Boukouvalas G, Antoniou K, Papalexi E, Kitraki E
Laboratory of Histology and Embryology, Medical School, University of Athens, M. Asias 75, Athens, Greece.
Neuroscience. 2008 May 2;153(2):373-82. doi: 10.1016/j.neuroscience.2008.02.023. Epub 2008 Mar 4.
Feeding adult rats with high fat (HF) diets can alter their hypothalamic pituitary adrenal (HPA) axis responsiveness. In the present study, we examined the effect of a high fat diet, applied in rats from weaning to puberty, on their behavior and HPA axis status at puberty onset. Wistar rats of both sexes were fed postweaning with two diets containing either 24% fat (high fat, HF) or 4.3% fat (normal chow) by weight. HF enhanced puberty onset in female rats, without increasing body weight gain in either sex, compared with chow-fed animals. In the forced swim test, HF males exhibited a more active behavioral response on the first day, whereas HF females a more passive response during the second day of the test, as compared with their chow-fed counterparts. In the open field test, HF females showed increased sniffing but reduced rearing, compared with chow-fed females and were less explorative than HF males in the central arena. All animals could learn and recall a water maze task though HF males spent more time in the opposite quadrant than chow-fed males during memory test. The HPA axis status of these animals was investigated under basal conditions. Pubertal fat-fed males had lighter adrenals, while females heavier ones, compared with their counterparts. In addition, plasma corticosterone levels of female rats were increased and glucocorticoid receptor levels in their hypothalamus were reduced due to fat diet, while in males no such changes were detected. We conclude that HF feeding during the prepubertal period can affect behavior and the HPA axis of rats at puberty onset, well before the appearance of the obese state, in a sexually dimorphic manner. Fat diet impacted more the female HPA axis, suggesting that their system is more sensitive to fat-induced nutritional imbalance during adolescence. Present data suggest that the fat-induced nutritional imbalance in young females may lead to neuroendocrine dysfunction that in turn may trigger the appearance of stress-related disorders during adolescence.
用高脂（HF）饮食喂养成年大鼠会改变其下丘脑-垂体-肾上腺（HPA）轴的反应性。在本研究中，我们研究了从断奶到青春期给大鼠喂食高脂饮食对其青春期开始时的行为和HPA轴状态的影响。对两性的Wistar大鼠断奶后分别喂食两种按重量计含24%脂肪（高脂，HF）或4.3%脂肪（正常饲料）的饮食。与喂食普通饲料的动物相比，HF饮食可促进雌性大鼠青春期开始，且不增加任何性别的体重增加。在强迫游泳试验中，与喂食普通饲料的雄性大鼠相比，HF雄性大鼠在第一天表现出更活跃的行为反应，而HF雌性大鼠在试验第二天表现出更被动的反应。在旷场试验中，与喂食普通饲料的雌性大鼠相比，HF雌性大鼠嗅探增加但竖毛减少，并且在中央区域比HF雄性大鼠探索性更低。所有动物都能学习并回忆水迷宫任务，不过在记忆测试中，HF雄性大鼠在对侧象限花费的时间比喂食普通饲料的雄性大鼠更多。在基础条件下研究了这些动物的HPA轴状态。与相应的对照组相比，青春期喂食高脂的雄性大鼠肾上腺较轻，而雌性大鼠肾上腺较重。此外，由于高脂饮食，雌性大鼠的血浆皮质酮水平升高，其下丘脑糖皮质激素受体水平降低，而在雄性大鼠中未检测到此类变化。我们得出结论，青春期前阶段的HF饮食可在肥胖状态出现之前很久，以性别二态性的方式影响大鼠青春期开始时的行为和HPA轴。高脂饮食对雌性HPA轴影响更大，表明其系统在青春期对脂肪诱导的营养失衡更敏感。目前的数据表明，年轻雌性大鼠中脂肪诱导的营养失衡可能导致神经内分泌功能障碍，进而可能引发青春期与应激相关疾病的出现。
