Timonin Mary E, Place Ned J, Wanderi Esther, Wynne-Edwards Katherine E
Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Reproduction. 2006 Oct;132(4):661-70. doi: 10.1530/rep.1.00019.
Golden (Mesocricetus auratus) and Siberian (Phodopus sungorus) hamsters are widely used as animal models for seasonal reproduction; but M. auratus shows no developmental delay in short days until after sexual maturity, whereas P. sungorus juveniles delay development in short days. As the photoperiodic response of Phodopus campbelli is not well established, litters of the two Phodopus species were gestated and reared under long days (14 h light:10 h darkness) or short days (10 h light:14 h darkness) until 70 days of age. As expected, under short photoperiod P. sungorus showed reduced body, testes, epididymides, uterus, and ovary weight; antral follicles and corpora lutea were absent and vaginae remained closed. Animals moulted to winter pelage, and low concentrations of each of leptin, testosterone, and prolactin were present in male serum. Phodopus campbelli juveniles also responded to the short photoperiod as measured by reduced body, testes, epididymides, and ovary weight. The summer pelage persisted. However, both sexes of P. campbelli developed functional reproduction under 10 h light:14 h darkness. All females had a patent vagina by 10 weeks; ovaries contained antral follicles and corpora lutea, and uteri were not reduced in weight. In males, the concentrations of testosterone, leptin, and prolactin were not reduced by short photoperiod. Developmental patterns in the three species of hamster, therefore, differ and are not predicted by relatedness or latitude of origin. Other ecological traits, such as predictability of summer rainfall, ambient temperature, and differential responses to social cues might be important.
金黄仓鼠（Mesocricetus auratus）和西伯利亚仓鼠（Phodopus sungorus）被广泛用作季节性繁殖的动物模型；但金黄仓鼠在短日照条件下直到性成熟后才出现发育延迟，而西伯利亚仓鼠幼崽在短日照条件下会延迟发育。由于坎氏毛足鼠（Phodopus campbelli）的光周期反应尚未明确，将这两种毛足鼠的幼崽在长日照（14小时光照：10小时黑暗）或短日照（10小时光照：14小时黑暗）条件下饲养至70日龄。正如预期的那样，在短光周期条件下，西伯利亚仓鼠的体重、睾丸、附睾、子宫和卵巢重量均减轻；没有窦状卵泡和黄体，阴道仍处于闭合状态。动物换上了冬毛，雄性血清中瘦素、睾酮和催乳素的浓度均较低。坎氏毛足鼠幼崽对短光周期也有反应，表现为体重、睾丸、附睾和卵巢重量减轻。夏毛持续存在。然而，在10小时光照：14小时黑暗的条件下，坎氏毛足鼠的两性都发育出了功能性繁殖能力。所有雌性在10周时阴道开放；卵巢中有窦状卵泡和黄体，子宫重量没有减轻。在雄性中，短光周期并没有降低睾酮、瘦素和催乳素的浓度。因此，这三种仓鼠的发育模式不同，且与亲缘关系或起源地的纬度无关。其他生态特征，如夏季降雨的可预测性、环境温度以及对社会线索的不同反应可能很重要。
