Takahashi L K, Kim H
Department of Psychiatry, University of Wisconsin Medical School, Madison 53792-2475, USA.
Physiol Behav. 1995 Apr;57(4):711-6. doi: 10.1016/0031-9384(94)00324-6.
Recent investigations revealed that adrenalectomized (ADX) rat pups exhibit deficits in behavioral inhibition. Furthermore, administration of exogenous corticosterone (CORT) restores behavioral inhibition in ADX pups. Although these studies suggest that CORT has an important role in the development of behavioral inhibition, the relative behavioral effects of elevated pituitary hormone secretion induced by ADX are not known. Therefore, experiments were conducted to assess the potential behavioral effects of elevated adrenocorticotropin (ACTH) secretion induced by ADX and to further evaluate the contribution of endogenous CORT to the development of behavioral inhibition. In Experiment 1., we verified that 10-day-old ADX rats exhibit high levels of plasma ACTH throughout the preweaning period associated with the development of behavioral inhibition. In Experiment 2, 10-day-old pups were hypophysectomized (HYPOX) and ADX and were compared behaviorally to sham-operated controls on day 14. When tested in the presence of an anesthetized unfamiliar adult male rat, HYPOX + ADX pups exhibited low levels of freezing accompanied by ultrasonic vocalizations. These pups also had reduced concentrations of plasma ACTH and CORT. In Experiment 3, 10-day-old pups were HYPOX and tested for behavioral inhibition on day 14. In comparison to sham-operated controls, HYPOX rats exhibited significantly lower levels of freezing and had reduced plasma concentrations of ACTH and CORT. Results demonstrate clearly that deficits in freezing occur even in the presence of low plasma ACTH concentrations. Therefore, elevated secretion of pituitary hormones is not a major factor that contributes to the ADX-induced deficits in behavioral inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)
最近的研究表明，肾上腺切除（ADX）的幼鼠在行为抑制方面存在缺陷。此外，给予外源性皮质酮（CORT）可恢复ADX幼鼠的行为抑制。尽管这些研究表明CORT在行为抑制的发展中起重要作用，但ADX诱导的垂体激素分泌升高的相对行为影响尚不清楚。因此，进行了实验以评估ADX诱导的促肾上腺皮质激素（ACTH）分泌升高的潜在行为影响，并进一步评估内源性CORT对行为抑制发展的贡献。在实验1中，我们证实10日龄的ADX大鼠在整个断奶前阶段血浆ACTH水平较高，这与行为抑制的发展相关。在实验2中，10日龄的幼鼠接受垂体切除（HYPOX）和ADX手术，并在第14天与假手术对照组进行行为比较。当在一只麻醉的陌生成年雄性大鼠面前进行测试时，HYPOX + ADX幼鼠表现出低水平的僵住行为并伴有超声波发声。这些幼鼠的血浆ACTH和CORT浓度也降低。在实验3中，10日龄的幼鼠接受HYPOX手术，并在第14天测试行为抑制。与假手术对照组相比，HYPOX大鼠表现出明显更低的僵住水平，且血浆ACTH和CORT浓度降低。结果清楚地表明，即使血浆ACTH浓度较低，僵住行为的缺陷依然会出现。因此，垂体激素分泌升高不是导致ADX诱导的行为抑制缺陷的主要因素。（摘要截断于250字）
