Substratum-induced modulation of acetylcholinesterase activity in cultured dorsal root ganglion neurons

Acetylcholinesterase (AChE) has been shown to be transiently expressed in the developing nervous system during periods of neuronal migration and axonal outgrowth. We are investigating the possible interaction of substratum with AChE activity in dorsal root ganglion neurons (DRGN) cultured on substrata with varying degrees of permissiveness for neurite outgrowth: (1) extracellular matrix substrata: reconstituted basal lamina Matrigel (MGEL), laminin (LAM) and type I collagen (COL), and (2) organotypic substrata: unfixed, frozen sections of sciatic nerve (SN) and spinal cord (SC). In group 1, histochemical staining for AChE in DRGN was lowest on MGEL where outgrowth was most vigorous, intermediate on LAM, and highest on COL where neurite outgrowth was reduced by 55% compared to Matrigel and highly fasciculated. A similar trend was seen when the cultures were assayed biochemically, 2.84 +/- 0.14 nmoles ACh hydrolyzed/ganglion/hr (MGEL), 4.42 +/- 0.19 (LAM), 5.79 +/- 0.37 (COL). In group 2, SN supported an expansive outgrowth with lower AChE activity than in DRGN grown on SC where outgrowth was minimal. These studies show that the levels of AChE activity can be modulated by substratum, perhaps in proportion to the permissiveness of the substratum to neuritic outgrowth. These results are discussed in relation to possible non-cholinergic roles of AChE.