Mauer M M, Bartness T J
Department of Biology, Georgia State University, Atlanta 30303, USA.
Am J Physiol. 1997 Jan;272(1 Pt 2):R68-77. doi: 10.1152/ajpregu.1997.272.1.R68.
Long-day (LD)-housed Siberian hamsters show compensatory increases in white adipose tissue (WAT) weight after lipectomy, whereas hamsters exposed to short days (SDs) for a long duration (22 wk) do not. We tested whether SD-induced body weight changes prevent fat pad compensation after lipectomy. In experiment 1, hamsters with lesions of the paraventricular nucleus of the hypothalamus (PVNx) rapidly increased body weight similarly to 22-wk SD-exposed hamsters. In experiment 2, LD-housed hamsters were food restricted for 22 wk and then pair fed with SD-housed hamsters for 12 wk to produce body weight changes mimicking those of ad libitum-fed SD-exposed animals. Epididymal WAT (EWAT) lipectomy (EWATx) of PVNx or food-restricted hamsters elicited compensatory increases in retroperitoneal and inguinal WAT (RWAT and IWAT) weights. Unlike other fat pads, EWAT was less affected by food restriction or PVNx than by SD exposure. In general, food restriction decreased adipocyte number, whereas SD exposure decreased adipocyte size. PVNx increased RWAT adipocyte size and IWAT adipocyte number. These results suggest that the lack of body fat compensation by EWATx hamsters exposed to SDs for a long duration is due to SD-associated responses other than body weight changes per se.
长期处于长日照（LD）环境中的西伯利亚仓鼠在进行脂肪切除术后，白色脂肪组织（WAT）重量会出现代偿性增加，而长期处于短日照（SD）环境（22周）的仓鼠则不会。我们测试了短日照引起的体重变化是否会阻止脂肪切除术后的脂肪垫代偿。在实验1中，下丘脑室旁核损伤（PVNx）的仓鼠体重迅速增加，与暴露于短日照22周的仓鼠相似。在实验2中，将长期处于长日照环境的仓鼠进行22周的食物限制，然后与长期处于短日照环境的仓鼠配对饲养12周，以产生与自由采食的短日照暴露动物相似的体重变化。对PVNx或食物限制的仓鼠进行附睾白色脂肪组织（EWAT）切除（EWATx）后，会引起腹膜后和腹股沟白色脂肪组织（RWAT和IWAT）重量的代偿性增加。与其他脂肪垫不同，EWAT受食物限制或PVNx的影响小于短日照暴露。一般来说，食物限制会减少脂肪细胞数量，而短日照暴露会减小脂肪细胞大小。PVNx会增加RWAT脂肪细胞大小和IWAT脂肪细胞数量。这些结果表明，长期暴露于短日照的EWATx仓鼠缺乏体脂代偿是由于短日照相关反应，而非体重变化本身。
