Levin B E, Hamm M W
Neurology Service, Department of Veterans Affairs Medical Center, East Orange, NJ 07018, USA.
Obes Res. 1994 May;2(3):230-8. doi: 10.1002/j.1550-8528.1994.tb00052.x.
Male Sprague-Dawley rats, which are prone to develop diet-induced obesity (DIO) on a high energy (HE) diet can be separated from rats which are diet-resistant (DR) by several prospective tests. Using such tests, chow-fed DRl-prone rats have higher binding of 3H paraminoclonidine (PAC) to brain alpha2-adrenoceptors than do DIO-prone rats. These differences disappear after 3 months on a HE diet. To study the predictive value of these tests and possible associated changes in presynaptic membrane composition, brain alpha3(1-) (1nM 3H prazosin) and (alpha2-adrenoceptor (1nM) 3-H PAC) binding and synaptosomal fatty acid composition were assessed in 3-month-old male rats separated by weight gain into DR and DIO groups after 1 month on a HE diet. DIO had comparable total caloric intake but gained 30% and 43% more weight and were hyperinsulinemic compared to DR and chow-fed rats, respectively. After 1 month on a HE diet, DR rats still had 15%-53% higher 3H PAC binding than DIO and/or chow-fed rats in 14 of 16 brain areas assessed. A phenotype effect was present primarily in the amygdala where DR rats had higher 3H PAC binding than DIO rats. A diet effect was seen in some hypothalamic nuclei where both DR and DIO rats had higher 3H PAC binding than chow-fed rats. Conversely, DIO rats had 14%-21% higher 3H prazosin binding than DR rats in 3 brain areas. Changes in brain synaptosomal membranes' fatty acids reflected both phenotype and diet effects. Thus, while diet composition affects presynaptic membrane composition and alpha2-adrenoceptor binding in both DR and DIO rats, the predominance of plasticity of these parameters is limited to the brains of DR rats. This suggests that such plasticity may be an important determinant of the ability to resist the development of diet-induced obesity on a HE diet.
雄性斯普拉格-道利大鼠在高能（HE）饮食下容易发生饮食诱导性肥胖（DIO），通过多项前瞻性测试可将其与抗饮食诱导性肥胖（DR）的大鼠区分开来。利用这些测试，以普通饲料喂养且易患DR1的大鼠，其大脑α2-肾上腺素能受体对3H-对氨基可乐定（PAC）的结合能力高于易患DIO的大鼠。在HE饮食3个月后，这些差异消失。为了研究这些测试的预测价值以及突触前膜成分可能的相关变化，对3月龄雄性大鼠进行评估，这些大鼠在HE饮食1个月后，根据体重增加情况分为DR组和DIO组，测定其大脑α3(1-)（1nM 3H-哌唑嗪）和α2-肾上腺素能受体（1nM 3-H PAC）结合情况以及突触体脂肪酸组成。DIO大鼠的总热量摄入相当，但体重分别比DR大鼠和以普通饲料喂养的大鼠多增加30%和43%，且存在高胰岛素血症。在HE饮食1个月后，在评估的16个脑区中的14个脑区，DR大鼠的3H PAC结合能力仍比DIO和/或以普通饲料喂养的大鼠高15% - 53%。表型效应主要出现在杏仁核，其中DR大鼠的3H PAC结合能力高于DIO大鼠。在一些下丘脑核团中观察到饮食效应，DR大鼠和DIO大鼠的3H PAC结合能力均高于以普通饲料喂养的大鼠。相反，在3个脑区中，DIO大鼠的3H-哌唑嗪结合能力比DR大鼠高14% - 21%。大脑突触体膜脂肪酸的变化反映了表型和饮食效应。因此，虽然饮食组成会影响DR大鼠和DIO大鼠的突触前膜组成及α2-肾上腺素能受体结合，但这些参数可塑性的优势仅限于DR大鼠的大脑。这表明这种可塑性可能是抵抗HE饮食诱导性肥胖发生能力的一个重要决定因素。
