Itoh H, Buñag R D
Department of Pharmacology, College of Health Sciences and Hospital University of Kansas Medical Center, Kansas City 66103.
Mech Ageing Dev. 1993 Feb;67(1-2):47-63. doi: 10.1016/0047-6374(93)90111-4.
To determine whether catecholaminergic lesions in the nucleus tractus solitarius (NTS) have age-related baroreflex effects, we compared conscious 3-month- and 14-month-old rats pretreated with either 6-hydroxydopamine (6-OHDA) or vehicle injected into the NTS. Body weights fell immediately in both age groups, but after 2 weeks the weight loss persisted only in 14-month-old rats. Mean pressures and heart rates, though diminished after 3 days, were later elevated slightly in 3-month- but not in 14-month-old rats. Two weeks after 6-OHDA pretreatment, reflex tachycardia was reduced in both age groups, but reflex bradycardia was reduced only in 3-month-old and not in 14-month-old rats. Corresponding changes in vehicle-treated rats were not significant. Because 6-OHDA induced lesions in the NTS inhibited reflex bradycardia selectively at 3 but not at 14 months of age, our results suggest that catecholaminergic mechanisms in the NTS for regulating reflex bradycardia become impaired with age.
为了确定孤束核（NTS）中的儿茶酚胺能损伤是否具有与年龄相关的压力反射效应，我们比较了经6-羟基多巴胺（6-OHDA）或注射到NTS中的赋形剂预处理的3个月和14个月大的清醒大鼠。两个年龄组的体重均立即下降，但2周后体重减轻仅在14个月大的大鼠中持续存在。平均压力和心率在3天后虽有所降低，但在3个月大的大鼠中随后略有升高，而在14个月大的大鼠中则没有。6-OHDA预处理2周后，两个年龄组的反射性心动过速均降低，但反射性心动过缓仅在3个月大的大鼠中降低，而在14个月大的大鼠中未降低。赋形剂处理的大鼠的相应变化不显著。由于6-OHDA诱导的NTS损伤在3个月大时选择性地抑制反射性心动过缓，而在14个月大时则不然，我们的结果表明，NTS中调节反射性心动过缓的儿茶酚胺能机制随年龄增长而受损。
