Department of Evolution and Environmental Biology, University of Haifa, Mount Carmel, Haifa 31905, Israel.
J Exp Biol. 2013 Sep 15;216(Pt 18):3495-503. doi: 10.1242/jeb.089607. Epub 2013 Jun 4.
We tested the effects of photoperiod, water and food availability on body mass, reproductive status and arginine vasopressin receptor 1A (Avpr1a) mRNA expression in males of desert-adapted golden spiny mice, Acomys russatus. In Experiment 1, males were acclimated to short-day (SD; 8 h:16 h light:dark) or long-day (LD; 16 h:8 h light:dark) photoperiods with either saline (control) or vasopressin treatment for 3 weeks. The results of this experiment revealed that under control conditions, SD mice increased body mass by ~5% while LD mice decreased it by ~4%. SD photoperiod had no effect on reproductive status and leptin levels, whereas LD males increased testes mass and serum testosterone, but the photoperiod had no effect on leptin levels. Vasopressin administration decreased LD-induced reproductive enhancement. Because no consistent effect of SD treatment was found on reproductive status, Experiment 2 was carried out only on LD-acclimated males kept under 75% food restriction (decrease from ad libitum) with saline or leptin treatment. Body mass, testes mass, serum testosterone, leptin concentrations and Avpr1a mRNA expression were measured. Food restriction remarkably decreased body mass, with a more potent effect in leptin-treated males, showing enhanced reproductive status and a significant increase in serum leptin compared with controls. Avpr1a expression was significantly upregulated in LD, vasopressin-treated and food-restricted males, with higher levels in the hypothalamus compared with the testes. We conclude that in A. russatus, LD photoperiod interacts with water and food availability to advance reproductive responses. Avpr1a is suggested to integrate nutritional and osmotic signals to optimize reproduction by modulating reproductive and energetic neuroendocrine axes at the central level. The interaction between photoperiod and other environmental cues is of an adaptive value to desert-adapted small rodents for timing reproduction in unpredictable ecosystems such as extreme deserts.
我们测试了光周期、水和食物供应对沙漠适应的金黄沙鼠（Acomys russatus）雄性个体的体重、生殖状态和精氨酸加压素受体 1A（Avpr1a）mRNA 表达的影响。在实验 1 中，雄性个体适应于短日照（SD；8 h：16 h 光照：黑暗）或长日照（LD；16 h：8 h 光照：黑暗）光周期，并接受盐水（对照）或加压素处理，持续 3 周。该实验的结果表明，在对照条件下，SD 组的体重增加了约 5%，而 LD 组的体重减少了约 4%。SD 光周期对生殖状态和瘦素水平没有影响，而 LD 雄性个体增加了睾丸质量和血清睾酮，但光周期对瘦素水平没有影响。加压素处理降低了 LD 诱导的生殖增强。由于在 SD 处理下没有发现对生殖状态的一致影响，因此仅在 LD 适应的雄性个体上进行了实验 2，这些雄性个体在 75%的食物限制（从自由采食减少）下，接受盐水或瘦素处理。测量了体重、睾丸质量、血清睾酮、瘦素浓度和 Avpr1a mRNA 表达。食物限制显著降低了体重，在瘦素处理的雄性个体中作用更为明显，表现出增强的生殖状态，与对照组相比，血清瘦素显著增加。在 LD、加压素处理和食物限制的雄性个体中，Avpr1a 表达显著上调，在下丘脑中的水平高于睾丸。我们得出结论，在金黄沙鼠中，LD 光周期与水和食物供应相互作用，促进生殖反应。Avpr1a 被认为整合了营养和渗透信号，通过调节中枢水平的生殖和能量神经内分泌轴来优化生殖。光周期与其他环境线索的相互作用对沙漠适应的小型啮齿动物具有适应价值，有助于它们在沙漠等不可预测的生态系统中定时繁殖。
