Somatotroph secretion

Several important features of thyroid hormone action have been obtained by using pituitary cell lines (GH3, GH , GC) derived from the somatotrophs, i.e., the cells which synthesize and secrete growth hormone [43,46], When cultured in thyroid hormone depleted media such cells are responsive to thyroid hormone. Tsai and Samuels [47] first demonstrated that GH cells synthesize 3-10-times more GH when cultured in the presence of physiological concentration of T3 (0.1-1 nM). A detectable increase in GH synthesis occurs 45-60 min after significant binding to nuclear sites. Such an increase is paralleled by changes in total cytoplasmic GH mRNA... 

Excess production of GH due to somatotroph adenomas may be treated by surgical resection, irradiation, or in some cases with somatostatin analogues (e.g., octreotide) that suppress GH secretion, or by a combination of these above. 

Ghrelin A 28-amino acid peptide that is octanoylated on serine-3. Ghrelin is synthesized and secreted by endocrine cells in the stomach and will bind to somatotrophic cells in the anterior pituitary to promote the release of growth hormone (somatotropin). 

Somatotropin Growth hormone a 191-amino acid polypeptide hormone that is synthesized and secreted from the somatotroph cells of the anterior pituitary. It acts primarily on hepatocytes, although muscle and adipose cells also have receptors for growth hormone. 

Growth hormone (somatotropin) is a polypeptide synthesized and secreted by somatotrophs in the anterior pituitary. Growth hormone synthesis and secretion is stimulated by the hypothalamic peptide growth hormone-... 

Growth hormone (somatotropin) is a polypeptide synthesized and secreted by somatotrophs in the anterior pituitary. 

Conversely, GH secretion is suppressed by growth hormone release-inhibiting hormone (GHRIH, also called somatostatin, which has already been discussed). In addition, IGF-I, produced primarily in the liver in response to the action of GH on hepatocytes, feeds back negatively on the somatotrophs to limit GH secretion. Other physiologic factors (e.g., exercise and sleep) and many pathologic factors conuol its release (Table 43.2). 

Evain-BrionD, DonnadieuM, Roger M, Job JC. Simultaneous study of somatotrophic and corticotrophic pituitary secretions during ornithine infusion test. Clin Endocrinol (Oxf) 1982 17 119-122. 

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