Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters
Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters
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DOI：
10.1152/ajpregu.00792.2004
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发表时间：
2005-05-01
影响因子：
2.8
通讯作者：
Bartness, TJ
中科院分区：
文献类型：
--
作者：
Bowers, RR;Gettys, TW;Bartness, TJ
西伯利亚仓鼠表现出一种自然发生的、可逆的季节性肥胖，体脂在长的夏季日(LDS)达到峰值，在短的冬季日(SDS)达到最低点。SD诱导的肥胖减少主要是通过交感神经系统(SNS)支配白色脂肪组织(Wat)，如Wat去甲肾上腺素(NE)周转增加所表明的。我们研究了十二烷基硫酸钠是否也增加了对去甲肾上腺素刺激的脂肪分解的敏感性。这是通过测量去甲肾上腺素和β(3)肾上腺素受体激动剂(BRL-37344)诱导的脂肪分解(甘油释放)以及去甲肾上腺素诱导的腹股沟、附睾和腹膜后水(IWAT、EWAT和RWAT)在LD和SD饲养的仓鼠的分离脂肪细胞中的cAMP积聚来完成的。十二烷基硫酸钠以一种暂时和脂肪垫特异的方式增加NE触发的脂解的效力/效力。因此，当Wat Pad质量下降最快时(5wk的SDS)，所有Wat Pad和IWAT的NE刺激的脂解活性(敏感性/EC50)和有效性(最大反应渐近线)都比LD对应的高。去甲肾上腺素和BRL-37344对IWAT脂肪细胞脂解的促进作用相似。这些结果，再加上我们之前的研究表明，SDS上调Wat beta(3)-AR mRNA的表达，表明增加的β(3)-ARs介导了SD诱导的NE敏感性的增加。与LDS相比，IWAT和EWAT在5wk和10wk后Ne刺激的脂肪细胞cAMP积聚明显增加，而RWAT则没有光周期效应。因此，SD诱导的SNS驱动对WAT的增加和对该驱动的敏感性增加可能共同作用，增加了SDS中的脂解作用。
Siberian hamsters (Phodopus sungorus) exhibit a naturally occurring, reversible seasonal obesity with body fat peaking in long "summerlike" days (LDs) and reaching a nadir in short "winterlike" days (SDs). These SD-induced decreases in adiposity are mediated largely via sympathetic nervous system (SNS) innervation of white adipose tissue (WAT), as indicated by increased WAT norepinephrine (NE) turnover. We examined whether SDs also increase sensitivity to NE-stimulated lipolysis. This was accomplished by measuring NE- and beta(3)-adrenoceptor (beta(3)-AR) agonist (BRL-37344)-induced lipolysis (glycerol release) as well as NE- induced cAMP accumulation by inguinal, epididymal, and retroperitoneal WAT (IWAT, EWAT, and RWAT) in isolated adipocytes of LD- and SD-housed hamsters. SDs increased potency/efficacy of NE- triggered lipolysis in a temporally and fat pad-specific manner. Thus when WAT pad mass decreased most rapidly (5 wk of SDs), potency (sensitivity/EC50) and efficacy (maximal response asymptote) of NE- stimulated lipolysis were increased for all WAT pads and also at 10 wk for IWAT compared with their LD counterparts. SD enhancement of lipolysis was similar for NE and BRL-37344 in IWAT adipocytes. These results, coupled with our previous demonstration that SDs upregulate WAT beta(3)-AR mRNA expression, suggest that increased beta(3)-ARs mediated the SD-induced increased NE sensitivity. NE- stimulated adipocyte accumulation of cAMP was greater after 5 wk of SDs for IWAT and EWAT and after 10 wk of SDs for IWAT compared with LDs, with no photoperiod effect for RWAT. Therefore, the SD-induced increase in SNS drive to WAT and increased sensitivity to this drive may work together to increase lipolysis in SDs.