Silverman W F, Aravich P A, Sladek J R, Sladek C D
Department of Neurobiology & Anatomy, University of Rochester School of Medicine and Dentistry, N.Y.
Neuroendocrinology. 1990 Aug;52(2):181-90. doi: 10.1159/000125571.
In order to resolve conflicting reports in the literature on the effect of aging on the hypothalamo neurohypophyseal system (HNS) in rats, multiple parameters associated with the HNS were evaluated in young (4 months), fully mature (14 months), and old (25 months) Fischer 344 rats under basal and stimulated conditions. The hypothalamic hormones oxytocin and vasopressin were compared in radioimmunoassay of serum, urine, brain and pituitary. Information on body weight, water intake, urine output, serum hematocrit and plasma osmolality was also obtained from the same subjects and analyzed together with these data. Finally, semi quantitative histofluorescence assessment of the noradrenergic innervation of the mediobasal hypothalamus from the same animals was performed to determine the extent of central afferent input to the HNS with advancing age. The circulating levels of vasopressin and oxytocin did not significantly differ in the three age groups under basal conditions. Serum vasopressin concentration was increased following water deprivation, and the increase was comparable in all age groups. Serum oxytocin was also increased following water deprivation in all groups, but the increase was greater in the 25-month-old rats relative to the 4-month-old rats. Urinary excretion of vasopressin was used as an index of daily vasopressin secretion. The urinary concentration of vasopressin was less in aged rats relative to young controls, though an increased urine volume in the mature and old animals meant that total vasopressin excretion in the urine was comparable at all ages studied. The increased urine volume in the mature and aged rats does not appear to reflect a decrease in renal sensitivity to vasopressin, since all age groups demonstrated a comparable reduction in urine volume during water deprivation, at comparable concentrations of circulating vasopressin. These data suggest that the increase in urine volume observed in the 14- and 25-month-old rats may be a function of increased fluid intake rather than hyperactivity in the HNS. The concentrations of both peptides were reduced in the posterior pituitary of aged rats, though again, the total amount of peptide in the gland did not change. Only oxytocin showed an age-related change in the hypothalamus, decreasing in the oldest subjects. These data indicate that the ability to secrete adequate quantities of vasopressin in response to dehydration is not compromised in Fisher 344 rats up to 25 months of age.
为了解决文献中关于衰老对大鼠下丘脑神经垂体系统（HNS）影响的相互矛盾的报道，在基础和刺激条件下，对年轻（4个月）、完全成熟（14个月）和老年（25个月）的Fischer 344大鼠中与HNS相关的多个参数进行了评估。在血清、尿液、脑和垂体的放射免疫分析中比较了下丘脑激素催产素和血管加压素。还从同一组动物中获取了体重、水摄入量、尿量、血清血细胞比容和血浆渗透压的信息，并与这些数据一起进行分析。最后，对同一批动物的中基底下丘脑去甲肾上腺素能神经支配进行了半定量组织荧光评估，以确定随着年龄增长HNS的中枢传入输入程度。在基础条件下，三个年龄组中血管加压素和催产素的循环水平没有显著差异。禁水后血清血管加压素浓度升高，且在所有年龄组中升高程度相当。所有组禁水后血清催产素也升高，但25月龄大鼠的升高幅度相对于4月龄大鼠更大。血管加压素的尿排泄量用作每日血管加压素分泌的指标。老年大鼠血管加压素的尿浓度相对于年轻对照组较低，尽管成熟和老年动物的尿量增加意味着在所有研究年龄组中尿中血管加压素的总排泄量相当。成熟和老年大鼠尿量增加似乎并非反映肾脏对血管加压素敏感性降低，因为在循环血管加压素浓度相当的情况下，所有年龄组在禁水期间尿量都有相当程度的减少。这些数据表明，在14月龄和25月龄大鼠中观察到的尿量增加可能是液体摄入量增加的结果，而非HNS功能亢进。老年大鼠垂体后叶中两种肽的浓度均降低，但腺体中肽的总量再次未发生变化。只有催产素在下丘脑中显示出与年龄相关的变化，在最年长的大鼠中减少。这些数据表明，在25月龄以下的Fisher 344大鼠中，脱水时分泌足够量血管加压素的能力并未受损。
