Alterations in GHRH binding and GHRH receptor mRNA in the pituitary of adult dw/dw rats.
Lewis dwarf (dw/dw) rats exhibit growth hormone (GH) deficiency and growth retardation linked to a malfunction of GHRH signaling. In this study, GHRH-receptor (GHRH-R) binding and mRNA in the pituitary of adult male dw/dw and age-matched normal Lewis rats was measured by radioligand binding assay and real-time PCR. Only one of nine pools of dw/dw pituitary membranes revealed detectable binding of [His(1), 125I-Tyr(10), Nle(27)]hGHRH(1-32) amide (B(max); 4.3 fmol/mg protein). In contrast, GHRH-R binding was 22.4 +/- 2.60 fmol/mg protein in normal Lewis rats. mRNA for GHRH-R was detectable in all dw/dw rat pituitaries examined, averaging 21% that of Lewis rats. Low expression of GHRH-R reflects reduced GHRH-R mRNA as well as a possible reduction in translation of the receptor protein.
Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164-6520, USA.
János
J
Gardi
Robert C
RC
Speth
Ping
P
Taishi
Bálint
B
Kacsóh
Ferenc
F
Obál
James M
JM
Krueger
D000818:Animals; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D018013:Receptors, Neuropeptide / Q000235:genetics*; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics*
D012333:RNA, Messenger; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D013007:Growth Hormone-Releasing Hormone; C048250:somatotropin releasing hormone receptor