GH-IGF1 axis has a crucial role in growth and development in mammalian species. Genes involved in this axis have been studied extensively, although there is not a comprehensive and detailed expression data set on tissue and developmental-stage specific expression in cattle. The present study demonstrated transcript abundance of GH-IGF1 axis genes in several bovine tissues in days 48 -60 samples- and 153 prenatal -73 samples-, day 277 at birth -6 samples-, and 1-year old juveniles -23 samples-. Quantitative real time-PCR was used to quantify transcript abundance of IGF1 overall transcript, IGF1 class 1 and class 2, IGF1R, insulin receptor -IR- overall transcript, IRA, IR-B, GH, GHR overall transcript, GHR-1A, GHR-1B, GHR-1C, insulin-like growth factor binding protein 1 -IGFBP1-, IGFBP2, IGFBP3, IGFBP4, IGFBP5, IGFBP6, IGFBP7 and IGFBP8, in brain, cotyledon, heart, kidney, liver, lung, skeletal muscle and testis. GH-IGF1 axis transcripts showed specific pattern of expression in each tissue that differed across developmental stages. There was no detectable GH mRNA in studied tissues. The present data showed that GHR transcript was expressed in a variety of bovine fetal and embryonic tissues. Since there is no published evidence of a direct role of GH in prenatal growth and development and since the ability of binding other ligands such as PRL and PL, which are specific to gestational age, there could be other mechanisms contributing to differential GHR transcription during bovine fetal development. The abundance of most transcripts in postnatal tissues was lower than in fetal tissue, except in liver, which showed increased IGF1, GHR and IGFBP4 expression and no change for IR, IGFBP1, IGFBP3 and IGFBP6 transcript. IGF1 and GHR transcripts were significantly correlated -0.73-0.99, P<0.05- across all tissues and developmental stages which could be explained by a role of GHR-IGF1 axis in prenatal growth and development in bovine.

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