The signals mediating growth hormone (GH)-dependent differentiation of 3T3-F442A preadipocytes under serum-free conditions have been studied. GH priming of cells was required before the induction of terminal differentiation by a combination of epidermal growth factor, tri-iodothyronine, and insulin. Cellular depletion of Janus kinase-2 (JAK-2) using antisense oligodeoxynucleotides (ODNs) preven...

Although stimulatory (feedforward) and inhibitory (feedback) dynamics jointly control neurohormone secretion, the factors that supervise feedback restraint are poorly understood. To parse the regulation of growth hormone (GH) escape from negative feedback, 25 healthy men and women were studied eight times each during an experimental GH feedback clamp. The clamp comprised combined bolus infusion...

Recent reports on growth hormone (GH) therapy have shown that GH has various beneficial effects in GH deficient adults. In most of these studies, GH was administered daily. Because GH is still expensive and has to be delivered by subcutaneous injection, we studied the 6-month therapeutic effects of thrice weekly GH injection therapy and compared it with daily therapy. Twenty eight adult patient...

Estradiol (E(2)) drives growth hormone (GH) secretion via estrogen receptors (ER) located in the hypothalamus and pituitary gland. ERalpha is expressed in GH releasing hormone (GHRH) neurons and GH-secreting cells (somatotropes). Moreover, estrogen regulates receptors for somatostatin, GHR peptide (GHRP, ghrelin), and GH itself, while potentiating signaling by IGF-I. Given this complex network,...

Norman C, Miles J, Bowers CY, Veldhuis JD. Differential pulsatile secretagogue control of GH secretion in healthy men. Am J Physiol Regul Integr Comp Physiol 304: R712–R719, 2013. First published March 13, 2013; doi:10.1152/ajpregu.00069.2013.—Pulsatile growth hormone (GH) secretion putatively reflects integrated regulation by GH-releasing hormone (GHRH), somatostatin (SST), and GH-releasing pe...

It has been suggested that (abdominally) obese individuals are hypersensitive to growth hormone (GH) action. Because GH affects glucose metabolism, this may impact glucose homeostasis in abdominal obesity. Therefore, we studied the effect of GH on glucose metabolism in abdominally obese (OB) and normal-weight (NW) premenopausal women. A 1-h intravenous infusion of GH or placebo was randomly adm...

Growth hormone (GH) secretion is subject to complex regulation. How pre- and postmenopausal age (PRE, POST), estradiol (E(2)) availability, and abdominal visceral fat (AVF) jointly affect peptidyl-secretagogue drive of GH secretion is not known. To this end, healthy PRE (n = 20) and POST (n = 22) women underwent a low- vs. high-E(2) clamp before receiving a continuous intravenous infusion of GH...

CONTEXT With aging, GH, IGF-I, and sex steroid concentrations and glucose tolerance decrease, and body fat and serum lipids increase. OBJECTIVE The aim of the study was to assess GH and/or sex steroid administration effects on serum glucose, insulin, insulin sensitivity, and lipids in older individuals. DESIGN A double-masked, 2 x 2 factorial, placebo-controlled, double-dummy design was use...

The aim of the study was to investigate the acute effect of GH per se, independent from its lipolytic activity, on glucose and lipid oxidation and glucose turnover in seven healthy subjects. Five tests lasting 360 min were performed. Each test consisted of a 4-h equilibration period followed by a euglycemic hyperinsulinemic (25 mU/kg x h) clamp lasting 2 h. In test 1 (control experiment) saline...