c-Fos- and JunB-immunoreactivities in the enteric nervous system of the guinea-pig ileum.

We examined the expression of c-Fos and JunB in four immunohistochemical subtypes of enteric neurones in the guinea-pig ileum. In whole mount preparations of the myenteric and submucous plexuses from isolated segments incubated in normal Krebs' solution, increased numbers of many cells expressed visible c-Fos- and JunB-immunoreactivities. These increases may have been associated with the process of isolation and/or incubation conditions. Depolarizing stimulation by veratridine or 50 mM K+ induced further increases of neuronal c-Fos and JunB expression with no obvious subtype preference. This probably reflected a non-specific activation of most enteric neurones by these stimuli and supports the idea that expression of c-Fos and JunB in most or all enteric neurones may be a useful determinant of activation.