Effects of acute endotoxemia on serum somatotropin and insulin-like growth factor I concentrations in prepubertal gilts

William Hevener From the Departments of Food Animal & Equine Medicine (Hevener, Almond) and Animal Science (Armstrong), North Carolina State University, Raleigh, NC 27606; and the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (Richards).

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Glen W. Almond From the Departments of Food Animal & Equine Medicine (Hevener, Almond) and Animal Science (Armstrong), North Carolina State University, Raleigh, NC 27606; and the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (Richards).

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Jeff D. Armstrong From the Departments of Food Animal & Equine Medicine (Hevener, Almond) and Animal Science (Armstrong), North Carolina State University, Raleigh, NC 27606; and the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (Richards).

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R. Gregg Richards From the Departments of Food Animal & Equine Medicine (Hevener, Almond) and Animal Science (Armstrong), North Carolina State University, Raleigh, NC 27606; and the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (Richards).

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Abstract

Objective

To evaluate effects of endotoxemia on serum somatotropin (ST) and insulin-like growth factor I (IGF-I) concentrations in finishing pigs.

Animals

Eight female pigs (98 ± 2 kg) randomly assigned to IV administration (time 0) of saline solution (n = 4) or Escherichia coli lipopolysaccharide (LPS; 5 μg/kg of body weight; n = 4).

Procedure

Serum ST concentration was determined in serum samples obtained at 20-minute intervals for 6 hours after treatment. Serum IGF-I concentration was determined in samples collected at 1-hour intervals for 6 hours and at 12, 15, 18, 24, 48, 72, and 96 hours after treatment.

Results

One distinct pulse of ST (peak 10.5 ± 0.5 ng/ml) was observed at 40 minutes in each pig after administration of LPS. Control pigs had 2.25 ± 0.48 ST pulses during the 6 hours of frequent sample collection; however, magnitude of the ST pulses was similar between gilts given LPS and control gilts. A temporal association between ST pulses and saline administration was not evident. Serum IGF-I concentration was similar between gilts of the LPS and control groups prior to treatment. The IGF-I concentration was lower (P < 0.01) in gilts of the LPS group (44 ± 5 ng/ml) than in gilts of the control group (157 ± 4 ng/ml) at 24 hours. The difference in IGF-I concentrations between groups was evident for 96 hours.

Conclusions

Immediate release of ST was attributed to stress associated with acute endotoxemia and stimulation of the pituitary gland; immune stimulation by LPS may have contributed to the changes in IGF-I concentration. Because feed consumption was similar between the 2 groups of pigs, suppression of IGF-I concentration for 96 hours after administration of LPS was attributable to factors in addition to transient feed restriction. Thus, acute endotoxemia altered the positive association between ST and IGF-I, and provided evidence for a potential mechanism of impaired growth in endotoxemic animals. (Am J Vet Res 1997;58:1010–1013)

Abstract

Objective

To evaluate effects of endotoxemia on serum somatotropin (ST) and insulin-like growth factor I (IGF-I) concentrations in finishing pigs.

Animals

Eight female pigs (98 ± 2 kg) randomly assigned to IV administration (time 0) of saline solution (n = 4) or Escherichia coli lipopolysaccharide (LPS; 5 μg/kg of body weight; n = 4).

Procedure

Serum ST concentration was determined in serum samples obtained at 20-minute intervals for 6 hours after treatment. Serum IGF-I concentration was determined in samples collected at 1-hour intervals for 6 hours and at 12, 15, 18, 24, 48, 72, and 96 hours after treatment.

Results

One distinct pulse of ST (peak 10.5 ± 0.5 ng/ml) was observed at 40 minutes in each pig after administration of LPS. Control pigs had 2.25 ± 0.48 ST pulses during the 6 hours of frequent sample collection; however, magnitude of the ST pulses was similar between gilts given LPS and control gilts. A temporal association between ST pulses and saline administration was not evident. Serum IGF-I concentration was similar between gilts of the LPS and control groups prior to treatment. The IGF-I concentration was lower (P < 0.01) in gilts of the LPS group (44 ± 5 ng/ml) than in gilts of the control group (157 ± 4 ng/ml) at 24 hours. The difference in IGF-I concentrations between groups was evident for 96 hours.

Conclusions

Immediate release of ST was attributed to stress associated with acute endotoxemia and stimulation of the pituitary gland; immune stimulation by LPS may have contributed to the changes in IGF-I concentration. Because feed consumption was similar between the 2 groups of pigs, suppression of IGF-I concentration for 96 hours after administration of LPS was attributable to factors in addition to transient feed restriction. Thus, acute endotoxemia altered the positive association between ST and IGF-I, and provided evidence for a potential mechanism of impaired growth in endotoxemic animals. (Am J Vet Res 1997;58:1010–1013)

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