GDNF and GFRalpha1 promote differentiation and tangential migration of cortical GABAergic neurons

Cellular and molecular control of neurogenesis in the mammalian telencephalon

The mammalian telencephalon exhibits an amazing diversity of neuronal types. The generation of this diversity relies on multiple developmental strategies, including the regional patterning of progenitors, their temporal specification, and the generation of intermediate progenitor populations. Progress has recently been made in characterizing some of the mechanisms involved. In particular, intermediate progenitors have been shown to play important roles in the generation of neurons in the cerebral cortex, and the properties and lineage relationships between radial glial cells and these intermediate progenitors have recently been examined by elegant time-lapse microscopic studies. Multiple pathways control the progression of neural lineages from multipotent stem cells to intermediate progenitors, postmitotic precursors and finally mature neurons. The regulation of two essential steps, neuronal commitment and specification of subtype identities, is increasingly well understood. These two steps are clearly distinct but co-ordinately regulated by common transcription factors such as neurogenins and Pax6. As our knowledge of the mechanisms of subtype specification of telencephalic neurons progresses, it will become possible to direct stem cells into generating particular telencephalic neuronal populations, opening the way to efficient neuronal replacement therapies.

GDNF and Addiction

Biochemical adaptations to drugs of abuse and alcohol are especially profound in midbrain dopaminergic neurons. Long-lasting molecular and structural changes in mesolimbic dopaminergic neurons that result from chronic exposure to drugs of abuse and alcohol are thought to underlie adverse behaviors such as compulsive drug seeking and relapse. Recent studies suggest that a subset of these changes is prevented/reversed by activation of the glial cell line-derived neurotrophic factor (GDNF) signaling pathway. Behavioral effects of drugs of abuse such as cocaine and alcohol are also negatively regulated by GDNF: inhibition of the endogenous GDNF pathway enhances the activity of drugs of abuse, while administration of GDNF reduces the severity of the effects. In this review, we summarize the data implicating GDNF as a negative regulator of drug and alcohol addiction. We also provide evidence to suggest that therapies that activate GDNF signaling may be useful for the treatment of drug and alcohol addiction.