BIOCHEMICAL INDEXES OF TUBEROINFUNDIBULAR DOPAMINERGIC NEURONAL-ACTIVITY DURING LACTATION - A LACK OF RESPONSE TO PROLACTIN
BIOCHEMICAL INDEXES OF TUBEROINFUNDIBULAR DOPAMINERGIC NEURONAL-ACTIVITY DURING LACTATION - A LACK OF RESPONSE TO PROLACTIN
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DOI：
10.1159/000123449
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发表时间：
1983-01-01
影响因子：
4.1
通讯作者：
MOORE, KE
中科院分区：
文献类型：
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作者：
DEMAREST, KT;MCKAY, DW;MOORE, KE
比较了大鼠间情期第2天和产后12天哺乳期大鼠的催乳素血清浓度和多巴胺能神经元（神经元活性）脉冲交通的生化估计值，这些大鼠要么被吸吮，要么被非哺乳（幼鼠衍生）。结节漏斗、结节垂体和黑质纹状体多巴胺（DA）神经元的活性指数通过测量α-DA神经元的活性指数来获得。甲基酪氨酸诱导的DA浓度下降，和多巴的积累后，芳香族L-氨基酸脱羧酶的抑制剂，在正中隆起，垂体后叶和纹状体，分别管理。幼鼠哺乳期大鼠结节漏斗DA神经元活动的生化指标和垂体前叶DA含量均低于动情对照组，且哺乳后进一步降低。这些变化似乎是特异性的结节漏斗DA神经元，因为生化估计结节垂体和黑质纹状体DA神经元的活动是相同的，在所有3组动物。取出幼仔后，母体中的血清催乳素浓度在4 h内降至基础水平，并保持低水平至少72 h。哺乳期大鼠正中隆起的多巴蓄积率在幼鼠取出后4 h增加，但在72 h内仍显著低于非发情值。急性吸吮刺激激活神经元回路，导致结节漏斗DA神经元活动迅速减少。这种减少可能在哺乳诱导的催乳素分泌增加中起作用。独立于这些急性变化，在哺乳期大鼠的结节漏斗DA神经元的基础活动减少。这种减少似乎是由于这些神经元对催乳素的刺激作用缺乏反应。这一点得到了以下事实的支持：侧脑室注射催乳素后12小时或氟哌啶醇给药（可增加血清催乳素浓度）后16小时，动情间期动物正中隆起中多巴蓄积率增加，但这些治疗对泌乳期动物无影响。在泌乳大鼠的tuberoinfundibular DA神经元催乳素的反应性降低，可能有助于在这些动物的垂体前叶的能力，以保持高分泌率的这种激素。
Serum concentrations of prolactin and biochemical estimates of impulse traffic in dopaminergic neurons (neuronal activity) were compared in rats on the 2nd day of diestrus and in 12-day postpartum lactating rats that were either sucked or were nonsuckled (pup-derived). Indices of the activities of tuberoinfundibular, tuberohypophyseal and nigrostriatal dopamine (DA) neurons were obtained by measuring the .alpha.-methyltyrosine-induced decline of DA concentrations, and the accumulation of dopa after the administration of an inhibitor of aromatic L-amino acid decarboxylase in the median eminence, posterior pituitary and striatum, respectively. Biochemical indices of tuberoinfundibular DA neuronal activity and the content of DA in the anterior pituitary gland were lower in pup-derived lactating rats than in diestrous controls, and were further reduced by suckling. These changes appeared to be specific for tuberoinfundibular DA neurons since biochemical estimates of tuberohypophyseal and nigrostriatal DA neuronal activity were the same in all 3 groups of animals. Following pup removal serum prolactin concentrations in the dam decreased to basal levels within 4 h and remained low for at least 72 h. The rate of dopa accumulation in the median eminence of lactating rats increased 4 h after pup removal, but remained significantly lower than diestrous values for 72 h. An acute suckling stimulus activates a neuronal circuit which causes a prompt decrease in tuberoinfundibular DA neuronal activity. This decrease may play a role in the suckling-induced increase in prolactin secretion. Independent of these acute changes, the basal activity of tuberoinfundibular DA neurons is reduced in lactating rats. This decrease appears to result from the lack of responsiveness of these neurons to the stimulating actions of prolactin. This is supported by the fact that the rate of dopa accumulation in the median eminence was increased in diestrous animals 12 h after the intracerebroventricular injection of prolactin or 16 h after the administration of haloperidol (which increases serum prolactin concentrations) but these treatments were without effect in lactating animals. The decreased responsiveness of tuberoinfundibular DA neurons in lactating rats to prolactin may contribute to the ability of the anterior pituitary gland in these animals to maintain a high secretion rate of this hormone.