Wade G N, Bartness T J
Am J Physiol. 1984 Jan;246(1 Pt 2):R26-30. doi: 10.1152/ajpregu.1984.246.1.R26.
Two experiments examined the effects of gonadectomy, photoperiod, and melatonin treatment on food intake, body weight, and carcass composition in male and female Siberian hamsters (Phodopus sungorus sungorus). Gonadectomy caused small decreases in body weight in both sexes but did not affect food intake. In males the weight reduction was due to small (nonsignificant) decreases in all carcass components. Ovariectomy caused a significant reduction in carcass lipid but did not affect lean body mass. A short photoperiod (8 h light, 16 h dark, LD 8:6) caused significant weight losses in all animals except ovariectomized females. Daily melatonin injections (12.5 micrograms sc, 3 h before lights-out) also reduced body weight in males and females housed in a long photoperiod (LD 16:8). The photoperiod- and melatonin-induced weight losses were almost entirely due to decreases in carcass lipid; lean body mass was unaffected by either treatment. Although short photoperiods and melatonin treatments decreased food intake, these changes were preceded by a significant loss of body weight. Thus photoperiod induced changes in food intake may be a consequence of the changes in body weight, rather than vice versa. These findings indicate that photoperiod and melatonin have important effects on adipose tissue mass in both Siberian and Syrian hamsters, even though one species gains weight (Syrian) and the other loses weight (Siberian) in short photoperiods.
两项实验研究了去势、光周期和褪黑素处理对雄性和雌性西伯利亚仓鼠（Phodopus sungorus sungorus）食物摄入量、体重和胴体组成的影响。去势导致两性体重略有下降，但不影响食物摄入量。在雄性中，体重减轻是由于所有胴体成分均有小幅（不显著）下降。卵巢切除导致胴体脂质显著减少，但不影响瘦体重。短光周期（8小时光照，16小时黑暗，LD 8:16）导致除卵巢切除的雌性外的所有动物体重显著减轻。每日注射褪黑素（12.5微克，皮下注射，熄灯前3小时）也使处于长光周期（LD 16:8）的雄性和雌性体重减轻。光周期和褪黑素诱导的体重减轻几乎完全是由于胴体脂质减少；两种处理均未影响瘦体重。尽管短光周期和褪黑素处理会减少食物摄入量，但这些变化之前体重已显著下降。因此，光周期诱导的食物摄入量变化可能是体重变化的结果，而非反之。这些发现表明，光周期和褪黑素对西伯利亚仓鼠和叙利亚仓鼠的脂肪组织量均有重要影响，尽管一个物种（叙利亚仓鼠）在短光周期中体重增加，而另一个物种（西伯利亚仓鼠）体重减轻。
