松果腺抑制麩胺酸鈉處理雌鼠接納性之機轉探討：(Ⅲ)與腦垂腺功能之關係

The Mechanism of the Pineal Gland in Inhibiting Sexual Receptivity of Female Rats Treated with Monosodium-L-Glutamate:(Ⅲ)Does it Concern with the Function of the Pituitary Gland

張慧秋(Hui-Chiu Chang) ； 何美泠(Mei-Ling Ho) ； 呂勝義(Seng-I Lue) ； 許勝光(Hseng-Kuang Hsu) ； 許勤(Chin Hsu)

《The Kaohsiung Journal of Medical Sciences》 9卷8期 (1993/08) Pp. 460-467

https://doi.org/10.6452/KJMS.199308.0460

摘要

為了探討松果腺對於麩胺酸鈉(monosodium lutamate(MSG)處理雌鼠接納性(receptivity)的影響，是否經由改變腦垂腺回饋控制及分泌的功能，繼而影響動情週期與性接網期之同步效應(synchronization)。本實驗採用Loong-Evans大花鼠，並分成四組；(1)正常對照鼠(control：C)，(2)松果腺切除鼠(Px)，(3) MSG處理鼠及(4) MSG處理合併松果腺切除鼠(Px-MSG)。MSG(4mg/g體重)，於雌鼠出山後第一及第三天皮下注射，造成雌鼠成熟後生殖功能低下的動物模式。松果切除則於42日齡時進行。各組分別於性接納期接納觀察脊柱前凸反應(lordosis) 來評估接納性，結果顯示，松果腺切除可顯著改善MSG雌鼠的接納性。
為了進一步測試松果腺對腦垂腺功能之影響，本論文進行下列二種試驗：(1)卵巢切除後黃體促性(LH)升高反應及(2)性釋素(LHRH)引起腦垂腺LH分泌之反應。第一種試驗是卵巢切除經四週之後，每隔10分鐘一採血一次，連續抽血三次，以放射免疫分析法(radioimmunoassay;RIA)定量血中RH濃度。結果顯示，MSG鼠LH濃度顯著低於對照鼠，但松果腺切除並不影響對照鼠及MSG鼠卵巢切除後LH濃度之升高，可見松鼠腺存在與否並未影響腦垂腺的負迴饋控制功能。第二種試驗，是在卵果切除五週之後，分別以三種劑量的LHRH靜脈注射，每個不同的劑量間隔二星期，並分別於注射前(0分鐘)及注射後15及60分鐘，抽血測定血漿LH濃度。結果顯示松果腺切除並不影響對照鼠及MSG鼠腦垂腺對三種劑量LHRH引起之LH分泌反應。因此，我們認為松果腺對MSG處理雌鼠接納性的影響，應該是作用在腦垂腺之上的層面(supra-pituitary level).

並列摘要

To elucidate whether pituitary function participates in the effect of the pineal gland on sexual receptivity, monosodium L-glutamate(MSG) was used as a neurotoxin to induce hypogonadal status. Long-Evans rats were divided into four groups: (1) normal control (C), (2) pinealectiomized (Px), (3) MSG-treated (Px-MSg). Pinealectomy was performed at sis weeks of age. In the first part of the experiment, the sexual receptivity was estimated at the age of 2.5 months by lordosis quotient (LQ). The result indicates that the decline of receptivity by neonatal MSG treatment can be significantly improved by pinealectomy. In the second part of the experiment, the effect of pinealectomy on pituitary function was examined by two tests including(1)Postcastrational LH rise and (2) pituitary response to LHRH.Ovariectomy was performed at the age of 2.5 months. Four weeks later three consecutive blood samples were collected at 10 minute intervals for LH radioimmunoassay. Then, three doses of LHRH (100 ng, 250 ng and 500 ng/100g of body weight) were administered separately at two-week intervals,serum samples were taken before as well as 15 and 60 minutes after LHRH administration. The results showed that there was no significant difference in serum LH levels between Px and control rats after ovariectomy. The LHRH-evoked Lh elevation in Px-MSG rats was just the same as that of the MSG rats, although the LH level in MSG rats was lower than in the control rats. The results demonstrated that pictuitary function was not significantly affected by pinealectomy. It is suggested that the action site of the pineal gland in inhibiting sexual receptivity may be at the supra-pituitary level.

並列關鍵字

pineal gladn ； receptivity ； pituitary function