SOMATOTROPIN INFLUENCE ON THE THYMUS IN AGING

免疫功能随着年龄的增长而下降，与年龄相关的 对感染、肿瘤性疾病和 自身免疫性疾病。免疫系统衰老的原因 是不被理解的，但它与，可能，在很大程度上， 由于胸腺的退化和胸腺的减少 性交后血液中胸腺激素的浓度 随着年龄的增长而成熟和进步。据观察， 随着年龄的增长，脑下垂体的生长激素分泌也会减少。 这种生长激素具有胸腺营养作用。这些观察结果导致了 可能通过以下方式减少生长激素的产生 腺垂体在胸腺体积进行性缩小中起作用。 以及胸腺激素的分泌随年龄增长。 拟议研究的目标是进一步描述 生长激素对小鼠胸腺和免疫系统的影响 上了年纪的狗。其具体目的是：1)确定正常狗的 胸腺激素胸腺肽α1和胸腺肽的血清浓度 从出生到老年；2)测定血清胸腺素α1和 中年犬胸腺素β4水平变化的研究 生长激素应用；3)评价胸腺超微结构 幼年犬和中年犬手术前后的上皮细胞 生长激素治疗。 如果给衰老的狗注射生长激素会刺激胸腺 增加它的胸腺激素的产生，它可能会对 与免疫衰老有关的疾病的发病率或严重程度 系统。在拟议的试验中获得的信息将 为生长激素的进一步实验提供依据 对自发性自身免疫性或老年犬的给药 肿瘤的情况。

Immune function decreases with age as evidenced by the age-correlated increase in susceptibility to infections, neoplastic diseases, and autoimmune diseases. The causes of the senescence of the immune system aren't understood but it is associated with and, probably, in large part, due to the involution of the thymus gland and the decrease in the concentration of thymic hormones in the blood which begins after sexual maturation and progresses through old age. It has been observed that growth hormone secretion by the pituitary also decreases with advancing age and that growth hormone has a thymotrophic effect. These observations lead to the hypothesis that perhaps decreasing production of growth hormone by the adenohypophysis plays a role in the progressive decrease in thymus size and the secretion of thymus hormones with age. The objective of the proposed research is to further characterize the influence of growth hormone on the thymus gland and immune system of the aging dog. The specific aims are to: 1) determine in normal dogs the serum concentration of the thymus hormones thymosin alpha 1 and thymosin beta 4 from birth through old age; 2) determine serum thymosin alpha 1 and thymosin beta 4 concentration in middle-aged dogs before, during and after growth hormone administration; and 3) evaluate the ultrastructure of thymic epithelial cells in young dogs and in middle-aged dogs before and after growth hormone treatment. If growth hormone administration to aging dogs will stimulate the thymus to increase its production of thymus hormones, it may have an impact on the incidence or severity of diseases associated with senescence of the immune system. The information gained in the proposed experimentation would provide the basis for further experimentation on growth hormone administration to aging dogs with spontaneously occurring autoimmune or neoplastic conditions.