Retrograde axonal transport of [¹²⁵I]nerve growth factor in ileal mesenteric nerves in vitro: Effect of streptozotocin diabetes

The retrograde axonal transport of intravenously administered [¹²⁵I]nerve growth factor ([¹²⁵I]NGF) was examined in ileal mesenteric nerves maintained for short periods in vitro. [¹²⁵I]NGF was injected systemically, and at various times thereafter mesenteric pedicles were ligated and incubated in vitro in Kerbs-Henseleit medium under a number of different conditions. Retrogradely transported [¹²⁵I]NGF began to accumulate distal to the ligature after an initial lag period and increased in a linear fashion for 3-4 h. The amount of retrogradely transported [¹²⁵I]NGF was proportional to the length of the ileum innervated by each pedicle, which allowed for comparison of ileal segments of different lengths. Retrograde axonal of [¹²⁵I]NGF was inhibited by vinblastine, colchicine and incubation in the cold, and was decreased by agents that interfere with oxidative or glycolytic metabolism. The accumulation of retrogradely transported [¹²⁵I]NGF in ileal mesenteric nerves of 1-9 day streptozotocin diabetic animals placed in an in vitro bath containing normal (5.5 mM) glucose was decreased 40% compared to control animals. The induction of diabetes in vivo resulted in a greater decrease in the early phases of [¹²⁵I]NGF export from ileal mesenteric nerve terminals compared to later phases. Ileal mesenteric nerve segments derived from untreated controls were incubated in vitro in media containing increased concentrations of glucose (27.5 and 50 mM) without reproducing the NGF transport defect found in diabetic animals.