Lee T F, Wang L C, Russell J C
Am J Physiol. 1987 Apr;252(4 Pt 2):R737-42. doi: 10.1152/ajpregu.1987.252.4.R737.
Previous studies on obese strains of rats (e.g., Zucker and LA/N cp) have shown that they are deficient in nonshivering thermogenesis and poor in cold tolerance. Our earlier studies have established that aminophylline (AMPY; 85% theophylline-15% ethylenediamine) is effective in significantly improving cold tolerance in the lean Sprague-Dawley rat regardless of age or thermogenic capacity. The present study tested whether AMPY may be also effective in improving cold tolerance in both young (12-18 wk) and older (36-42 wk) lean and corpulent LA/N cp rats. Contrary to previous reports, however, the norepinephrine (NE)-stimulated nonshivering thermogenesis was not only present but also equal in magnitude in the corpulent rats to that of their lean controls. Further, no difference in cold tolerance was observed between the two groups regardless of age. Similarly, AMPY (18.7 mg/kg ip) significantly improved thermogenesis and cold tolerance in both lean and corpulent rats, again without any age-related difference in response. These results indicate that, despite the existence of obesity, no difference in thermogenic capacity to either NE or cold stimulation is evident in the LA/N cp rats. Thus the ontogeny of obesity in this strain may be caused by factors other than deficiency in NE- or cold-stimulated thermogenesis at the end-organ level.
先前对肥胖大鼠品系（如Zucker和LA/N cp）的研究表明，它们缺乏非寒战产热，耐寒能力差。我们早期的研究已证实，氨茶碱（AMPY；85%茶碱-15%乙二胺）能有效显著提高瘦型Sprague-Dawley大鼠的耐寒能力，无论其年龄或产热能力如何。本研究测试了AMPY是否也能有效提高年轻（12 - 18周）和老年（36 - 42周）的瘦型和肥胖型LA/N cp大鼠的耐寒能力。然而，与先前的报道相反，去甲肾上腺素（NE）刺激的非寒战产热不仅在肥胖大鼠中存在，而且其产热幅度与瘦型对照大鼠相同。此外，无论年龄如何，两组之间未观察到耐寒能力的差异。同样，AMPY（18.7 mg/kg腹腔注射）显著提高了瘦型和肥胖型大鼠的产热和耐寒能力，同样在反应上没有任何与年龄相关的差异。这些结果表明，尽管存在肥胖，但LA/N cp大鼠对NE或寒冷刺激的产热能力没有差异。因此，该品系肥胖的个体发生可能是由终末器官水平上NE或寒冷刺激产热不足以外的因素引起的。
