Long-Term Elevation of Endogenous GDNF (This Study) |
|---|---|---|---|
| Increase in dopamine turnover, but no changes in striatal dopamine tissue level | striatal or nigral recombinant lentiviral vector delivery of GDNF in unlesioned animals | 16 | elevated and sustained striatal dopamine levels |
| Downregulation of TH levels in the STR and SN | striatal recombinant lentiviral vector delivery of GDNF | 16, 17, 18 | no changes in TH levels in the STR and SN |
| Striatal dopaminergic fibers sprouting toward GDNF injection site | nigrostriatal recombinant GDNF injection and viral gene delivery | 18, 19, 20 | no increase of striatal TH-positive dopaminergic fibers density |
| Hyperactivity | nigrostriatal recombinant GDNF injection | 19,21, 22, 23 | no difference in spontaneous locomotor activity |
| Loss in body weight | nigrostriatal virus-mediated GDNF delivery | 24 | no change in body weight |
| Tumors in testes in all mice used by 12 months of age | transgenic overexpression of GDNF in undifferentiated spermatogonia | 28 | no tumors found in testes |
| Thyroid and adrenal neoplasia | GDNF receptor RET constitutive activation due to point mutation (MEN2B mice) | 26 | no tumors found in thyroid and adrenal glands |