Basal and Short-term Food Denial Stress-Induced Plasma Cortisol in Four Lineages of Miniswine

Abstract

Rationale/Scope: This study was initiated to compare basal and stress–induced plasma cortisol levels in four lineages of miniswine (MS) typically used in drug discovery.

Experimental Procedures: Four lineages of MS were evaluated for cortisol levels. Included were Hanford, Yucatan, Sinclair S-1 and Göttingen strains. Animals were age and weight-matched castrated juvenile males (4.2-5.1 mos age) weighing 11-14 kg. Sixteen animals were studied (N = 3 or 4 for each lineage group). Standard manipulations for blood sampling by vascular access ports (VAP) were used. Baseline cortisol levels were determined based on the average of seven sampling points. A short-term stressor was applied (food denial consisting of presentation of feed bin into animal room without offering feed for ~30 min). The animals were then fed and cortisol samples taken at ~30 min post initial food exposure.

Results: The Sinclair S-1 MS lineage baseline plasma cortisol levels were the lowest of the four lineages prior to the stress event. Average cortisol levels: Sinclair S-1 < Yucatan ~ Hanford ~ Göttingen. The average group post-stress cortisol levels were elevated for all lineages. The Yucatan and Göttingen were hyper-responders while the Hanford was a moderate responder, and the Sinclair S-1 a low to non-responder. All animals except one Sinclair S-1 showed an increase in cortisol. The post-stress cortisol for Yucatan increased an average of 129%, Göttingen 125%, Hanford 71%, and Sinclair S-1 14%. The response difference between baseline and post-stressor cortisol levels in Sinclair S-1 was significantly smaller than responses in Yucatan and Göttingen (Tukey-Kramer HSD, p<0.01), while not significantly different than the Hanford strain.

Conclusions:The Sinclair S-1 lineage had the lowest average basal cortisol level. The stressor increased cortisol from a range of 14% to 129% (means) across the four lineages. All lineages responded to the stressor as reflected by increased plasma cortisol but the Sinclair S-1 increase was very modest. The Sinclair S-1 lineage was essentially a non-responder to the short-term stressor (food denial).

Authors

Stricker-Krongrad, A., Patel, N., Yumibe, N., Yurek, D., Huang, N., Renna, S., White, D., Brown, L.D., Liu, J., Bouchard, G.F.

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