REGULATION OF PITUITARY OPIATE PEPTIDE SECRETION

主要目的是研究调节性神经元的可塑性程度。 幼年大鼠垂体阿片肽分泌机制，以及 衰老的动物。 有待检验的主要假设是， 垂体中间叶前阿黑皮素细胞 保留了再生和调节肽分泌的能力， 在年轻人中去神经支配，而在衰老过程中， 调节神经和内分泌细胞的分泌 潜在的退行性改变 问题是：1. POMC如何 内分泌细胞对去神经支配和潜在的再神经支配作出反应， 时间？ 年轻的成年雄性大鼠将用儿茶酚胺处理 神经毒素，6-羟基多巴胺（6-OHDA_），可诱导神经突变性 脑垂体中。 免疫反应性儿茶酚胺和5-羟色胺神经支配将 在药物处理和对照动物中研究8天，3 以及治疗后6-8周，以确定去神经支配的程度，以及 内分泌细胞潜在的神经再支配。 2. POMC细胞是否会改变 它们的受体群体以适应去神经支配和潜在的重新支配， 神经支配？ 将使用以下方法研究6-OHDA处理的大鼠的胰腺组织： 放射自显影技术与特异性放射性配体结合， 多巴胺-2（D-2）和5-羟色胺-2（5-HT-2）受体的变化， 受体模式，这可能会发生与去神经支配和再神经支配。 3. POMC细胞如何响应特定的调节分子， 失神经支配，以及潜在的神经再支配期间？ 6-OHDA的垂体 处理的动物将在体外孵育，以检查 抑制性或刺激性分子对肽分泌的影响。 肽将 通过放射免疫测定法（RIA）进行测量，并通过以下方法研究组织 免疫细胞化学和电子显微镜（EM）技术。 4. 什么 POMC分泌细胞及其神经支配在正常 动物个体的衰老 衰老大鼠（6、12、18）垂体 月）将检查神经支配模式的潜在改变 以及调节肽分泌，使用免疫细胞化学 和放射免疫分析来检测组织或血液样本。 EM技术将用于 衰老垂体细胞学与免疫反应性 缩氨酸 为了确定D-2和5-HT-2受体是否随年龄变化， 将检查配体结合的放射自显影模式。 5. 做老化 POMC细胞保留了对调节分子的反应能力， 抑制或刺激分泌？ 衰老老鼠的脑垂体 利用神经递质和肽进行体外研究， 调节幼鼠体内阿片肽的释放 阿片肽具有 对疼痛调节和稳态机制的显著影响 与压力有关。 研究调节机制的可塑性， 以潜在的轴突再生和受体调节的形式 POMC细胞的模式，无论是在年轻的和老年动物，将是一个基础 对于阿片肽分泌的适当药理学操作， 动物模型和人体模型。

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.