Demarest K T, Moore K E, Riegle G D
Neuroendocrinology. 1987 May;45(5):333-7. doi: 10.1159/000124755.
The regulation of prolactin secretion by tuberoinfundibular dopamine (DA) neurons appears to be altered in the aged rat: the concentration of prolactin in the serum increases and the activity of the tuberoinfundibular DA neurons decreases. In the young female rat a brief period of stress reduces the tuberoinfundibular DA neurosecretory activity and increases the secretion of prolactin. The purpose of the present study was to determine if the responsiveness of tuberoinfundibular DA neurons to restraint stress is altered in the aged female rat. The activity of these neurons was estimated from the rate of DA synthesis in their terminals in the median eminence, as measured by the rate of accumulation of dihydroxyphenylalanine (DOPA) after the administration of a decarboxylase inhibitor. Thirty minutes of restraint stress increased serum prolactin concentrations in both young (3 months) and aged (26 months) constant estrous rats, but reduced the rate of DOPA accumulation in the median eminence of only the young rats. Restraint also decreased the rate of DOPA accumulation in the median eminence of intermediate-aged rats (14 months) independently of whether the rats were exhibiting normal ovarian cycles (measured on the day of estrus) or were in a constant estrus. This suggests that the loss of ovarian cyclicity per se is not associated with the age-related change in the response of tuberoinfundibular DA neurons to restraint stress.(ABSTRACT TRUNCATED AT 250 WORDS)
结节漏斗多巴胺（DA）神经元对催乳素分泌的调节在老年大鼠中似乎发生了改变：血清中催乳素浓度升高，而结节漏斗DA神经元的活性降低。在年轻雌性大鼠中，短暂的应激会降低结节漏斗DA神经分泌活动并增加催乳素的分泌。本研究的目的是确定老年雌性大鼠中结节漏斗DA神经元对束缚应激的反应性是否发生改变。这些神经元的活性通过在给予脱羧酶抑制剂后，根据正中隆起终末中DA合成速率来估计，该速率通过二羟基苯丙氨酸（DOPA）的积累速率来测量。30分钟的束缚应激使年轻（3个月）和老年（26个月）持续发情大鼠的血清催乳素浓度均升高，但仅降低了年轻大鼠正中隆起中DOPA的积累速率。束缚也降低了中年大鼠（14个月）正中隆起中DOPA的积累速率，无论这些大鼠是处于正常卵巢周期（在发情日测量）还是持续发情状态。这表明卵巢周期性的丧失本身与结节漏斗DA神经元对束缚应激反应的年龄相关变化无关。（摘要截短于250字）
