Immunohistochemical characterization of neurons and neuronal processes in the dorsal vagal nucleus of the pig

The vagus nerve is responsible for efferent and afferent innervation of the gastrointestinal tract. The efferent fibres originate from neurons located in the dorsal motor nucleus of the vagus (DMX) and control mainly the gastric motor and secretory function. The main goal of our study was to examine expression of ChAT, SP, LENK, NOS and CART in the neuronal matrix of the porcine DMX. Double-labeling immunofluorescence revealed plenty of ChAT-IR neuronal cell bodies and fibres distributed throughout the nuclear matrix. Between the cholinergic somata and processes numerous SP-, LENK- and CART-IR neuronal protrusions forming dense networks were identified. While net of the NOS-IR fibres presented moderate density, the SP- and LENK-IR processes were often observed to form a basket-like structure closely surrounding the cholinergic parasympathetic neurons. Individual CART-IR basket-like formations were also encountered. A few double labeled ChAT-/NOS-IR perikarya in the rostral segment of the nucleus were also found. We confirm expression of studied antigens in the porcine DMX and provide morphological foundations for a possible regulatory role of SP, LENK, NOS and CART in porcine vago-visceral signaling.