Distribution of Immunoreactive Growth Hormone-Releasing Hormone in the Human Brain and Intestine and Its Production by Tumors*

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Abstract
A recently developed RIA for human pancreatic tumor GH-releasing hormone (hpGRH1—44NH2) was used to investigate its distribution in the human gastrointestinal tract and brain, and to determine the incidence of its production by tumors. GRH-immunoreactivity (GRH-IR) was present in several regions of the human brain, the highest concentration occurring in the hypothalamus, septum, and substantia inominata. In the gastrointestinal tract GRH-IR was present in the upper intestine, where it was confined to the epithelial mucosa. Approximately one third of all tumors examined (35 out of 97) contained significant amounts of GRH-IR. Gel chromatography of brain and intestinal extracts, and of several tumors, revealed the presence of two molecular forms of GRH-IR, one coeluting with the synthetic hpGRH1—44 amide standard (and also hp-GRH1—40) and another eluting significantly later. The earlier eluting GRH-IR peak was found to be similar to the synthetic hpGRH1—44 NH2 and hpGRH1—40 on high pressure liquid chromatography analysis.