Neurons of the A1/A2 region in the guinea pig medulla oblongata containing glucagon, glicentin, and dopamine-beta-hydroxylase immunoreactivity.

Glucagon- (GLU-IR), glicentin- (GLI-IR) and dopamine-beta-hydroxylase (DBH-IR) immunoreactive neurons were mapped in the medulla oblongata of colchicine pretreated guinea pigs. Numerous GLU-IR and GLI-IR perikarya are located in the area of the nucleus ambiguus, in the adjacent formatio reticularis, and less frequently in the nucleus reticularis lateralis, the nuclei raphe obscurus and commissuralis and the caudal part of the nucleus solitarius. In these nuclei, the coexistence of glicentin and glucagon within the same perikarya is demonstrated. DBH-IR is also found in neurons of the nuclei commissuralis, solitarius and reticularis lateralis (A1/A2 system of Dahlström and Fuxe 1964, 1965). However, a coexistence of GLU/GLI-IR and DBH-IR within the same neuron is not observed.