哺乳動(dòng)物的繁殖是一個(gè)昂貴的生理過(guò)程，母體需要花費(fèi)很大的能量代價(jià),。繁殖過(guò)程中,，動(dòng)物的體溫調(diào)節(jié)和能量代謝等生理學(xué)過(guò)程都會(huì)發(fā)生較大的變化。中國(guó)科學(xué)院動(dòng)物研究所王德華研究組以內(nèi)蒙古草原的野生布氏田鼠為研究對(duì)象,，近幾年集中研究了繁殖期的產(chǎn)熱和能量代謝特征及其機(jī)理,，最近有較大進(jìn)展。
在妊娠期和哺乳期,，布氏田鼠都表現(xiàn)出攝食量增加和適應(yīng)性產(chǎn)熱受到抑制的現(xiàn)象,，然而1994年發(fā)現(xiàn)的由脂肪組織分泌的調(diào)節(jié)體重的激素－瘦素(leptin)，其對(duì)母體產(chǎn)熱和能量代謝的生理功能在兩個(gè)時(shí)期是不同的,。妊娠期瘦素水平較高,，但并沒(méi)有抑止動(dòng)物的攝食，失去了“飽食信號(hào)”的作用,，暗示可能發(fā)生了瘦素抵抗現(xiàn)象,。在哺乳期，血清瘦素水平較低,，此期動(dòng)物的攝食量也增加,，說(shuō)明瘦素可能充當(dāng)了“饑餓信號(hào)”的作用。進(jìn)一步研究發(fā)現(xiàn),，在妊娠期瘦素抵抗的形成與下丘腦瘦素的長(zhǎng)型受體（Ob-Rb）的表達(dá)降低和控制瘦素作用敏感性的細(xì)胞因子信號(hào)抑制子-3（suppressor-of-cytokine-signaling-3,，SOCS-3）的表達(dá)升高有關(guān)。下丘腦抑止攝食的神經(jīng)肽POMC（proopiomelanocortin）的表達(dá)下調(diào)可能是導(dǎo)致妊娠布氏田鼠攝食增加的原因之一,。通過(guò)施加外源瘦素處理實(shí)驗(yàn)進(jìn)一步證明,，哺乳期低水平的瘦素水平可以增加下丘腦的兩種促進(jìn)攝食的神經(jīng)肽NPY （neuropeptide Y）和AgRP （agouti-related protein）的表達(dá)量，降低POMC的表達(dá)，來(lái)促進(jìn)動(dòng)物的攝食量和抑制動(dòng)物的產(chǎn)熱能力,。無(wú)論是妊娠期還是哺乳期,，當(dāng)動(dòng)物受到低溫刺激時(shí)，血清瘦素的濃度沒(méi)有發(fā)生明顯變化,，但能量攝入和褐色脂肪組織線粒體內(nèi)膜上的解偶聯(lián)蛋白－1(uncoupling protein 1,，UCP1)的表達(dá)卻顯著增加，表明布氏田鼠能夠通過(guò)提高產(chǎn)熱能力和增加攝食量來(lái)應(yīng)對(duì)寒冷和繁殖的雙重壓力,，瘦素在寒冷環(huán)境條件下對(duì)能量代謝的調(diào)控作用與常溫條件下不同,。一些與冷有關(guān)的應(yīng)激激素如去甲腎上腺素、皮質(zhì)酮等可能也參與了對(duì)動(dòng)物攝食和產(chǎn)熱的調(diào)節(jié),，同時(shí)這些激素與瘦素之間可能存在互作作用,。
相關(guān)研究成果發(fā)表在《實(shí)驗(yàn)生物學(xué)雜志》（Journal of Experimental Biology）(2007，210: 512-521) ,、《比較生物化學(xué)與生理學(xué)C》（Comparative Biochemistry and Physiology C）（2008,，148 : 390–400.）和《神經(jīng)內(nèi)分泌學(xué)雜志》（Journal of Neuroendocrinology）(2008，20:1038-44)等刊物上,。（生物谷Bioon.com）
生物谷推薦原始出處：
Journal of Neuroendocrinology,，Volume 20 Issue 9, Pages 1038 - 1044，G.-B. Tang,，D.-H. Wang
Hypothalamic Suppressor-of-Cytokine-Signalling 3 mRNA is Elevated and Pro-Opiomelanocortin mRNA is Reduced During Pregnancy in Brandt's Voles (Lasiopodomys brandtii )
G.-B. Tang*?, J.-G. Cui*? and D.-H. Wang*
1State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Datun Lu, Chaoyang, Beijing, China.
2Graduate School of the Chinese Academy of Sciences, Yuquan Lu, Beijing, China.
ABSTRACT
Leptin acts within the hypothalamus to diminish food intake. In Brandt's voles (Lasiopodomys brandtii), both circulating leptin levels and food intake are elevated during pregnancy, suggesting an ineffectiveness of leptin to reduce food intake. Diminished hypothalamic leptin receptors and impaired leptin signal transduction are characteristic of central leptin resistance. The present study aimed to determine whether these characteristic modulations of leptin sensitivity occurred in pregnant Brandt's voles. The mRNA expression of the long form of the leptin receptor (Ob-Rb), suppressor-of-cytokine-signalling 3 (SOCS3), neuropeptide Y (NPY), agouti-related protein (AgRP), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus were examined on dioestrous, day 5, day 10 and day 18 of pregnancy. Compared to controls, there was no significant change in hypothalamic Ob-Rb mRNA during the pregnancy. SOCS3 mRNA was increased significantly by 68% on day 10% and 93% on day 18 of pregnancy compared to controls. Despite elevated leptin levels, POMC mRNA was decreased significantly by 60% on day 18 of pregnancy, whereas no differences were found in the mRNA expression of NPY, AgRP and CART in pregnant voles compared to controls. The elevation of SOCS3 mRNA together with disrupted leptin regulation of neuropeptides in the hypothalamus suggests that leptin resistance may develop in pregnant Brandt's voles.
