Cunningham M L, Pippin L L, Anderson N L, Wenk M L
Chemistry Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Toxicol Appl Pharmacol. 1995 Apr;131(2):216-23. doi: 10.1006/taap.1995.1064.
Methapyrilene (MPH) was a widely used antihistamine until it was found to produce hepatocellular carcinoma and cholangiocarcinoma in Fischer 344 rats. The structurally similar antihistamine pyrilamine (PYR) was marginally or noncarcinogenic in a similar study. The peroxisome proliferator Wy-14,643 was included in this study as a positive control. As part of a program to investigate the mechanisms whereby structurally similar chemicals produce different toxicities, we studied these three chemicals for the induction of cell proliferation in the liver of F344 rats. Male rats were treated for up to 13 weeks with feed dosed with MPH (HCl salt) at 0, 50, 100, 250, or 1000 ppm or PYR (maleate salt) at 1000 ppm to duplicate the route of administration and high-dose groups used in the carcinogenesis assay. In addition, the nongenotoxic hepatocarcinogen peroxisome proliferator Wy-14,643 was included as a positive cell-proliferating chemical. Cell proliferation was quantitated by measuring the incorporation of bromodeoxyuridine (BrDU) administered by osmotic minipump for 7 days and the appearance of proliferating cell nuclear antigen (PCNA) immunohistochemically. The BrDU-labeling index showed a large and sustained increase in rats treated with MPH at 250 and 1000 ppm, sustaining greater than 50% labeling in the higher dose group of 4-, 6-, and 13-week treatment groups. PYR at 1000 ppm demonstrated no significant increase in labeling above control levels at any time point. PCNA-labeling indexes showed similar but reduced increases for MPH and were comparable to control for the PYR dose groups. Two-dimensional gel electrophoresis was used for the detection of quantitative changes in gene expression and qualitative changes in the charges of specific mitochondrial and cytosolic proteins. Quantitative changes in 32 proteins induced by MPH and 39 changes induced by Wy-14,643 were detected throughout the 13-week study. Specific mitochondrial protein charge shifts were associated with high-dose MPH treatment that were not observed in animals treated with Wy-14,643. PYR induced no significant qualitative or quantitative protein alterations. Hepatocellular proliferation of the large magnitude observed following dietary administration of MPH, and not PYR may contribute to the mechanism of carcinogenesis of MPH.
在发现甲吡咯啉（MPH）可在Fischer 344大鼠中引发肝细胞癌和胆管癌之前，它是一种广泛使用的抗组胺药。在一项类似研究中，结构相似的抗组胺药吡咯胺（PYR）致癌性很弱或无致癌性。过氧化物酶体增殖剂Wy-14,643作为阳性对照被纳入本研究。作为研究结构相似化学物质产生不同毒性机制的项目的一部分，我们研究了这三种化学物质对F344大鼠肝脏细胞增殖的诱导作用。雄性大鼠用含0、50、100、250或1000 ppm的MPH（盐酸盐）或1000 ppm的PYR（马来酸盐）的饲料处理长达13周，以重复致癌试验中使用的给药途径和高剂量组。此外，将无基因毒性的肝癌致癌物过氧化物酶体增殖剂Wy-14,643作为一种阳性细胞增殖化学物质纳入研究。通过测量经渗透微型泵给药7天的溴脱氧尿苷（BrDU）掺入量以及免疫组织化学检测增殖细胞核抗原（PCNA）的出现情况来定量细胞增殖。BrDU标记指数显示，在250和1000 ppm的MPH处理大鼠中出现了大幅且持续的增加，在4周、6周和13周治疗组的高剂量组中，标记率持续高于50%。1000 ppm的PYR在任何时间点的标记增加均未显著高于对照水平。PCNA标记指数显示MPH的增加相似但程度较低，且与PYR剂量组的对照相当。二维凝胶电泳用于检测基因表达的定量变化以及特定线粒体和胞质蛋白电荷的定性变化。在整个13周的研究中，检测到MPH诱导的32种蛋白质的定量变化以及Wy-14,643诱导的39种变化。高剂量MPH处理导致特定线粒体蛋白电荷转移，而在Wy-14,643处理的动物中未观察到这种情况。PYR未诱导显著的定性或定量蛋白质改变。经口给予MPH而非PYR后观察到的大量肝细胞增殖可能有助于MPH的致癌机制。
