Abstract: Objective: To determine the effects of cardiac myocytes on nodose ganglial neuronal migration and substance P expression in co-cultures of nodose ganglion and cardiac myocytes of newborn Wistar rats. Methods: Neuromuscular co-cultures of nodose ganglion and cardiac myocytes were established. The living cells of the cultures were observed with an inverted contrast microscope at different culture ages. At 72 h and 96 h of culture, the cultures were examined by the Holmes-reduced silver stain technique to observe neuronal migration. An immunohistochemical staining method was used for investigating the expression of substance P (SP). Results: The number of migrated neurons increased in neuromuscular co-cultures compared with that in the cultures of nodose ganglial explants alone at 72 h and 96 h of culture (P＜0.05). SP-immunoreactive neurons and nerve fibers were observed in the co-cultures at 96 h of culture age. However, in the neuromuscular co-cultures at 72 h of culture, and in the cultures of nodose ganglial explants alone at 72 h and 96 h of culture, no SP-immunoreactive neurons and nerve fibers were observed. Conclusion: Cardiac myocytes may have inductive effects on nodose ganglial neuronal migration and SP expression in neuromuscular co-cultures. The neuronal morphorlogical maturation cannot represent the maturation of neurotransmitter synthesis. The synthesis of neurotransmitters had not maturated in the neuromuscular co-cultures until 96 h of culture. The results provide a new method to study the selective innervation of cardiac myocytes and the interactions between neurons and cardiac myocytes.

Key words: Ganglia, Neurons, Substance P, Cardiac myocytes, Rats