Cónsole G M, Gómez Dumm C L, Goya R G
Cátedra de Histología y Embriología B, Universidad Nacional de La Plata, Argentina.
Acta Anat (Basel). 1995;152(1):28-32.
Thyrotrophs were studied by quantitative immunohistochemistry in the pituitary gland of young (4 months), old (20 months) and very old (29 months) male rats. An attempt was also made to correlate morphometric parameters with serum levels of thyrotropin (TSH), thyroxine (T4) and triiodothyronine (T3). Cells were immunostained by the peroxidase-antiperoxidase method and hormones were measured in serum by specific radioimmunoassays. There was a marked age-related reduction in TSH cell number, volume density and surface density but a significant increase in TSH cell area and perimeter. Basal serum levels of TSH increased, T4 decreased and T3 remained unchanged with age. There was a highly significant (p < 0.001) negative correlation between serum TSH and T4, but no significant correlation was found between TSH and morphometric parameters. The present results suggest that aged rats possess a reduced but functionally preserved thyrotrophic cell population. The coexistence of high circulating levels of TSH with reduced serum T4 suggests that aging brings about a progressive desensitization of the thyroid to TSH.
采用定量免疫组织化学方法，对年轻（4个月）、老年（20个月）和高龄（29个月）雄性大鼠垂体中的促甲状腺细胞进行了研究。同时，还尝试将形态学参数与促甲状腺激素（TSH）、甲状腺素（T4）和三碘甲状腺原氨酸（T3）的血清水平进行关联分析。采用过氧化物酶-抗过氧化物酶法对细胞进行免疫染色，并用特异性放射免疫分析法测定血清中的激素水平。TSH细胞数量、体积密度和表面密度随年龄增长显著降低，但TSH细胞面积和周长显著增加。随着年龄增长，血清TSH基础水平升高，T4降低，T3保持不变。血清TSH与T4之间存在高度显著的负相关（p < 0.001），但TSH与形态学参数之间未发现显著相关性。目前的结果表明，老年大鼠促甲状腺细胞数量减少，但功能仍然保留。血清TSH水平升高与血清T4降低并存，提示衰老导致甲状腺对TSH逐渐脱敏。
