In Vivo and in Vitro Studies on the Release of Thyrotropin in Aging Rats

老年大鼠促甲素釋放之活體及離體研究

張世芳(Shih-Fang Chang) ； 劉哲育(Jer-Yuh Liu) ； 楊祖琛(Bernard Tsu-Chen Yang) ； 黃建碩(Chensol Hwang) ； 黃志揚(Chih-Yang Hwang) ； 戴瑄(Cecilia Hsuan Day) ； 王錫崗(P. Shyi-Gang Wang)

《The Chinese Journal of Physiology》 32卷1期 (1989/06) Pp. 13-20

摘要

本文旨在研究老化對雄性及雌性大鼠離體腦下腺前葉釋放促甲素，及血清促甲素濃度之效應。取24-26月齡之老年大鼠及3-5月齡之年輕大鼠作實驗動物。部份雌鼠並先予切除卵巢約 10週後使用。所有的動物去頭犧牲。血液收集後離心，分出血清。腦下腺前葉均切半，在37℃下先以Krebs-Ringer磷酸緩衝液培養一小時。再與0或10nM之甲釋素培養30分鐘。更換培養液後，再與磷酸鹽緩衝液培養三次，每次30分鐘。一個培養瓶中放入半片腦下腺前葉，每組瓶數為7瓶或8瓶。血清及培養液中促甲素濃度以放射免疫法檢測。在雌鼠，無論是否去卵巢，其血清促甲素濃度均因年老而顯著降低；而腦下腺與甲釋素離體培養半小時後，所釋放的促甲素濃度均以年老鼠比年輕鼠低；唯基礎釋放值卻與年輕鼠無差異。雄鼠血清促甲素濃度及腦下腺離體釋放促甲素之濃度均不因老化而改變。以上結果顯示，雌鼠腦下腺經甲釋素刺激所釋放之促甲素因老化而降低，但雄鼠則否。此種性別不同造成之差異，可能係腦下腺促甲素細胞對甲釋素反應不同所致。

並列摘要

Chang, S. F., J. Y. Liu, B.T.C. Yang, C. Hwang, C. Y. Hwang, C. H. Day and P.S.G. Wang. In vivo and in vitro studies on the release of thyrotropin in aging rats. Chinese J. Physiol. 32(1): 13-20, 1989. Effects of aging on the concentration of serum thyrotropin (TSH) and the release of TSH in vitro from anterior pituitary glands (APs) of male and female rats were investigated. Rats with 3-5 (young) and 24-26 (old) months of age were used. Some female rats were ovariectomized (Ovx) 10 weeks before use. After decapitation, trunk blood was collected. APs were bisected and preincubated with Krebs-Ringer phosphate buffer (KRB) at 37℃ for 60min. They were then incubated with or without 10nM thyrotropin-releasing hormone (TRH) for 30min. The media were collected and replaced by fresh KRB. Incubations were continued and KRB media were changed three times, once every 30min. One hemi-AP per flask and 7 or 8 flasks per group were used. The concentration of TSR in the medium and serum samples was measured by radioimmunoassay. The level of serum TSR in the diestrous, estrous and Ovx rats was reduced by aging. Thirty mm after incubation with TRH, the release of TSH from APs of old intact female or Ovx rats was significantly (P＜0.01) less than that of corresponding young rats. The concentration of serum TSR and TRH-stimulated release of TSH from APs of male rats was not altered by aging. There was no difference in the basal release of TSH from APs between old and young animals. These data suggest that the release of TSH from APs in response to TRH is decreased by aging in female but not in male rats.

並列關鍵字

TSH ； TRH ； aging ； rats ； anterior pituitary