Stimulatory effect of growth hormone on in vitro maturation of bovine oocytes is exerted through cumulus cells and not mediated by IGF-I

Abstract

A previous study reported that the addition of bovine growth hormone (bGH) during in vitro maturation of bovine oocytes accelerates nuclear maturation and stimulates subsequent embryonic development. The aim of this study was to investigate whether bovine cumulus oocyte complexes (COCs) contain growth hormone receptor (GHR), and whether the stimulatory effect of GH on oocyte maturation is cumulus‐dependent and mediated by insulin‐like‐growth factor (IGF‐I). The expression of growth hormone receptor mRNA in mural granulosa cells, in cumulus cells, and in the oocyte was studied using reverse transcriptase polymerase chain reaction (RT‐PCR). To investigate the importance of cumulus cells for GH‐promoted maturation, COCs and denuded oocytes were cultured for 16 hr in M199 with or without bGH (NIH‐GH‐B18). To investigate whether GH action is mediated by IGF‐I, COCs were cultured in 1) 100 ng/ml bGH, 2) 100 ng/ml bGH plus anti‐IGF‐I, 1:100 dilution, 3) 100 ng/ml h‐IGF‐I, 4) 100 ng/ml h‐IGF‐I plus anti‐IGF‐I, 1:100 dilution, and 5) anti‐IGF‐I, 1:100 dilution. Culture was performed at 39°C in a humidified atmosphere with 5% CO2 in air, and the nuclear stage of oocytes was assessed using 4,6‐diamino‐2‐phenyl‐indole (DAPI) staining. PCR on cDNA of mural granulosa cells, cumulus cells, and oocytes revealed that mRNA for GHR was present in all cell types. Addition of GH (100 ng/ml) to the culture medium of denuded oocytes did not affect the number of metaphase II oocytes after 16 hr, while a significant (P < 0.001) increase was observed, when COCs were cultured in the presence of GH. Addition of the antibody against IGF‐I to the culture medium completely suppressed the stimulatory effect of IGF‐I on oocyte maturation and cumulus expansion, while stimulation by GH was not affected by the antibody. It is con‐ cluded that bovine cumulus cells, mural granulosa, and oo‐ cytes express mRNA for the GH receptor. The stimulatory effect of GH on bovine oocyte maturation is dependent on the cumulus cells and is not mediated by IGF‐I. Mol. Reprod. Dev. 47:175–180, 1997. © 1997 Wiley‐Liss, Inc.

Growth hormone and in vitro maturation of rhesus macaque oocytes and subsequent embryo development

“…GHRs located on the oocyte and within the ooplasm in the rhesus macaque support the view that GH may have a direct effect on the oocyte as shown in the mouse [37]. The localization of GHRs on cumulus cell surfaces in immature macaque COCs also indicate that GH action on the oocyte may be mediated through cumulus cells similar to what is observed in the rat and bovine [7,8,38]. To our knowledge the mechanism of GH action in human or primate COCs has not been investigated.…”

“…The addition of GH to culture media has stimulatory effects on oocyte maturation in cattle, rats, horses, pigs and rabbits [7][8][9][10]. Growth hormone is produced by the pituitary, affecting growth, metabolism and reproduction [11,12].…”

Channel Catfish Follicle-Stimulating Hormone and Luteinizing Hormone: Complementary DNA Cloning and Expression During Ovulation

“…CPE contains the full multiplicity of pituitary hormones that may directly work on the gonad. In addition to the direct roles of GTHs, growth hormone and IGF are known to be vital for gamete development and maturation (Kagawa et al, 1994;Izadyar et al 1997;Maestro et al, 1997;Huang et al, 1998;Weil et al, 1999;Baker et al, 2000;Tacon et al, 2000). We also found significant induction of endogenous growth hormone gene expression during CPEinduced ovulation (Karsi et al, 1998).…”

Extrapituitary growth hormone

“…This possibility is supported by the finding of GHR protein and GHR mRNA in mural granulosa cells, cumulus cells, and oocytes [89]. Indeed, it is well established that GH accelerates nuclear and cytoplasmic maturation in COCs of cattle [90][91][92][93], dogs [94], sheep [95], and mice [96].…”

“…Indeed, it is well established that GH accelerates nuclear and cytoplasmic maturation in COCs of cattle [90][91][92][93], dogs [94], sheep [95], and mice [96]. This action is IGF-1-dependent in the rat [97], and rabbit [98] but is IGF-1-independent in the bovine ovary [89,91,99]. This action is thought to be mediated through the cumulus cells, since it does not occur in cumulus-denuded oocytes [97].…”