Growth hormone and ghrelin receptor genes are differentially expressed between genetically lean and fat selection lines of sheep

Abstract

The objective of this study was to determine whether differences in mRNA levels of key pituitary genes that regulate GH production, pituitary development, and growth were present and/or associated with divergent body composition phenotypes observed between sheep from genetically divergent lean and fat selection lines. Real-time PCR transcription profiles for pituitary specific transcription factor 1, prophet of pit1, GH, GH receptor, GH secretagogue receptor, GHRH receptor, leptin receptor, and somatostatin receptors 1 and 2 were determined in pituitary tissue. There was a difference in the amount of both GH (P < 0.001) and GH secretagogue receptor (P < 0.001) mRNA between the selection lines (5 females and 5 males per line; 20 wk of age); the lean line had greater abundance than the fat line, irrespective of which endogenous control gene was used. The results obtained for GHRH receptor were equivocal but suggestive; there were greater GHRH receptor mRNA levels (P < 0.001) in the lean line using beta-2-microglobulin as the endogenous control but not when hypoxanthine phosphoribosyltransferase and glyceraldehyde-3-phosphate dehydrogenase were used. No difference in pituitary specific transcription factor 1, prophet of pit1, GH receptor, leptin receptor, or somatostatin receptors 1 and 2 mRNA concentration was observed between the lines. The greater abundance of GH mRNA in the pituitary somatotropes from genetically lean animals appears to be associated with increased levels of GH secretagogue receptor mRNA and possibly GHRH receptor mRNA. This suggests that the difference in GH secretion between the lines may be due to differences in the afferent signals, such as ghrelin and/or GHRH, arising from the hypothalamus, or as a result of differential pituitary sensitivity to these hormones.

Attenuated Cyclooxygenase-2 Expression Contributes to Patent Ductus Arteriosus in Preterm Mice

“…Primer/probe assays for COX-1, COX-2, EP2, EP3, EP4, and TP were purchased from Applied Biosystems (Foster City, CA). mRNA encoding the housekeeping gene, HPRT was quantitated for a normalizing control (14). There was no significant difference in HPRT mRNA levels throughout gestation, when compared with other housekeeping genes (data not shown).…”

Comparative Transcriptomic Analyses by RNA-seq to Elucidate Differentially Expressed Genes in the Muscle of Korean Thoroughbred Horses

“…Our result suggests that the difference in growth hormone secretion between Eonjena Taeyang and Jigusang Seryeok horses may result from differences in the afferent signals from the hypothalamus, or as a result of differential pituitary sensitivity to these hormones [56]. The adrenergic receptor beta 2 (ADRB2) gene plays a role in the physiological responses of muscle to exercise [57]. Expression of ADRB2 was upregulated in Jigusang Seryeok horses [58,59].…”

New concepts of the central control of reproduction, integrating influence of stress, metabolic state, and season

“…Certainly, leptin acts directly on gonadotropes in the rat [137] and the swine [138]. The expression of the receptor was not different in genetically lean and fat sheep, with differences in circulating leptin levels, but this study did not examine different pituitary cell types [139].…”