Growth hormone therapy initiated before starvation ameliorates the catabolic state and enhances the protein-sparing effect of total parenteral nutrition

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Abstract
The effect of 7 days of subcutaneously administered bovine growth hormone (bGH) (0.2 mg kg−1 day−1; n = 4) or an equivalent volume of 0.15 mol l−1 saline (n = 3) on protein metabolism was assessed in lambs. The catabolic response to 48 h of starvation and subsequent hypocaloric total parenteral nutrition (TPN) was measured using primed constant intravenous infusions of [15N]urea and[14C]leucine. Following 48h, of starvation and 7 h of TPN, bGH‐treated animals had a significantly decreased rate of net protein catabolism compared with controls (mean(s.e.m.) 2.4(0.2) versus 3.2(0.3)g kg−1 day−1, P < 0.01). The means(s.e.m.) rate of whole‐body protein catabolism was also significantly decreased in bGH‐treated animals at 10.9(0.3) g kg−1 day−1 compared with 12.9(0.7) g kg−1 day−1 in saline‐treated controls (P < 0.05). In addition, the rates of net and whole‐body protein catabolism decreased significantly (P < 0.05) during the period of hypocaloric parenteral feeding to mean(s.e.m.) values of 2.3(0.2) and 8.6(0.6) g kg−1 day−1 respectively in bGH‐treated animals. By contrast, in saline‐treated controls net and whole‐body protein catabolism continued to increase during hypocaloric parenteral feeding. There was a significant decrease (P < 0.05) in the rate of[14C]leucine uptake in tissues of the gastrointestinal tract, heart and diaphragm in bGH‐treated animals compared with controls. These results demonstrate that daily administration of growth hormone decreases the catabolic response to a metabolic stress, resulting in the conservation of protein in the heart, diaphragm, gastrointestinal tract and musculoskeletal system by a primary anticatabolic action. In addition, growth hormone therapy initiated before induction of the catabolic state enhances the protein‐sparing effects of TPN. Further study is justified to determine whether growth hormone therapy initiated before elective or urgent surgery in the nutritionally depleted patient may have a role in reducing the severity of the postoperative catabolic state, particularly in the patient in whom a complicated course is anticipated.
Funding Information
  • Health Research Council of New Zealand