Leibowitz S F, Shor-Posner G, Brennan G, Alexander J T
The Rockefeller Univ., New York, NY 10021, USA.
Obes Res. 1993 Jan;1(1):29-39. doi: 10.1002/j.1550-8528.1993.tb00005.x.
Norepinephrine (NE) injected into the paraventricular nucleus (PVN) of the hypothalamus of rats is a potent stimulant of food intake, more specifically ingestion of the carbohydrate nutrient. In 2 experiments of the present study, this effect was found to be dose-dependent, and the effectiveness of NE in potentiating total food consumption was greatly reduced when the carbohydrate diet was removed. In addition, experiments using a computer-automated data acquisition apparatus were performed to characterize, in detail, the impact of PVN injection of NE and peripheral administration of the alpha2-noradrenergic agonist clonidine (CLON) on the macrostructure of feeding behavior in animals given 3 pure macronutrient diets. These 2 compounds, injected at the onset of the nocturnal feeding cycle, had very similar effects on meal patterns, with both affecting nutrient intake by increasing meal size and duration rather than by increasing meal frequency. They both affected primarily the first meal of the dark cycle, selectively enhancing carbohydrate ingestion by increasing Kcal intake, percent composition in the total diet and feeding time, and also by decreasing the satiating impact of this macronutrient. These stimulatory effects of NE and CLON on carbohydrate ingestion during the first meal were followed by complete recovery over the next 1 to 2 hours after injection. In addition to these predominant effects on carbohydrate intake, PVN NE at the highest doses tested (10 and 20 nmoles) produced a small increase in fat intake, whereas peripheral CLON actually decreased intake of fat and protein over the 12-hour cycle. The similarities in the impact of NE and CLON on carbohydrate feeding patterns support the hypothesis that both agonists may be acting via the same PVN alpha2-noradrenergic system controlling ingestion of the carbohydrate-rich meals which predominate at dark onset.
向大鼠下丘脑室旁核（PVN）注射去甲肾上腺素（NE）是一种强力的食物摄入刺激剂，更具体地说是碳水化合物营养素摄入的刺激剂。在本研究的2个实验中，发现这种效应具有剂量依赖性，并且当去除碳水化合物饮食时，NE增强总食物消耗的有效性大大降低。此外，使用计算机自动化数据采集设备进行了实验，以详细表征向PVN注射NE和外周给予α2-去甲肾上腺素能激动剂可乐定（CLON）对给予3种纯宏量营养素饮食的动物进食行为宏观结构的影响。这2种化合物在夜间进食周期开始时注射，对进食模式有非常相似的影响，两者都通过增加餐量和持续时间而不是增加进餐频率来影响营养素摄入。它们主要影响暗周期的第一餐，通过增加千卡摄入量、在总饮食中的百分比组成和进食时间，以及通过降低这种宏量营养素的饱腹感来选择性地增强碳水化合物摄入。NE和CLON对第一餐期间碳水化合物摄入的这些刺激作用在注射后接下来的1至2小时内完全恢复。除了对碳水化合物摄入的这些主要影响外，在测试的最高剂量（10和20纳摩尔）下，PVN NE使脂肪摄入量略有增加，而外周CLON实际上在12小时周期内降低了脂肪和蛋白质的摄入量。NE和CLON对碳水化合物进食模式影响的相似性支持了这样的假设，即两种激动剂可能通过相同的PVNα2-去甲肾上腺素能系统起作用，该系统控制在黑暗开始时占主导地位的富含碳水化合物餐的摄入。
