Bartolome J, Lau C, Slotkin T A
Dev Neurosci. 1982 Mar-Jun;5(2-3):208-15. doi: 10.1159/000112678.
Baroreceptor-mediated reflex control of cardiac sympathetic activity does not appear fully until the third week of postnatal age in the rat, possibly because central processing of baroreceptor sensory input is deficient in the neonate. Hyperthyroidism, which accelerates synaptogenesis in the peripheral sympathetic and central nervous systems, was produced by administering 3,3',5-triiodothyronine (T3) daily, and effects on development of baroreceptor-mediated sympathetic reflexes were evaluated. To test baroreceptor-mediated reflexes, control and T3-treated rats of different ages were given hydralazine acutely to produce a decrease in blood pressure, which in adult rats results in a large, sympathetically-mediated stimulation of cardiac ornithine decarboxylase (ODC) activity. In control neonates, cardiac ODC responses to hydralazine were absent until the 3rd week of age, but the T3-treated animals showed increases as early as 8 days of age. Furthermore, increased turnover of norepinephrine in cardiac sympathetic nerves in response to the hydralazine-induced hypotension was 2- to 3-fold higher in the 8-day-old T3-treated animals than in controls. These data indicate that the early appearance of the ODC response to hypotension in hyperthyroid rats results, at least in part, from precocious development of the ability of baroreceptor input to influence efferent sympathetic function.
压力感受器介导的心脏交感神经活动反射性控制在大鼠出生后第三周之前似乎尚未完全发育，这可能是因为新生儿对压力感受器感觉输入的中枢处理存在缺陷。通过每日给予3,3',5-三碘甲状腺原氨酸（T3）诱导甲状腺功能亢进，甲状腺功能亢进会加速外周交感神经系统和中枢神经系统的突触形成，并评估其对压力感受器介导的交感反射发育的影响。为了测试压力感受器介导的反射，对不同年龄的对照大鼠和T3处理的大鼠急性给予肼屈嗪以降低血压，在成年大鼠中，这会导致由交感神经介导的心脏鸟氨酸脱羧酶（ODC）活性大幅升高。在对照新生大鼠中，直到3周龄时心脏ODC对肼屈嗪才会产生反应，但T3处理的动物早在8日龄时就出现了反应增强。此外，在8日龄的T3处理动物中，肼屈嗪诱导的低血压引起的心脏交感神经中去甲肾上腺素周转增加比对照高2至3倍。这些数据表明，甲状腺功能亢进大鼠中ODC对低血压反应的早期出现至少部分是由于压力感受器输入影响传出交感神经功能的能力早熟发育所致。
