Farabollini F, Heinsbroek R P, Facchinetti F, van de Poll N E
University of Siena, Italy.
Pharmacol Biochem Behav. 1991 Apr;38(4):795-9. doi: 10.1016/0091-3057(91)90244-v.
The present experiment was designed to study whether or not prior exposure to inescapable shock is accompanied by sex-dependent changes in pituitary and central levels of immunoreactive beta-endorphin, which is proposed to play an important role in opioid analgesia induced by aversive stimulation. Further, the effects of brief reexposure (5 min) to the chamber where inescapable shock was experienced earlier, were established in both sexes. Elevated levels of beta-endorphin were found 24 hours after inescapable shock, in the anterior pituitary of males and in the midbrain periaqueductal gray of both males and females. Reexposure to the experimental chamber only affected beta-endorphin levels if shock had been experienced in this chamber. Reexposure after inescapable shock reduced beta-endorphin content of the arcuate nucleus of males and beta-endorphin content of the periaqueductal gray of males and females. The present results are related to previous findings of sensitization and conditioning of analgesic reactions. The sex differences found in the present experiment are discussed with respect to sex-dependent behavioral consequences of inescapable shock.
本实验旨在研究预先暴露于不可逃避的电击是否伴随着垂体和中枢免疫反应性β-内啡肽水平的性别依赖性变化，β-内啡肽被认为在厌恶刺激诱导的阿片类镇痛中起重要作用。此外，还确定了两性短暂重新暴露（5分钟）于先前经历过不可逃避电击的实验箱的影响。在不可逃避电击24小时后，在雄性动物的垂体前叶以及雄性和雌性动物的中脑导水管周围灰质中发现β-内啡肽水平升高。只有当在该实验箱中经历过电击时，重新暴露于该实验箱才会影响β-内啡肽水平。不可逃避电击后的重新暴露降低了雄性动物弓状核的β-内啡肽含量以及雄性和雌性动物导水管周围灰质的β-内啡肽含量。本研究结果与先前关于镇痛反应的敏化和条件作用的研究结果相关。结合不可逃避电击的性别依赖性行为后果，对本实验中发现的性别差异进行了讨论。
