Nagasaka T
Department of Pediatric Dentistry. Hokkaido University, School of Dentistry, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1988 Sep;63(5):811-26.
Restricted daily feeding (RF), in which free access to food and water is restricted to a fixed time of the day, has been demonstrated to elevate the plasma corticosterone level in rats prior to meal (prefeeding corticosterone peak). But the central mechanism for the hormone peak is unknown. In this study, the metabolism of the hypothalamic biogenic amines was investigated to know whether or not it was associated with the prefeeding corticosterone peak under RF. Male rats were subjected to RF (meal time from 10:00 to 12:00 h) under the light-dark cycle (lights from 06:00 to 18:00 h). Norepinephrine metabolism was estimated from the rate of decrease in norepinephrine content after the administration of a synthesis blocker, alpha-methyl-p-tyrosine (alpha-MPT). Dopamine and serotonin metabolisms were estimated from the accumulation rate of precursor amine after the inhibition of aromatic L-amino acid decarboxylase by m hydroxybenzylhydrazine (NSD 1015). Rats were sacrificed by decapitation and four hypothalamic nuclei (SCN, PVN, VMH, LH) were punched out according to Palkovits method. Amine contents in each nucleus were measured by HPLC. Results obtained are as follows; 1) Catecholamine was significantly involved in the formation of prefeeding corticosterone peak under RF in rats. 2) Norepinephrine metabolism was different in each hypothalamic nucleus. Especially, that in PVN seems to be parallel with the plasma corticosterone level under RF. This result suggests that norepinephrine in PVN stimulates corticotropin releasing hormone (CRH). 3) Dopamine metabolism in the four hypothalamic nuclei showed similar changes; prefeeding rise (except for VMH), high activity during feeding, decrease after food deprivation, and persistence of high activity during fast. 4) Serotonin metabolism in the four hypothalamic nuclei showed similar changes; prefeeding rise (except for VMH), decrease during feeding, and persistence of high activity during fast.
限时每日进食（RF），即食物和水的自由获取被限制在一天中的固定时间，此前已证明其能使大鼠在进食前（进食前皮质酮峰值）血浆皮质酮水平升高。但该激素峰值的中枢机制尚不清楚。在本研究中，对下丘脑生物胺的代谢进行了研究，以了解其是否与限时每日进食条件下的进食前皮质酮峰值有关。雄性大鼠在明暗循环（06:00至18:00开灯）下接受限时每日进食（进食时间为10:00至12:00）。通过给予合成阻滞剂α-甲基-对-酪氨酸（α-MPT）后去甲肾上腺素含量的下降速率来评估去甲肾上腺素代谢。通过m-羟基苄基肼（NSD 1015）抑制芳香族L-氨基酸脱羧酶后前体胺的积累速率来评估多巴胺和5-羟色胺代谢。大鼠断头处死，根据帕尔科维茨方法取出四个下丘脑核（视交叉上核、室旁核、腹内侧核、外侧下丘脑核）。通过高效液相色谱法测量每个核中的胺含量。结果如下：1）儿茶酚胺在限时每日进食条件下大鼠进食前皮质酮峰值的形成中起重要作用。2）每个下丘脑核中的去甲肾上腺素代谢不同。特别是，室旁核中的去甲肾上腺素代谢似乎与限时每日进食条件下的血浆皮质酮水平平行。该结果表明室旁核中的去甲肾上腺素刺激促肾上腺皮质激素释放激素（CRH）。3）四个下丘脑核中的多巴胺代谢表现出相似的变化；进食前升高（腹内侧核除外）、进食期间高活性、禁食后下降以及禁食期间高活性持续存在。4）四个下丘脑核中的5-羟色胺代谢表现出相似的变化；进食前升高（腹内侧核除外）、进食期间下降以及禁食期间高活性持续存在。
