Evidence against neurotransmitter mediation of sprouting in granuloprival cerebellar cultures.

Cerebellar cultures derived from neonatal mice undergo a remarkable sprouting of Purkinje cell recurrent axon collaterals after exposure for the 1st 5 days in vitro to cytosine arabinoside to destroy granule cells. Such cultures were simultaneously exposed to large concentrations of the putative neurotransmitters glutamate and GABA, with subsequent continued exposure to the amino acids until the time of fixation at 15 or 16 days in vitro. Axon collateral sprouting was not prevented by glutamate or GABA, suggesting the sprouting is not mediated by the relevant neurotransmitters, but is more likely due to an alteration or lack of development of some trophic interaction between granule cells and their target Purkinje cells.