Effect of extracts of injured nerve on initiating the regenerative response in the hypoglossal nucleus in the rat.

The uptake of 2-deoxy-[14C]glucose (2-DG) by motor neurons in adult rat hypoglossal nuclei was studied 3 days after subepineural injection of 'crude' soluble protein extracts from intact and injured peripheral nerves into normal hypoglossal nerves. Injured nerve extracts were obtained from 'proximal' and 'distal' segments of sciatic nerves which were transected between two ligatures 3 days earlier. In one group of animals the hypoglossal nerve (experimental) was injected with a particular nerve extract. In another group of animals (control) the hypoglossal nerve was injected with physiological saline solution. Both proximal and distal nerve extracts caused a significant increase in 2-DG uptake. In turn, no 2-DG was detected after treatment with uncut nerve extracts or saline. These findings support the ideas that a substance(s) produced upon nerve injury is taken up by the axons and transported to the cell bodies where it triggers certain metabolic regenerative changes.