Whole ovaries RNA sequencing; WT and ghrelin o-acyltransferase (GOAT) knockout mice

Ghrelin, an orexigenic gut-derived peptide, is gaining increasing attention due to its multifaceted role in a number of physiological functions, including metabolism, cardiovascular health, stress and reproduction. Ghrelin exists in circulation primarily as des-acylated and acylated ghrelin. Des-acyl ghrelin, until recently considered to be an inactive form ghrelin, is now known to have independent physiological functionality. However, the relative contribution of acyl and des-acyl ghrelin to reproductive development and function is currently unknown. Here we used ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no measurable levels of endogenous acyl ghrelin and chronically high levels of des-acyl ghrelin, to characterise how the developmental and life-long absence of acyl ghrelin affects ovarian development and reproductive capacity. We have combined ovarian transcriptome analysis using RNA sequencing with measures of ovarian morphometry, as well as with the assessment of markers of reproductive maturity and the capacity to breed. Our data show pronounced specific changes in the ovarian transcriptome in the juvenile GOAT KO ovary, indicative of advanced ovarian development. These changes corresponded with diminished ovarian reserve in the juvenile and adult ovaries of these mice, due to a continuous reduction in the number of small follicle populations. These changes did not affect the timing of puberty onset or reproductive capacity under optimal conditions. These data suggest that an absence of acyl ghrelin does not prevent reproductive success but that appropriate levels of acyl and des-acyl ghrelin may be necessary for optimal ovarian maturation. 4 WT and 4 GOAT KO ovaries were used for this analysis饥饿素（ghrelin）是一种促食欲肠道肽，因其在代谢、心血管健康、应激与生殖等多种生理功能中发挥多层面作用而受到越来越多的关注。循环中的饥饿素主要以去酰基饥饿素（des-acylated ghrelin）与酰基饥饿素两种形式存在。此前去酰基饥饿素被认为是无活性的饥饿素形式，如今已知其具备独立的生理功能。然而，目前尚不清楚酰基饥饿素与去酰基饥饿素对生殖发育与生殖功能的相对贡献。本研究使用了饥饿素O-酰基转移酶（ghrelin-O-acyltransferase，GOAT）基因敲除（knockout，KO）小鼠，这类小鼠体内无法检测到内源性酰基饥饿素，且长期维持高浓度的去酰基饥饿素，以此探究终身缺乏酰基饥饿素对卵巢发育与生殖能力的影响。我们结合RNA测序（RNA sequencing）开展卵巢转录组分析，并辅以卵巢形态计量学检测，同时评估生殖成熟标记物与繁殖能力。研究数据显示，幼年GOAT KO小鼠的卵巢转录组出现显著的特异性变化，提示卵巢发育提前。由于小型卵泡种群数量持续减少，这类小鼠的幼年与成年个体卵巢均出现卵巢储备降低的情况。上述变化并未影响最优饲养条件下的青春期启动时间与生殖能力。本研究结果表明，缺乏酰基饥饿素并不会阻碍生殖成功，但维持合适水平的酰基饥饿素与去酰基饥饿素，或许对卵巢的最优成熟发育不可或缺。本次分析共使用4只野生型（wild type，WT）与4只GOAT KO小鼠的卵巢组织。