Growth hormone inhibits apoptosis in in vitro produced bovine embryos.
Growth hormone (GH) has recently been shown to exert distinct effects on the differentiation and metabolism of early embryos. Up to now, however, it is not clear whether GH is able to modulate apoptosis during early embryogenesis. Differential cell staining of 8-day-old bovine embryos cultured with 100 ng bovine recombinant GH (rbGH) per ml medium (synthetic oviduct fluid-polyvinylalcohol) demonstrated that GH significantly increased the number of inner cell mass (ICM) and trophectoderm cells in bovine expanded blastocysts. As shown by terminal deoxynucleotidyl transferase mediated dUTP labeling (TUNEL) supplementation of bGH decreased the percentage of 8-day-old embryos showing at least one apoptotic cell from 58 to 21%. The percentage of apoptotic cells in one blastocyst was significantly (P < 0.01) reduced from 4.6 to 1.1% by GH treatment. Incubation of the embryos with 150 mM vanillylnonanamide induced apoptosis in all embryos. Whereas in control embryos 14% of the embryonic cells were TUNEL-positive, the percentage of apoptotic cells declined to 2.7% in the GH treated embryos. Expression of immunoreactive bcl-2 in blastocysts was not affected by GH treatment. Synthesis of the bax protein which is known to promote apoptosis was reduced in embryos cultured with GH. Our results suggest that GH acts as survival factor during in vitro culture and reduces apoptosis by altering the bax to bcl-2 ratio during early embryogenesis.
Kölle
Sabine
S
Department of Veterinary Anatomy II, University of Munich, Munich, Germany. s.koelle@anat.uni-muenchen.de
Stojkovic
Miodrag
M
Boie
Gudrun
G
Wolf
Eckhard
E
Sinowatz
Fred
F
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002417:Cattle; D004622:Embryo, Mammalian / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D013006:Growth Hormone / Q000494:pharmacology*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014641:Vanillic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D051028:bcl-2-Associated X Protein
D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051028:bcl-2-Associated X Protein; C005871:vanillyl-N-nonylamide; D013006:Growth Hormone; D014641:Vanillic Acid