Figure 3.

Pancreatic β cells secrete a molecule with NGF-like biological activity. (A) PC12 cells cultured in the presence of the CM extended neuritic processes. (B) When an NGF-neutralizing antibody was added to the CM, extension of neurites by PC12 was abolished to control levels because cells did not extend neuritic processes and eventually (48 h) detached from the plate. (C) The addition of the CM to PC12 cells induced a fourfold increase in the percentage of neurite-bearing cells (n = 4; *P < 0.01, ANOVA, followed by two-tailed Student’s t test). Control, chemically defined medium (20 mM glucose); CM, conditioned medium (20 mM glucose); CM + anti-NGF, conditioned medium (20 mM glucose) + anti-NGF antibody.