REGULATION OF PITUITARY OPIATE PEPTIDE SECRETION

主要目标是检查监管机构的可塑性程度 垂体阿片肽分泌的机制，在幼鼠和 在衰老的动物身上。需要检验的主要假设是，对 垂体中间叶阿片黑素皮质素原(POMC)细胞 保留再生和调节多肽分泌的能力 年轻个体的神经丧失，在衰老过程中，有 神经和内分泌细胞都经历分泌的调节 潜在的退行性改变。问题是：1.POMC如何 内分泌细胞对去神经和潜在的再神经支配做出反应。 时间？年轻的成年雄性大鼠将被儿茶酚胺治疗 神经毒素6-羟基多巴胺(6-OHDA_)，可诱导轴突变性 在脑下垂体。免疫反应儿茶酚胺和5-羟色胺神经支配 在药物治疗和对照动物中进行研究，为期8天，3 和治疗后6-8周，以确定去神经的程度，以及 内分泌细胞的潜在再神经支配。2.POMC单元格是否修改 它们的受体种群适应失神经和潜在的再 神经支配？用6-OHDA处理的大鼠的脑垂体组织将用 结合特定放射性配基的放射自显影技术 多巴胺-2(D-2)和5-羟色胺-2(5-HT-2)受体对血管紧张素转换酶的影响 在去神经和再神经支配时可能出现的受体模式。3. POMC细胞如何对特定的调控分子做出反应 去神经，以及在潜在的再神经支配期间？6-羟基多巴胺脑下垂体 经过处理的动物将在体外孵化，以检验 抑制或刺激多肽分泌的分子。多肽将 通过放射免疫分析(RIA)进行测量，并通过 免疫细胞化学和电子显微镜(EM)技术。4.什么 正常情况下POMC分泌细胞及其神经支配的变化 个体动物的衰老？老龄大鼠的脑下垂体(6、12和18) 月)将检查神经支配模式的潜在变化 以及利用免疫细胞化学调节多肽分泌 组织或血液样本的放射免疫分析。将使用EM技术来 衰老脑垂体细胞学与免疫反应改变的关系 多肽。为了确定D-2和5-HT-2受体是否会随着年龄的增长而改变， 将检查配基结合的放射自显影模式。5.做老化工作 POMC细胞保留了对调节分子做出反应的能力 抑制还是刺激分泌？衰老大鼠的脑下垂体将是 利用已发现的神经递质和多肽进行体外研究 调节幼年动物体内阿片肽的释放。阿片肽有 对疼痛调节和内环境平衡机制的显著影响 与压力有关。调节机制的可塑性研究， 以潜在的轴突再生和受体调节的形式 幼年和老年动物的POMC细胞的模式将是一个基础 为了对阿片肽的分泌进行适当的药理学操作，在 动物模型，在人类身上。

The major goals are to examine the extent of plasticity in regulatory mechanisms for pituitary opiate peptide secretion, both in young rats, and in aging animals. The major hypothesis to be tested is that innervation to pro-opiomelanocortin (POMC) cells of the pituitary intermediate lobe retains the ability to regenerate and regulate peptide secretion after denervation in young individuals, and that during aging, there is modulation of secretion as both nerves and endocrine cells undergo potential degenerative alterations. Questions are: 1. How do POMC endocrine cells respond to denervation and to potential re-innervation over time? Young adult male rats will be treated with a catecholamine neurotoxin, 6-hydroxydopamine (6-OHDA_, which induces neurite degeneration in pituitary. Immunoreactive catecholamine and serotonin innervation will be studied in drug treated and control animals over periods of 8 days, 3 and 6-8 weeks after treatment, to determine the extent of denervation, and of potential re-innervation of endocrine cells. 2. Do POMC cells modify their receptor population to adapt to denervation and potential re- innervation? Pituitary tissue of 6-OHDA treated rats will be studied using autoradiographic techniques with specific radioligands which bind to dopamine-2 (D-2) and serotonin-2 (5-HT-2) receptors, for alterations in receptor patterns which may occur with denervation and re-innervation. 3. How do POMC cells respond to specific regulatory molecules after denervation, and during potential re-innervation? Pituitaries of 6-OHDA treated animals will be incubated in vitro to examine direct effects of inhibitory or stimulatory molecules on peptides secretion. Peptides will be measured by radioimmunoassay (RIA) and tissues studied by immunocytochemical and electron microscopic (EM) techniques. 4. What changes occur in POMC secretory cells and their innervation during normal aging of individual animals? Pituitaries of aging rats (6, 12 and 18 months) will be examined for potential alterations in innervation patterns as well as for modulation of peptide secretion, using immunocytochemistry and RIA for tissue or blood samples. EM techniques will be used to correlate cytology of aging pituitaries with alteration in immunoreactive peptides. To determine if D-2 and 5-HT-2 receptors are altered with age, autoradiographic patterns of ligand binding will be examined. 5. Do aging POMC cells retain the ability to respond to regulatory molecules which inhibit or stimulate secretion? Pituitaries from aging rats will be studied in vitro using neurotransmitters and peptides which have been found to modulate opiate peptide release in young animals. Opiate peptides have significant effects on regulation of pain and on homeostatic mechanisms related to stress. Investigations of plasticity of regulatory mechanisms, in the forms of potential neurite regeneration and modulation of receptor patterns on POMC cells, both in young and aging animals, will be a basis for appropriate pharmacologic manipulation of opiate peptide secretion, in animal models, and in man.