The Role of Somatostatin in the Regulation of Anterior Pituitary Hormone Secretion and the Use of Its Analogs in the Treatment of Human Pituitary Tumors

Abstract

I. Introduction THE PRESENCE of GH-inhibitory substances in hypothalamic extracts was originally detected accidentally by Krulich et al. (1) during investigations into the distribution of GH-releasing factors throughout the rat hypothalamus. Several years later Brazeau et al. (2) isolated and characterized this somatotropin releaseinhibiting factor, called somatostatin (SRIF), which turned out to be a cyclic peptide consisting of 14 amino acids. SRIF was the first hormone to broaden the classic concepts of endocrinology because it has physiological effects both at the periphery and the central nervous system (3). Several reviews and proceedings from international symposia are available, which summarize the developments in the field of SRIF (4–12). In recent years SRIF analogs have been developed which can be used clinically. In the present review the physiological role of SRIF in the regulation of anterior pituitary function has been summarized as far as it contributes to the understanding of the use and effectiveness of SRIF analogs in patients with anterior pituitary tumors. In addition, the current clinical indications for long term treatment with SRIF analogs and the adverse effects of these compounds are reviewed.