Department of Evolutionary and Environmental Biology, University of Haifa, Mount Carmel, Haifa 31905, Israel.
Horm Behav. 2012 Jan;61(1):84-90. doi: 10.1016/j.yhbeh.2011.10.006. Epub 2011 Oct 29.
Understanding the ways environmental signals, regulate reproduction and reproductive behavior of desert adapted rodents is a major gap in our knowledge. In this study, we assessed the roles of photoperiod and diet salinity, as signals for reproduction. We challenged desert adapted common spiny mice, Acomys cahirinus, males and females with osmotic stress, by gradually increasing salinity in their water source - from 0.9% to 5% NaCl under short and long days (SD and LD, respectively). Photoperiodicity affected testosterone levels, as under LD-acclimation, levels were significantly (p<0.05) higher than under SD-acclimation. Salinity treatment (ST) significantly reduced SD-acclimated male body mass (W(b)) and testis mass (p<0.005; normalized to W(b)). ST-LD-females significantly (p<0.005) decreased progesterone levels and the numbers of estrous cycles. A reduction in white adipose tissue (WAT) to an undetectable level was noted in ST-mice of both sexes under both photoperiod regimes. Receptors for vasopressin (VP) and aldosterone were revealed on testes of all male groups and on WAT in control groups. Our results suggest that photoperiod serves as an initial signal while water availability, expressed by increased salinity in the water source, is an ultimate cue for regulation of reproduction, in both sexes of desert-adapted A. cahirinus. We assume that environmental changes also affect behavior, as water seeking behavior by selecting food items, or locomotor activity may change in extreme environment, and thus indirectly affect reproduction and reproductive behavior. The existence of VP and aldosterone receptors in the gonads and WAT suggests the involvement of osmoregulatory hormones in reproductive control of desert adapted rodents.
理解环境信号调控沙漠适应型啮齿动物繁殖和繁殖行为的方式是我们知识中的一个主要空白。在这项研究中，我们评估了光周期和饮食盐度作为繁殖信号的作用。我们通过逐渐增加水源中的盐度，从 0.9%到 5%的 NaCl，对沙漠适应型普通沙鼠 Acomys cahirinus 雄性和雌性进行了渗透胁迫挑战，分别在短日（SD）和长日（LD）条件下。光周期影响睾酮水平，因为在 LD 适应条件下，水平明显（p<0.05）高于 SD 适应条件下。盐度处理（ST）显著降低了 SD 适应的雄性体重（W(b)）和睾丸质量（p<0.005；标准化到 W(b)）。ST-LD-雌性显著（p<0.005）降低了孕酮水平和发情周期数。在两种光周期条件下，ST 雄性和雌性的白色脂肪组织（WAT）减少到无法检测的水平。所有雄性组的睾丸和对照组的 WAT 上都发现了加压素（VP）和醛固酮受体。我们的结果表明，光周期作为初始信号，而水的可用性，通过水源中盐度的增加来表达，是调节沙漠适应型 A. cahirinus 两性繁殖的最终线索。我们假设环境变化也会影响行为，因为通过选择食物来寻找水的行为，或在极端环境中的运动活动可能会发生变化，从而间接影响繁殖和繁殖行为。在性腺和 WAT 中存在 VP 和醛固酮受体表明，渗透调节激素参与了沙漠适应型啮齿动物的生殖控制。
