Smith G W, Sen A, Folger J K, Ireland J J
Laboratory of Mammalian Reproductive Biology and Genomics, Department of Physiology, Michigan State University, East Lansing, MI 48824-1225, USA.
Soc Reprod Fertil Suppl. 2010;67:105-17.
The mechanisms regulating development of a single (dominant) follicle capable of ovulation during each follicular wave in cattle and atresia of remaining follicles (dominant follicle selection) are not well understood. FSH and IGF1 are known regulators of follicle growth and granulosa cell estradiol production during follicular waves. Recent evidence indicates cocaine and amphetamine regulated transcript (CARTPT), with intraovarian expression only in single-ovulating species, is a novel regulator of follicular development. The mature CARTPT peptide (CART) is a potent negative regulator of FSH and IGF1 action on granulosa cells in vitro and can inhibit follicular estradiol production in vivo. Follicular fluid CART concentrations in healthy follicles decrease after dominant follicle selection and CARTPT mRNA is lower in healthy versus atretic follicles collected prior to and early after initiation of follicle dominance, suggestive of a regulatory role in the selection process. The inhibitory actions of CART on FSH signaling and estradiol production are dependent on the G(o/i)-subclass of inhibitory G proteins and linked to multiple components of the FSH signal transduction pathway resulting in reduced CYP19A1 mRNA and estradiol production. Evidence to date supports a potential important functional role for CART in regulation of dominant follicle selection and the species-specific ovulatory quota in monotocous species.
在牛的每个卵泡波期间，调节能够排卵的单个（优势）卵泡发育以及其余卵泡闭锁（优势卵泡选择）的机制尚未完全明确。已知促卵泡素（FSH）和胰岛素样生长因子1（IGF1）是卵泡波期间卵泡生长和颗粒细胞雌二醇产生的调节因子。最近的证据表明，可卡因和苯丙胺调节转录物（CARTPT）仅在单排卵物种的卵巢内表达，是卵泡发育的一种新型调节因子。成熟的CARTPT肽（CART）在体外是FSH和IGF1对颗粒细胞作用的有效负调节因子，并且在体内可抑制卵泡雌二醇的产生。优势卵泡选择后，健康卵泡中的卵泡液CART浓度降低，并且在卵泡优势开始之前和之后早期收集的健康卵泡与闭锁卵泡相比，CARTPT mRNA较低，这表明其在选择过程中具有调节作用。CART对FSH信号传导和雌二醇产生的抑制作用取决于抑制性G蛋白的G(o/i)亚类，并与FSH信号转导途径的多个成分相关，导致细胞色素P450芳香化酶1（CYP19A1）mRNA和雌二醇产生减少。迄今为止的证据支持CART在调节单胎物种的优势卵泡选择和物种特异性排卵配额方面可能具有重要的功能作用。
