松果腺抑制雌鼠性接納之機轉探討：(II)與助孕酮之關係

The Mechanism of The Pineal Gland in Inhibiting Sexual Receptivity of Female Rats: (II) Does it Concern Progesterone?

10.6452/KJMS.199204.0225

許勤(Chin Hsu)；呂勝義(Seng-I Lue)；許勝光(Hseng-Kuang Hsu)；李昭男(Jau-Nan Lee)

Pinealgand ； progesterone ； reproductive behavior

The Kaohsiung Journal of Medical Sciences

8卷4期（1992 / 04 / 01）

225 - 230

繁體中文

麸氨酸鈉（Monosodium L-glutamate；MSG）的神經毒性造成雌鼠生殖內分泌及性接納功能受損，而松果線切除可改善MSG雌鼠的性接納。為了探討助孕酮在松果線抑制性接納的機轉上所可能佔有的角色，乃進行本實驗。第一部分實驗將大花鼠分成四組：（一）正常，（二）MSG處理鼠，（三）松果腺切除鼠，（四）MSG合併松果腺切除鼠。連續記錄三星期陰道抹片，觀察動情週期的出現率（Incidenc of Estrous Cycle；IEC)，並測定動情期血中助孕酮濃度。之後切除卯巢，經二星期技給與連續三天雌二醇，第四天皮下注射外源性助孕酮（0.5毫克／鼠），觀察引誇行為（solicitation）並以脊柱前凸商（Lordosis quotient；LQ）來評估性接納（receptivity )。結果顯示，MSG雌鼠經松果腺切除後，血中助孕酮濃度及動情週期出現率增加，卵巢切除之後則對外源性助孕酮之性接納反應及引許行為亦顯著提高。第二部分實驗，則將大花鼠分成二組：( I）正常鼠，（II）松果腺切除鼠，此兩組動物約先將卵巢切除並植入2毫米長之20％雌二醇矽膠管，以維持血中較長時問穩定的雌二醇濃度，之後採用四種劑量的助孕酮（0， 0.02，0.1，0.5毫克／雙），觀察松果腺切除是否影響雌鼠對助孕酮的劑量反應關係。結果顯示，松果腺切除鼠對於各種劑量之助孕酮性接納反應皆高於正常鼠。因此，我們認為松果線對雌鼠卵巢的功能及性接納反應都佔有重要角色，且松果腺對性接納反應的影響可能與助孕酮關係密切，至於作用部位與機轉則有待進一步探討。

The present study was designed to find the role of progesterone in modulating the effect of pineal gland upon reproductive behavior in the female rat. Monosodium L-glutamate (MSG) was used as a neurotoxin to induce hypogonadal function. In the first part of the experiment, rats were divided into four groups: (1) normal, (2) pinealectomized (Px), (3) MSGtreated (MSG), and (4) pinealectomized MSGtreated (Px-MSG), as immature rats became mature, the IEC (Incidence of Estrous Cycle) in each group was determined by vaginal smear for three weeks. Serum samples for estimating the levels of progesterone were collected at estrous. Then, ovariectomy was performed. Two weeks later, estradiol was primed for three days following progesterone administration and sexual receptivity as well as solicitation were observed. The results showed that, the serum progesteone levels and IEC of Px-MSG rats were significantly higher than that of the MSG group. In addition, Px and Px-MSG rats showed a higher sexual receptivity than normal and MSG rats, respectively. In the second part of the experiment, rats were divided into two groups: (1) normal and (2) Px. All rats were ovariectomized at 2.5 months of age and implanted with a 2-mm 20% estradiol benzoate-filled silastic capsule. Then, sexual receptivity to various doses of progesterone (0, 0.02, 0.1, 0.5 mg/rat) were observed. The results showed that receptivity of Px rats was significantly higher than that of the normal ones in a dose-dependent manner. It is concluded that pineal gland plays an important role in the regulation of ovary function as well as sexual receptivity in female rats. Also, progesterone may be one of the factors modulating the effect of pineal gland on sexual receptivity.