Abstract:

Objective   To investigate activities of cholinergic and catecholaminergic neurons in the nucleus ambiguous (NA) in response to water-immersion stress (RWIS) in rats. Methods  Ten rats were randomly divided into the control group and the RWIS group. Fos-immunoreactive (Fos-IR), choline acetyltransferase immunoreactive (ChAT-IR), tyrosine hydroxylase immunoreactive (TH-IR) and double labeled (Fos+ChAT-IR and Fos+TH-IR) neurons were counted using immunohistochemistry. Results   In the NA, ChAT-IR neurons were fusiform or polygonal, with a large amount of TH-IR ending. Compared with unstressed rats, the number of Fos-IR neurons was dramatically increased in the NA of RWIS rats (P<0.05), and the number of Fos+ChAT-IR neurons was greater in RWIS rats than unstressed rats (P<0.05). The percentage of Fos-IR nuclei in ChAT-IR neurons in unstressed and RWIS rats were 7.5% and 29.8%, respectively (P<0.01). Conclusion   Cholinergic neurons in the NA, which might be regulated by catecholaminergic neurons in other nuclei, are involved in the RWIS response.

Key words: Stress; Nucleus ambiguous; Choline 0-acetyltransferase; Tyrosine hydroxylase; Fos