title: Age-related changes in gene expression of the growth hormone secretagogue and growth hormone-releasing hormone receptors in Holstein-Friesian cattle.
abstract: Growth hormone secretion from the anterior pituitary gland is controlled by interactions between three hormone receptors, between GHRH and GHRH receptor (GHRH-R), between ghrelin and growth hormone secretagogue receptor (GHS-R1a), and between somatostatin and somatostatin receptors in the hypothalamus and anterior pituitary gland. Ghrelin-GHS-R1a is involved in many important functions, including GH secretion and appetite. We investigated age-related changes in the expressions of GHS-R1a, GHS-R1b (the truncated-type receptor), and GHRH-R mRNAs by real-time reverse transcription-PCR using 16 tissues, leukocytes, oocytes, and cumulus cells in Holstein-Friesian cattle. The tissue samples were divided into three age classes: 1) 19 to 26 d of age (preweaning calves), 2) 2 mo to 6.5 mo of age (postweaning calves), and 3) 3.2 to 8.1 yr of age (cows). The GHS-R1a mRNA was highly (P < 0.05) expressed in the arcuate nucleus, pituitary gland, and liver compared with that of the other tissues in all age classes. Expression of GHS-R 1a mRNA in the arcuate nucleus of postweaning calves was > 10-fold greater (P < 0.01) than those of preweaning calves and cows, and its expression level was the greatest (P < 0.01) in all tissues examined in age group 2. GHS-R1a and GHRH-R mRNA expressions in the pituitary gland of preweaning calves tended to be greater (P < 0.20 and P < 0.17, respectively) than those of postweaning calves and cows. GHS-R1b mRNA expression was detected in all tissues examined, and abundance was greater (P < 0.05) in the pancreas, pituitary gland, spleen, arcuate nucleus, adipose tissue, and leukocyte compared with that of the other tissues examined in age group 3. Interestingly, a relatively large animal-to-animal variation was observed in pancreas GHS-R 1b mRNA expression. The GHRH-R mRNA was markedly increased (P < 0.01) in the pituitary gland in all age groups compared with that of the other tissues. GHRH-R mRNA abundance in the arcuate nucleus, pituitary gland, liver, spleen, adipose tissue, and heart of preweaning calves tended to be greater than those of postweaning calves and cows. The GHRH-R mRNA was not detected in the mammary gland and adipose tissue of nonlactating cows.
authors: National Institute of Livestock and Grassland Science, Ikenodai 2, Tsukuba, Ibaraki 305-0901, Japan. mkomatsu@affrc.go.jp
authors: M
authors: M
authors: Komatsu
authors: M
authors: M
authors: Kojima
authors: H
authors: H
authors: Okamura
authors: M
authors: M
authors: Nishio
authors: M
authors: M
authors: Kaneda
authors: T
authors: T
authors: Kojima
authors: H
authors: H
authors: Takeda
authors: A E O
authors: AE
authors: Malau-Aduli
authors: H
authors: H
authors: Takahashi
mesh_terms: D000367:Age Factors; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology*; D002417:Cattle / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D016018:Least-Squares Analysis; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D054440:Receptors, Ghrelin / Q000096:biosynthesis* / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000096:biosynthesis* / Q000235:genetics; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D054440:Receptors, Ghrelin; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D013006:Growth Hormone; C048250:somatotropin releasing hormone receptor