Glial cell line-derived neurotrophic factor stimulates the morphological differentiation of cultured ventral mesencephalic calbindin- and calretinin-expressing neurons

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for mesencephalic dopaminergic neurons. Subpopulations of these neu rons express the calcium-binding proteins calbindin (CB) and calretinin (CR ). Understanding the specific effects of GDNF on these neurons is important for the development of an optimal cell replacement therapy for Parkinson's disease. To investigate the effects of GDNF on the morphological complexit y of mesencephalic tyrosine hydroxylase (TH)-immunoreactive (-ir), CB-ir, a nd CR-ir neurons, dissociated cultures of embryonic (E14) rat ventral mesen cephalon were prepares. Chronic administration of GDNF (10 ng/ml) for 7 day s promoted the survival of TH-ir and CB-ir neurons but did not alter the de nsity of CR-ir neurons. Total fiber length/neuron and number of branching p oints/neuron of CB-ir and CR-ir cells were significantly increased after GD NF treatment (2x for CB-ir cells and 1.4x and 1.7x, respectively, for CR-ir cells), which resulted in a significantly larger size of neurite field/neu ron (2.9x and 1.5x for CB-ir and CR-ir neurons, respectively). The number o f primary neurites/neuron of CB-ir neurons was found to be 1.5x larger, whi le no difference could be detected for CR-ir cells. Assessment of the effec ts of GDNF on TH-ir neurons unveiled a similar outcome with an increased to tal fiber length/neuron (1.5 x), an increased number of primary neurites/ne uron (1.6x), and a twofold larger size of neurite field/neuron. In conclusi on, our findings recognize GDNF as a neurotrophic factor that stimulates th e morphological differentiation of ventral mesencephalic CB-ir and CR-ir ne urons. (C) 2000 Academic Press.