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Title: Age-related reduction of reflex bradycardia in conscious rats by catecholaminergic nucleus tractus solitarius lesions. Author: Itoh H, Buñag RD. Journal: Mech Ageing Dev; 1993 Feb; 67(1-2):47-63. PubMed ID: 8469033. Abstract: 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.[Abstract] [Full Text] [Related] [New Search]