Assessment of GH releasing hormone activity in sephadex-separated fractions of porcine hypothalamic extracts by hypophyseal portal vessel infusion in the rat.
Growth hormone-releasing hormone (GH-RH) activity in Sephadex G-25 fractions of porcine stalk median eminence (SME) extracts was examined in vivo by infusing these samples into a rat hypophyseal portal vessel. The increment of immunoreactive GH levels in the serum was used as the index for GH-RH activity. The GH-RH activities were found in two different locations: in the early fractions Nos. 3-4, and in somewhat retarded fraction No. 7. These GH-RH activities were not due to TRH, vasopressin, or potassium. The location of LH releasing hormone (LH-RH) and prolactin release-inhibiting hormone (PR-IH) determined in this in vivo system was in agreement with those found in other in vivo and in vitro assay systems for LH-RH and PR-IH, respectively. These results help validate this assay system.
D000818:Animals; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D007987:Gonadotropin-Releasing Hormone / Q000302:isolation & purification; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000302:isolation & purification*; D007030:Hypothalamo-Hypophyseal System / Q000032:analysis*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008473:Median Eminence / Q000032:analysis*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000097:blood; D011389:Prolactin Release-Inhibiting Factors / Q000097:blood*; D011863:Radioimmunoassay; D051381:Rats; D013552:Swine
D007987:Gonadotropin-Releasing Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D011389:Prolactin Release-Inhibiting Factors