Journal of animal science1999; 77(7); 1815-1822; doi: 10.2527/1999.7771815x

Effects of recombinant equine somatotropin on wound healing, carbohydrate and lipid metabolism, and endogenous somatotropin responses to secretagogues in geldings.

Smith, LA
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Thompson, DL
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French, DD
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Leise, BS

Abstract: The primary purpose of this experiment was to assess the possible beneficial effects of recombinant equine somatotropin (reST) administration on wound healing in adult geldings. The effects of the 21-d reST treatment on carbohydrate and lipid metabolism and on endogenous ST characteristics were monitored as well. Single, full-thickness skin incisions (7.62 x 7.62 cm) were made in the pectoral region of all geldings on d 0. Treated geldings received reST at 20 microg/kg BW i.m., and control geldings received vehicle (10 mM sodium borate) at equivalent volumes daily from d 0 (immediately after surgery) through d 20. Tracings of the wounds were made with acetate transparencies, and wound areas were calculated via a digital analyzer. In addition to once-daily blood samples collected at specified days throughout the treatment period, an i.v. glucose tolerance test was performed on d 16, and three assessments of endogenous ST secretion were performed in the 2 d immediately following the end of treatment: epinephrine administration during the morning of d 21, an exercise test during the afternoon of d 21, and i.v. aspartic acid infusion on d 22. There was no effect (P > . 1) of reST treatment on wound healing as assessed by changes in wound areas. Daily plasma ST, IGF-I, glucose, and insulin concentrations were higher (P < .05) and urea-nitrogen concentrations were lower (P < .001) in geldings receiving reST relative to controls. Glucose, NEFA, and insulin concentrations were all higher (P < .01) in reST-treated geldings before glucose infusion on d 16, and the responses to glucose were greater (P < .05) as well. Epinephrine administration increased (P < .02) ST concentrations in control geldings on d 21 but not in reST-treated geldings; a similar suppressive effect of reST treatment was observed for the ST response to exercise (P < .001). After aspartic acid infusion on d 22, reST-treated geldings had a much smaller (P < .001) ST response than did control geldings. In conclusion, reST administered to geldings at 20 microg/kg BW i.m. caused hyperglycemia, hyperinsulinemia, insulin insensitivity, mobilization of fatty acids, and an apparent negative feedback on the pituitary's ST response to various stimuli known to induce ST secretion. However, there was no beneficial effect of reST treatment with the wound model used in this experiment.

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Publication Date: 1999-08-07 PubMed ID: 10438029DOI: 10.2527/1999.7771815xGoogle Scholar: Lookup

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Summary

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The research article looks at how administering recombinant equine somatotropin (reST) may affect the process of wound healing in geldings, or adult male horses. The administration of reST had no observable positive impact on wound healing in the study but did affect the metabolism of carbohydrates and lipids and responses to endogenous somatotropin (growth hormones).

About the Study

The experiment involved making single full-thickness skin incisions on adult geldings. The wounds were monitored for size, healing, and other characteristics.
The treated group of geldings received doses of reST, while the control group was given vehicle (10 mM sodium borate) in equivalent volumes every day post-surgery.
Apart from observing the wounds’ progress, the researchers also studied the geldings’ carbohydrate and lipid metabolism and the effects of the reST treatment on their endogenous growth hormones.
To understand metabolism and hormone response, the researchers conducted glucose tolerance tests and assessments of growth hormone secretion.

Findings

The reST treatment had no significant impact on wound healing. The wound areas in the reST treated geldings did not differ significantly from the control group.
However, reST treatment did show observable effects on carbohydrate and lipid metabolism. The geldings receiving reST were found to have higher plasma somatotropin, IGF-I (Insulin-like Growth Factor-I), glucose, and insulin concentrations than the control group.
The levels of urea-nitrogen were considerably lower in geldings treated with reST.
Various stimuli, known to induce growth hormone secretion, resulted in distinctly different responses in the reST treated and untreated horses, indicating the growth hormone suppression brought about by reST.
The experiment also found the proliferation of fatty acids and insulin insensitivity in geldings treated with reST, symptoms that correspond to a metabolic condition like diabetes.

Conclusion

In conclusion, this research found no positive correlation between administering reST and improved wound healing in geldings.
However, reST was found to dramatically affect carbohydrate and lipid metabolism and endogenous growth hormones, which could suggest a link between its administration and the onset of metabolic disorders.
The authors point out that these findings warrant further study of reST and understanding its potential implications and side effects.

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APA

Smith LA, Thompson DL, French DD, Leise BS. (1999). Effects of recombinant equine somatotropin on wound healing, carbohydrate and lipid metabolism, and endogenous somatotropin responses to secretagogues in geldings. J Anim Sci, 77(7), 1815-1822. https://doi.org/10.2527/1999.7771815x