Nerve growth factor‐induced stimulation of α‐aminoisobutyric acid uptake in PC 12 cells: Evaluation of its biological significance

Publisher Website
Google Scholar
Abstract
In the clonal PC12 pheochromocytoma cell line, the observed effects of nerve growth factor (NGF) on the uptake rates of α‐aminoisobutyric acid (AIB) depend upon the assay conditions employed. In orthodox uptake assays calling for serum removal prior to the addition of AIB, 50 ng/ml NGF causes a stimulation of uptake of 62% after 40 minutes and 46% after 24‐hours exposure. However, serum stimulates AIB uptake to a similar extent and the effects of serum and NGF are not additive. An uptake assay which directly measures the AIB uptake experienced by PC12 cells undergoing NGF‐induced morphological differentiation was therefore employed. When compared with control cells growing in serum‐containing medium, NGF‐induced differentiating PC12 calls experience (1) only a transient and modest increase in AIB uptake, and (2) a significant long‐term decrease in AIB uptake under conditions optimal for differentiation. It is concluded that NGF‐directed neurite outgrowth is not mediated by NGF effects on amino acid uptake via the A‐system.