Peptide hormone growth hormone, which acts on bone, muscle, and the liver. The posterior pituitary gland secretes antidiuretic hormone, also called vasopressin, and oxytocin. The parathyroid gland secretes parathyroid hormone, the main hormone responsible for regulating serum calcium and phosphorus levels. Peptide hormones are also produced by many different organs and tissues, including the heart (atrial-natriuretic peptide (ANP) or atrial natriuretic factor (ANF)) and pancreas (glucagon, insulin and somatostatin), the gastrointestinal tract (cholecystokinin, gastrin), and adipose tissue stores (leptin). Peptide hormone Peptide hormones or protein hormones are hormones whose molecules are peptides or proteins, respectively. The latter have longer amino acid chain
Pulsatile insulin factors. Continuous exposure to insulin and glucagon is known to decrease the hormones’ metabolic effectiveness on glucose production in humans due to the body developing an increased tolerance to the hormones. Down-regulation at the cellular level may partially explain the decreased action of steady-state levels of insulin, while pulsatile hormone secretion may allow recovery of receptor affinity and numbers for insulin. Intermittent intravenous insulin administration with peaks of insulin concentrations may enhance suppression of gluconeogenesis and reduce hepatic glucose production. Dr. Thomas Aoki, former Head of Metabolism Research at the Joslin Diabetes Center in Boston, Massachusetts, and a former Professor