title: Nerve growth factor-induced stimulation of alpha-aminoisobutyric acid uptake in PC12 cells: relationship to plasma membrane receptor occupancy.
abstract: Nerve growth factor (NGF) stimulates the uptake rate of the nonmetabolized amino acid alpha-aminoisobutyric acid (AIB) in the clonal PC12 pheochromocytoma cell line by 40-70%. This effect reaches a maximum after a 1-hour incubation with the hormone and then drops over 50%, reaching a minimum after 4 hours of NGF administration. Longer exposure to the hormone leads to a gradual rise in stimulation, and by 24 hours, the cells regain about 80% of the original 1-hour rate. Results of NGF-binding studies indicate that stimulation of AIB uptake follows closely behind the amount of NGF bound to the low-affinity NGF receptors. Dose-response experiments indicate that full stimulation occurs biphasically. Within the NGF concentration range of 0.1 ng/ml to 1 ng/ml, the AIB uptake rate is 30% of the maximum 1-hour response. At 2.5 ng/ml NGF, the stimulation jumps to about 75% maximal response while 100% response is reached between 5 ng/ml and 50 ng/ml NGF. We suggest that the two states of the NGF plasma membrane receptor on PC12 cells may both be involved in mediating NGF stimulation of AIB uptake.
mesh_terms: D000042:Absorption; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D002999:Clone Cells; D004305:Dose-Response Relationship, Drug; D009414:Nerve Growth Factors / Q000494:pharmacology*; D010673:Pheochromocytoma; D051381:Rats; D011956:Receptors, Cell Surface / Q000502:physiology*; D017475:Receptors, Nerve Growth Factor; D013268:Stimulation, Chemical; D013997:Time Factors
chemical_list: D000621:Aminoisobutyric Acids; D009414:Nerve Growth Factors; D011956:Receptors, Cell Surface; D017475:Receptors, Nerve Growth Factor; C100049:2-aminoisobutyric acid