The invention features a method for promoting
neural growth in vivo in the mammalian
central nervous system by administering a
neural cell adhesion molecule which can overcome inhibitory molecular cues found on glial cells and
myelin to promote
neural growth. Also featured active fragments, cognates, congeners, mimics, analogs, secreting cells and soluble molecules thereof, as well as antibodies thereto, and
DNA molecules, vectors and transformed cells capable of expressing them. The neuroprotective of the agents as well as their ability to promote and effect myelination and
remyelination are also disclosed, as are the concomitant benefits that these capabilities confer, in the former instance, with regard to reduction of
apoptosis and
necrosis, and in the latter instance, the treatment of
Parkinsonism, Alzheimer's
disease and
multiple sclerosis. The invention also includes transgenic mouse lines expressing a neural adhesion molecule in differentiated astrocytes, and cells and tissues derived therefrom. The expression of the neural adhesion molecule enhances
neurite outgrowth on
central nervous system tissue derived from these transgenic mice. The invention also features methods for enhancing neuronal outgrowth of CNS neurons, for enhancing memory and for increasing synaptic
efficacy. Also featured are methods of testing drugs which modulate the effects of the neural adhesion molecule, and
assay systems suitable for such methods.