Orosco M, Gerozissis K, Rouch C, Nicolaïdis S
CNRS URA 1860, Collège de France, Paris.
Brain Res. 1995 Feb 6;671(1):149-58. doi: 10.1016/0006-8993(94)01347-k.
The presence of insulin in the brain and its anorectic effect when centrally infused are well-established today. The question of physiological and dynamic changes in brain insulin in relation to meals is still unanswered and addressed here. Immunoreactive insulin (IRI) was measured using a sensitized RIA in 30-min microdialysates from VMH and PVN nuclei during and after a scheduled meal in male Wistar rats. We indeed observed elevations in hypothalamic IRI during the first 30 min of 1-h meals with a progressive return towards premeal levels in spite of a robust satiety. When the rats were accustomed to the scheduled meals, an anticipatory rise in IRI was found in the hypothalamus, but not in the plasma, during the 30 min preceding the due time of the meal whether the meal was presented or not. This anticipatory rise was proportional to the number of repeated scheduled meals. These results first suggest that hypothalamic IRI changes reflect in some instances those in the plasma although there are exceptions that cannot be accounted for by a simple plasma-brain tissue delivery. Besides, hypothalamic IRI can hardly be proposed as a satiety signal. The present data suggest a role in satiation rather than in satiety or, perhaps, in the inhibition of the behavioral response of feeding that can include the anticipatory rise.
如今，大脑中胰岛素的存在及其脑室内注射时的厌食作用已得到充分证实。本文探讨了与进食相关的大脑胰岛素生理及动态变化这一尚未解决的问题。在雄性Wistar大鼠预定进食期间及之后，使用灵敏放射免疫分析法（RIA）测定腹内侧下丘脑核（VMH）和室旁核（PVN）30分钟微透析液中的免疫反应性胰岛素（IRI）。我们确实观察到，在1小时进食的前30分钟内，下丘脑IRI升高，尽管饱腹感强烈，但随后逐渐恢复到进食前水平。当大鼠习惯了预定进食时间后，无论是否提供食物，在预定进食时间前30分钟，下丘脑出现IRI预期升高，但血浆中未出现。这种预期升高与预定进食的重复次数成正比。这些结果首先表明，下丘脑IRI变化在某些情况下反映了血浆中的变化，尽管存在一些无法用简单的血浆-脑组织传递来解释的例外情况。此外，几乎不能将下丘脑IRI视为饱腹感信号。目前的数据表明其在饱腹感而非饱足感中起作用，或者可能在抑制包括预期升高在内的进食行为反应中起作用。
