Relationship between choline acetyltransferase positive neurons in parabrachial nucleus and development of fear memory in mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between choline acetyltransferase (ChAT) positive neurons in parabrachial nucleus and development of fear memory in mice.Methods:Eighteen healthy male ChAT-ires-cre mice, aged 8-9 weeks, weighing 22-25 g, were divided into 3 groups ( n=6 each) using a random number table method: Cre-dependent AAV-DIO-hM 3Dq-mcherry (Gq) virus/clozapine-N-oxide (CNO) group (group Gq/CNO), Gq/normal saline (NS) group (group Gq/NS) and Cre-dependent AAV-DIO-mcherry (mc) virus/CNO group (group mc/CNO). Gq virus was injected into parabrachial nucleus, and CNO 2 mg/kg was injected intraperitoneally 3 weeks later in group Gq/CNO.Gq virus was injected into parabrachial nucleus, and the equal volume of normal saline was injected intraperitoneally 3 weeks later in group Gq/NS.In group mc/CNO, mc virus was injected into parabrachial nucleus, and CNO 2 mg/kg was injected intraperitoneally 3 weeks later.The fear conditioning test was performed at 30 min after intraperitoneal injection in all the 3 groups.The brains were then removed and sliced.The virus expression and areas of the brain projected by ChAT positive neurons were observed. Results:Compared with group Gq/CNO, the percentage of freezing time was significantly increased during testing phase in Gq/NS and mc/CNO groups ( P<0.05). Gq/mc virus carrying fluorescent protein mcherry was expressed in parabrachial nucleus and was co-expressed with mcherry-ChAT.The fibers of ChAT positive neurons projected to the red nucleus, substantia nigra, central amygdala, anterodorsal thalamic nucleus and bed nucleus of stria terminalis. Conclusion:The ChAT positive neurons in parabrachial nucleus are involved in the regulation of the development of fear memory in mice, which can impair fear memory, and the regulation is carried out probably through central amygdala.