Rodriguez C, Kotler M, Antolin I, Sainz R M, Menendez-Pelaez A
Departamento de Morfologia y Biologia Celular, Universidad de Oviedo, Spain.
Microsc Res Tech. 1996 May 1;34(1):65-70. doi: 10.1002/(SICI)1097-0029(19960501)34:1<65::AID-JEMT9>3.0.CO;2-V.
The Syrian hamster Harderian gland has been advocated as a model to study the porphyrin biosynthetic pathway, since it shows by far the highest porphyrin concentration known to date. Another particular characteristic is the sexual dimorphism at both the morphological and the biochemical levels. We found a variation in the ALV-S (aminolevulinate synthase) gene expression according to sex, with females exhibiting much higher mRNA levels than do males. After castration, ALV-S mRNA rose considerably in males, this increase being inhibited by darkness or treatment with melatonin. Treatment with hCG or progesterone did not vary the ALV-S mRNA levels in females. Castrated males, however, showed a much larger increase when they were treated with hCG. No variations have been found in the expression of the ALV-S gene in female HG throughout the estrous cycle. During development, males and females showed similar ALV-S mRNA levels until they were 20 days old. Afterwards, they started showing gender-associated differences. In females, ALV-S mRNA levels rose during the first 3 months of life, and thereafter they decreased progressively with aging. A circadian rhythm has been found in the gene expression of ALV-S mRNA in females, showing very low levels in the morning and reaching a peak during the first hours of darkness. It was an endogenous rhythm, probably regulated at the transcriptional level. It is proposed that the light-dark period duration modulates this rhythm through the suprachiasmatic nucleus which in turn acts on the pineal secretion of melatonin that regulates ALV-S gene expression.
叙利亚仓鼠的哈德氏腺被认为是研究卟啉生物合成途径的一个模型，因为它目前显示出已知的最高卟啉浓度。另一个特别的特征是在形态学和生物化学水平上的两性差异。我们发现，ALV-S（氨基乙酰丙酸合酶）基因表达存在性别差异，雌性的mRNA水平比雄性高得多。阉割后，雄性的ALV-S mRNA大幅上升，这种增加受到黑暗或褪黑素处理的抑制。用hCG或孕酮处理不会改变雌性的ALV-S mRNA水平。然而，阉割后的雄性用hCG处理时，其增加幅度要大得多。在雌性哈德氏腺的整个发情周期中，未发现ALV-S基因表达有变化。在发育过程中，雄性和雌性在20日龄之前显示出相似的ALV-S mRNA水平。此后，它们开始出现与性别相关的差异。在雌性中，ALV-S mRNA水平在生命的前3个月上升，此后随着年龄的增长逐渐下降。在雌性中发现ALV-S mRNA的基因表达存在昼夜节律，早晨水平很低，在黑暗的最初几个小时达到峰值。这是一种内源性节律，可能在转录水平上受到调节。有人提出，光暗周期的时长通过视交叉上核调节这种节律，视交叉上核进而作用于松果体分泌的褪黑素，褪黑素调节ALV-S基因的表达。
